Nutrient Management Research Database

Nitrous oxide and N2 are the major denitriflcation products in irrigated corn (lea mays L.). In addition, N2O is considered a gas that contributes to global warming and stratospheric O3 depletion. Minimizing N2O emissions in cropping systems is therefore an economic as well as an important environmental concern. In a 1989 field experiment, the nitrification inhibitor encapsulated calcium carbide (ECC) (0,20, or 40 kg CaC2 ha-') or nitrapyrin (0.5 L a.i. ha*1) was banded with urea (218 kg N ha-') 7 wk after planting com. Between 1 and 14 wk after fertilization in 1989, N2O losses of 3226, 1109,1017, and 1005 g N2O-N ha-' from urea alone, urea plus nitrapyrin, urea plus20 kg ECC ha-1, and urea plus 40 kg ECC ha-1, respectively, were measured from vented chambers. Nitrous oxide fluxes were positively correlated with soil NO, levels, indicating that the nitrification inhibitors indirectly controlled N2O emissions by preventing NO3 from accumulating in the soil. Carbon dioxide emissions from the root zone were generally not affected by ECC or nitrapyrin. In 1990, losses o fN2O were less than in 1989 (1651 g N ha-' with urea alone), probably because there were fewer irrigations. Nitrapyrin and ECC addition to urea resulted in 980 and 459 g N ha'1 N2O being emitted the second year. Nitrification inhibitors appear to be a useful tool in mitigating N2O emissions in agricultural systems.

This study investigated the effects of two nitrification inhibitors, encapsulated calcium carbide (ECC) and nitrapyrin, on nitrous oxide as compared to conventional urea fertilization.

Corn was fertilized with urea along with either ECC or nitrpyrin. All plots were fertilized with 195 lbs N/ac as urea. The ECC plots received either 0, 18, or 36 lbs DCC per ac. The nitrpyrin plots received 0.13 gallons nitrpyrin per acre.

Nitrous oxide and carbon dioxide readings were taken approximately 3 times week for 14 weeks after fertilization.

Soil ammonium and nitrate levesl were measured at 2, 4, 6, and 9 weeks after fertilization.

Both nitrification inhibitors effectively reduced N₂O emissions in both years of the study.

Nitrification inhibitors limited the build up of soil nitrate, indicating that they reduced nitrous oxide emissions by effectively inhibiting nitrification.

Carbon dioxide emissions were not affected by either of the nitrification inhibitors.