Avaliação da eficiência de diversos produtos na recuperação de um solo salino-sódico e seus efeitos na cultura de arroz (Oryza sativa L.).

Abstract

The present study was carried out with the objective to evaluate effects of different products (gypsum, farm yard manure, sulphuric acid and polimaleic acid) in reclamation of saline sodic soil and in growth and yield of irrigated rice (Oryza sativa L.) during the period of Aug. 1996 to Jan. 1997 at Experiment Station of EMBRAPA Cotton localised in Irrigation District of Sao Goncalo-PB/Brazil. A completely randomised design with 5 treatments and 5 replications each of 1 Ox 10m was adopted for the experiment. After soil preparation and construcion of dike, around the experimental plots, the treatment in corresponding doses (gypsum 10 T.ha"1, •sulphuric acid 320 L. ha"1, polimaleic acid 6 L. ha"1, farm yard manure 20 T. ha"1, and control) were applied. After incorporation of products in soil, 8 cm water layer was maintained during 35 days and afterwards transplanting of rice seedlings, 3 per whole, at a spacing of 0,25x 0,10 m, was performed. Nitrogen fertilization at the rate of 80 kg N, ha"1 was done in 3 split doses. The incorporation of products resulted in improvement of soil structure with consequent decrease in disperse clay content and incrase in degree of floculation and hydraulic conductivity. The electrical conductivity of saturation extract and percentage of exchangeable sodium (ESP) decreased in all treatments and gypsum showed best results. Nevertheless, pH did not show appreciable variations in any treatments. All products used in this study, except sulphuric acid, showed significant effects in growth and yield of rice with an average yield of 4,5 T. ha"1. The analysis of soil samples collected after harvest confirmed contribuition of rice crop in reduction of ESP in all treatments.