Effects of biotechnology byproducts and organic acids on nitrification in soils

摘要

Recent developments in biotechnology industries produce increasing amounts of byproducts with potential uses in agriculture. The present research focused on the nitrification of NHinf4sup+-N in biotechnology byproducts added to soils, and on the effects of 29 naturally occurring organic acids (19 aliphatic and 10 aromatic) on nitrification in soils. A 10-g soil sample was incubated for 10 days at 30°C with 2.0 mg NHinf4sup+-N in a byproduct or with 10 or 50 μmol organic acid and 2.0 mg reagent-grade NHinf4sup+-N. In condensed molasses-fermentation solubles, produced during the microbial fermentation of sugar derived from corn (Zea maysL.) and molasses derived from beets (Betasp.), in the production of lysine as a supplement in animal food, the nitrification of NHinf4sup+-N was similar to that of byproduct or reagent-grade (NH4)2SO4. Nitrite accumulated when either of these materials was added to a calcareous Canisteo soil. The NHinf4sup+-N in slops (produced during microbial fermentation processes occurring in the production of citric acid) was not nitrified in soils. Some organic acids inhibited, whereas others activated, nitrification in soils. Formic, acetic, and fumaric acids enhanced the production of NOinf2sup--N in a calcareous Canisteo soil, whereas all other aliphatic and aromatic acids studied decreased the accumulation of NOinf2sup--N. It is concluded that the addition or production of organic acids in soils affects the microbial dynamics, leading to significant changes in rates of nitrification and possibly in other N-transformation processes in soil