Long-term Crop Diversity Improves Soil Chemical Attributes, Nutrient Cycling and Soybean Yield

Abstract

Crop diversity, particularly cover crops under no-tillage, increases agricultural efficiency in the use of nutrients and the soil carbon management. The objective of the present study was to evaluate the impact of single cover crops and intercropping (MIX) under long-term no-tillage on shoot dry mass (SDM) production, nutrient cycling, soil chemical attributes, and soybean yield in the Cerrado of Mato Grosso. The treatments consisted of MC: monocropped; CS1: Crotalaria spectabilis; CS2: Pennisetum glaucum (millet); CS3: Urochloa ruziziensis; CS4: Cajanus cajan (pigeon pea); and MIX: all four crops intercropped (C. spectabilis + P. glaucum + U. ruziziensis + C. cajan). The shoot dry mass of the cover crop was evaluated at 0, 90, 105, 120, 150, 180, and 210 days after cover crop management (CM) (desiccation) in the crop years from 2014/15 to 2020/21. The chemical properties of the soil were evaluated after the 2019/20 soybean crop harvest. SDM accumulation in MIX was approximately 22% higher than that in CS2 and CS3 and 60% higher than that in MC. Soybean yields were 20% higher in MIX, CS3, and CS4 than in MC, corresponding to an increase of approximately 14 bags of soybean. MIX and CS3 improved soil chemical attributes through nutrient cycling and SDM production under long-term no-tillage. MIX, CS3, and CS4 promoted increases in soybean yield after the stabilization phase of the system. The accumulation and release of nutrients by the shoots was an important indicator of nutrient cycling under no-tillage and consequent increases in the yield of soybean in succession.