Soil Chemical, Physical, and Biological Properties of a Sandy Soil Subjected to Long-Term Organic Amendments

Abstract

Although landfills are the most common destination for organic waste materials in the United States, these materials might be better utilized for compost and recycled as organic amendments. However, there is little information available on the effects on soil quality of long-term application of these materials. Over a 10-year period, we applied composted and non-composted amendments, including municipal solid waste (MSW), yard trimmings (YT), and biosolids to a sandy soil in vegetables production in a replicated design with a no amended control. Amendments increased the soil content of most nutrients including P, K, Ca, Mg, Mn, and Zn as well as organic matter (OM) and cation exchange capacity (CEC) by three-fold. Effects on P and OM were restricted to the top 30 cm of the soil profile. Bulk density was decreased from 1.6 to 1.4 g.cm 3 by organic amendments, and available water-holding capacity (AWHC) was increased by 35%. Organic amendments also enhanced the overall soil microbial activity (species number and diversity), especially of the desirable groups such as heterotrophic aerobes, actinomycetes, and pseudomonads. Thus, the quality of amended soils was improved by all criteria measured, although increased P content could create a water quality concern.