Production and nutritional value of forage sorghum in potassium doses function and soil management systems

The knowledge of the adequate amount of nutrients for soil correction in the different agricultural systems is very important to become economically efficient. The culture of sorghum has a high potential for use as silage due to have high dry matter production and excellent nutritional quality. This study aimed to assess the production of three sorghum hybrids cultivated using different amounts of potassium and crop systems. These plants were cultivated in yellow latosol of low fertility at the Federal Rural University of Amazon. The experimental design was a factorial 4x3x2 with four repetitions. The factors were four amounts of potassium (50, 100, 200 e 300 kg ha-1), using KCl as the potassium source, three sorghum hybrids (Qualimax, Volumax e AG 2005-E) and two crop systems (minimum tillage and conventional). Were collected five plants in each business area and heavy plant material to obtain green mass. Later it was determined the macro and micronutrients. The results of the experiment were subjected to analysis of variance were compared by Duncan test, where appropriate, and regression studies, by adjusting the equations according to the KCl doses used. To obtain the results we used the statistical program SISVAR (FERREIRA, 2007). The tillage showed higher dry matter production of the aerial part of the sorghum (11567 kg ha-1) and maximum economic efficiency (10140 kg ha-1) were achieved with doses of 170 and 153 kg ha-1 KCl, respectively, being that Volumax hybrids (10.7 t ha-1) and Qualimax (10.1 t ha-1) had higher yields to AG2005-E (9.3 t ha-1). It is concluded that the dry mass of shoot was influenced by the K levels, management system and hybrid, and the interaction of doses factors K x SM.