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Comparison of paddy soil fertility under conventional rice straw application versus cow dung compost application in mixed crop–livestock systems in a cold temperate region of Japan
Abstract
After the rice harvest in Japan, rice straw (RS) is usually cut by combine harvester and incorporated into the soil to improve its fertility. In mixed crop–livestock systems, however, RS is collected and used as livestock feed, and cow dung compost (CDC) is then applied to the soil. This system utilizes the residual organic matter from both rice production and livestock husbandry to make each product. CDC application is also considered to improve the fertility of paddy soil. However, the nutrient input from CDC and the effect of CDC application on soil fertility vary among regions and/or soil types. We compared soil fertility between RS application (RS treatment, avg. 32 years) and RS removal plus CDC application (CDC treatment, avg. 21 years) in 79 paddy fields in Mamurogawa town, Yamagata Prefecture, a cold temperate region of Japan, and measured the nutrient contents in the applied RS and CDC. The total C content of RS was significantly higher than that of CDC, whereas the N, P, K, and Si contents of CDC were significantly higher than those of RS. However, there was no significant difference in paddy soil fertility – as measured by soil organic C, total N, CEC, available N, P, and Si, exchangeable K, Ca, and Mg, base saturation percentage, pH, and bulk density – between the treatments. The soil fertility of most fields was adequate by RS or CDC treatment. Thus, leaving RS in paddy fields or removing it and then adding CDC to the paddy fields has a similar effect in maintaining adequate soil fertility for single rice production or rice–livestock production systems.
... Few studies have examined the difference in soil fertility under conventional RS application versus CDC application in mixed croplivestock systems. In our previous study, we found that the application of CDC in a mixed crop-livestock system supplied more N to the fields than RS but resulted in similar soil total N and available N (Nguyen et al. 2019). The status of total N and available N in soil is also driven by factors other than RS and CDC inputs, such as other N inputs, N outputs from the field, and the N balance of the field. ...
... In our previous research (Nguyen et al. 2019), 79 paddy fields were selected based on the application of RS or CDC. In the RS treatment, RS was applied in the conventional manner to the fields. ...
... The N input from CDC was significantly greater than that of RS, due to the higher N content in CDC than in RS (Table 1). This is comparable with the result reported by Nguyen et al. (2019). The N input from both RS and CDC showed large variation among fields, ranging from 16.0 to 43.5 kg ha -1 in the RS Values are mean ± SD. ...
In Japan, rice straw (RS) is commonly incorporated into the soil after harvest to maintain the fertility of paddy soil. However, in mixed crop–livestock systems, RS is collected to feed livestock and then cow dung compost (CDC) is applied to the fields. We found in previous research that CDC supplied more N to the fields than RS, but the soil total N and available N of fields to which CDC was applied were similar to those receiving conventional RS application. To identify the reason for this result, we investigated the N inputs (organic matter, fertilizer, N fixation), N outputs (plant N uptake, N leaching loss), and the N balance of RS application (RS treatment) and RS removal plus CDC application (CDC treatment) in 10 neighboring paddy field pairs in Mamurogawa town, Yamagata Prefecture, Japan. The N fertilizer contributed the highest percentage to total N input, followed by organic matter and N fixation. The amounts of N fertilizer and N fixation in the RS treatment were similar to those in the CDC treatment. CDC contributed significantly more N to the fields than RS, but the total N input was similar between treatments. The N output from plant N uptake and leaching loss were higher in the CDC treatment than the RS treatment, but the difference was not significant. Plant N uptake was the main N output, accounting for 98% of total N output. The N balance was positive and similar between treatments. Therefore, the non-significant differences in total N input, total N output, and N balance between treatments explain the similarity in soil total N and available N.
... Also, the soil contained over 1000 ppm of total N, 496.7 ppm of total K, and 2.32% of organic matter. Overall, this was considered nutrient-rich and fertile soil [31]. Although high P availability in soil is known to inhibit the establishment of AMF symbiosis [18], we asked whether inoculation of an AMF cocktail could still improve AMF colonization and growth of 'Chaew Khing' rice seedlings despite high P supply. ...
... While P deficiency promotes AMF associations, high content of available P in soil has been shown to negatively impact AMF colonization in rice [18]. Compared to the standard nutrient profile of fertile soil in paddy fields [31], the soil used in this study has relatively high P content and is optimal for rice growth. Nevertheless, here we showed that the application of AMF inoculum increases AMF colonization in 'Chaew Khing' rice seedlings (Fig. 1). ...
Arbuscular mycorrhizal fungi (AMF) provide benefits to host plants mainly by improving nutrition. In rice, as in other plants, AMF colonization is promoted under phosphorus (P) deficiency, and the symbiosis can lead to an improvement in P uptake and plant biomass. While there is economic potential for the fungi to substitute chemical fertilizers for sustainable rice production, the current dogma holds that their benefits are nullified when used in fertile soil. Here we show that inoculation of an AMF mixture in non-sterilized lowland paddy soil with high P availability increased the degree of fungal colonization and the development of arbuscular mycorrhizal structures in 'Chaew Khing' rice seedlings. The increase in AMF colonization was correlated with higher shoot growth in the AMF-inoculated plants. Analysis of plant nutrient status indicated that the AMF treatment caused a reduction in the total P and Fe concentrations in the shoot tissues and a reduction in the total N concentration in the root tissues of the mycorrhizal plants. Nevertheless, the enhanced mycorrhizal colonization led to an increase in P utilization efficiency as well as N:P and C:P ratios in the AMF-inoculated seedlings. These results indicate that, under high P supply, AMF can benefit the host plant by enhancing more efficient use of P, rather than improving its uptake. This work highlights the potential benefit of AMF inoculation for rice cultivation under high P availability.
... Cow manure is considered to be a good source of P for crops [11,12], and an excellent alternative source for chemical P fertilizer. The application of manure in combination with chemical P fertilizer enhances P availability and improves crop yield [13][14][15][16]. ...
... The P content of cow manure used in this experiment was 8.0 g P kg −1 , which was higher than that of the manure taken from the same region, as reported by Nguyen et al. [12]. The application of 10 tons of cow manure in fresh weight supplied 37.3 kg P ha −1 of total P to the field. ...
Cow manure is a good source of phosphorus (P). Here, we investigated whether the amount of P fertilizer can be reduced when cow manure is applied to paddy soil based on growth, P uptake, yield, and soil P status evaluation. Treatments included unfertilized control (CK); manure plus chemical nitrogen (N), potassium (K), and P fertilizer (MNK P); MNK and 75% P (MNK ¾ P); MNK and 50% P (MNK ½ P); MNK and 25% P (MNK ¼ P); and MNK. Manure was applied at the rate of 10 t ha−1 in fresh weight base. The P fertilizer was applied at 34.9 kg P ha−1 as full dose. Treatment with MNK resulted in the same growth, P uptake, and yield as that with the P fertilizer. P uptake and yield did not respond to P input from chemical fertilizer owing to high soil Olsen P levels. Moreover, MNK could maintain soil Olsen P and total P. Manure application resulted in a positive partial P balance. These results suggest that manure application can cut P fertilizer requirements in P-rich soils, while maintaining soil P for optimal rice growth and yield. By using cow manure in rice production, farmers can conserve finite P resources.
... poultry manure, chemical fertilizers, straw compost, biochar, etc.) (Boudjabi et al., 2015(Boudjabi et al., , 2019(Boudjabi et al., , 2019Jeong et al., 2019). Grobelak et al. (2017) and Nguyen et al. (2020) considered soil fertilization using different SS doses in order to determine the level that better improves soil fertility and produces high crop yields. Other studies focused on evaluating the heavy metal-related toxicity of the SS on soil, plants and soil fauna (Alvarenga et al., 2007;Singh and Agrawal, 2007;Orman et al., 2014;Florentino et al., 2019). ...
... This land management should also consider regional climatic conditions, initial pedological characteristics and land use, especially in arid and semi-arid regions constantly exposed to different forms of land degradation, including salinization and desertification caused by severe drought and wind erosion (Arar et al., 2009;Chenchouni et al., 2010;Neffar et al., 2013;Aliat et al., 2016). Many studies have dealt with this aspect, for example Carabassa et al. (2018) and Nguyen et al. (2020) demonstrated that mulching the surface reduces evaporation following high temperatures. Within the framework related to the selection of the adequate method for SS application into the soil, this study seeks to fill the gaps in the scientific knowledge about this specific topic of soil amendment using organic by-products. ...
The fertilization using sewage sludge (SS) and/or SS-derived products have been extensively studied and known to increase crop yield as soil nutrients and plant growth are improved. This study aimed to evaluate two SS application methods (i.e. mulching and mixing with the soil) on soil fertility parameters and the productivity of cereal crops. It compared the effect of SS fertilization methods on changes in soil physicochemical parameters in order to highlight the application mode which gives the best agronomic values and sustains soil productivity. Foliar surface, grain starch content and grain yield of durum wheat (Triticum durum) were determined in plants grown in plastic planters for different fertilization treatments (SS-mulched, SS-mixed, urea, and unfertilized). Each SS treatment was applied in three levels (SS1=1% w/w ratio, SS2=4%, SS3=8.3%). The application of SS improved all soil properties compared to the control and urea, with the SS mulching treatment was the best. The significant improvement of soil fertility was confirmed by soil C:P ratio which indicated a good soil mineralization status, in particular under the screen formed by mulching that helped to conserve high soil moisture for optimizing plant growth. Soil calcium accumulated in greater amount in biosolid-soil mixtures than in SS-mulched soils. Regardless of SS doses, the highest crop grain yields were obtained with the SS mulch treatments. Mulching SS, compared to SS-mixed soils, brings better results in terms of improving soil fertility and yielding high productions. The applicable of this method is also easy in the field and/or large-scale cultures.
