The effect of humus fertilizers on soil biological activity and productivity of spring rape

Biological activity is agronomically and ecologically significant component of soil fertility and a sensitive indicator of the anthropogenic effect. At present, increasing intensification of agricultural production and inadequate farm management practices result in the deterioration of soil physical and chemical properties. A partial solution to this problem could be the use of humic acids in the system of crop fertilization. The objective of this research was to study the effect of humic and fulvic acids (humus acid fertilizer) on soil biological activity, available P205 and K20 the variation in spring rape productivity and to determine the relationships between the parameters studied. Our experimental evidence suggests that humic and fulvic acids (humus acid fertilizers) significantly increased the activity of urease (0.03-0.07 mg NH3 per 24 h). The activity of saccharase significantly increased (4.5 mg glucose per 48 h) having used 1,67 kg of humic acid, and that of dehydrogenase (1.8 mg formazane per 24 h) having used 3.3 kg of humic acid. A significant seed increase of 0.32-0.46 t ha-1 in spring rape was obtained under the effect of humic and fulvic acids. The highest yield (2,72 t ha-1) and yield increase (0.46 t ha-1) were obtained when humic and fulvic acids had been spray-applied to the rapeseed crop at the bud formation stage. A linear correlation was identified between the yield of spring rape seed and available variation of phosphorus during the crop growing season (r=0.88*). Humic and fulvic acids significantly increased the yield of crude fat (0.941 ha-1). The highest content of crude fat was recorded after the humic and fulvic acid treatments at the bud formation stage of spring rapeVytauto Didžiojo universitetasŽemės ūkio akademij