Rendimiento del doble cultivo anual trigo/soja en función de los años de agricultura continua

The anticipated increase in global food demand for the coming years must be met within current agricultural land, as the incorporation of new areas entails high environmental costs. The country's climate makes double annual cropping possible due to water availability and year-round temperature conditions. Sustainable agriculture has revived interest in crop rotation and the incorporation of pastures into the rotation. In Uruguay, deteriorating soil fertility and erosion are factors that significantly limit crop production. Tillage systems and crop rotation are management practices that can modify soil quality. The objective of this study is to evaluate the effect of soil quality as a determinant of the gap between current yield and that achievable when nutrient input is unrestricted. The experimental design involved plots divided into three randomized complete blocks. The larger plot was assigned five soil management history (HMS) treatments, while the smaller plot was assigned fertilizer management. The HMS treatments applied were LCP: conventional tillage, 50% of the time in crops, 50% of the time in pastures, with soybeans predominating in the agricultural phase; SDPsj: direct seeding, rotation with pastures and soybeans predominating; SDCsj: direct seeding, continuous cultivation and soybeans predominating; SDCsj-bch: direct seeding, continuous cultivation and high frequency of soybean-fallow; and SDCsg: direct seeding, continuous cultivation and sorghum predominating. Developing a continuous cultivation system under direct seeding and with a high frequency of first-crop soybeans in the rotation causes a deterioration in the physical properties of the soil, negatively affecting penetration resistance. It also negatively affects soil water infiltration, as does conventional tillage in rotation with pastures. Continuous cropping sequences under no-till cultivation with a predominance of sorghum maintain elevated levels of soil water infiltration. Incorporating no-till pastures into the rotation maintains higher surface COS, while conventional tillage or no-till cultivation with a predominance of early soybean in the sequence would result in lower COS levels, deteriorating soil fertility. Crop yields for wheat, soybean, and the wheat/soybean sequence were not significantly affected by any of the HMS treatments evaluated. Multivariate analysis quantified the positive impact of maintaining soil carbon and stable aggregates greater than 2 mm on wheat yield, and soil water infiltration on soybean yield. HMS, defined by no-till cultivation, would maintain better soil quality compared to conventional tillage. Treatments that incorporate pastures or grasses into the rotation show better results in maintaining soil quality.