... poultry manure, chemical fertilizers, straw compost, biochar, etc.) (Boudjabi et al., 2015(Boudjabi et al., , 2019(Boudjabi et al., , 2019Jeong et al., 2019). Grobelak et al. (2017) and Nguyen et al. (2020) considered soil fertilization using different SS doses in order to determine the level that better improves soil fertility and produces high crop yields. Other studies focused on evaluating the heavy metal-related toxicity of the SS on soil, plants and soil fauna (Alvarenga et al., 2007;Singh and Agrawal, 2007;Orman et al., 2014;Florentino et al., 2019). ...
... This land management should also consider regional climatic conditions, initial pedological characteristics and land use, especially in arid and semi-arid regions constantly exposed to different forms of land degradation, including salinization and desertification caused by severe drought and wind erosion (Arar et al., 2009;Chenchouni et al., 2010;Neffar et al., 2013;Aliat et al., 2016). Many studies have dealt with this aspect, for example Carabassa et al. (2018) and Nguyen et al. (2020) demonstrated that mulching the surface reduces evaporation following high temperatures. Within the framework related to the selection of the adequate method for SS application into the soil, this study seeks to fill the gaps in the scientific knowledge about this specific topic of soil amendment using organic by-products. ...
This study assessed the impact of prickly pear plantations (PPPs) on soil characteristics and plant diversity in arid and semi-arid steppes of northeastern Algeria. The symbiosis of arbuscular mycorrhizal fungi (AMF) with Opuntia ficus-indica roots was seasonally estimated. In arid and semi-arid climates, stations with PPPs were studied along with unplanted rangelands (NP). At each station, soil physicochemical parameters namely pH, electrical conductivity (EC), total and active CaCO3, organic matter (SOM), total nitrogen (Nt), plant-available phosphorus (PAP) and C/N ratio were determined. Vegetation was surveyed using vegetation cover and species abundance, which were used to compute species diversity indices, disturbance index, and plant functional traits. Mycorrhizal infectivity and intensity were measured for PPPs of both climates. Regardless of the climatic region, PPPs significantly improved vegetation cover (P <0.01), species abundance (P = 0.015), species richness (P <0.001), and SOM (P <0.001) compared to the NP. Plant functional traits revealed that plant community was dominated by therophytes (41–80%), anemochorous (34–48%) and zoochorous species (6–44%), ruderal–stress-tolerant species (80%), and arido-passive species (61–90%), with a Mediterranean chorological trend (61–89%). Endomycorrhizal symbiosis (mycorrhizal frequency = 58–90%, mycorrhizal intensity = 3–25%) was high in roots of PPPs. Redundancy analysis revealed that SOM, EC, Nt, PAP were positively associated with diversity parameters in PPPs. The multifactorial analysis indicated a close linkage between soil, vegetation parameters, and plant functional traits in planted stations compared to NP. This study suggests that PPPs can significantly improve soil properties and contribute to the rehabilitation of arid and semi-arid rangeland steppes.
... Our observations on the significant effects of COIF treatments on TK contents in both wheat and rice soils were in agreement with the findings of Nguyen et al. [44] CF (P < 0.05) (Figure 4a and b). Because co-application of organic and inorganic fertilizers causes a higher rate of K conversion than the chemical fertilization alone [45]. ...
Alternative fertilizations are essential to minimize the deteriorating effects of chemical fertilizers on soil and water quality/health. Accordingly, the present work investigated the effects of combined organic-inorganic fertilization (COIF) on wheat and rice yields, soil nutrients, and soil Cd accumulation. Hence, seven different treatments were set up: control (CK); conventional fertilization (CF); optimized fertilization (OF); organic fertilizer replacing 25% (T1) and 50% (T2) of OF; and organic nitrogen (N) replacing 25% (M1) and 50% (M2) of OF-N. Overall, significant increases occurred in the yields of COIF crops. Compared with the CF, the highest wheat and rice yields happened in M1 treatment (approximately by18.5%) (P < 0.05). COIF slightly alleviated soil acidification, and improved the cation exchange capacity (CEC) of the study soils. Besides, COIF treatments significantly increased the contents of total phosphorus, total potassium, available phosphorus, and available potassium by 6.35 to 16.9 %, 3.17 to 10.9 %, 5.53 to 28.7 %, and 2.6 to 12 %, respectively (P <0.05). Nevertheless, negligible increases took place in Cd content of COIF soils compared with the CK. Altogether, our results concluded on 25% replacement of OF-N by organic N (M1) to effectively improve the fertility/ecological sustainability of the study soils.
... Our observations of the significant effects of COIF treatments on TK contents in both wheat and rice soils were in agreement with the findings of Nguyen et al. [41] for CF (p < 0.05) (Figure 4a,b) because the co-application of organic and inorganic fertilizers causes a higher rate of K conversion than does chemical fertilization alone [42]. This can also explain the increases in TK content that took place with increasing rates of manure replacement [43]. ...
Alternative fertilizers are essential to minimizing the deteriorating effects of chemical fertilizers on soil and water quality/health. Accordingly, the present work investigated the effects of combined organic–inorganic fertilization (COIF) on wheat and rice yields, soil nutrients, and soil Cd accumulation. Hence, seven different treatments were set up: control (CK); conventional fertilization (CF); adequate fertilization (OF); organic fertilizer replacing 25% (T1) and 50% (T2) of OF; and organic nitrogen (N) replacing 25% (M1) and 50% (M2) of OF-N. Overall, significant increases occurred in the yields of COIF crops. Compared with the CF, the highest wheat and rice yields happened in the M1 treatment (with a difference of approximately 18.5%) (p < 0.05). COIF slightly alleviated soil acidification, and improved the cation exchange capacity (CEC) of the study soils. Furthermore, COIF treatments significantly increased the contents of total phosphorus, total potassium, available phosphorus, and available potassium by 6.35 to 16.9%, 3.17 to 10.9%, 5.53 to 28.7%, and 2.6 to 12%, respectively (p < 0.05). Nevertheless, negligible increases took place in the Cd content of COIF soils compared with that of the CK. Altogether, our results concluded that 25% replacement of OF-N by organic N (M1) effectively improved the fertility/ecological sustainability of the study soils.
... Dalam pemanfaatan lahan pantai menjadi produktif maka perlu adanya teknologi untuk memperbaiki kualitas dan kesuburan tanah sehingga kebutuhan sayur masyarakat pesisir dan kepulauan Sulawesi Tenggara akan terpenuhi. Dengan demikian e-ISSN: 2963-7813;p-ISSN: 2963-8178, Hal 25-34 diperlukan input teknologi, diantaranya bisa menggunakan bahan organik tanah yang bisa memperbaiki struktur tanah (Muhammad et al. 2012), biota tanah, mikroflora (mikoriza) (Mbusango et al. 2019), ataupun juga pupuk kandang dan pupuk dari dedaunan (Olowokere & Odulate, 2018) ; (Mondal et al., 2019) ; (Nguyen et al., 2020), sehingga memberikan lingkugan yang produktif dan berkelanjutan. ...
Organic fertilizers are materials derived from plant residues, and animal waste, both those that have undergone decomposition and those that are undergoing a decomposition process that functions to add nutrients. Substantially organic fertilizers are composed of humus and non-humus materials so that they can improve marginal soils and sand-dominated soils. The purpose of this study was to determine the effect of various organic fertilizers on sand planting media, and to determine the growth response of pakcoy on various types of organic fertilizers. The research was conducted at the Field Laboratory I Experimental Garden and Agrotechnology Laboratory of the Faculty of Agriculture, Halu Oleo University, the research took place from September to November 2020. This study was arranged in a randomized group design (RAK) with the treatment of various organic fertilizers, which were divided into; no organic fertilizer/control (B0), cow manure (B1), chicken manure (B2), comba-sheep green manure (B3), calopogonium green manure (B4). Each treatment was repeated four times as a group, resulting in 20 experimental units. Each experimental unit consisted of six polybags, resulting in a total of 120 polybags of pakcoy plants. The variables observed were plant height, number of leaves, fresh weight and dry weight of pakcoy plants. The results showed that organic fertilizer had a very significant effect on all observed growth variables of pakcoy plants. Cow manure treatment in the first and second week plant height variables showed the highest value (5.04 cm, and 6.71 cm). But in general, in the third to fifth week, the average chicken manure gave the highest growth response on the variable of plant height, number of leaves, fresh weight and dry weight of pakcoy plants.
... "If the rice is cultivated in the next crop, it grows very well and gives a relatively higher yield than the field that uses completely chemical fertilizers". Cow manure contains 24 minerals, such as nitrogen and potassium, and additional trace amounts of sulfur, iron, magnesium, copper, cobalt, and manganese [16], [17]. Cow manure contributes to an increase in the organic matter content of the soil, leading to improved water retention in the sandy soil, helps resistance to drought, and increases cation exchange capacity that mobilizes nutrients to provide plants [18]. ...
Indigenous knowledge (IK) can provide useful information on local people's activities within environmental contexts. For countries vulnerable to climate change as Vietnam, research on IK might assist in revealing information about local people's responses to environmental stresses and potentially support decision-making. To enrich the study context in this field, this study aims at determining the IK of peanut cultivation of the Khmer ethnic groups. The study site is in the mountainous area in An Giang province, Vietnam, where the Khmer people are located. The methods of documentary collection, focus group discussion, semi-structured interviews, and experiments were applied in this study. The investigation results showed the innovation of local people in the cultivation. For instance, applying cow manure to a sandy soil can reduce chemical fertilizers and improve peanut yield. The IK reported that the application of the broadcasting method could achieve the cultivation economic profit approximately 2.5 times higher than the dibbling method. The former method is mostly preferred due to its time/labor saving and the growing aged population in the study location. The experimental results indicated that the combination of indigenous and scientific knowledge in peanut cultivation, such as chemical fertilizer application, crop calendar, crop rotation, and varieties, could bring high economic efficiency, improve soil nutrients, and ability to adapt to climate change. The research approaches in this study comprehensively revealed the IK, which can be potentially applicable to similar studies.
