Nutrient Management Research Database

Nitrous oxide (N20) and methane(CH4) are greenhouse gases thatare contributing to global warmingpotential. Nitrogen (N) fertilizeris one of the most important sources of anthropogenic N20 emissions.A field study was conducted to compareN-use efficiency and effecton NzOand CH4fillx, of urea, urea plus the nitrification inhibitordicyandiamide(U 4- DCD),and a control release fertilizer, polyolefincoated urea (POCU)in irrigated spring barley (Hordeumvulgare L.)in northeastern Colorado. Each treatment received 90 kg urea-N ha- iand microplots labeled with ~SN-fertilizer were established. AverageN~Oemissions were 4.5, 5.2, 6.9, and 8.2 g N ha-~ d-1 for control,U + DCD, POCU,and urea, respectively. During the initial 21 dafter fertilization, N~Oemissions were reduced by 82 and 71%in theU 4- DCDand POCUtreatments, respectively, but continued releaseof N fertilizer from POCUmaintained higher N~Oemissions throughthe remainder of the growing season. No treatment effect on CH4oxidation in soils was observed. Fertilizer ~SNfound50 to 110 cm belowthe soil surface was lower in the POCUand U + DCDtreatments. Atharvest, recovery of ~SN-fertilizer in the plant-soil system was 98, 90,and 85% from POCU,urea, and U + DCD,respectively. Grain yieldwas 2.2, 2.5, and 2.7 Mg ha-~ for POCU, urea, and U + DCD,respectively. Dicyandiamide and POCUshowed the potential to beused as mitigation alternatives to decrease NzOemissions from Nfertilizer and movementof N out of the root zone, but N releasefrom POCUdoes need to be formulated to better match crop growthdemands.

This study investigated the effects of urea, urea with nitrification inhibitor DCD, and polymer coated urea on nitrous oxide and methane emissions.

Nitrogen was applied at a rate of 80 lbs/ac. DCD was applied at a rate of 8 lbs/ac.

Nitrous oxide and methane emissions were measured for 100 days following fertilization.

Methane emissions were not affected by N fertilization or DCD.

Nitrous oxide emissions were elevated for a week following the first irrigation following fertilization. Emissions were higher in urea only plots than the urea + DCD or polymer coated urea plots.

More than 85% of overall emissions occured within the first 21 days following fertilization.

N fertilization increased yield, and use of DCD further increased yields.