Changes in Irrigation Practices Likely Mitigate Nitrous Oxide Emissions From California Cropland

Abstract

Crop production with intensive nitrogen (N) application is an important source of atmospheric nitrous oxide (N2O). However, there remains large uncertainty in quantifying cropland N2O emissions and their mitigation potential, especially in regions where cropping systems and farming management practices are highly diverse. Because N2O production in soils is tightly linked to N application rate and type, soil moisture, and oxygen status, improving irrigation is a potential strategy for N2O mitigation. We applied a process‐based biogeochemical model, DeNitrification‐DeComposition, to evaluate the influence of irrigation management on N2O emissions from California cropland, where cropping systems are extremely diverse and irrigation management has changed rapidly. We constructed a database containing data on weather, crop types and areas, soil properties, and farming management practices and predicted N2O emissions from California cropland under four typical irrigation methods (surface gravity, sprinkler, drip, and subsurface drip). We also assessed impact on N2O emissions of large‐scale changes in irrigation management experienced in California from 2001 to 2010 that was driven by the demand of reducing water use in agriculture. Simulations under different irrigation methods indicated that drip and subsurface drip irrigation reduced N2O emissions by 55% and 67%, respectively, compared to surface gravity irrigation. We estimated baseline N2O emissions from California cropland as 7.94 × 103 metric ton (MT) N/year under actual irrigation management in 2002. The large‐scale changes in irrigation management likely reduced N2O emissions by 7.3% from 2001 to 2010. This study showed the potential for reducing N2O emissions by using low‐volume irrigation.

Irrigation and tillage effects on soil nitrous oxide emissions in maize monoculture

“…The large difference found between irrigation systems was in the range of the results reported by Deng et al. (), who predicted a reduction of the 38% on soil N 2 O emissions for sprinkler‐irrigated maize systems compared with surface‐irrigated systems in Californian croplands. In two previous meta‐analysis for Mediterranean conditions, Cayuela et al.…”

“…The large difference found between irrigation systems was in the range of the results reported by Deng et al (2018), who predicted a reduction of the 38% on soil N 2 O emissions for sprinkler-irrigated maize systems compared with surface-irrigated systems in Californian croplands. In two previous meta-analysis for Mediterranean conditions, Cayuela et al (2017) reported mean cumulative N 2 O emission values of 3.7 ± 3.3 kg N 2 O-N ha −1 for sprinkler irrigation systems, with a mean N application rate of 226 ± 75 kg N ha −1 , while Aguilera, Lassaletta, Sanz-Cobena, Garnier, and Vallejo (2013) estimated 4 ± 2.6 kg N 2 O-N ha −1 for furrow and sprinkler irrigation systems, with a mean N application rate of 137 kg N ha −1 .…”

“…Similarly, Deng et al. () evaluated the impact of the irrigation system on soil N 2 O emissions for the California cropland using the DNDC model and predicted a reduction of 38% on soil N 2 O emissions under sprinkler irrigation compared with flood irrigation.…”

“…Moreover, in Mediterranean areas, several studies have concluded that irrigation is an important agricultural practice contributing to soil N 2 O emissions (Aguilera et al, 2013;Cayuela et al, 2017;Sanz-Cobena et al, 2017). Similarly, Deng et al (2018) evaluated the impact of the irrigation system on soil N 2 O emissions for the California cropland using the DNDC model and predicted a reduction of 38% on soil N 2 O emissions under sprinkler irrigation compared with flood irrigation.…”

Assessment of Nitrogen Oxide Emissions and San Joaquin Valley PM2.5 Impacts From Soils in California

“…The DNDC model used in this study had been calibrated and validated in a prior project with extensive N 2 O measurements in cropland and was found to perform well with an r 2 of 0.92 and a p value of <0.001 (Deng, Guo, et al, 2018;, indicating that the model we used adequately represented the biophysical conditions of agro-ecosystems in California. We have a much smaller data set for NO x emissions than for N 2 O, which was collected from major California's cropping systems over the past decade.…”