Acúmulo de nutrientes e produção do feijoeiro irrigado sob doses de nitrogênio em semeadura e cobertura

Abstract

Nitrogen (N) is the most absorbed nutrient by bean plants, its management is considered one of the most difficult one because of its wide dynamic in soil- plant system. The aim of this study was to evaluate the production and accumulation of nutrients in doses and growth stages of winter common bean. The statistical design was in randomized blocks with three replications in a 4 x 4 factorial scheme, corresponding to four levels of nitrogen in sowing (0, 40, 80 and 120 kg ha¹) and four levels of nitrogen topdressing (0, 40, 80 and 120 kg ha ). The following characteristics were evaluated: number of pods per plant, number of seeds per pod, average weight of 100 grains, final stand, grain yield and nutrient content. Each plot consisted of 6 rows of 5 m long, with spacing of 0,5 m between rows, being considered as useful area the four central lines, ignoring 0,5 m at both borders. The fourth and fifth lines were used for evaluation of production and grain yield, while the second and third lines were used to assess the nutrient content. Data were subjected to analysis of variance by means of the SAEG 8.0 program and when significant (p <0,05) it was performed regression analysis for the doses of N on sowing and topdressing for evaluated characteristics. The unfolding of the N levels in sowing versus topdressing for the studied traits was graphically described by the response surface. The applications of 72,52 kg ha N in sowing and 25,96 kg ha topdressing provided the highest yield (3.534 kg ha). The application of topdressing N provided the highest accumulations of grains/pod and pods/plant. Nitrogen doses in sowing resulted in the highest accumulation of macro and micronutrients. The order of decreasing nutrient uptake by bean plants was: K > N > Ca > S > P = Mg > Zn > Mn Fe > Cu. The decreasing nutrient export order by bean grains was: N > K > P > Ca > S > Mg >Zn > Mn > Cu > Fe.