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During the 1993-94 cotton season, two irrigated farming system experiments were established in NSW. One at 'Auscott' Warren and the second at 'Beechworth' located at Merah North. These two experimental sites were the initiative of the CRC for Sustainable Cotton Production. The sites are now starting to provide valuable insight into the effects and...
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... By definition, a permanent bed implies that the bed stays in place for several seasons in comparison with being ploughed down and reconstructed every year as with more intensive tillage systems (McGarry, 1995;McKenzie et al., 2003). Long-term use of permanent beds can lead Queensland (82%) sow either a cereal or leguminous crop in rotation with cotton (Doyle and Coleman, 2007), with most (70-75%) sowing wheat (Triticum aestivum L.) (Cooper, 1999;Hickman et al., 1998). This may be because the combination of wheat rotation crops and permanent beds was far superior to cotton monoculture and cotton-legume rotations sown either on permanent beds or after conventional tillage in maintaining soil physical and chemical quality (Hulugalle and Scott, 2008). ...
Comparative studies of drainage and leaching under tillage systems in irrigated tropical and sub-tropical Vertisols are sparse. The objective of this study was to quantify drainage under cotton-based cropping systems sown on permanent beds in an irrigated Vertisol. Drainage and soil water storage were measured with the chloride mass balance method and neutron moisture meter, respectively, during the 2002-03, 2004-05, 2006-07 and 2008-09 cotton seasons in an on-going experiment in a Vertisol in NW NSW. The experimental treatments were: cotton monoculture sown either after conventional tillage or on permanent beds, and a cotton-wheat rotation on permanent beds where the wheat stubble was retained as in situ mulch into which the following cotton crop was sown. Subject to in-crop rainfall, irrigation frequency varied between 7 and 14 days for cotton and 2-3 months for wheat. In 2005, a split-plot design was superimposed on the existing experiment such that the main-plot treatments were irrigation frequency ("frequent", 7-14-day irrigation interval; "infrequent", 14-21-day irrigation interval), and sub-plot treatments were the historical tillage system/crop rotation combinations. In comparison with cotton monoculture sown either after conventional tillage or on permanent beds, soil water storage, particularly during the early part of growing season when rainfall provided the major proportion of crop water requirements, and drainage were greatest when a cotton-wheat rotation was sown on permanent beds. Seasonal drainage out of the 1.2Â m depth, averaged among all seasons, was of the order of 25Â mm, 33Â mm and 70Â mm with cotton monoculture sown either after conventional tillage or on permanent beds, and a cotton-wheat rotation on permanent beds, respectively. Soil water storage and drainage were also greater when irrigation frequency was greater. Seasonal drainage out of the 1.2Â m depth, averaged between the 2006-07 and 2008-09 seasons, was 54Â mm with "frequent irrigation", and 28Â mm with "infrequent" irrigation. Infiltration was less in management systems which resulted in wetter soil; viz. frequent irrigation or a cotton-wheat rotation on permanent beds with in situ stubble retention. Drainage water losses in a furrow-irrigated Vertisol may be reduced and soil water storage increased (i.e. water conservation improved) by sowing a cotton-wheat rotation with in situ stubble retention under less frequent irrigation.
... A survey of 155 cotton farms (100% of the irrigated cotton area in the central-west and 54% in the north-west of New South Wales) conducted during December 1992 indicated that 53% and 81% of cotton growers in the central-west and north-west, respectively, of New South Wales frequently sowed rotation crops after cotton (Cooper 1999). A follow-up survey in 1998 indicated that the proportions of growers practicing rotation cropping were similar (~79%) in both regions (Hickman et al. 1998). The most recent survey, which was conducted during the 2005-06 cotton season, indicated that in both New South Wales and Queensland, rotations were used by 82% of cotton growers (Doyle and Coleman 2007). ...
... This survey also indicated that 97% of cotton growers in the Namoi valley and 88% in the southern cotton regions (Macquarie and Murrumbidgee valleys) of New South Wales sowed a rotation crop at least once in 3 years, whereas in the northern cotton regions (Darling Downs, Dawson valley, Emerald) only 66% did so. Wheat was the favoured rotation crop in irrigated systems, with 71% of cotton growers who sowed rotation crops in the central-west and 74% in the north-west of New South Wales sowing wheat in either a 1 : 1 or 2 : 1 cotton-wheat rotation (Hickman et al. 1998;Cooper 1999). Cereal crops also dominate the rotations used by dryland cotton growers, with 51% preferring winter cereals such as wheat and barley, 8% summer cereals such as sorghum and corn, and 16% summer and winter cereals (Walker et al. 2005). ...