... Manure compost showed the most extensive content of organic carbon, total nitrogen, phosphate, and calcium. As Nguyen et al. (2020) stated, compost from animal residue was more nutritious than plant residue. However, both animal-based compost and plant-based compost have unique benefits. ...
span>An agroforestry system consisting of fast-growing aromatic plants, such as citronella grass ( Cymbopogon nardus L.) and tree crops that produce aromatic substances, such as ylang-ylang ( Cananga odorata (Lam.) Hook. f. & Thomson forma genuina), was an alternative to the sustainable agricultural system. The growth and oil production of citronella grass can be enhanced by fertilization and planting patterns. The effects of planting patterns of citronella grass and ylang-ylang and compost application from various organic wastes on plant growth, biomass weight, and citronellal and geraniol content of citronella grass were investigated in a field experiment. The experiment consisted of two factors: planting patterns and types of fertilizer. Planting patterns (main plot) consisted of two levels, with citronella grass planted between ylang-ylang rows (IR) and between and within ylang-ylang rows (IWR). Five levels of fertilizer types comprised the subplot: no fertilization (P0), bamboo leaf compost (P1), vetiver leaf compost (P2), dairy cow dung compost (P3), and inorganic fertilizer (P4). Compost made from dairy cow manure significantly increased leaf length, tiller count per plant, canopy width, and citronellal content. Furthermore, its application in the IWR pattern revealed the optimal interaction that significantly increased citronella grass canopy width 4 and 8 weeks after planting. This result indicated that local organic wastes greatly aided the development of aromatic plants in agroforestry.</span
... Differing trends observed for Umbeluzi (e.g., differences in electrical conductivity and NO 3 − -N were significant) and Chokwe (e.g., differences in SOC was significant) on comparisons of nutrient levels in their respective fallow and rice-cultivated fields are most likely due to wide variation in soil fertility status, soil physical properties and/or soil management practices, such as irrigation, tillage, fertilization types and application rate between the two regions. Studies have shown that different soil management practices and soil fertility status account for variations in nutrient availability in the soil and rice productivity across rice-growing regions [72][73][74][75][76][77][78][79][80]. Thus, the transfer of technological initiatives to farmers across rice-growing regions of Mozambique is crucial for minimizing inherent soil-based productivity restrictions in lower rice productivity areas and for the improvement of technical efficiency among farmers. ...
Soil ecosystem perturbation due to agronomic practices can negatively impact soil productivity by altering the diversity and function of soil health determinants. Currently, the influence of rice cultivation and off-season periods on the dynamics of soil health determinants is unclear. Therefore, soil enzyme activities (EAs) and bacterial community compositions in rice-cultivated fields at postharvest (PH) and after a 5-month off-season period (5mR), and fallow-fields (5-years-fallow, 5YF; 10-years-fallow, 10YF and/or one-year-fallow, 1YF) were assessed in two agroecological regions of Mozambique. EAs were mostly higher in fallow fields than in PH, with significant (p < 0.05) differences detected for β-glucosidase and acid phosphatase activities. Only β-glucosidase activity was significantly (p < 0.05) different between PH and 5mR, suggesting that β-glucosidase is responsive in the short-term. Bacterial diversity was highest in rice-cultivated soil and correlated with NO3−, NH4+ and electrical conductivity. Differentially abundant genera, such as Agromyces, Bacillus, Desulfuromonas, Gaiella, Lysobacter, Micromonospora, Norcadiodes, Rubrobacter, Solirubrobacter and Sphingomonas were mostly associated with fallow and 5mR fields, suggesting either negative effects of rice cultivation or the fallow period aided their recovery. Overall, rice cultivation and chemical parameters influenced certain EAs and shaped bacterial communities. Furthermore, the 5-month off-season period facilitates nutrient recovery and proliferation of plant-growth-promoting bacteria.
... They compare the differences between rice straw and rice straw compost applications in Niigata Prefecture (Takakai et al. 2020a) and between rice straw compost or livestock manure compost applications over more than 40 years in Akita Prefecture (Takakai et al. 2020b). Nguyen et al. (2020 a, b) describe the effects of long-term applications of conventional rice straw and cow dung compost on the fertility of soil used for rice production Nguyen et al. (2020a) and the N balance (Nguyen et al. 2020b) in paddy fields in Yamagata Prefecture. Nguyen-Sy et al. (2020) report a long-term rice experiment in Yamagata that looked at stable C isotope ratios of water-extractable organic C affected by application of rice straw and rice straw compost. ...
Aim: To investigate the integrated nutrient management in agricultural fields using cow dung manure and poultry manure as organic, and NPK as inorganic fertilizer at varied ratios. Methodology: Four rice varieties were selected for the experiment viz., MTU 1010, IET 4786, IET 17430, and IET 9947 under nine organic manure and inorganic fertilizer combinations in different ratios with one control treatment. The cultivation was carried out in three replications in a randomized complete block design. The biometric observations were noted at 30, 55, and 80 days after transplant (DAT). Leaf Area Index (LAI), Crop Growth Rate (CGR), and grain yield were calculated for the varieties under varied treatments. Results: Biometric observation and growth indices confirmed that the treatment T showed the highest value among all other treatments for shoot length, 3 dry matter, LAI and LAD for all varieties. Treatment T recorded the maximum root length. For CGR treatment T and T recorded highest value for 7 2 3 different varieties. Soil nutrient results suggest that treatment T-T and T-T showed the highest N, P and K content. The results showed significant 2 4 6 8 difference (p<0.05) in grain yield for all the treatments in all varieties, where T recorded the highest value. 3 Interpretation: The year experiment revealed that integrated nutrient application resulted in considerably greater growth and productivity compared to the control and 100% inorganic fertilizer-treated cultivation.
The present field trial investigated the impacts of combined organic-inorganic fertilization (COIF) on crop quality, soil nutrients, and ecological risks (e.g., soil Cd) using the entire growth period of wheat. To do so, we set up seven different treatments in this study: control (CK); chemical nitrogen (N) fertilizer (CF); optimized fertilization (OF); organic fertilizer replacing 25% (T1) and 50% (T2) of chemical fertilizer; and organic N replacing 25% (M1) and 50% (M2) of chemical N fertilizer. Overall, our results suggested that COIF caused a significant increase in the yield of wheat. Compared with the CK, the highest wheat yield happened in M1 treatment (18.27%), although significant increases also occurred in T1 (13%), T2 (6.40%), and M2 (9.63%) treatments (P < 0.05). Besides, COIF increased the grain protein content by 31.9%. In terms of the soil properties, COIF could alleviate soil acidification while improving the cation exchange capacity (CEC). In addition, COIF treatments significantly increased the contents of total phosphorus, total potassium, available phosphorus, and available potassium, by 6.35–16.9%, 3.17–10.9%, 5.53–28.7%, and 2.6–12% (P < 0.05), respectively. Altogether, the results of the present work suggested that the replacement ratios of CF with 25%~50% cow manure are the most effective practices to improve the wheat yield, soil fertility, and the ecological sustainability of the study soils.
Potassium (K) fertilizer consumption in rice production has increased in developing countries where negative K balance was observed, but it has recently decreased in Japan. This situation raises a question of how K fertilization is managed in Japanese paddy fields and how it affects soil K balance and soil K status. Rice straw (RS) is a good source of K, and RS recycling after harvesting is a common practice in Japan. However, in mixed crop–livestock systems, RS is taken at harvesting time to use as the feed for cows and substituted with the application of cow dung compost (CDC) to the fields. We investigated soil K balance and soil K status in 8 (2017) and 10 (2018) pairs of adjacent RS- and CDC-treated fields in Mamurogawa, Yamagata, Japan. The K balance was calculated from K inputs (RS or CDC, fertilizer, and irrigation water) and K outputs (plant uptake and leaching). K fertilizer application varied widely in both treatments, with no significant difference between RS and CDC fields. K fertilizer was applied in amounts lower than those recommended for paddy rice in the study area in 56% of the fields in both treatments. The K balance was positive in most fields with RS recycling even if K fertilizer application was lower than recommended, but it was negative in half of the fields where RS was substituted with CDC. Most fields in the RS treatment had higher soil exchangeable K than the standard value for fertile soil. Therefore, K input through RS is sufficient for maintaining positive K balance, whereas K input in the CDC treatment from CDC or fertilizer may need to be increased to ensure positive K balance.
This study investigated the long-term (31 years) effects of mineral slag fertilizer (fused magnesium phosphate [FMgP] and calcium silicate [CaSi]) application on changes in the main soil chemical properties, including pH, electrical conductivity (EC), available phosphorus (P), soil organic carbon (SOC), and total nitrogen (TN) contents in paddy soils. Soil samples were obtained from six fertilizer treatments [(1) Nitrogen, phosphorus, and potassium chemical fertilizer only (CF); (2) CF + mineral slag fertilizer (CF+); (3) CF + rice straw (RS); (4) CF + rice straw + mineral slag fertilizer (RS+); (5) CF + rice straw compost (CM); and (6) NPK + rice straw compost + mineral slag fertilizer (CM+)] at five depth soils (0–5, 5–10, 10–15, 15–20, and 20–25 cm). An anaerobic incubation experiment was performed at 30°C to determine carbon (C) decomposition and nitrogen (N) mineralization potentials at every 2-week interval (0, 2, 4, 6, and 8 weeks). The results indicated that compared to non-mineral slag additions, both EC and available P increased by 36.6–136.6% in mineral slag addition treatments. Still, only compost addition mostly influenced pH values; meanwhile, SOC and TN exhibited an increase (~23.8%) in compost addition treatments but a reduction (~12.7%) in rice straw treatments by applying mineral slag fertilizer. Mineral slag addition reduced the C decomposition potential but enhanced N mineralization potential observed by the first-order reaction kinetic models. Our study suggested that mineral slag fertilizers affected the soil organic matter and its mineralization potentials.
