Correção de solos salino-sódicos e seu efeito no crescimento inicial do cajueiro anão-precoce (Anacardium occidentale L.).

Abstract

Correction of saline-sodic soils and its effect on early growth of early dwarf cashew (Anacardium occidentale L.). The degradation for salts in the soils of irrigated perimeters of the semi-arid proportion reduction of the agricultural production and I abandon of the lots. The reintegration of those areas to the agricultural exploration is constituted in priority goal to solve that it records social-economicalenvironmental problem. The research had as objective verifies the effect of the agricultural gypsum in the characteristics chemistries of soils saline-sodic of several areas and in the initial growth of clones of dwarf-precocious cashew tree. The research consisted of the installation of two experiments in different periods, 2001 and 2002, in greenhouse in the Center of Health and Rural Technology with originating from soil the Irrigated Perimeter of Sao Goncalo. In the experiment I the treatments understood 2 levels of gypsum (0 and 100% of the maximum need), soils of 5 areas (7/1, 8/1, 9/1, 9/3 and 10/3), 1 clone (CCP 06) and 3 repetitions totaling 30 vases with capacity for 10 Liters of soil. The experiment I I consisted of 3 levels of gypsum (0, 100 and 200% of the maximum need), 2 cashew tree clones (CCP 76 and CCP 1001) and 4 repetitions, totaling 24 vases with capacity for 4 Liters of soil, collected in the area 10/17 of the Irrigated Perimeter of Sao Goncalo. In both experiments, after 15 days of incubation of the vases with the correctives and with 70% of CC, and after the wash of the soil (150%CC), they were CE 1:5, PST, Na and pH. The seedlings produced they were transplanted for the soils, where they were made weekly measurements of height and diameter during 120 and 112 days for the first and second experiments, respectively. The results showed that the application of gypsum to the soil allows a larger leaching of salts, it reduces the electric conductivity, the pH and the percentage of exchangeable sodium and it increases the exchangeable contents of Ca+2 and Mg+2. The cashew tree seedlings cultivated in soils degraded by salts and sodium they presented severe deficiency symptoms in nutrients. The clone CCP 1001 presented a larger growth in height in relation to CCP 76 after 90 days. The gypsum reduced the tenors of sodium and it increased the one of potassium in the leaves of the cashew tree clones CCP 76 and CC 1001.