Planting spacings and sowing dates may influence nutrient absorption. Therefore, a field experiment was carried out from 1991 to 1992, at the experimental station of Embrapa/Soil Research National Center, located in Senador Canedo, Goiás, Brazil, to determine the N, P and K uptake levels in the aerial part of sunhemp (Crotalaria juncea), Crotalaria ochroleuca, black velvet bean (Mucuna aterrima) and pigeonpea cv. Kaki (Cajanus cajan), under three sowing times (beginning, middle and end of the growing season) and two spacings between the planting rows. The experiment was arranged in a randomized split plot design, with three replications, with the sowing dates in the main plots and the planting spacings in the split plots. The results indicated that there the levels of N, P and K uptake varied among the species. N, P and K uptake levels in the legume shoot dry matter were influenced by the sowing times, and the species x sowing time interaction was significant for N and P. Nevertheless, N, P and K uptake levels were not influenced by the spacings between the planting rows.
population; nitrogen; phosphorus; potassium; Crotalaria juncea; Crotalaria ochroleuca; Mucuna aterrima; Cajanus cajan