Efeito do gesso, fósforo e adubo verde na absorção de nutrientes pelo feijoeiro (Vigna unguiculata (l.) (walp) cultivado em solo salino sódico.

Abstract

The process of physical and chemical degradation of the soils for salts and sodium is one of the main limitations faced by the producer in irrigated areas. Several techniques have been used in the attempt of recovery of the productive power of these soils, among them, the application of correctives and organic matter. The objective of this work was to evaluate the influence of the gypsum, phosphorus and vegetable residue in the growth and absorption of nutrients of the bean vigna (Vigna unguiculata (L.) Walp.) cultivated in a saline-sodic soil of the section 10 of the Irrigated Perimeter of São Gonçalo-PB. The experiment was led in greenhouse of CSTR/UFCG, being used saline-sodic soil, in factorial outline 4 x 2 x 2, corresponding to four doses of agricultural gypsum (zero; 33; 67 and 100% of the need of gypsum calculated in agreement with the chemical attributes of the soil); two phosphorus doses, through phosphoric acid (zero and 200mg kg-1) and two of pricked vegetable residues (00 and 35 g.vaso-1), distributed entirely in random design with four repetitions. As green fertilizer was used the legume Black Mucuna (Stizolobium aterrimum Piper& Tracy). The legume was pricked and incorporated together with the doses of gypsum in your respective vases. After that stage the vases were incubated to 70% of the field capacity for 60 days. After the incubation the soil was washed in the vases by 72 h, and it was proceeded the application of the phosphorus doses, to sow of the bean and application of nitrogen through urea, as basic fertilization. After 50 days of the germination, the plants were cut, evaporated in greenhouse and analyzed with relationship to the production of dry mass and the contents of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), iron (Fe), copper (Cu), manganese (Mn) and zinc (Zn) in the aerial part of the bean plant. The application of P through phosphoric acid increased the vegetable production and the contents of P, Ca, Mg, S, Fe and Mn; it didn't influence the content of N and it reduced the contents of K, Cu and Zn. The doses of gypsum didn't modify the vegetable production and the content of Zn; they increased the contents of Ca, S, Mn and Cu; they reduced the contents of P, K, Mg, Fe and they promoted the reduction of the content of N in the presence of P and green fertilizer and increase in the presence of P and green fertilizer. The green fertilizer reduced the contents of Ca and Mg in the presence of phosphoric acid, not altering any other variable significantly.