Rice straw (RS) and cow dung compost (CDC) are good sources of phosphorus (P) to support rice production. Our previous research found that CDC application in mixed crop-livestock systems supplied more total P to the paddy soil than RS, but available P did not differ significantly between the CDC and RS fields. To explain these results, we investigated the soil total P and soil P balance in RS and CDC fields. From the 79 paddy fields managed by farmers in Mamurogawa, Yamagata, Japan, which were investigated in previous research, we selected 10 pairs of adjacent RS and CDC fields, then measured soil total P, P inputs (RS or CDC and fertilizer), and P outputs (plant uptake and leaching), and calculated the resulting soil P balance. The result showed that soil total P did not differ significantly between treatments. The higher P input from CDC would let farmers apply less fertilizer P in CDC fields than in RS fields, but there was no significant difference in total P input between treatments. Plant P uptake and leaching did not differ significantly between treatments. The soil P balance was positive (i.e., net P accumulation) and did not differ significantly between treatments. The lack of differences in the total P input, total P output, and soil P balance between treatments explains the non-significant differences in soil total P and available P.
To determine methane (CH4) emission differences between edible and forage rice cultivars, we conducted a pot experiment in Yamagata, Japan to grow edible rice Haenuki, and forage rice Fukuhibiki (for feed rice) and Tachisuzuka (for whole-crop silage (WCS) rice) under similar soil and meteorological conditions. The total amounts of N, P, and K fertilizers applied for Fukuhibiki and Tachisuzuka were 1.7, 1.3, and 1.3 times, respectively, higher than those of Haenuki. CH4 fluxes, and rice plant night respirations were measured once weekly or fortnightly. As per the results, for the whole growth period, shoot height, maximum and productive tiller numbers, and plant biomass were significantly different among the three rice varieties. The rice growth period for Haenuki and Fukuhibiki was 107 days after transplanting (DAT), while that for Tachisuzuka was 135 DAT. The highest peak of CH4 flux occurred around the heading stage for the three varieties. Consistently significant (P < 0.05) or obvious (P < 0.1) positive correlations between CH4 flux and night respiration among the varieties were observed from 9 weeks after rice transplanting to harvest, indicating that much of the CH4 flux was from newly produced root exudates and plant debris through plant photosynthesis. The cumulated CH4 emissions during the same growth period, 106 DAT, from Haenuki, Fukuhibiki, and Tachisuzuka were 55.36, 77.46, and 78.40 g C m⁻², respectively. Additionally, Tachisuzuka emitted 25.11 g C m⁻² more CH4 between 106–134 DAT. The final cumulated CH4 emissions from Fukuhibiki and Tachisuzuka were 39.9% and 87.0% higher than that from Haenuki, respectively, throughout their growth period.
The field experiment was carried out to study the variation in organic carbon content and carbon nitrogen (C/N) ratio in different crop straws used as substrate during the process of vermicomposting during 2011-12 in CCS Haryana Agricultural University, Hisar. In the present experiment, the agricultural wastes like wheat straw, millet straw, pulse brawn, mustard straw and cow dung were used as substrates for vermicomposting and the decrease in organic carbon (%) was observed for 90 days. Maximum reduction in organic carbon was found to be 25.6 to 5.7 per cent after 90 days in cow dung substrate during the composting process and maximum reduction in C/N ratio was found to be 40.12 to 6.55 after 90 days in mustard straw + cow dung. Thus, over the course of the composting and vermicomposting the concentration of organic carbon declined up to 90 days (after the release of earthworms).
To evaluate the available silicon (Si) content in agricultural soils in Japan and to investigate the determining factors of this content, we collected 180 soil samples from the surface layer of paddies and upland fields in Japan and determined their available Si contents. A phosphate buffer (PB; 0.02 M, pH 6.9) or an acetate buffer (AB; 0.1 M, pH 4.0) was used to extract available Si from the soil samples, and the Si concentrations in the extracts were determined by inductively coupled plasma-atomic emissions spectroscopy (ICP-AES). The total Si content and selected physicochemical properties were also determined for the soil samples. The median values of the available Si contents by the PB and AB methods were 48.8 and 79.7 mg kg⁻¹ and corresponded to 0.017% and 0.027% of the total Si content, respectively. The overall data showed log-normal distributions. The available Si content of the upland soils was significantly higher than that of the paddy soils by both the PB (p < 0.01) and AB methods (p < 0.05). The available Si contents by the PB and AB methods had a significant positive correlation (p < 0.01) and they had significant negative correlation with the total Si content (p < 0.01). The values of the available Si contents by the PB and AB methods correlated positively with the pH, total carbon (C) content, and dithionite-citrate bicarbonate extractable iron (Fed) and aluminum (Ald), acid oxalate extractable iron (Feo) and aluminum (Alo), Fed-Feo and Alo+1/2Feo values (p < 0.01). A multi-regression analysis indicated that pH, amorphous minerals and crystalline iron (Fe) oxides were the dominant determining factors of available Si in the soils, and these three variables explained approximately two thirds of the variation of available Si content in agricultural soils in Japan. In terms of soil type, Terrestrial Regosols, Dark Red soils and Andosols had relatively high available Si contents, whereas Sand-dune Regosols, Red soils and Gray Lowland soils had relatively low contents. In terms of region, the soils in the Kanto and Okinawa regions had relatively high available Si contents and those in the Kinki, Shikoku and Chugoku regions had relatively low contents. In conclusion, the available Si content and its determining factors for agricultural soils in Japan were quantitatively elucidated, and this will contribute to the establishment of rational soil management —including the application of silicate materials, taking into account the Si-supplying power of the relevant soils—for sustainable and productive agriculture in Japan.
A long-term experiment on combined inorganic fertilizers and organic matter in paddy rice (Oryza sativa L.) cultivation began in May 1982 in Yamagata, northeastern Japan. In 2012, after the 31st harvest, soil samples were collected from five fertilizer treatments [(1) PK, (2) NPK, (3) NPK + 6 Mg ha−1 rice straw (RS), (4) NPK + 10 Mg ha−1 rice straw compost (CM1), and (5) NPK + 30 Mg ha−1 rice straw compost (CM3)], at five soil depths (0–5, 5–10, 10–15, 15–20 and 20–25 cm), to assess the changes in soil organic carbon (SOC) content and carbon (C) decomposition potential, total nitrogen (TN) content and nitrogen (N) mineralization potential resulting from long-term organic matter addition. The C decomposition potential was assessed based on the methane (CH4) and carbon dioxide (CO2) produced, while the N mineralization potential was determined from the potassium chloride (KCl)-extractable ammonium-nitrogen (NH4+-N), after 2, 4, 6 and 8 weeks of anaerobic incubation at 30°C in the laboratory. Compared to NPK treatment, SOC in the total 0–25 cm layer increased by 67.3, 21.0 and10.8%, and TN increased by 64.2, 19.7 and 10.6%, in CM3, RS and CM1, respectively, and SOC and TN showed a slight reduction in the PK treatment by 5.2 and 5.7%, respectively. Applying rice straw compost (10 Mg ha−1) instead of rice straw (6 Mg ha−1) to rice paddies reduced methane production by about 19% after the soils were measured under 8 weeks of anaerobic incubation at 30°C. Soil carbon decomposition potential (Co) and nitrogen mineralization potential (No) were highly correlated with the SOC and TN contents. The mean ratio of Co/No was 4.49, lower than the mean ratio of SOC/TN (13.49) for all treatments, which indicated that the easily decomposed organic matter was from soil microbial biomass and soil proteins.
Submerged rice paddies are a major source of methane (CH4) which is the second most important greenhouse gas after carbon dioxide (CO2). Accelerating rice straw decomposition during the off-rice season could help to reduce CH4 emission from rice paddies during the single rice-growth season in cold temperate regions. For understanding how both temperature and moisture can affect the rate of rice straw decomposition during the off-rice season in the cold temperate region of Tohoku district, Japan, a modeling incubation experiment was carried out in the laboratory. Bulk soil and soil mixed with 2% of δ13C-labeled rice straw with a full factorial combination of four temperature levels (−5 to 5, 5, 15, 25°C) and two moisture levels (60% and 100% WFPS) were incubated for 24 weeks. The daily change from −5 to 5°C was used to model the freezing–thawing cycles occurring during the winter season. The rates of rice straw decomposition were calculated by (i) CO2 production; (ii) change in the soil organic carbon (SOC) content; and (iii) change in the δ13C value of SOC. The results indicated that both temperature and moisture affected the rate of rice straw decomposition during the 24-week aerobic incubation period. Rates of rice straw decomposition increased not only with high temperature, but also with high moisture conditions. The rates of rice straw decomposition were more accurately calculated by CO2 production compared to those calculated by the change in the SOC content, or in its δ13C value. Under high moisture at 100% WFPS condition, the rates of rice straw decomposition were 14.0, 22.2, 33.5 and 46.2% at −5 to 5, 5, 15 and 25°C temperature treatments, respectively. While under low moisture at 60% WFPS condition, these rates were 12.7, 18.3, 31.2 and 38.4%, respectively. The Q10 of rice straw decomposition was higher between −5 to 5 and 5°C than that between 5 and 15°C and that between 15 and 25°C. Daily freezing–thawing cycles (from −5 to 5°C) did not stimulate rice straw decomposition compared with low temperature at 5°C. This study implies that to reduce CH4 emission from rice paddies during the single rice-growth season in the cold temperate regions, enhancing rice straw decomposition during the high temperature period is very important.
