Forage quality in a neotropical savanna based on different types of fertilization

Abstract

The application of different sources of nutrients to the soil with varying degrees of solubility, as well as the use of organic and inorganic fertilizers, can generate different responses in agroecosystems. The objective of this study was to evaluate the effect of different fertilization options on the quality of forage in the conservation-based agroecosystems of neotropical savannas. Both perennial species Brachiaria dictyoneura and the legume Centrosema macrocarpum are associated with corn cultivation. Four fertilization treatments were evaluated within each cover crop, applying 150 kg ha-1 of nitrogen, 150 kg ha-1 of P2O5, 100 kg ha-1 of K2O, and varying the source of phosphorus, being the treatments distributed as follows: i) phosphoric rock, high dose of phosphorus (100% of P2O5 as phosphoric rock), ii) diammonium phosphate, high dose of P (50% of P2O5 as phosphoric rock and 50% as diammonium phosphate), iii) biological fertilization, low dose of P (25% of P2O5 as phosphoric rock and inoculation with biofertilizer based on native arbuscular mycorrhizal fungi, such as Gigaspora, Scutellospora, Acaulospora, and Glomus), and finally, iv) the unfertilized treatment. The results show that under direct sowing and the use of biological fertilization sources using phosphoric rock as a source of P, similar and even higher levels of raw protein can be reached than when using fertilization with soluble sources such as the diammonium phosphate, which induce greater sustainability of the cover biomass, being an alternative in the management of this types of agroecosystems.