NITROUS-OXIDE PRODUCTION FROM INJECTED LIQUID DAIRY MANURE

Injection of liquid organic wastes into soil promotes conditions that may be conducive to denitrification by creating an anaerobic environment abundant in inorganic N and readily oxidizable C. To quantify gaseous N loss, we measured N2O emissions from simulated waste injections applied to soils in large wooden containers (71 by 42 by 44 cm). Liquid dairy manure was injected into the soil at rates commonly used for crop production (79 000 L ha-1). The nitrification inhibitor nitrapyrin [2-chloro-6-(trichloromethyl)pyridine] was used to further evaluate nitrification-dentrification losses. Nitrous oxide emissions, with and without C2H2 treatment, were estimated by passing air across the soil surface above an injection zone and trapping emitted N2O onto a molecular sieve. The largest emission of N2O occurred shortly after injection, followed by a shift to N2.