Incorporation of straw together with microbial inoculant (a microorganism agent, accelerating straw decomposition) is being increasingly adopted in rice cultivation, thus its effect on greenhouse gas (GHG) emissions merits serious attention. A 3-year field experiment was conducted from 2010 to 2012 to investigate combined effect of straw and microbial inoculant on methane (CH4) and nitrous oxide (N2O) emissions, global warming potential (GWP) and greenhouse gas intensity (GHGI) in a rice field in Jurong, Jiangsu Province, China. The experiment was designed to have treatment NPK (N, P and K fertilizers only), treatment NPKS (NPK plus wheat straw), treatment NPKSR (NPKS plus Ruilaite microbial inoculant) and treatment NPKSJ (NPKS plus Jinkuizi microbial inoculant). Results show that compared to NPK, NPKS increased seasonal CH4 emission by 280-1370%, while decreasing N2O emission by 7-13%. When compared with NPKS, NPKSR and NPKSJ increased seasonal CH4 emission by 7-13% and 6-12%, respectively, whereas reduced N2O emission by 10-27% and 9-24%, respectively. The higher CH4 emission could be attributed to the higher soil CH4 production potential triggered by the combined application of straw and microbial inoculant, and the lower N2O emission to the decreased inorganic N content. As a whole, the benefit of lower N2O emission was completely offset by increased CH4 emission, resulting in a higher GWP for NPKSR (5-12%) and NPKSJ (5-11%) relative to NPKS. Due to NPKSR and NPKSJ increased rice grain yield by 3-6% and 2-4% compared to NPKS, the GHGI values for NPKS, NPKSR and NPKSJ were comparable. These findings suggest that incorporating straw together with microbial inoculant would not influence the radiative forcing of rice production in the terms of per unit of rice grain yield relative to the incorporation of straw alone.
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Excess phosphorus (P) has accumulated in Japanese paddy soils, due to fertilizer P inputs over crop requirement for several decades, and improvement of the excess of P is necessary in view of environmental conservation. This study aimed to evaluate the input/output balance of P related to soil P status in paddy rice systems, and to obtain a practical indication. Irrigated rice (Oryza sative L.) was cultivated on a gley soil from 1997 to 2006. Six field plots fertilized with commercial fertilizer, animal waste composts, green manure and none were included. Phosphorus input varied among plots from 0 to 73 kg ha-1 yr-1. Rice P uptake was approximately 20 kg ha-1, indicating no response to the P input. This was attributed to a large amount of plant-available Bray- and Truog-P in our soils. In our fields, paddy rice could be cultivated with no P-containing fertilizer or amendment. As a result, increase in the P input led to an increase in partial P balance (PPB). Cumulative increase in PPB resulted in the increase in soil total P, whereas cumulative decrease of PPB tended to decrease it. Excess accumulation of the soil P results in a loss of P into the environment. We concluded that P fertilization should be restricted to 20 kg ha-1 yr-1 (corresponding to 46 kg ha-1 yr-1 as P2O5), based on evenly balanced P input with the rice P uptake. It is also important to include all of the P-containing fertilizers and amendments when determining the amount of application.
Increasing K+ adsorption can be an effective alternative in building an available K pool in soils to optimize crop recovery and minimize losses into the environment. We hypothesized that long-term fertilization might change K+ adsorption because of changes in the chemical and mineralogical properties of a rice (Oryza sativa L.). The aims of this study were (i) to determine clay minerals in paddy soil clay size fractions using X-ray diffraction methods and a numerical diagram-decomposition method; (ii) to measure K+ adsorption isotherms before and after H2O2 oxidation of organic matter, and (iii) to investigate whether K+ adsorption is correlated with changes in soil chemical and mineral properties. The 30-yr long-term fertilization treatments caused little change in soil organic C (SOC) but a large variation in soil mineral composition. The whole-clay fraction (<5 μm) corresponded more to the fertilization treatment than the fine-clay fraction (<1 μm) in terms of percentage of illite peak area. The total percentage of vermiculite-chlorite peak area was significantly negatively correlated with the total percentage of illite peak area in the <5 μm soil particles (R=-0.946, P<0.0006). Different fertilization treatments gave significantly different results in K+ adsorption. The SOC oxidation test showed positive effects of SOC on K+ adsorption at lower K+ concentration (⩽120 mg L−1) and negative effects at higher K+ concentration (240 mg L−1). The K+ adsorption by soil clay minerals after SOC oxidization accounted for 60–158% of that by unoxidized soils, suggesting a more important role of soil minerals than SOC on K+ adsorption. The K+ adsorption potential was significantly correlated to the amount of poorly crystallized illite present (R=0.879, P=0.012). The availability of adsorbed K+ for plant growth needs further study.
Solid waste management is a worldwide problem and it is becoming more and more complicated day by day due to rise in population, industrialization and changes in our life style. Transformation of industrial sludges into vermicompost is of double interest: on the one hand, a waste is converted into value added product, and, on the other, it controls a pollutant that is a consequence of increasing industrialization. Garden waste, kitchen waste and cow dung were subjected to recycle through vermicomposting by using the epigeic earthworm Eisenia fetida under field conditions. The pH, moisture content, total organic carbon, humus, nitrogen, phosphorous and potassium in vermicompost was analysed. It was found that moisture content, total organic carbon, humus, nitrogen, phosphorous and potassium was high in cow dung, followed by kitchen waste and garden waste. This study clearly indicates that vermicomposting of garden waste, kitchen waste and cow dung can not only produce a value added produce (vermicomposting) but at the same time reduce the quantity of waste.
N-labeled rice straw, wheat straw, and cattle manure sawdust compost were used to evaluate the N remaining rate of organic matter by the application of the glass fiber-filter paper bag method, and to demonstrate the discrepancy between the N remaining rate of organic matter evaluated by the N content and the N remaining rate of organic matter directly evaluated by the N content. In all three kinds of organic matters examined, a discrepancy in the N remaining rate of organic matter was observed between the evaluation by the N content and the evaluation by the N content. Loss of N from organic matter was observed using the N content, though the N remaining rates of wheat straw and rice straw evaluated by the N content were above 100% throughout the experimental period. The N inflow into and N outflow from the glass fiber-filter paper bag occurred simultaneously. The discrepancy between the N remaining rate of organic matter evaluated by the N content and the N remaining rate of organic matter evaluated by the N content became larger as the C / N ratio of organic matter increased.
Animal compost, organic fertilizer and straw management are among the factors affecting soil fertility in organic cropping systems. However, few studies have compared the effects of organic amendments on soil fertility of organic paddy fields. We conducted a survey of organic farmers’ paddy fields to compare soil nutrients (N, P, K, Ca and Mg), nutrient budgets and partial factor productivity of N (PFPN), and to relate them to organic amendments. The study fields were located in the Higashi Okitama area (38°N, 140°E) of Yamagata prefecture, Japan, and organically managed by a group of farmers using their management standard. Soil samples from 40 rice fields were collected in October 2001. The fields were grouped into three types in terms of organic amendments: application of cattle/chicken compost and straw incorporation (CA), application of cattle composts and straw removal (CR), and straw incorporation only (FA). Purchased organic fertilizers were applied to all the fields. Most of the fields had received the same managements for 5 years or more prior to the survey. Organic amendments had significant effects on pools (the amount of nutrients to 0.4 m depth) of Bray-2 P and NH4OAC extractable K, input, output and balances of the nutrients. Annual surpluses of N, P, K, Ca and Mg (+100, +102, +130, +133 and +33 kg ha−1, respectively) were found in the CA field due to the compost application, but K balance of the CR field was −27 kg ha−1. Nutrient budgets were well balanced in the FA field, but NH4OAC extractable K in the FA soil was lower than the medium range of the conventional soil diagnosis by 37 mg kg−1, suggesting K depletion. The pools of Bray-2 P and NH4OAC extractable K were correlated with balances of P and K (r = 0.597 and 0.540, P < 0.001), but those of NNM, total N and NH4OAC extractable Ca and Mg were not related with nutrient balances (P > 0.05). PFPN of the FA fields (89 kg kg−1) was twice as high as that of the CR and CA fields (45 and 37 kg kg−1). The former value was comparable to PFPN (78 kg kg−1) of conventional rice fields with mineral fertilizer use of the surrounding area. Two alternative scenarios for fine-tuning nutrient inputs in organic farming practices are better compost quality and reallocation of chicken/cattle compost among organic rice fields.
