Acumulation of dry matter, N, P and K in cowpea grown under minimum and conventional tillage in a mollisol of Venezuela

Abstract

The knowledge of the pattern of dry matter (DM) production and nutrient uptake by cowpea, Vigna unguiculta, could be useful to improve the quantity and application time of fertilizers. We evaluated the accumulation of DM, N, P, and K in leaf, stem, grain, pod, and foliar area (FA) a the 15, 29, 43, 58, and 73 days after germination (DAG) in cowpea (variety Tuy), sowed under minimum (MT) and conventional tillage (CT), in a Mollisol soil located at Aragua state in Venezuela, in an experiment of random block design with three repetitions. In each sampler time, three plants were collected in each experimental unit. We found that the patter of DM accumulation and of nutrient uptake was similar between MT and CT, and in average 69% of the DM, and 92, 79, and 78% of the N, P, and K were accumulated in the period between 43 and 58 DAG. The DM, N, P, and K in CT were statistically greater than in MT at the 15 and 58 DAG for N, at the 58 DAG for P, and 43 and 58 DAG for K. The ratio FA/DM were similar in CT and MT: in average, it decreased since 412.95 cm2/g DM at the 15 DAG, until 72 cm2/g DM at the 58 DAG. The P, K, and N took up, individually, explain between 99 and 94%, 98 and 90%, and 73 and 37% of the variation in DM in CT and MT respectivelly.