Levantamento de cafezais do estado de são paulo pela análise química foliar II— Solos podzolizados de lins e marília, latossolo roxo e podzólico vermelho amarelo orto

Abstract

Em amostras de 134 cafèzais, distribuídos nos principais grupos de solos do Estado de São Paulo, colhidas em três estações do ano, foram determinados 12 elementos químicos essenciais, sódio e alumínio. A percentagem de cafèzais deficientes em nitrogênio foi superior a 80% em todos os solos. No Podzolizado de Lins e Marília, o segundo elemento em falta foi o ferro. No Latossolo Roxo, depois do nitrogênio, a maior deficiência foi a de potássio e zinco; no Podzólico Vermelho Amarelo-Orto, a de boro.

Roughly, coffee fields are distributed on. the main types of soil in the State of São Paulo as follows: Podzolized Soils of Lins and Marilia, 70%; latosolic B "Terra Roxa", 15%; Ortho-Red Yellow Podzol, 10%; other types, 5%. This paper presents and discusses data on foliar analyses of coffee, plants cultivated on the 3 first soil types. It complements a previous survey made on red-yellow ortho podzol. Leaf samples were collected in the spring, summer and fall, from 134 "Mundo Novo" coffee fields. Besides the content of 12 essential elements, amount of Na and Al were also determined in these samples. Fe, Zn, Mn, and Cu were determined by atomic absorption spectro- photometry. The first 3 elements were determined in a wet digest of 0.5 g of dry plant material with a mixture of HNO -H SO -HC10 , in a final volume of 20 ml. Determination of Cu, on the other hand, required an extract obtained by dissolving in 10 ml of 0.25N HC1, ashes from 1.25 g of dry leaf tissue, incinerated at 500°C for 2 hours. The same extract used for Fe, Zn and Mn analyses served for Na and Al determination. However, content of Al was estimated by colorimetric method of Aluminon (1) whereas amount of Na was determined by flame emission photometry (2). The remaining elements — N, P, K, Ca Mg, S-S0 , B and Mo — were determined according to the process described by Lott et al (4, 5). 3 2 4 4 4 Evaluation of the nutritional condition of the coffee fields in each soil type was based upon the amount of the elements present in the leaf tissue sampled in the summer, compared to the levels considered as critical (4). The results of these evaluations showed a high proportion of plants defficient in nitrogen, in all soil types, indicating the importance of nitrogen fertilization. In Podzolized Soils of Lins and Marilia, attention should be given to Fe, Ca and Zn defficiency; there is also the possibility of toxic effects induced by excess of Mn in such soils. Besides N defficiency, latosolic B "Terra Roxa" had frequently defficiency of K and Zn, while Ortho-Red Yellow Podzol, of boron.