Potassic and nitrogen fertilization in a modern hybrid of sorghum for biomass production cultivated in an Oxisol

Abstract

Biomass sorghum [Sorghum bicolor (L.)] is a promising option for the supply of dedicated biomass for energy cogeneration in Brazil. However, it is still necessary to better understand gaps around the nutrient requirement and fertilization management, especially for modern materials. The aim of this study was to evaluate the effect of nitrogen (N) and potassium (K) doses on dry matter (DM) and nutrient accumulation in a modern hybrid of biomass sorghum cultivated in an Oxisol. For that, two separate trials were carried out with the hybrid Palo Alto 2562, grown in 2015/16 summer season in the central-western region of Brazil. Both trials were carried out in a randomized block design with four replicates and five doses: 0, 70, 140, 210 and 280 kg ha-1 (of N or K). The hybrid Palo Alto 2562 responded positively to N fertilization. The DM production and N accumulation hybrid of Palo Alto 2562 was increased as N fertilization added, reaching, respectively, values of 24.6 Mg ha-1 and 206 kg ha-1 at dose of 280 kg ha-1 N. Also, in order to avoid depletion of N levels in the soil we required a fertilization of at least 140 kg ha-1 N. The Palo Alto 2562 hybrid has a high absorption capacity of K, which is the most absorbed nutrient by the plant, reaching values of 316 kg ha-1. However, in this study due to high levels of K in the soil and high K saturation in CEC, the K fertilization may be not necessary to produce sorghum biomass.