Organic Amendment Effects on Physical and Chemical Properties of a Sandy Soil

Abstract Effects of repeated applications of sewage‐sludge compost on soil properties have not been sufficiently evaluated with field trials. Field studies were established on an Evesboro loamy sand soil (mesic, coated Typic Quartzipsamment, 97% sand) to compare the effects of sewage‐sludge compost, beef manure, and fertilizer amendments on soil properties. The study site had been fallow for 26 yr and should have provided a positive response to the added organic matter. Compost application rates were based on the assumption that material would be applied either only once or annually. Application rates ranged from those that were too low to supply the total N requirement of a crop (e.g., 33 Mg ha −1 ) to excessively high rates that would produce maximum soil benefits from the added organic matter (e.g., 268 Mg ha −1 ). Soil properties such as strength (penetrometer resistance), bulk density, water retention, pH, surface area, total N and P contents, and organic matter were evaluated for 5 yr. Addition of sewage‐sludge compost significantly reduced penetration resistance when compared with the control and fertilizer‐amended soils. Compost significantly reduced bulk density, increased soil water content, and modified pH to greater depths. Specific surface area of the soils increased linearly with the addition of compost and C levels indicated that 24 and 37% of the annually added organic matter decomposed during the 1st yr from the sewage‐sludge compost and beef manure, respectively.