These studies were conducted to evaluate the use of materials derived from swine waste solids as pre-plant soil incorporated and topdressing fertilizers for roadside grass mix establishment. Four locations in North Carolina were used to determine the stability of the applied nutrients. Plots were established beginning in 2004, at the Horticultural Crops Research Station in Castle Hayne, Sandhills Research Station in Jackson Springs, Lake Wheeler Turfgrass Field Laboratory in Raleigh, and Mountain Horticultural Crops Research Station in Fletcher. Initially, a material derived from an anaerobically digested swine lagoon solid (Orbit) was used. In 2005, the use of this material was discontinued due to unavailability and a second material, SuperSoil which was an aerobically composted combination derived from swine waste solids and cotton gin residue was used. Soils were fertilized with either a standard check inorganic fertilizer of a 10-8.8-16.6 (N-P-K) material at 45 lbs/acre or using the organic source at either 0.5% v/v or 1.0% v/v incorporated to a depth of 6 inches. For the runoff studies, in year 2, a single topdressing application was made at rates equivalent to 45 lbs/acre. Soil samples were taken every week for the first 2 to 4 weeks depending on location and then every 4 to 6 weeks thereafter and the nutrient concentrations analyzed. Overall, the nutrient and pH results in the soil treated with 0.5% v/v SuperSoil are not different from the soil treated with a standard inorganic fertilizer. However the 1% v/v SuperSoil treatment consistently showed higher nutrient concentrations and higher pH values than the other two treatments. However, the Fletcher location showed the least change in nutrients or pH due to any fertilizer augmentation. Twenty-four plots were constructed at the Lake Wheeler Turfgrass Field Lab in Raleigh North Carolina specifically to collect surface runoff. Two types of fertilizer were applied to the plots -- an organic fertilizer, SuperSoil (4% N, 0.88% P, 2.5% K) and an inorganic fertilizer (10% N, 8.8% P, 16.6% K), referred to in this study as standard. Additionally, non treated plots were used as a check. Both a linear regression test and an analysis of variance using Least Squared Means found that there was no significant difference in nitrogen or phosphorus concentrations in runoff depending on type of fertilizer and the control. Therefore, this study concludes that there is no greater environmental threat from runoff from organic fertilizers than from inorganic fertilizers or unfertilized areas. Two nitrogen mineralization experiments were conducted using a Cecil Sandy Loam soil from the Lake Wheeler Turfgrass Field Lab in Raleigh and a Wakulla soil from Sandhills Research Station in Jackson Springs, North Carolina. This study found that Wakulla soil has about three times less NH4 + -N than the Cecil soil. The Orbit treatment seems to bind nitrogen in both Cecil and Wakulla soils so that is not immediately accessible for mineralization or plant nutrient uptake. The SuperSoil treatment has a similar effect. Therefore using either the Orbit or the SuperSoil treatments does not appear to contribute immediate nitrogen in accessible forms for plant uptake and that an additional nitrogen component may need to be added to the final fertilizer product to fulfill immediate plant needs.
