Macronutrients in cowpea cultivated under two doses of phosphorus and different planting times

摘要

The objective of this research was to evaluate the effect of the soil preparation system on the nutrition of cowpea (Vigna unguiculata L.) due to environmental alterations caused by different planting times. The study was conducted in an experimental field in Igarapé-Açu, Pará. Four planting times and two fertilizations were tested, in randomized blocks and subdivided plots. The evaluation of the nutritional state of the cowpea crop was accomplished at the harvest. The macronutrient concentrations in the plants, green beans and in the grains were determined. In the plants and in the green beans, the largest observed concentrations were of K, N and Ca, while in the grains they were of N, K and P. The concentrations of the nutrients were affected significantly by the planting times, but this did not impede the observation of concentrations considered appropriate in the plants and cowpea grains for most of the appraised nutrients. The manuring with larger doses of P significantly increased the concentrations of most of the nutrients in the different parts of the plant.