Desenvolvimento de cebola e atributos químicos de dois neossolos flúvicos irrigados com águas salinas

Abstract

The increasing demand for food has made the use of irrigation imperative in the world, especially in semi-arid regions, such as the Northeast, where water deficit occurs in the soil during most of the year. One of the most relevant aspects, regarding the success of irrigation and agricultural practice concerns the quality of irrigation water, especially in cases of arid and semi-arid areas, where there may be an increase in the salt concentration, degrading the soil, and thus preventing the production. This study aimed to assess the development of onion (Allium cepa L.) and degradation of soils of different textures of semi-arid region of Pernambuco under irrigation with saline solutions. Two soils were studied irrigated with solutions to meet the three values of EC and six of SAR, and combined treatments of salinity. Thus the experiment consisted of a factorial arrangement 2 x 3 x 6 (two soils, three EC and six SAR), in four replicates, counting 144 experimental units. The experimental design was randomized blocks, with one repetition per block. Seedlings were used for onion cultivar IPA 11. The samples of soil, plant and leachate were performed monthly, totaling three collections at the end of the cycle of onion. There was a reduction in the variables of growth in terms of increasing the electrical conductivity of the solution irrigation in the three phases of development of the culture studied. The SAR of the irrigation water didn’t significantly affect the variables of growth of onion. There was an increase in the accumulation of elements in dry matter of onion plants with increasing salinity of irrigation solutions in all parts examined. Part of the plant where there was a greater accumulation of evidence was the root, followed by leaves and bulb. The potassium ion was predominant in the dry onion, which we observed an increase in the accumulation of sodium with increasing salinity of the irrigation water. The salinity of the leachate, and the contents of the elements examined increased significantly with increasing salinity of the irrigation solution. The sandy soil promoted a greater leaching of ions from the ground up to free sandy clay sixty days. To ninety days, there was a balance between the leachate compositions from both soils, probably due to a slower removal of the sandy clay soil free. There was a significant increase in levels of exchangeable sodium, the ESP, the SAR and the EC, with the increased salinity of the irrigation water. Among the soil, the finest textured soil had greater retention of salts than the coarse textured soil, obtaining higher values of EC and exchangeable sodium.