Fertigation of humic substance: effects on soil properties of a xanthic ferralsol (DENSIC)

The complexity of humic substances (HS) and their properties in agricultural applications have attracted the attention of many researchers. However, controversial results have been obtained, because of the difficulty in identifying a precise relationship between the structure and activity of these substances. This study aimed to evaluate the influence of different frequencies and concentrations of humic substances on the behavior of physical, chemical and microbiological soil attributes. The experiment was carried out at Embrapa Cassava and Fruticulture in Latossolo Amarelo Distrocoeso [(Xanthic Ferralsol (Densic); Oxisol], with a completely randomized block design with four repetitions in a split-plot scheme, with three application frequencies (F1 = 15 days, F2 = 30 days and F3 = 45 days) and four concentrations of humic substances (C1 = 0 ml.L-1, C2 = 3 ml.L-1, C3 = 6 ml.L-1 and C4 = 9 ml.L-1). The humic substance applied at a frequency of 45 days positively favored the physical and chemical attributes of the soil, mainly at concentrations of 6 and 9 ml.L-1, due to the increase in microporosity. This information can be used to improve the performance of agricultural practices, especially those related to soil preparation, use of agricultural inputs, water management, soil water content and, especially, soil management practices.