Effects of fertilizer and organic amendments on groundwater nitrogen transport in south Florida

Experiments were conducted on calcareous and sandy soils to investigate the effects of organic amendments for vegetable production on groundwater nitrogen (N) concentration in south Florida. The treatments consisted of applying yard and food compost, biosolids compost, a co-compost of the municipal solid waste and biosolids, and inorganic fertilizer for comparison. Nitrate nitrogen (NO 3-N), ammonium nitrogen (NH 4-N), and total N concentrations were collected for a period of two years at both sites. Statistical analysis indicated that for the three species tested, there were no significant differences among treatments. NO 3-N concentrations remained less than the maximum contamination level (10 mg/L) for all treatments. NO 3-N transport was more prominent in calcareous soil (mean=5.3 mg/L) than in sandy soil (mean=0.6 mg/L). NH 4-N concentration was relatively low throughout the experiment (0-13.6 mg/L). Calcareous soil had lower NH 4-N concentrations (mean=0.1 mg/L) than sandy soils (mean=0.7 mg/L). Total N was also low for all treatments (0.4-21.7 mg/L) for both soils reflecting high adsorption of dissolved organic N in both soils. The results indicated that compost was comparable to inorganic fertilizer with regard N leaching and N concentrations in the groundwater.

Effects of fertilizer and organic amendments on groundwater nitrogen transport in south Florida Conference Paper