Teores de nitrogênio em folhas de cafeeiro, em relação à adubação química. I- Latossolo roxo transição para latossolo vermelho amarelo orto

Abstract

Resultados de análises foliares obtidos durante cinco anos em ensaio de adubação química nitrogenada em café, cultivar Mundo Nôvo, instalado em Latossolo Roxo transição para Latossolo Vermelho Amarelo orto, reve- laram, para amostras colhidas no verão, teores médios de 2,8% a 3% de nitrogênio total como indicativos de uma nutrição adequada. Produções elevadas de frutos estiveram associadas com teores da ordem de 500 ppm de nitrogênio nítrico nas fôlhas. A análise de fôlhas para ambas as formas de nitrogênio mostrou que a aplicação do adubo nitrogenado em pelo menos três parcelas, no perío- do que vai de outubro a março, parece importante para prevenir a deficiência.

Nitrogen is highly demanded by coffee (Coffea arabica L.) plants, and previous survey, made by foliar analysis, indicated that most of them, grown in São Paulo State, suffer nitrogen deficiency. A study was made to observe the variation of the total and nitric nitrogen, as judged by foliar chemical analysis, in relation to the type, amount and the timing of the application of several different nitrogen fertilizers (Nitrocálcio, nitrate of soda from Chile, ammonium sulphate, and urea). The experiment, a factorial of 4 x 4 x 4 , was installed in a mixture of Latosolic B "Terra Roxa" and Ortho Red-Yellow Latosol at Experimental Center of Campinas, SP. The amount of the fertilizer used was 45, 90, 135 and 180 g N/plant, subdivided in 1 to 4 applications throughout the year. P O (120 g) and K 0 (180 g) were uniformly applied to all plants. Leaf samples were collected at 45 days intervals between October and March, and another at July, from 1964 to 1969. 2 5 2 The results of the analysis indicated that: (a) sampling during summer (January-March) is better to evaluate nitrogen deficiency in coffee; (b) total nitrogen content of 2.8-3% (and about 500 ppm of nitric N) was correlated to a production of more than 2,500 kg/ha of treated beans; (c) the subdivision of the fertilizers applied, at least 3 times during the rainy season, seemed to be important to avoid N deficiency.