Greenhouse Gas Fluxes from Irrigated Sweet Corn (Zea mays L.) and Potato (Solanum tuberosum L.)

Intensive agriculture and increased N-fertilizer use have contributed to elevated emissions of the greenhouse gases, CO2, CH4, and N2O. In this study, the exchange of the greenhouse gases, CO2, N2O, and CH4, between a Quincy fine sand (mixed, mesic Xeric Torripsamments) soil and atmosphere was measured in a sweet corn (Zea mays L.) sweet corn potato (Solanum tuberosum L.) rotation during the 2005 and 2006 growing seasons under irrigation in eastern Washington. Gas samples were collected using static chambers installed in the second year sweet corn and potato plots under conventional tillage (CT) or reduced tillage (RT). Total emissions of CO2-C from sweet corn integrated over the season were 1887 and 1684 kg CO2-C ha-1 for the 2005 and 2006 growing seasons, respectively. For the same period, CO2 emission from potato plots was 1578 and 1290 kg of CO2-C ha-1. Cumulative CO2 fluxes from sweet corn and potato fields were 15 times higher, than adjacent non-irrigated, native shrub steppe vegetation (NV) in 2005. Nitrous oxide losses accounted for 0.25% (0.55 kg N ha-1) of the applied fertilizer (224 kg N ha-1) in corn and 0.18% (0.59 kg N ha-1) of the 336 kg N ha-1 applied fertilizer. Sweet corn and potato plots, on average, absorbed 1.7 g CH4-C-ha-1 d-1 and 2.3 g CH4-C-ha-1 d-1, respectively. The global warming potential (GWP) contribution from NV, corn and potato fields were 448, 7175, and 6487 kg CO2-equivalents ha-1, respectively for the 2005 growing season and was 14% lower in 2006.