Phosphorus dynamics, organic matter fractions, and soil microbial activity under phosphate sources and cover crops

Abstract

The frequent use of phosphate fertilizers may result in the accumulation of P in soils (also known as Legacy P) in organic (Po) and inorganic (Pi) forms. However, most of these forms of P are not available for absorption by commercial crops. The cultivation of cover crops, in the off-season, can increase the availability of P for commercial crops because they have different P acquisition strategies that can access the soil Legacy P. In addition, its crop residues can alter the quantity and quality of soil organic matter and exert a strong influence on soil microbial activity. The hypothesis is that the less labile P cycling by cover crops is strongly connected with changes in organic matter and the activity of soil microorganisms. This study will be carried out in a long-term experiment cultivated with maize/soybean (commercial crops), with two phosphate sources (single superphosphate, rock phosphate) and without P addition (Nil-P); five winter cover crops and a fallow. In this project, it is expected (i) to identify alterations promoted by the cover crops in P fractions and forms obtained by the magnetic resonance of 31P in the soil; (ii) to relate the fractions and forms of P with the organic matter, microbial activity, nutrition and productivity of maize crop. (AU)