Substâncias húmicas e fontes de fósforo na cultura do milho

Abstract

The objective of this study was to verify the effect of the application of different rates of a commercial product based on humic substances (HS) on the dry matter contents, and P accumulation in maize plants and the agronomic efficiency of phosphorus sources in two soils with different adsorption capacities. The experiment was conducted in a greenhouse. The treatments consisted of four rates of humic substances (0, 100, 200, and 400 kg ha-1) and two phosphorus sources (triple superphosphate – TSP; and reactive natural phosphate – RNP) in two types of soils (Rhodic Hapludox – RH; and Typic Quartzipsamment – TQ). The response of the shoot dry weight (SDW), root dry weight (RDW), shoot accumulated P, and root accumulated P to the application of HS was statistically significant (P <0.05). In the RH, the SDW, RDW, shoot and root accumulated P, and relative agronomic efficiency of the P sources increased with increasing HS rates; thus, the best results were found with the use of the highest rate (400 kg ha-1). In the TQ, the best responses were found with the application of 100 kg ha-1 of HS. These results indicate that the use of humic substances is efficient to increase dry matter and accumulated P contents in maize plants.