Biosolid Effects on Soil Carbon and Nutrient Content at Depth on a Loblolly Pine Plantation.

The application of biosolids as an alternative to conventional fertilizer and soil amendment is becoming increasingly widespread in pine plantations in the Southeast USA. Land application of biosolids is a beneficial practice whose ecological effects depend in part on forest soil properties. It may be possible to improve tree growth and soil quality with the addition of biosolids. The objectives of this work were to evaluate the effect of biosolids on tree growth, and soil carbon and nutrient content at four different depths through the soil profile. Different rates and type of materials were applied on March 2006 to a 17 years old Loblolly pine plantation located in the Virginia Piedmont on Amelia County. Anaerobically digested biosolids (rates of 200, 800, and 1600 PAN), lime stabilized biosolids (200 PAN), palletized biosolids (200 PAN), and urea + DAP (200 lb/acre) were surface applied. Tree growth and foliage nutrient samples were collected by the end of each growing season. Soil was sampled at four different depths before and after the application. Biosolids and conventional fertilizer treatments increased foliage nutrient content. Lime stabilized, and digested materials increased surface soil nutrient content in comparison with the unfertilized control treatment. Increasing biosolids rates increased topsoil carbon, nitrogen and phosphorus content.