APLICAÇÃO DE FOSFATOS EM SISTEMA INTEGRADO DE PRODUÇÃO AGROPECUÁRIA: APROVEITAMENTO PELA SOJA E ATRIBUTOS QUALI-QUANTITATIVOS DO AZEVÉM ANUAL

Abstract

Integrated systems of agricultural production (ISAP), when well managed, can result in environmental benefits, including the optimization of the use of phosphorus (P) for food production. Brazilian soils are presented naturally low in P, and practices aimed at efficient use of this nutrient can result in economic and environmental benefits to society. The objectives of this study were: (i) measure the quantitative yield of annual ryegrass (Lolium multiflorum Lam) and soybean (Glycine max (L.) Merrill); (ii) to evaluate the accumulation of P (annual ryegrass and soybean); (iii) investigate the changes in the attributes of soil fertility (pH and available-P); (iv) to assess the yield of dry matter available for grazing (DMA); (v) yield of crude protein (YCP); and (vi) concentrations of neutral detergent fiber (NDF), acid detergent fiber (ADF), crude protein (CP) and P in ryegrass in ISAP undergo sources (triple superphosphate - TSP, reactive phosphate - RP Arad and magnesium thermophosphate - MTP) and P levels (0, 60, 120 and 180 kg ha-1 P2O5 total). The experiment was installed in April / 2009 at farm Capon do Cipo, in the municipality of Castro (PR). The experimental design was a randomized complete block in incomplete factorial (3x3 + 1). After 48 months of study, soil samples from the 0-5, 5-10, 10-15 and 15-20 cm were collected to determine the concentrations of available P by two methods (Mehlich-1 – M-1 and ion exchange resin - IER) to assess the availability of P for the soybean crop (2012/13). Similar yields were observed among the evaluated sources (TSP, RP and MTP) at 48 months of experimental evaluation; However, higher accumulation of P were observed for the most soluble sources. The determination of P by the extractors (M-1 and IER) overestimated the concentrations of P in the soil in condition of application of RP. But best fixes between soil P and crop attributes were higher for extraction by IER in 0-20 cm layer. Lower concentrations of NDF in annual ryegrass were verified by applying MTP, without, however, presenting the highest concentrations of P.