Shuaixiang Zhao's research while affiliated with China Agricultural University and other places

Apples have become a major source of income for smallholder farmers in Bohai Bay. However, the annual productivity of apples in the area is relatively low and the interannual yield gap varies drastically. Identifying the apple yield gap and interannual production constraints can potentially promote the sustainable development of apple production. Based on track monitoring data of 45 smallholder farmers from 2016 to 2018, the yield gap and constraint factors were determined by adopting boundary analysis methodology. The results showed that the yield potential of apples during 2016–2018 was 75, 108, and 87 t ha−1, and actual yields were 36.8, 52.3, and 35.2 t ha−1, respectively. The explainable yield gaps were 40.5, 56.9, and 55.1 t ha−1. Soil, management, and climatic factors limit apple yield improvement. Among these, low temperatures during the bud break and flowering periods can induce yield losses. Soil nutrient content and fertilizer management are also important limiting factors that have polynomial relationships with yield. Too much fertilizer and high levels of nutrients in the soil have already caused yield losses in some fields. Sound scientific guidance to help farmers adopt reasonable management techniques adapted to climate change is necessary to close the yield gap.

Compost represents an important input for sustainable agriculture, but the use of diverse compost types causes uncertain outcomes. Here we performed a global meta-analysis with over 2,000 observations to determine whether a precision compost strategy (PCS) that aligns suitable composts and application methods with target crops and growth environments can advance sustainable food production. Eleven key predictors of compost (carbon-to-nutrient ratios, pH and salt content electric conductivity), management (nitrogen N supply) and biophysical settings (crop type, soil texture, soil organic carbon, pH, temperature and rainfall) determined 80% of the effect on crop yield, soil organic carbon and nitrous oxide emissions. The benefits of a PCS are more pronounced in drier and warmer climates and soils with acidic pH and sandy or clay texture, achieving up to 40% higher crop yield than conventional practices. Using a data-driven approach, we estimate that a global PCS can increase the production of major cereal crops by 96.3 Tg annually, which is 4% of current production. A global PCS has the technological potential to restore 19.5 Pg carbon in cropland topsoil (0–20 cm), equivalent to 26.5% of current topsoil soil organic carbon stocks. Together, this points to a central role of PCS in current and emerging agriculture. A global meta-analysis identifies the key predictors of compost on crop yield, soil organic carbon and nitrous oxide emissions. The proposed precision compost strategy has the technological potential to increase the production of major cereal crops by 4% and restore 26.5% of current topsoil soil organic carbon stocks on a global scale.

The use of vermicompost (VC) in growing medium can potentially promote plant growth and provide a way to reuse biowaste. Although VC has widely been studied recently in the production of growing medium, a quantitative assessment of the effects of VC on the physicochemical properties of the growing medium and plant growth is lacking. Therefore, we conducted a meta-analysis to synthetically evaluate the effects of VC on the physicochemical properties of growing medium and plant growth. We observed that VC significantly increased the nutrient content of the growing medium; in particular, it increased the contents of available nitrogen and phosphorus by 133.8% and 256.7%, respectively. Furthermore, VC significantly improved the water-holding porosity of the growing medium by 25.3% but slightly reduced total pore space by 2.6%. Moreover, during plant growth, VC increased seed germination rate, seedling index, shoot biomass, root biomass, and total biomass on an average by 30.4%, 57.8%, 52.6%, 58.3%, and 54.4%, respectively. Comprehensively, we also observed that cattle manure-VC was the most promising material for the production of growing medium and that the optimum proportion of VC for plant growth in growing medium was 40–60%. These results are therefore proposed to provide a reference for the regulation of the physicochemical properties of growing medium, including the selection of waste materials and the VC proportion during the production of growing medium. Similarly, the positive effects of VC on plant growth will provide more possibilities for reducing fertilizer input and cycling waste.

Accurate nitrogen (N) fertilization and optimum plant density increase crop yields. In this study, I report the effects of N fertilization rate and plant density on maize yield in a meta-analysis, by using observations from 15 studies conducted in Ethiopia since the 2000s for possible refinement of N fertilizer and plant density recommendations. I assessed the response of maize to different N rates ha−1 compared to the control using the yield response approach. Application of N fertilizer significantly increased maize yields by 31.5% - 65.9% compared to control. plant density increased maize yields by 42% - 72.4% compared to the control. The interaction effect of the N rate increased maize yields by 27.6% - 95.9%, with Plant density, 58.7% - 152% on loam soil, compared to control yield. The interaction effect of Plant density with soil type increased maize yields by 47% - 108% on loam soil. In conclusion, the grain yield of maize increased with increasing N rate and plant density up to the optimum. Therefore, it’s possible to recommend using a high N rate with both low and medium plant density (< 45,000 plants ha-1) and (45,000 to 65,000plants ha-1) to harvest high grain yield.