... Cereal crops also dominate the rotations used by dryland cotton growers, with 51% preferring winter cereals such as wheat and barley, 8% summer cereals such as sorghum and corn, and 16% summer and winter cereals (Walker et al. 2005). The 1992 survey indicated that legumes such as field pea (Pisum sativum L.) and soybean were preferred as rotation crops by 13% of cotton growers in the central-west, wheras 6% in the north-west (increasing to about 10% by 1998) preferred legumes such as soybean, field pea, faba bean (Vicia faba L.), chickpea (Cicer arietinum L.), and dolichos (Lablab purpureus L.) (Hickman et al. 1998;Cooper 1999). Walker et al. (2005) in their 2001 survey of dryland cotton growers noted, however, that only 2% used legumes alone as rotation crops, whereas 16% used a combination of legumes and cereals. ...
In agricultural systems, soil quality is thought of in terms of productive land that can maintain or increase farm profitability, as well as conserving soil resources so that future farming generations can make a living. Management practices which can modify soil quality include tillage systems and crop rotations. A major proportion of Australian cotton (Gossypium hirsutum L.) is grown on Vertosols (~75%), of which almost 80% is irrigated. These soils have high clay contents (40-80g/100g) and strong shrink-swell capacities, but are frequently sodic at depth and prone to deterioration in soil physical quality if incorrectly managed. Due to extensive yield losses caused by widespread deterioration of soil structure and declining fertility associated with tillage, trafficking, and picking under wet conditions during the middle and late 1970s, a major research program was initiated with the objective of developing soil management systems which could improve cotton yields while concurrently ameliorating and maintaining soil structure and fertility. An outcome of this research was the identification of cotton-winter crop sequences sown in a 1:1 rotation as being able to sustain lint yields while at the same time maintaining soil physical quality and minimising fertility decline. Consequently, today, a large proportion (~75%) of Australian cotton is grown in rotation with winter cereals such as wheat (Triticum aestivum L.), or legumes such as faba bean (Vicia faba L.). A second phase of research on cotton rotations in Vertosols was initiated during the early 1990s with the main objective of identifying sustainable cotton-rotation crop sequences; viz. crop sequences which maintained and improved soil quality, minimised disease incidence, facilitated soil organic carbon sequestration, and maximised economic returns and cotton water use efficiency inthe major commercial cotton-growing regions of Australia. Theobjective of this review was tosummarise thekey findingsofboththese phasesof Australianresearch with respect tosoilqualityandprofitability, and identify future areas of for research. Wheat rotation crops under irrigated and dryland conditions and in a range of climates where cotton is grown can improve soil quality indicators such as subsoil structure, salinity, and sodicity under irrigated and dryland conditions, while leguminous crops can increase available nitrogen by fixing atmospheric nitrogen, and by reducing N volatilisation and leaching losses. Soil organic carbon in most locations has decreased with time, although the rate of decrease may be reduced by sowing crop sequences that return about 2kg/m2.crop cycle of residues to the soil, minimising tillage and optimising N inputs. Although the beneficial effects of soil biodiversity on quality of soil are claimed to be many, except for a few studies on soil macrofauna such as ants, conclusive field-based evidence to demonstrate this has not been forthcoming with respect to cotton rotations. In general, lowest average lint yields per hectare were with cotton monoculture. The cotton-wheat systems generally returned higher average gross margins/ML irrigation water than cotton monoculture and other rotation crops. This indicates that where irrigation water, rather than land, is the limiting resource, cotton-wheat systems would be more profitable. Recently, the addition of vetch (Vicia villosa Roth.) to the cotton-wheat system has further improved average cotton yields and profitability. Profitability of cotton-wheat sequences varies with the relative price of cotton to wheat. In comparison with cotton monoculture, cotton-rotation crop sequences may be more resilient to price increases in fuel and fertiliser due tolower overall input costs. The profitability of cotton-rotation crop sequences such as cotton-wheat, where cotton is not sown in the same field every year, is more resilient to fluctuations in the price of cotton lint, fuel and nitrogen fertiliser. This review identified several issues with respect to cotton-rotation crop sequences where knowledge is lacking or very limited. These are: research into 'new' crop rotations; comparative soil quality effects of managing rotation crop stubble; machinery attachments for managing rotation crop stubble in situ in permanent bed systems; the minimum amount of crop stubble which needs to be returned per cropping cycle to increase SOC levels from present values; the relative efficacy of C3 and C4 rotation crops in relation to carbon sequestration; the interactions between soil biodiversity
... The most recent survey (2005/06 season) indicated that across the industry rotations were used by 82% of cotton growers (Doyle and Coleman, 2007). Wheat was the favoured rotation crop with over 70% of NSW cotton growers who used rotation crops growing either a 1:1 or 2:1 cotton:wheat rotation (Hickman et al., 1998;Cooper, 1999). ...
