摘要
Increasing salt-affected agricultural land due to low precipitation, high surface evaporation, irrigation with saline water, and poor cultural practices has triggered the interest to understand the influence of salt on nitrous oxide （N20） and carbon dioxide （CO2） emissions from soil. Three soils with varying electrical conductivity of saturated paste extract （ECe） （0.44-7.20 dS m-1） and sodium adsorption ratio of saturated paste extract （SARe） （1.1-27.7）, two saline-sodic soils （S2 and S3） and a non-saline, non-sodic soil （S1）, were incubated at moisture levels of 40%, 60%, and 80% water-filled pore space （WFPS） for 30 d, with or without nitrogen （N） fertilizer addition （urea at 525μg g-1 soil）. Evolving CO2 and N20 were estimated by analyzing the collected gas samples during the incubation period. Across all moisture and N levels, the cumulative N20 emissions increased significantly by 39.8% and 42.4% in S2 and S3, respectively, compared to S1. The cumulative CO2 emission from the three soils did not differ significantly as a result of the complex interactions of salinity and sodicity. Moisture had no significant effect oi1 N20 emissions, but cumulative CO2 emissions increased significantly with an increase in moisture. Addition of N significantly increased cumulative N20 and CO2 emissions. These showed that saline-sodic soils can be a significant contributor of N20 to the environment compared to non-saline, non-sodic soils. The application of N fertilizer, irrigation, and precipitation may potentially increase greenhouse gas （N20 and CO2） releases from saline-sodic soils.
Increasing salt-affected agricultural land due to low precipitation,high surface evaporation,irrigation with saline water,and poor cultural practices has triggered the interest to understand the influence of salt on nitrous oxide(N_2O) and carbon dioxide(CO_2)emissions from soil.Three soils with varying electrical conductivity of saturated paste extract(EC_e)(0.44-7.20 dS m^(-1)) and sodium adsorption ratio of saturated paste extract(SARe)(1.0-27.7),two saline-sodic soils(S2 and S3) and a non-saline,non-sodic soil(S1),were incubated at moisture levels of 40%,60%,and 80%water-filled pore space(WFPS) for 30 d,with or without nitrogen(N)fertilizer addition(urea at 525 μg g^(-1) soil).Evolving CO_2 and N2 O were estimated by analyzing the collected gas samples during the incubation period.Across all moisture and N levels,the cumulative N_2O emissions increased significantly by 39.8%and 42.4%in S2 and S3,respectively,compared to S1.The cumulative CO_2 emission from the three soils did not differ significantly as a result of the complex interactions of salinity and sodicity.Moisture had no significant effect on N_2O emissions,but cumulative CO_2 emissions increased significantly with an increase in moisture.Addition of N significantly increased cumulative N_2O and CO_2 emissions.These showed that saline-sodic soils can be a significant contributor of N_2O to the environment compared to non-saline,non-sodic soils.The application of N fertilizer,irrigation,and precipitation may potentially increase greenhouse gas(N2O and CO_2) releases from saline-sodic soils.