Excessive NPK inputs but low grain yield and high environmental impact are common issues in maize production in North China Plain (NCP). The objective of our study was to test whether a combined strategy of optimizing plant density, balancing NPK input, and innovating one-time fertilizer products could achieve a more sustainable maize production in NCP. Thus, a field experiment was conducted at Luanna County NCP with the treatments of unfertilized control (CK), farmer practice (FP, conventional plant density and NPK input), conventional one-time urea-based coated fertilizer (CF, optimized plant density and NPK input), and five newly designed innovative one-time NPK fertilizers of ammonium sulphate and urea synergy (IF, optimized plant density and NPK input), innovative fertilizer with various additives of urea inhibitors (IF + UI), double inhibitors (IF + DI), micro-organisms (IF + MI), and trace elements (IF + TE). The grain yield, N sustainability indicators (N use efficiency NUE, partial factor productivity of N PFPN, and N surplus), and cost-benefits analysis were examined over the maize growing season of 2020. Results had shown that on average the five innovative fertilizers (IF, IF + UI, IF + DI, IF + MI, and IF + TE) and CF that had optimized plant density and NPK input achieved 13.5%, 98.6%, 105.9%, 37.4% higher yield, PFPN, NUE, net-benefits as well as 207.1% lower N surplus compared with FP respectively. Notably, the innovative fertilizer with various effective additives (IF + UI, IF + DI, IF + MI, and IF + TE) which can be commonly found in the fertilizer market hadn’t resulted in a significant improvement in yield and NUE rather a greater cost and lower net benefits in comparison to IF. In summary, our study highlighted the effectiveness of the combined strategy of optimized plant density, balancing NPK input, and innovative NPK fertiliser on sustainable maize production in NCP, however, the innovative fertilisers with effective additives should be properly selected for better economic benefits.

Excessive NPK inputs but low grain yield and high environmental impact are common in maize production in North China Plain (NCP). The objective of our study was to test whether a combined strategy of optimizing plant density, balancing NPK input, and innovating one-time fertilizer products could achieve a more sustainable maize production in NCP. Thus, a field experiment was conducted at Luanna County NCP with the treatments of unfertilized control (CK), farmer practice (FP, conventional plant density and NPK input), conventional one-time urea-based coated fertilizer (CF, optimized plant density and NPK input), and five newly designed innovative one-time NPK fertilizers of ammonium sulphate and urea synergy (IF, optimized plant density and NPK input), innovative fertilizer with various additives of urea inhibitors (IF+UI), double inhibitors (IF+DI), micro-organisms (IF+MI), and trace elements (IF+TE). The grain yield, nitrogen sustainability indicators (nitrogen use efficiency NUE, partial factor productivity of nitrogen PFPN, and nitrogen surplus), and cost-benefits analysis were measured and calculated over the maize growing season of 2020. Results had shown that on average the five innovative fertilizers (IF, IF+UI, IF+DI, IF+MI, and IF+TE) and CF that had optimized plant density and NPK input achieved 13.5%, 98.6%, 105.9%, 37.4% higher yield, PFPN, NUE, net-benefits as well as 67.5% lower N surplus compared with FP respectively. Notably, the innovative fertilizer with various effective additives (IF+UI, IF+DI, IF+MI, and IF+TE) which can be commonly found in the fertilizer market hadn’t resulted in an improvement in yield and NUE rather a greater cost and small net benefits in comparison to IF. In summary, our study highlighted the effectiveness of the combined strategy of optimized plant density, balancing NPK input, and innovative NPK products on sustainable maize production in NCP, however, the innovative fertilizers with effective additives should be properly selected for better economic benefits.

Compost use in agriculture has the potential to increase the productivity and sustainability of food systems and to mitigate climate change. But the use of diverse compost types in unsuitable biophysical conditions cause uncertain outcomes for crop yields, soil organic carbon (SOC) and nitrous oxide (N 2 O) emissions. Here, we performed a global meta-analysis with over 2000 observations to determine whether a Precision Composting Strategy (PCS) that aligns suitable composts and application methods with target crop and environment can advance sustainable food production. Eleven key predictors of compost (carbon-to-nutrient ratios, pH, salt content), management (nitrogen supply) and biophysical settings (crop type, soil texture, SOC, pH, temperature, rainfall) determined 80% of the effect on crop yield, SOC, and N 2 O emissions. We estimate that a PCS could increase global cereal production by 354.5 Tg annually, approximately 1.7-times Africa’s current cereal yield. We further estimate that annual Carbon sequestration could increase by 170.4 Tg Carbon, approximately 20% of the global potential of croplands. This points to a central role of PCS in current and emerging agriculture consistent with the United Nations’ Sustainable Development Goals.

Composting is an important technology to treat biowastes and recycle nutrients, but incurs nitrogen (N) losses that lower the value of the final products and cause pollution. Technologies aimed at reducing N losses during composting have inconsistent outcomes. To deepen insight into mitigation options, we conducted a global meta-analysis based on 932 observations from 121 peer-reviewed published studies. Overall, N losses averaged 31.4% total N (TN), 17.2% NH3-N, and 1.4% N2O-N, with NH3-N accounting for 55% of TN losses. The primary drivers affecting N losses were composting method, type of biowaste, and duration of composting. N losses were significantly impacted by the carbon-to-nitrogen (C/N) ratio of the input materials (feedstock of nutrient dense biowastes and C-rich bulking agents), moisture content and pH. Our analysis revealed N-conserving optima with C/N ratios of 25-30, 60-65% moisture content and pH 6.5-7.0. In situ mitigation technologies that control feedstock and processing conditions reduced average N losses by 31.4% (TN), 35.4% (NH3-N) and 35.8% (N2O-N). Biochar and magnesium-phosphate salts emerged as the most effective N-conserving strategies, curbing losses of TN by 30.2 and 60.6%, NH3 by 52.6 and 69.4%, and N2O by 66.2 and 35.4% respectively. We conclude that existing technologies could preserve ~0.6 Tg of biowaste-N globally, which equates to 16% of the chemical N-fertilizer used in African croplands, or 39% of the annual global increases of 1.58 Tg fertilizer-N. However, the adoption of N-conserving technologies is constrained by a lack of knowledge of best practice, suitable infrastructure, policies and receptive markets. To realize an N-conserving composting industry that supports sustainable practices and the circular nitrogen economy, stakeholders have to act collectively. Benefits will include lowering direct and indirect greenhouse gas emissions associated with agriculture, and facilitating the recarbonization of soils.