The influence of the long-term combination of rice straw removal and rice straw compost application on methane (CH4) and nitrous oxide (N2O) emissions and soil carbon accumulation in rice paddy fields was clarified. In each of the initial and continuous application fields (3 and 39−51 years, respectively), three plots with different applications of organic matter were established, namely, rice straw application (RS), rice straw compost application (SC) and no application (NA) plots, and soil carbon storage (0−15 cm), rice grain yield and CH4 and N2O fluxes were measured for three years. The soil carbon sequestration rate by the organic matter application was higher in the SC plot than in the RS plot for both the initial and continuous application fields, and it was lower in the continuous application field than in the initial application field. The rice grain yield in the SC plot was significantly higher than those in the other plots in both the initial and continuous application fields. Cumulative CH4 emissions followed the order of the NA plot < the SC plot < the RS plot for both the initial and continuous application fields. The effect of the organic matter application on the N2O emissions was not clear. In both the initial and continuous application fields, the increase in CH4 emission by the rice straw application exceeded the soil carbon sequestration rate, and the change in the net greenhouse gas (GHG) balance calculated by the difference between them was a positive, indicating a net increase in the GHG emissions. However, the change in the GHG balance by the rice straw compost application showed negative (mitigating GHG emissions) for the initial application field, whereas it showed positive for the continuous application field. Although the mitigation effect on the GHG emissions by the combination of the rice straw removal and rice straw compost application was reduced by 21% after 39 years long-term application, it is suggested that the combination treatment is a sustainable management that can mitigate GHG emissions and improve crop productivity.
Great efforts have been made on the assessment of the effects of straw managements or tillage practices on rice yield and greenhouse gas (GHG) emissions. However, their interactive effects were not well documented. Based on a seven-year field experiment under a double rice system, we tested the effects of rotary tillage (RT) vs. plough tillage (PT) on rice yield, methane (CH4) and nitrous oxide (N2O) emissions with or without straw incorporation. As compared to straw removal, straw incorporation increased rice yield by 12.7% and 1.3% under the PT and the RT, respectively. Straw incorporation significantly stimulated CH4 emissions under both tillage regimes in the late rice season, while no significant effect occurred in the early rice season. Compared to the RT, PT significantly decreased DOC concentrations and methanogen abundances, resulting in a reduction in CH4 emission. The PT decreased yield-scaled global warming potential (GWP) with or without straw incorporation by 31.0% and 15.5%, respectively, as compared to the RT. Together, our results indicate that straw incorporation with plough tillage benefits rice production for higher-yield with less GHG emissions in double rice cropping areas.
Over-production of rice has been a problem for the past 40 years in Japan. On the other hand, there is also a need for an increase in the production of domestic bulk feed in Japan. Whole crop silage (WCS) rice is being promoted by the government. The whole aerial parts consisting of grains, leaves and stems are harvested at the yellow ripening stage. At present, about 12 WCS rice varieties have been bred and are commonly used in Japan. The total digestible nutrients (TDN) yields of WCS varieties are 3 to 27% higher than those of ordinary rice varieties. The lodging resistances of most of the WCS varieties are "High". Most WCS varieties are basically Japonica, but a few Indica varieties have been used in their parentage.
By treating 0.5 g DW of a plant sample directly with 10 ml of a dilute hydrofluoric acid solution (HF solution, 1.5 M HF-0.6 M HCl), all the silica in plant (as much as 150 mg SiO2) was dissolved within 1 h. After dilution of the extract with 40 mL of distilled water, the silica in the extract was measured by the spectrometric molybdenum yellow method. The molybdenum yellow method, in which silica in 0.1 mL of the diluted extract can be determined in 8 min, is well suited to rapid, micro-estimations of the silica content in plants. In the micromodification, the size of the plant sample was reduced to 100 mg DW. The analytical procedure was simple, and the analytical time was less than 2 h. The method can save much labor and time, compared with the gravimetric analysis. The dissolution with HF solution and the molybdenum yellow method were also applied to the measurement of the content of silica separated by acid digestion of rice plants. Excellent agreement in the silica measurement of rice plants was confirmed among the direct extraction method, the gravimetric method and the digestion-separation-dissolution method. In the molybdenum yellow method, the addition of boric acid enabled to mask the interference of hydrofluoric acid, and the least amount of citric acid required for the elimination of phosphorus interference was proposed. In conclusion in this report, recommended methods for the rapid estimation of the silica content in rice plants were presented.
From 1991 to 2000, a rice cultivar Koshihikari was grown in the field, with either farmyard manure or chemical fertilizer continuously applied using a minimum of agricultural chemicals. After six years of continuous application of the manure, grain yield was the highest (63.7 kg/a) in the field supplemented with a small amount of chemical fertilizer. Continuous application of the farmyard manure increased the pH, available phosphorus content and gas phase of the soil, and also the uptake of phosphorus and potassium by plants although it slightly decreased the nitrogen absorption. Extension of the period of continuous application of the farmyard manure beyond five years did not change the soil properties or nutrient absorption by plants, but decreased the grain yield. Continuous application of 200 kg/a manure is inadequate for raising the soil fertility, but it may be possible to increase the yield by applying nitrogen at appropriate stages, because the continuous application of farmyard manure improved the soil conditions and increased the uptake of phosphorus and potassium by plants.
Effects of four years of inorganic and organic nitrogen (N) management on the emission of three major greenhouse gases (GHGs): methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2O), and on soil labile carbon fractions such as water-soluble carbon (C, WSC), microbial biomass carbon (MBC), KMnO4 oxidizable organic carbon (KMnO4-C), carbon management index (CMI) and soil carbon storage were investigated in a flooded rice (Oryza sativa L.) field in India. The treatments included an unfertilized control, inorganic nitrogen fertilizer, rice straw + inorganic nitrogen fertilizer and rice straw + green manure. Maximum global warming potential (GWP) (10,188 kg CO2 equivalent ha−1) was determined for the combined application of rice straw and green manure. Total carbon content and carbon storage in the topsoil were significantly increased for the rice straw + inorganic nitrogen fertilizer treatment. The combined application of rice straw and green manure was more effective in increasing WSC, MBC, KMnO4-C concentrations and CMI than the inorganic fertilizer treatments, although it increased gaseous carbon emission. The combined application of rice straw and an inorganic fertilizer was most effective in sequestrating soil organic carbon (1.39 Mg ha−1), resulting in a higher grain yield. Therefore, it could be the best option for improving productivity and carbon storage in the rice–rice cropping system.
Methane and nitrous oxide emissions, their global warming potential, carbon efficiency ratio and related biogeochemical properties of a tropical soil planted to rice were investigated under different N management [i.e. urea-N (120 kg N ha− 1), rice straw (RS) (30 kg N ha− 1) + urea-N (90 kg N ha− 1), compost (C) (30 kg N ha− 1) + urea-N (90 kg N ha− 1) and poultry manure (PM) (30 kg N ha− 1) + urea-N (90 kg N ha− 1)]. CH4 fluxes were increased by 82.7%, 65.1%, 63.4% and 31.9% in RS + urea-N, C + urea-N, PM + urea-N and urea-N, respectively whereas percentage increase in cumulative N2O emission was 390.6, 371.8, 315.6, and 253.1 in PM + urea-N, urea-N, C + urea-N and RS + urea-N, respectively over control (no fertilizer amendment). However, increase of GWPs in different manure + urea-N over that of control were 85.5%, 69.2%, 68.8% and 37.6% in RS + urea-N, C + urea-N, PM + urea-N and urea-N, respectively. Microbial biomass carbon (MBC), readily mineralizable carbon (RMC) and fluorescence diacetate (FDA) hydrolysis activity were significantly affected by integrated N-management and followed the order of C + urea-N > PM + urea-N > RS + urea-N > urea-N > control. With considerably high microbial biomass C and microbial activity, high C efficiency ratio, high yield and low greenhouse gas intensity, C + urea-N could be a better option to mitigate CH4 and N2O emissions and to maintain soil biological quality and yield in tropical paddy.
A long-term experiment was conducted to investigate how long-term fertilization and rice straw incorporation into soil affect soil glomalin, C and N. The combined application of chemical fertilizer and straw resulted in a significant increase in both soil easily extractable glomalin (EEG) and total glomalin (TG) concentrations, as compared with application of only chemical fertilizer or no fertilizer application. The EEG and TG concentrations of the NPKS (nitrogen, phosphorus, and potassium fertilizer application + rice straw return) plot were 4.68% and 5.67% higher than those of the CK (unfertilized control) plot, and 9.87% and 6.23% higher than those of the NPK (nitrogen, phosphorus, and potassium fertilizer applied annually) plot, respectively. Application of only chemical fertilizer did not cause a statistically significant change of soil glomalin compared with no fertilizer application. The changes of soil organic C (SOC) and total N (TN) contents demonstrated a similar trend to soil glomalin in these plots. The SOC and TN contents of NPKS plot were 15.01% and 9.18% higher than those of the CK plot, and 8.85% and 14.76% higher than those of the NPK plot, respectively. Rice straw return also enhanced the contents of microbial biomass C (MBC) and microbial biomass N (MBN) in the NPKS plot by 7.76% for MBC and 31.42% for MBN compared with the CK plot, and 12.66% for MBC and 15.07% for MBN compared with the NPK plots, respectively. Application of only chemical fertilizer, however, increased MBN concentration, but decreased MBC concentration in soil.
We estimated the application of cattle, swine, and poultry manure and of rice straw and rice straw compost for seven crop groups (paddy rice, upland crops, vegetables, orchards, tea, forage, and fodder) from a bottom-up analysis of government questionnaire data. Vegetable crops consumed the most manure and received the largest amount of swine and poultry manure and of rice straw compost, and the second-highest amount of cattle manure. Paddy rice received the least manure, and depended mainly on organic matter from non-composted rice straw. Fodder (timothy (Phleum pratense. L.), etc.) and forage (dent corn (Zea mays L.), etc.) crops used for cattle husbandry consumed the most cattle manure; however, fodder crops received only one-quarter of the cattle manure received by forage crops. We hypothesized phosphorus (P) is not lost during composting, then estimated the amount of raw materials for livestock manure inversely from applied livestock manure P and carbon (C):nitrogen (N):potassium (K):P ratio of kinds of livestock excreta. More than half of livestock excreta (6224 Gg C, 589 Gg N, 90 Gg P, and 278 Gg K) was utilized for manure. However, manure applied (2300 Gg C, 158 Gg N, 90 Gg P, 154 Gg K) was lower than in a previous study based on a top-down analysis (161 Gg N, 92 Gg P), possibly because mainly poultry excreta (520 Gg C, 75 Gg N, 11 Gg P, 13 Gg K) and a considerable amount of livestock excreta (3654 Gg C, 353 Gg N, 53 Gg P, 174 Gg K, not including loss during storage) were not utilized. A newer survey to grasp the present state of fertilization done by the government could update our assessment of the use of livestock excreta for crop production based purely on top-down approaches.
