Effects of fertilization and tillage on soil biological parameters

A short field assay was established to study the potential of soil biological parameters (i.e., soil enzymes, potentially mineralizable nitrogen, soil respiration, abundance of earthworms, and microbial community metabolic profiles) as early and sensitive indicators of the effects of agricultural practices (i.e., fertilization and tillage) on soil properties. The field assay consisted of growing a variety of forage corn for just 3 months under mineral and organic fertilization and conventional and no-tillage. In general, highest values of biological parameters were found in organically fertilized, no-tillage plots, while conventional tillage and mineral fertilization led to lower values. Values of potentially mineralizable N, basal respiration, substrate induced respiration, and earthworm abundance were 23.1, 35.3, 55.7, and 226.9% higher in organically fertilized, no-tillage plots than in inorganically fertilized, conventional tillage plots, respectively. Among the different soil enzymes studied (i.e., dehydrogenase, β-glucosidase, arylsulphatase, and acid phosphatase), dehydrogenase activity appeared most sensitive to the treatments. It was concluded that biological parameters have great value as early and sensitive indicators of changes in soil properties induced by different management strategies. On the contrary, conventional physicochemical parameters were not sensitive enough to detect the relatively subtle changes in soil properties caused by these management practices in the short-term.