| Soil microbial activity is often used as a biological indicator of soil health since microbes are sensitive and respond rapidly to soil alteration. A soil amendment product that increases microbial activity could be beneficial to the soil's overall health. In 2013 and 2014 we studied the effect of inorganic fertilizer and organic soil amendments on soil microbial activity and field coin (Zea mays) yield. The organic amendment, GreatGrow (GG), is a proprietary mixture of microorganisms, fermented chicken manure, plus oyster and crab shells. The study was conducted at two field sites (one irrigated; one non-irrigated) on Maryland's Eastern Shore. Corn yield and six microbial activity measurements were carried out on the soil samples: biomass carbon, dehydrogenase activity, fluorescein diacetate hydrolysis (FDA), nitrogen mineralization, sediment basal respiration (SBR), and substrate-induced respiration. When assessing soil microbial activity in the future it would be beneficial to measure SBR, dehydrogenase, and FDA. All of these assays showed correlations both years therefore they are able to determine an accurate relationship between yield and microbial activity. Both years the inorganic amendment resulted in the highest corn yield compared to control, GG, and poultry manure treatments. Future studies could examine a combination of poultry manure with SI to increase soil quality and produce similar yields that farmers would need. |