Using data from a longitudinal survey (the Basic Soil Environment Monitoring Project, Stationary Monitoring, 1979–1998, launched by the Ministry of Agriculture, Forestry and Fisheries of Japan), it was found that livestock possession, soil type, utilization form of paddy fields and full-/part-time status of farmers were important factors controlling application rates of organic amendments (OA) in Japanese paddy fields. When data points were categorized in terms of these four factors, application rate of livestock waste compost (LWC) on the basis of fresh weight (FW) varied remarkably. Application rates of LWC decreased during the survey period, whereas rice straw residue (RSR) application rates increased. The smallest LWC application rate (average 0.3 ± 0.2 Mg FW ha for the period between 1994 and 1998) was found among rice (Oryza sativa L.) single-cropping, poorly drained lowland paddy soils (PDLPS) including Histosols, with full-time farmers possessing no livestock. Even among rice single-cropping, the application rate was clearly larger (average 10.6 ± 0.5 Mg FW ha for the period between 1979 and 1983) for non-poorly drained lowland paddy soils (non-PDLPS), with full-time farmers possessing livestock. Much greater than this was the LWC application rate for converted paddy fields (average 29.9 ± 4.3 Mg FW ha for the period between 1989–1993), non-PDLPS, with full-time farmers possessing livestock. Accordingly, this study emphasizes the importance of categorizing data points at least in terms of soil type, utilization form of paddy fields, livestock possession and part- or full-time farming status when constructing an inventory, exploring changes in OA application rate, and making policy.
Emission rates of CH4 from four Japanese paddy fields were measured throughout the cultivation period in 1988 by using the closed chamber method. Large seasonal variations of the CH4 flux were observed. The emission was closely related to the decrease of the redox potential (Eh) in paddy soils. Drainage and supplementary application of mineral fertilizer substantially reduced the CH4 emission. Emission rates of CH4 differed markedly with the soil types. The highest rate was observed in a paddy field consisting of Peat soil (44.8 g-CH4/m during a cultivation period), followed by Gley soil (8.0-27.0). The emission rates in the Andosols were significantly lower (0.6-12.6). Application of rice straw at a rate of 6-9 t/ha to the paddy fields increased the CH4 emission rates 1.8- to 3.5-fold. Application of compost slightly increased the CH4 emission. Annual emission rates of CH4 from individual plots were positively correlated with the contents of readily mineralizable carbon (RMC) in paddy soils collected before flooding, suggesting that RMC is one of the main factors affecting CH4 emission from flooded soils.
(Jpn. J. Soil Sci.Plant Nutr., 77, 283–291, 2006)Nutrient amounts in livestock manure management, including manure treatment and use, were estimated using published statistical data and other information. The eight categories for manure treatment were defined in this study as composting at facility, composting at stockyard, raw feces, dried feces, urine, slurry, purification and other. The three categories for use of manure were defined as application to farmland, sale and exchange and other.The regional daily excretion units per head of dairy and beef cattle, including the amount of excreta, nitrogen (N), phosphorus (P) and potassium (K), were calculated based on the quantities and qualities of feed in each region. There was found to be a difference in the values for Hokkaido and other regions.Concerning manure treatment methods in the dairy sector, the sum of the proportion of raw feces and compost at stockyard was high in Hokkaido. On the other hand, the sum of the proportion of composting at facility and dried feces was high in Hokuriku, Tokai, Kinki and Shikoku. In Kyushu, the proportion of slurry production was higher than in any other region.The amounts of N, P, and K in compost estimated in this study were compared with those calculated from published statistics. The results were as follows. The amounts of N, P, and K in dairy cattle compost, N and K in beef cattle compost, and N in poultry compost in this study were similar to the amounts cited in reported statistics. The amounts of P in beef cattle, swine, and poultry compost in this study were lower than those cited in reported statistics.As for the use of manure, application to farmland is the most common use of manure in the dairy and beef cattle sector. The proportions of purification, and sale and exchange were high for the swine and poultry sectors, respectively.Large amounts of liquid manure, such as urine and slurry, are applied to farmland. To clarify the nutrient load resulting from liquid manure, the usable amount of dairy slurry was calculated based on both the standard application rate of fertilizer and the area of grassland and forage crops. As a result, the amount of usable N was lower than the amount of liquid manure N in the Kanto-Tosan, Tokai and Kinki regions.
Soils around Taihu Lake area, located in Yangtze River Delta (Jiangsu Province, China), have been continuously applied with phosphorus (P) fertilizer for at least 40 years and growing rice (Oryza sativa L.) under water submergence in summer, in rotation with wheat (Triticum aestivum L.) in winter. Because of the accelerated eutrophication of Taihu Lake, there is great concern as to whether P from rice cropping systems is one of the non-point pollutants responsible for the eutrophication. The experiment was carried out with five treatments and four random arranged replications under rice and wheat rotation on Gleyi-stagnic Anthrosols installed in large-scale monolith lysimeter from 2002 to 2003, and soil water penetration rate was adjusted to 3–5mmd−1, a typical rate in corresponding field soil. The leachate samples were collected at certain intervals for analysis of dissolved P. Soil samples were collected for P fractionation after rice was harvested in 2003. Data indicated that there was no correlation between concentration of dissolved P in leachates (at the 70cm depth) and the P fertilization rates under present experiment condition, suggesting that the soil still had strong affinity to P despite long history of continuous P fertilization. However, considerable number of leachate samples, collected particularly in early submergence, contained P at concentrations that could cause eutrophication. Calculated leaching losses of P were 0.11 and 0.071kgPha−1 in 2002 and 2003, respectively. More P fertilizer application resulted in more accumulation at top soil layer and deeper downward P movement in soil profile. Downward movement of Olsen-P, Al-P, and Ca2-P was observed in deeper soil layers than that of Fe-P and Ca8-P, and accumulation of Fe-P and Al-P were quantitatively more significantly than Ca2-P and Ca8-P.
The study was carried out to investigate the water balance and runoff and infiltration losses of nutrients in a paddy field plot located in southern Korea. Field monitoring was carried out during the cropping season from May 1, 1999 to September 30, 2000. The soil of the experimental paddy field belonged to the Jisan series (SiL; fine loam, mixed, mesic Fluventic Haplaquepts) covering on area of 5,000 m (100 m × 50 m). The measured input quantities of N and P into the paddy field were as follows: 122 and 140 kg N ha and 29 and 30 kg P2O5 kg ha from chemical fertilizer, 20 and 28 kg N ha and 0.35 and 0.36 kg P ha from precipitation, and 26 and 35 kg N ha and 0.57 and 0.72 kg P ha from irrigation water, respectively. The measured outputs of N and P during the study period were as follows: 48 and 52 kg N ha and 1.1 and 1.6 kg P ha from runoff water, and 9 and 12 kg N ha and 0.04 and 0.05 kg P ha from infiltration. The runoff loading was the highest in June, presumably because of the higher concentrations of chemical components associated with chemical fertilizer application. The runoff losses of nutrients were compared to the amounts of nutrients supplied by chemical fertilizers. It was found that the losses of N accounted for 34.3 and 42.6% of the chemical fertilizer applied, while those of P accounted for 3.8 and 5.3%. The ratio between nutrient losses by infiltration and the chemical fertilizer applied was 6.4 and 9.8% for N and 0.1 and 0.2% for P, respectively.
Widespread yield stagnation and productivity declines in the rice–rice cropping system have been reported and many of the associated issues are related to soil quality. A long-term experimental study was initiated in 1969 to assess the impact of continuous cultivation of rice as a single crop grown in wet as well as dry seasons using varying levels of chemical fertilizer and manure applications on soil quality indicators (physical, chemical and biological), a sustainable yield index (SYI) and a soil quality index (SQI). The treatments comprised chemical fertilizers and farmyard manure (FYM) either alone or in combination viz. control, N, NP, NK, NPK, FYM, N+FYM, NP+FYM, NK+FYM and NPK+FYM, laid out in a randomized complete block design with three replications. Soil samples were collected after the wet season rice harvest in 2010 and were analysed for physical, chemical and biological indicators of soil quality. A SYI based on long-term yield data and SQI using principal component analysis (PCA) and nonlinear scoring functions were calculated. Application of NPK fertilizers in combination with FYM significantly increased the average grain yield of rice in both wet and dry seasons and enhanced the sustainability of the system compared to the control and plots in receipt of fertilizers. The SYI for the control was higher in the wet season than in the dry one, whereas the reverse was true for NPK+FYM treatment. The value of the dimensionless SQI varied from 1.46 in the control plot to 3.78 in the NPK+FYM one. A greater SYI and SQI in the NPK+FYM treatment demonstrated the importance of using a chemical fertilizer in combination with FYM. For the six soil quality indicators selected as a minimum data set (MDS), the contribution of DTPA-Zn, available-N and soil organic carbon to the SQI was substantial ranging from 59.4 to 85.7 per cent in NPK+FYM and control plots, respectively. Thus, these soil parameters could be used to monitor soil quality in a subhumid tropical rice–rice system.
