Estudo da disponibilidade de fósforo através dos extratores Mehlich-1, Mehlich-3, Bray-1 e Olsen com uso de fertilizantes em argissolo e latossolo da Amazônia Central

Abstract

The presence of phosphorus in soil is generally required for soil fertility assessment, and its availability to plants is a limiting factor for agricultural yields. Found throughout the Amazon basin, Argisol and Latosol, are soils with low availability and phosphorus, therefore, the recommendation of fertilizer use is necessary to increase agricultural production. The objective of this work was to evaluate phosphorus availability in Oxisol and Argisol in the Amazon region, with and without application of doses of reactive natural phosphate sources and triple superphosphate over a period of 30 days. Samples were collected at depths 0–20 and 20–40 cm from an Oxisol on the Embrapa Occidental Amazon Trail (AM 010 Highway) and from an Ultisol on the Caldeirão Experimental Field (Manoel Urbano - Iranduba Road). The soil samples were dried and sieved in 2 mm mesh and their characterization were made by pH analysis, organic matter, Na, K, P, remaining phosphorus, Ca, Mg, Al, Fe, Zn, Mn, Cu, texture. (sand, silt and clay) and mineralogy (X-ray diffraction) and evaluation of phosphorus availability by Mehlich-1 (M1), Mehlich-3 (M3), Bray-1 (B) and Olsen (OL) extractors. The available phosphorus results for Oxisol were 1,00 mg L-1 (0 cm –20 cm and 20 cm – 40 cm) and Argisol, 2,00 mg L-1 (0 cm – 20 cm) and 1,00 mg L- 1 (20 cm – 40 cm). The Oxisol presented clay texture with a clay content of 657,00 g kg-1 (0 cm – 20 cm) and 657,50 g kg-1 (20 cm – 40 cm) and the clayey clay argisol 351,50 g kg-1 (0 cm –20 cm) and 409,50 g kg-1 (20 cm – 40 cm). For the remaining phosphorus it was obtained for the Oxisol (0 cm – 20 cm) 16,73 mg L-1 and 17,38 mg L-1 (20 cm – 40 cm) and Argisol (0 cm – 20 cm) 20,35 mg L-1 and 15,62 mg L-1 (20 cm – 40 cm). The observed results corroborate the available phosphorus deficiency in the region; therefore, it is necessary a better knowledge of the phosphorus behavior pattern in the Argisols and Oxisols of the Amazon and to identify its adsorption potential. Regarding the availability of P, the results show that in all experiments, Mehlich-1 (M1) was the extracting solution that most extracts phosphorus for both Oxisol and Argisol using Arad fertilizer. While for SPT fertilizer, it was identified that the extraction solutions M1, M3 and B extracted similar amounts of P and the OL presented lower values for both studied soils. However, we can suggest that P sources with lower water solubility may be more agronomically efficient in highly weathered and high clay soils.