Influência da palhada residual, espécie forrageira e nível de nitrogênio na produção e valor nutricional da aveia e azevém em sistema integrado de produção agropecuária

Abstract

The objective of the present study was to assess the forage potential of white oat (Avena sativa L.) and annual ryegrass (Lolium miltiflorum Lam) cultivated on rice or soybean straw with nitrogen fertilizer (N) incorporation in a Integrated Crop-Livestock System (ICLS) with rice, ryegrass or oat (pasture) and soybean crop rotation. A randomized block design with four replications was conducted from 2020 to 2021 in the Estação Experimental do Instituto Riograndense do Arroz (IRGA), located in Uruguaiana-RS, Brazil. Four rates of topdressing N fertilization were evaluated (0; 50; 100; and 150 Kg/ha) for three growth cycles of oat and ryegrass in an area with soybean or rice straw. Forage dry matter (DM) content and nutritional value were both evaluated. In 2020, the greater DM content was observed in soybean straw in the first and second growth cycles. During the second cycle, the highest DM content per each Kg of N applied was observed, where there was a ryegrass and oat yield of 13.672 Kg and 10.929 Kg, respectively. Despite the yield variation among growth cycles in 2020, ryegrass was greater than oat. In 2021, the greater productivity was also in the soybean straw for both the first and second cycles, where oat was superior compared with ryegrass. Due to the drought that occurred in 2021, the oat showed the greater DM content in the studied period. The N fertilization also showed the greater responses during the second cycle in the soybean straw, where the yield per each Kg of N applied of ryegrass was increased to 17.250 Kg compared with 13.310 Kg of oat. Regarding the nutritional value in 2020 and 2021, the main results were the positive linear response for GP, NDF, DAF and EC, and negative for DMCLW, TND, DIGDM and RFV, TCHO and CNF. The oat and reygrass are alternative for the crop diversification in the Lowlands and the N fertilization can enhance DM content as well as improve the nutritional parameters of ryegrass and oat forage.