Pearl millet (Penisetum glaucum) is an interesting species to be used as cover crop in tropical areas, showing a high ability in potassium uptake. Potassium (K) is not linked to organic compounds in the plant, and can easily be released from decaying straw becoming available for subsequent crops. This experiment evaluated K leaching from millet straw grown under potassium rates (0, 100, 200, and 300 mg dm), and submitted to five levels of simulated rain (5, 10, 20, 40, and 80 mm). Plants were grown in soil filled pots in a greenhouse. On the 50th day after emergence, the plants were desiccated with glyphosate. Artificial rain was applied over the straw. Potassium deficiency speeds up millet dehydration after herbicide application and increases lightly rain water retention in the straw. The amount of K leached right after plant desiccation is correlated with the residue nutrient content and can be as high as 64 kg ha considering a mulch of 8 t ha. Although well‐nourished millet plants release considerable amounts of K with the first rains, a large percentage of the nutrient is still retained in the straw.
By treating 0.5 g DW of a plant sample directly with 10 ml of a dilute hydrofluoric acid solution (HF solution, 1.5 M HF—0.6 M HCl), all the silica in plant (as much as 150 mg SiO2) was dissolved within 1 h. After dilution of the extract with 40 mL of distilled water, the silica in the extract was measured by the spectrometric molybdenum yellow method. The molybdenum yellow method, in which silica in 0.1 mL of the diluted extract can be determined in 8 min, is well suited to rapid, micro-estimations of the silica content in plants. In the micro-modification, the size of the plant sample was reduced to 100 mg DW. The analytical procedure was simple, and the analytical time was less than 2 h. The method can save much labor and time, compared with the gravimetric analysis. The dissolution with HF solution and the molybdenum yellow method were also applied to the measurement of the content of silica separated by acid digestion of rice plants. Excellent agreement in the silica measurement of rice plants was confirmed among the direct extraction method, the gravimetric method and the digestion-separation-dissolution method. In the molybdenum yellow method, the addition of boric acid enabled to mask the interference of hydrofluoric acid, and the least amount of citric acid required for the elimination of phosphorus interference was proposed. In conclusion in this report, recommended methods for the rapid estimation of the silica content in rice plants were presented.
Rice paddy fields are a major source of methane (CH4) emissions, a potent greenhouse gas. We assessed CH4 emissions from five existing paddy fields farmed in a snowy temperate region in central Hokkaido, Japan. All fields had continuous flooding and a paddy–fallow–paddy (rice) crop rotation system, but with different amounts of rice straw application. The rice straw application rate in the fields ranged from 0 to 219 g dry matter m−2. CH4 emission increased with increasing amounts of rice straw. A peak in CH4 emission at the end of the reproductive stage was observed in all fields receiving rice straw. When continuous flooding was interrupted by drainage for harvesting, emissions from all fields also dropped quickly. Total CH4 emissions ranged from 4.04 to 40.8 g CH4-C m−2 per growing season. We found that CH4 emissions (g CH4-C m−2 per g dry matter) as per unit (dry matter) of rice straw applied in this study were significantly (P < 0.05) higher than those of calculated reported values, presumably because of the retardation of straw decomposition rates during the winter fallow. There was a significant correlation between rice straw carbon application (SCA) rate and total CH4 emission in continuously flooded fields (CH4 emission [g C m−2 per growing period] = 0.486 × SCA [g C m−2] − 1.644, r2 = 0.884, P < 0.05), and emissions were 2–10-fold greater than from fields with no rice straw. The results indicate that the presence of rice straw has a significant influence on CH4 emissions from paddy fields.
A long-term experiment beginning in 1981 in Jinxian County of Jiangxi Province, subtropical China, was conducted in a paddy field under a double rice cropping system with four different fertilization regimes, including 1) no fertilizer as control (CK), 2) balanced chemical N, P, and K fertilizers (NPK), 3) organic manure using milk vetch and pig manure in the early and late rice growing season, respectively (OM), and 4) balanced chemical fertilizers combined with organic manure (NPKM). Samples (0–17 cm) of the paddy field soil, which was derived from Quaternary red clay, were collected after the late rice harvest in November 2003 for determination of total organic carbon (TOC) and total nitrogen (TN) and fractions of organic C and N. Results showed that TOC and TN in the NPKM and OM treatments were significantly higher than those in other two treatments (CK and NPK). Application of organic manure with or without chemical fertilizers significantly increased the contents of all fractions of organic C and N, whereas chemical fertilizer application only increased the contents of occluded particulate organic C (oPOC) and amino acid N. In addition, application of organic manure significantly enhanced the proportions of free particulate organic carbon (fPOC) and oPOC in total C, and those of amino sugar N and amino acid N (P < 0.01) in total N. In contrast, chemical fertilizer application only increased the proportions of oPOC and amino acid N (P < 0.05). There were no significant differences in either contents or proportions of soil organic C and organic N fractions between the NPKM and OM treatments. These indicated that organic manure application with or without chemical fertilizers played the most significant role in enhancing soil organic C and N quantity and quality in the paddy field studied.
To evaluate the relationship between the amount of available Silicon (Si) in paddy soils and their mineral properties on the Shounai Plain in Japan, which is formed from several parent materials, we evaluated the amount of available Si, the particle size distribution, the oxide composition of crystalline minerals and the amount of oxalate-extractable Si (Sio), iron (Feo) and aluminum (Alo) in the soil. The amount of available Si in the soil and the oxide content of the crystalline minerals differed among four soil groups that were distinguished by their clay mineral composition. There was no difference in the particle size distribution among the soil groups. The amount of available Si was positively related to the SiO2/Al2O3 ratio of clay, the CaO concentration of silt and fine sand, and the amounts of Sio, Feo and Alo in the soil. The amount of available Si in the soils was negative correlated with the Na2O and K2O concentrations of silt, the K2O concentration of fine sand, and the coarse sand content. These results suggest that the amount of available Si in soils is affected by the weathering resistivity of their minerals and that the particle size distribution and mineral composition are related to the available Si of the soils. Mineralogical properties, including the particle size distribution and mineral composition such as the SiO2/Al2O3 ratio × clay fraction content and the amounts of CaO and MgO in silt-sized particles, were positively correlated with the amount of available Si in the soil, but these correlations were not found for fine sand-sized particles. The Sio, Feo and SiO2/Al2O3 ratio × clay fraction contents contributed approximately 50% to the amount of available Si in the soils. The amount of available Si in the soil was divided into two groups according to the location of the paddy field. The amount of soil-available Si in the alluvial plain was affected by the geology upstream through the mineral composition.
Kahokugata Lake, a closed lake, has been subject to eutrophication. This research was conducted to clarify the actual phenomena
and evaluation of the discharges of N and P from paddy test fields in the lowlands into Kahokugata Lake. A comprehensive mass
balance of N and P was obtained from 4years of study. About N, the mean value of harvested unhulled rice (79.9kg/ha) was
greater than mean controlled release fertilizer inputs (56.7kg/ha). Other inputs and outputs include N in atmospheric acid
deposition (21.4kg/ha) and N fixation–denitrification (9.2kg/ha). The rice straw recycled after harvest was balanced by
straw produced in the succeeding year. The runoff and percolation losses discharged into the lake was 11.3kg/ha, (8.6% of
total inputs). Since the rice harvested was consumed domestically, which taking out from the farmland and, therefore, nitrogen
pollutant into the lake was becoming small, paddy rice at this site is considered an “anti-polluting, purifying or cleansing”
crop. The P content in harvested rice (39.4kg/ha) was balanced by fertilizer inputs (36.4kg/ha). Previous studies examining
inflow–outflow relationships without considering a comprehensive mass balance may lead to erroneous conclusions. Our findings
indicate paddy rice in lowlands could be an environmentally friendly crop and can play an important role in reducing pollution
of lakes, and therefore should be considered in land use planning.
An Engineering Guidance for Low Cost Agricultural Production.” preliminary version
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Studies on the Behavior and Balance of Nitrogen in Paddy Field near the Lake and Its Influence on Environment Especially on the Water Quality
- K Hasegawa
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Paddy Field near the Lake and Its Influence on Environment Especially
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K. Inubushi and T. Anzai, 6-10. Tokyo: Asakura Publishing. (in Japanese).
Studies on the Soils of Arable Land in Mie Prefecture. VI the Effects of Continuous Application of Organic Matter to Paddy Field on the Soil Fertility and Paddy Rice Yields
- H Izuoka
- I Miyabayashi
- C Yamaguchi
- T Nakagawa
- H Ishikawa
- N Yasuda
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N. Yasuda. 1996. "Studies on the Soils of Arable Land in Mie Prefecture.
VI the Effects of Continuous Application of Organic Matter to Paddy Field
on the Soil Fertility and Paddy Rice Yields." Bulletin of the Mie Agricultural
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Effect of Fertilizers and Preparation Methods after Harvesting Rice on Mineral and DCAD of Rice Straw
- X Jin
- N Yoshida
- H Matsuyama
- K Horiguchi
Jin, X., N. Yoshida, H. Matsuyama, and K. Horiguchi. 2015. "Effect of
Fertilizers and Preparation Methods after Harvesting Rice on Mineral
and DCAD of Rice Straw." Japanese Journal of Grassland Science 61:
151-157. (in Japanese).
Comparison of Three Methods for Evaluation of Available Silicon in Paddy Soils
- N Kato
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- F Nakagawa
- H Sumida
Kato, N., K. Kumagai, F. Nakagawa, and H. Sumida. 2002. "Comparison of
Three Methods for Evaluation of Available Silicon in Paddy Soils." In
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August 22-26, pp. 58-61, Tsuruoka, Yamagata, Japan.