Efeitos de fontes, doses e épocas de aplicação de adubos nitrogenados sobre a cultura do feijão (Phaseolus vulgaris L.)

Resumo

Ammonium sulphate, sodium nitrate, and urea were applied at the rate of 60 kg/ha of N to dry bean culture, on a sandy clay loam soil of medium fertility. The experimentalarea had received an application of 1 ton of dolomite per hectare one month earlier. The area also received a uniform application of P and K in the row at planting time. The N-bearing fertilizers were applied using the following three methods: (a) 1/2 of the total amount at planting time and the other 1/2 ten days after emergence of the bean plants; (b) 1/3 at planting time, 1/3 ten days after emergence,and 1/3 twenty five days after emergence; (c) none at planting time, 1/2 ten days after emergence, and 1/2 twenty five days after emergence. This study was carried out in the so-called "rainy season" and "dry season". 

In other dry bean experiments in both "seasons" on medium clay loam soil, ammonium sulphate, sodium nitrate, urea, ammonium chloride, and diammonium phosphate were applied. Liming (only in the "dry season") and PK fertilization were similar tothe abovetrials. Each N-bearing fertilizer was applied as follows: 20, 40, 60, and 80 kg/ha of N, a portion applied in the row at planting and another in side-dressing form.

During the development of the plants, there was a shortage ofrain in the two planting "seasons'!, impairing seriously the crop.

It can be concluded that: (1) the absence of an application ofnitrogen fertilizer in the row at planting time impaired the drybean crop; (2) the ammonium chloride was damaging to the crop, possibly because of the chlorine it adds to the soil; (3) the other nitrogen fertilizers were similar in the effects they produced; (4) there was no effect due tothe quantity of the nitrogen fertilizers, with the exception of the final stand, which was thinner with higher quantities.