Produção, decomposição de palhada e liberação de nutrientes por plantas de cobertura em sistemas integrados na região Meio-Norte

Abstract

Piauí and Maranhão make up the northern portion of MATOPIBA, contributing significantly to increased production in this region due to the existence of arable land still available for expansion. Agricultural areas exhibit high variability in soil types, climate, and vegetation, which directly affects soil fertility and organic matter content and stocks. In addition, the different possibilities for land use and occupation make soil and organic matter management a complex and relevant factor for the sustainability of agriculture in this part of the Northeast. Integrated systems are an important alternative for optimizing the use of natural resources with synergies between agricultural production, in the economic and environmental spheres. Although integrated systems are recognized as relevant to the sustainability of agroecosystems, research is still needed to identify promising cover crops in the challenging soil and climate conditions of the Mid-North region. The objective was to evaluate biomass production, decomposition dynamics, and nutrient release of forage grass species in consortium with corn, used as ground cover crops in integrated production systems in the Mid-North Cerrado of Brazil. The experiments were conducted in an Agroforestry System (ILF) at Fazenda Vó Desidério, in Bom Jesus-PI, in the Cerrado of Southwest Piauí, and in an Agro-Livestock System (ILP) at Fazenda Barbosa, in Brejo-MA, in Eastern Maranhão. The experimental design was randomized blocks with five treatments and four replicates. The treatments were: forage grasses of the genus Megathyrsus and Urochloa in consortium with corn and corn alone, as a control. Plant residue decomposition, grain yield and dry forage mass, and soil fertility were evaluated. The data were submitted and verified for normality and homogeneity of variances and subjected to analysis of variance. When significant, productivity data (grass biomass and corn and soybean grains) and nutrient contents were compared using Tukey's test (P<0.05). There was no significant effect on residual biomass production in Brejo-MA. In Bom Jesus-PI, M+Massai differed from the other treatments. For soil fertility after intercropping, only the chemical attributes K+

, Fe3+ and Mn in Bom Jesus and Zn in Brejo showed a difference. There was a significant effect on soybean productivity in Bom Jesus. The M+Ruziziensis intercrops in Bom Jesus provide greater availability of K+

, Fe3+ and Mn in the soil. In Brejo M+Marandu, it provides an increase in Zn. The intercropping of forage grasses of the genus Megathyrsus and Urochloa does not reduce corn productivity when intercropped. The cultivation of M+Ruziziensis in Bom Jesus and M+Tamani in Brejo, although not resulting in increased soybean productivity, shows potential as cover crops in the Cerrado of the Mid-North region of Brazil. Further studies are needed to assess the long-term effects of the interaction between the corn and forage grass intercropping system on soil fertility, nutrient cycling, and intercropping system productivity under other experimental or seasonal conditions.