Effects of organic composite fertilizer on soil nitrogen status and mineralization

Abstract

A short-term soil incubation experiment was set up to obtain information to clarify the effect of our developed organic composite fertilizer on soil nitrogen mineralization. The composite was designed to have beneficial effects on the properties of chicken manure and to improve soil water management properties in addition to organic matter replenishment. In the incubation experiment, two different additives, bentonite, and super absorbent polymer, were used to enhance the properties of fermented chicken manure. Developed prototype products were tested in a four-week-long soil incubation experiment in two typical Hungarian soils: brown forest soil with a sandy texture and chernozem soil at two different water capacities (40 w/w % and 60 w/w %). Soil pH, and inorganic nitrogen forms, like nitrate and ammonium, were measured weekly. Furthermore, the potentially mineralized nitrogen and net mineralization rate were calculated. The applied composite was not affected the soil pH significantly in the examined period. The soil nitrate and ammonium ratio was changed during the incubation as the ammonium content in the soil decreased while nitrate content increased continuously throughout the experiment. This suggests that the incubation experiment successfully monitored the delicate balance of soil nitrogen forms. It was found that the chernozem soil type had a higher mineralization potential compared to brown forest soil due to its higher nutrient and organic matter contents. Moreover, our results pointed out that soil moisture content did not significantly affect the mineralization process. The amount of mineral nitrogen, generated per week can be described by a linear relationship for both soil types and water regimes. The composite product showed efficacy in promoting mineralization processes, particularly in soils with low nutrient status and mineralization potential.