Response of nitrogen and phosphorus leaching and soil properties to applications of biosolids during turfgrass establishment

摘要

Regulations for total maximum daily loads require management of phosphorus loading from farms and municipalities. This study evaluated environmental impacts of a system for using and exporting the phosphorus in composted dairy manure (CDM) and composted municipal biosolids (CMB) through turfgrass sod. Responses of soil physical, chemical, and biological properties within and below the sod layer were monitored during turfgrass establishment in two experiments under greenhouse conditions. During turf establishment in column lysimeters, phosphorus and nitrogen leaching from an amended surface layer through soil were evaluated. In addition, growth of turf was related to the observed changes in soil nutrients and properties. In the first experiment, four replications of a factorial design comprised three soil types (USGA greens sand, Windthorst fine sandy loam [fine, mixed, thermic Udic Paleustalf], Houston black clay [fine, smectitic, thermic, Udic Hapustert]), two dairy manure rates ( 200 kg P ha-1, 400kg P ha-1), and two turf species (St. Augustinegrass (Stenotaphrum secundatum [Walt.] Kuntze var. Raleigh) and Tifway 419 Bermudagrass (Cynodon dactylon [L.] Pers. x C. transvaaleensis Burtt-Davy). Columns received three separate leaching events in which a 9-cm depth of distilled water was applied. A similar experimental design was implemented for Experiment 2 in January 2004. Treatments consisted of the same three soils and three volume-based rates of CDM and CMB (0, 150, 250 cm3 L-1) during establishment of St. Augustinegrass turf. Columns received one pore volume of distilled water on three separate occasions. In both experiments, soil physical properties (bulk density, water infiltration rate, and water content) and microbial populations were unaffected by CDM or CMB. Applications of CDM at P-based rates utilized in the first experiment yielded no variation of leaching loss among rates of P or N. Most of the P applied was retained in the top 10 cm of soil. When large volume-based rates were used, leaching losses of P and N varied among CDM or CMB application rates. Leaching losses were only observed in the USGA sand and were highest for the 250 cm3 L-1 rate of CDM or CMB. Regardless of compost source, applications of organic amendments at volume-based rates can increase leaching loss of P and N on sandy soils. However, if P-based rates are used there is little risk for leaching loss of N and P during sod establishment.