Diversified production systems in sandy soils of the Brazilian Cerrado: nutrient dynamics and soybean productivity

Abstract

Increased functional diversity, given by the Integrated Crop-Livestock System (ICLS), is an alternative of quantitative and qualitative technical evolution for soybean (Glycine max) cropping in sandy soils. The objective of the present research was to investigate production systems with different levels of functional diversity in sandy soils of the Brazilian Cerrado regarding their (a) soil microbiological activity, (b) macronutrient accumulation and release, and (c) soybean yield. The experimental design was randomized blocks with three replications and the treatments corresponded to different levels of functional diversity: very low (Fallow), low (Ruziziensis), medium (Ruziziensis, niger, radish and rattlepod), and high (Ruziziensis, niger, radish and rattlepod with animal entrance). The plants were desiccated and the phytomass contained within a frame was collected at ground level. The evaluation of phytomass decomposition and nutrient release was performed at 0, 15, 30, 60, 90 and 120 days after desiccation (DAD) of the plants. Functional diversity levels increase the carbon content of the microbial biomass in the sandy soil, with an emphasis on systems with high plant diversity and the presence of animals. High functional diversity with the presence of the animal results in higher rates of phytomass decomposition and nutrient release with a shorter half-life (t 1/2=85 DAD), mainly with respect to potassium. This functional diversity increases soybean yield by up to 25% in the high diversity system compared to a system with very low diversity. The high functional diversity in ICLS enriches soil microbiological quality and increases soybean productivity in the sandy soil in the short term.