Nitrate Leaching from Compost-Amended Soils

Abstract

Nitrate in ground water was measured for three years beneath a sandy terrace soil with high conductivity which had been amended yearly with spent mushroom compost (SMC) and chicken manure compost (CMC) at rates of 25 and 50 T/A. The compost provided all the fertilizer requirements for intensive vegetable production. Nitrate concentrations in ground water from beneath all compost-amended plots remained below 10 ppm during the course of the study while concentrations beneath the fertilized control climbed to 14.7 ppm in an unusually wet spring. After heavy rains, control plots were more susceptible to nitrate leaching than compost-amended plots in the first two years of the study. The overall mean of the control (4.2 ppm) was significantly higher than all the other compost-amended plots except SMC amended at 25 T/A (3.4 ppm). Nitrate concentrations in ground water from CMC plots amended at 50 T/A peaked at 9.2 ppm after three consecutive years of compost application indicating a cumulative effect in the soi...