Nitrogen fertilizers for the sugar cane

This paper presents the results from a fertilizer trial comparing nitrogen sources for the sugar cane. It was carried out at the Estação Experimental de Ribeirão Prêto, Instituto Agronômico de Campinas, on a "terra roxa" type of soil. This nitrogen was applied at the rate of 120 kg per hectare split three times as top-dressings. Phosphorus was applied in the furrow at planting time whereas half of the potassium was applied with the phosphorus and half with the nitrogen as a top-dressing. The PK fertilizers were applied at the rates of 120 and 180 kg of the element per hectare, respectively. The treatments and correspondig yields were the following in ton per hectare: a) PK________________________________ 113_0 b) PK + ammonium sulfata ______________ 134_8 c) PK + calnitro _______________________ 136_3 d) PK + uréa ___________________________ 133_6 The statistical analysis of the data permitted the following conclusions to be drawn: a) The mean efiect of the nitrogen obtained comparing the mean oi nitrogen sources with the control (PK) was of 19.4%. b) The differences between the sources of nitrogen applied were not significant, indicating that the choice should be based on the unitary price of the nitrogen.