Phosphorus distribution after three decades of different soil management and cover crops in subtropical region

International audienceThe no-tillage system with normally comprise winter cover crops and crop rotation may increase the efficiency use of soil P and phosphate fertilizer. The objective of this study was to evaluate the effect of three decades of different soil management systems and winter cover crops on the fractions of P in a clayey oxisol of Paraná State, Brazil. The bi-factorial experiment with three replicates was installed in 1986. The main plots consisted of seven treatments of winter cover plants and in the subplots, two tillage systems were used: no-tillage and conventional tillage. The soil was sampled in the 0-10 cm soil layer in the post-harvest periods of the corn (harvest 2014-2015), the flowering of the winter cover plants (2015) and soybean flowering (harvest 2015-2016). The different pools of P were evaluated. In a short time of no-tillage adoption (30 years) with phosphate fertilizers addition, the amount of P organic pools and type of P organic compound were likewise to the natural biome. The notillage guaranteed higher inorganic and organic P, both rapid and moderately available, in comparison to the conventional tillage system. However, in the conventional tillage during (40 years-80 plows + 160 harrows), despite the addition of 3 Mg ha-1 of P 2 O 5 , the available and moderately phosphorus in soil surface were very similar to soil under natural forest. In the natural biome, the amount of P stored in soil microbial biomass was stable in the time showing a homeostatic equilibrium. Nevertheless, in cultivated soil and fertilized with inorganic phosphate, there was a synchronism between plant demand and storage in soil microbial biomass