Aplicação dos níveis de enxofre na forma de gesso, para cultivo de leguminosas forrageiras

A pot experiment was carried out n a greenhouse in the Instituto de Zootecnia at Nova Odessa, State of Sap Paulo. Four forage legumes (siratro, galactia, perennial soybean and centro) were grown in Psamments soil from Brotas (cerrado region) and in a Red-Yellow Podzolic soil Laras variation from Nova Odessa. These species grew since November until January (Spring-Summer). Five levels of sulphur (0;30;60;90 and l20kg/ha) as gypsum were applied. The best responses to sulphur were obtained with siratro grown in the Psamments sou. Maximum values for dry matter production, nitrogen content and dry weight of nodules in siratro were obtained with applications of 76 to 86kg S1ha. Galactia grown in the soil from Brotas increased its nodulation with the level of 60kg S/ha. The mineralization of the organic matter during the experimental period would have released mineral sulphur to the soil and would have prevented other responses to the levels of sulphur, specially in the Podzolic soil. Gypsum resulted in a reduction of soil pH in the pots that received lime to neutralize exchangeable aluminum and increased soil exchangeable calcium irrespective to the limestone level. Centro and galactia grown in the soil from Brotas showed deformed leaflets. These symptoms were not related to the treatments studied but they were similar to those obtained with the application of 2.4-D herbicide on the plant tops.