Ensaios de adubação química do feijoeiro

Resumo

Three bean fertilizer trials are reported using combinations of N, P, and K. The work was done in the counties of Muriaé, Viçosa, and Inhapim, in the State of Minas Gerais clayey “massapé” soils.

1) In Muriaé the effect of superphosphate, potassium chlorate aud mixtures of the two were tested using the fertilizer in direct contact with the seed. All treatments were made with seeding in hills. Thirty-five kg/ha. of K.O as potassium chlorate (1 dose) gave a similar reduction in stand as 60 kg/ha of P,O; as superphosphate (1 dose). The loss of stand using either phosphate or potash or a mixture of the two was approximately 40% with 1 dose, 60% with 2 doses, 65% with 3 doses, and 75% with 4 doses.

2) In Viçosa, where the fertilizer was separated from the seed, only phosphorus increased yield. The bean crop fertilized gave a response of 31/2 times to 1 dose of P,Os (60 kg/ha) and 5 times to 2 doses. The residual effect on a crop planted 7 months later was equal between levels, about double that of the check plots. No residual effect was found with a third crop planted a year alter the original.

3) In Inhapim, phosphorus at a rate of 80 kg/ha of P:0s increased the yield approximately 170 kg/ha or 28%. No effect of nitrogen or potassium was found.