The Effects of Dairy Manure Compost Used In Urban Landscapes On Soil Enzyme Activities.

Reestablishment of natural ecological functions in post-construction urban soils is usually hindered by the loss of organic matter and nutrients and may be improved by the addition of dairy manure compost (DMC). Understanding the effects of DMC on microbial enzyme activities in disturbed urban soils will help determine whether long-term landscape performance can be improved by the addition of organic matter. The objective of this study was to evaluate the effect of dairy manure compost on soil enzyme activities seven years after application to an urban landscape. Composted dairy manure was applied at 0, 9, 18, and 27 kg m^-2 in 2003 prior to the establishment of landscape plants consisting of annual and perennial plants plus turf grass. Soil was extracted in June 2010 from the upper 15 cm of a bermuda grass area in each plot.  Selected soil chemical properties and biological characteristics (dehydrogenase, cellulase, β-glucosidase, alkaline phosphatases, and L-asparaginase) were examined. The results showed that organic matter, total N, and plant available P increased with rate of compost application. Soil respiration and the activities of β-glucosidase and alkaline phosphatase also increased, while L-asparaginase activity generally decreased with compost rate. The different compost rates had no significant effects on dehydrogenase or cellulose activity. All enzymatic activities examined showed linear correlations with the organic matter contents of the soil. The results demonstrate that seven years after application, dairy manure compost continues to positively influence biological parameters that improve soil quality.