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The effect of fertility management on soil surface fluxes of greenhouse gases in an irrigated maize-based agroecosystem

Brigid Amos, University of Nebraska - Lincoln

Abstract

An understanding of the effect of fertility management on soil surface fluxes of CO2, N2O, and CH4 is essential in evaluating carbon sequestration measures that increase soil organic carbon by increasing the amount of crop residue returned to the soil. While the data from this study suggest that the levels of NH4NO3 applied in an intensive fertility management regime (M2) caused a slight decrease in soil surface CO2 flux over the 27-month sampling period, soil surface CO2 flux in continuous maize under the M2 regime was not significantly different from that under recommended best management (M1). Annual estimates of soil surface CO2 flux based on an empirical equation were 11,600 kg C ha−1 yr−1 for the M2 treatment and 11,500 kg C ha−1 yr −1 for the M1 treatment in continuous irrigated maize. ^ The amount of residue left by the previous crop had a significant effect on soil surface CO2 flux. Flux was generally higher in continuous maize plots than in maize plots that were part of a maize-soybean rotation. Root and rhizosphere respiration apparently exerted a consistent and highly significant influence on soil surface CO2 flux. Within row flux was, on average, 66% higher than between row flux. Three plant populations tested did not significantly affect measured soil surface CO2 flux. ^ Nitrous oxide flux was significantly higher in the high N M2 treatment during the 2000 growing season compared to both the M1 treatment and the unfertilized control areas. However, in 2001, no significant differences were observed, possibly due to changes in N application rate and timing as well as lower soil moisture. The M2 treatment significantly lowered soil pH during the 2001 growing season. Fertility management had no significant effect on CH 4 flux. ^ Electrical conductivity (EC) was significantly higher in the M2 treatment than in the M1 treatment and the control. Laboratory-measured EC was highly correlated with NO3-N concentration, and high field-measured EC values were associated with high N2O flux. ^

Subject Area

Agriculture, Agronomy|Agriculture, Soil Science|Environmental Sciences

Recommended Citation

Amos, Brigid, "The effect of fertility management on soil surface fluxes of greenhouse gases in an irrigated maize-based agroecosystem" (2003). ETD collection for University of Nebraska - Lincoln. AAI3092525.
http://digitalcommons.unl.edu/dissertations/AAI3092525

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