Abstract
ABSTRACT Research on the performance of cover crops in crop systems of annual crops in the Brazilian state of Piauí contributes to increases in yield, greater efficiency of fertilizers and mitigation of environmental impacts. The aim of this study was to evaluate the performance of cover crops in terms of biomass production and the accumulation and release of nutrients during the crop season (November to April) in an oxisol in the Brazilian Cerrado in the state of Piauí that was submitted to different crop production systems including soybeans, maize and upland rice. The experiment was established during the 2010/11 and 2011/12 crop years in the rural area near the municipality of Bom Jesus, Piauí. The experimental design was a randomized block in a split-plot array. Different soil management systems (conventional and no-till) were evaluated in the main plots. Different crop production systems consisting of cover crops sown in the off-season (April to November), and annual crops sown during the crop season (November to April) were implemented in the subplots. The crop production systems that included Urochloa ruziziensis and Pennisetum glaucum overseeded on soybeans and Urochloa ruziziensis simultaneously intercropped with maize stood out in terms of biomass production and the accumulation and release of nutrients. Yields of maize and upland rice declined when sown under newly implemented no-till soil management.
Highlights
The Brazilian state of Piauí has emerged as one of the frontiers of agricultural expansion
At the moment of desiccation (0DAD), the treatments submitted to SPD allowed a significant presence of biomass on the soil surface, which resulted in high TCS
Crop systems that used overseeding of soybean with U. ruziziensis (S3) and P. glaucum (S4) and that involved U. ruziziensis intercropped with maize (S5) were the most promising, attested by values of FS ranging from 10,800 kg ha-1 to 12,700 kg ha-1 and 100% TCS
Summary
The Brazilian state of Piauí has emerged as one of the frontiers of agricultural expansion. Another relevant factor is the recalcitrance of the residues on the soil surface, which is related to the C/N ratio, and other recalcitrant compounds from biomass (CARVALHO et al, 2011) In this system, cover crops contribute to protect the soil from weather agents, sequester atmospheric carbon, increase the soil organic matter, and mobilize and recycle nutrients. Considering that frequent dry spells that occur in the agricultural area of the Brazilian Cerrado of Piauí during the development of annual crops, the presence of biomass on the soil surface contributes significantly to increasing the efficiency of water usage (CARVALHO et al, 2011)
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