Substância húmica e fontes de fósforo em latossolo vermelho e neossolo quartzarênico

Abstract

Processes of phosphorus adsorption in soil diminish the availability of this nutrient to plants. Humic and fulvic acids present in humic substances (SH) can block the phosphorus adsorption sites in the soil. Thus, this study aimed to verify the effect of adding doses of a SH, availability of P in two types of soils with different adsorption capacities. The treatments consist of four levels of SH (0, 100, 200 and 400 kg.ha-1), two phosphorus sources (Triple superphosphate – SFT and Natural Reactive phosphate – FNR), and three assessment time (7, 14 and 28 days) in two soil types (Red Latosol – LV and Quartzipsamment – NQ). The application of SH altered the availability of P in different soils. Statistical analysis of the data showed a significant difference (P<0,05) for all factors. In LV the P availability increased for both sources, with increasing SH dose up to 14 days. At 28 days the P-available decreases, with no significant difference between doses, but remains superior to treatment without addition of SH. In the NQ the P-available decreases from the addition of the doses of 200 and 400 kg ha-1 of SH up to 14 days of incubation. After 28 days with the degradation of SH values of P-available for these doses begin to increase. These results indicate that the use of SH is effective in increasing the availability of phosphorus in different soils.