Efeito de fontes e níveis de fósforo em cunhã - Clitoria ternatea, L., na região do sertão central cearense

Abstract

This paper reports research on the effects on cunhã (Clitoria ternatea, L.) of three sources of phosphorus (superphosphate, triple superphosphate and phoscal 10) in five levels (30, 60, 90, 120 and 150 kg/ha of P2O5) added to the soil. Sources and levels were tested in a 15-treatment experiment in randomized blocks with four replicates and one extra zero treatment with no phosphorus added to the soil. The experiment was planted in the "Posto Experimental de Área Seca" of the National Departament of Dry Areas (DNOCS/DR2) in Quixadá, in the interland of Ceará State, in podzolic soil (this type of soil is typical of 28,9% of the State area); average yearly rainfall in Quixadá is 680 mm; the experiment was performed under dryland conditions. Analysis of the experimental results allowed the following conclusions about cunhã: 1 - it is a forage legume with low phosphorus requirement; 2 - it has a good dry matter and crude protein production ability for the Brazilian Northeastern Region; 3 - it shows uniformity of production in successive years; 4 - it may be cultivated possibly under dryland conditions with a light potassium fertilization on about 28,9% of the Ceará State area (podzolic soils). It was also shown that the amount of available soil phosphorus increases linearly with increasing additions of fertilizers.