Effect of fulvic acid on the phosphorus availability in acid soil

An important issue for soil conservation and waste disposal is the use of biosolids in agriculture and for land reclamation. Most biosolids contain valuable nutrients that could be used to improve soil fertility. The aim of this work was to establish the effects of the application of biosolids on some chemical, biological and physical properties in an Andisol from southern Chile. This study was carried out under farm conditions during the wheat (Triticum aestivum) growing cycle. Five land plots of 10 x 4 m each were prepared: control soil (TAT), chemical fertilisation (TAF) and applications equivalent to 30 ton biosolids/ha (TA30), 60 ton biosolids/ha (TA60) and 90 ton biosolids ha(-1) (TA90). The soil samples of both treatment and non-treatment groups were collected after the application of biosolids, after sowing and before the wheat harvest. The evaluated chemical soil parameters were modified by the application of biosolids. Base levels of organic carbon, pH and P increased. Biological activity measured by the evolution of C-CO2 followed the sequence TA90>TA60>TA30>TAF>TAT. The physical properties evaluated, namely water infiltration rate, accumulated infiltration and water retention capacity, all increased with the increasing dose of biosolids. The results show a strong correlation between the biosolids dose applied and the change in the soil properties studied.