CO2 emission and soil carbon sequestration from spring- and fall-applied poultry litter in corn production as simulated with RZWQM2

Poultry litter has increasingly been used as fertilizer in row crop production systems in the southeastern USA, leading to potential improvement of soil carbon (C) stocks. However, this improvement is accompanied by substantial losses of litter-derived C as CO2 emission, the balance of which has not been well investigated. A calibrated and validated Root Zone Water Quality Model (RZWQM2) with continuous 3-yr comprehensive field data was used to simulate and quantify soil CO2 emission and gain and loss of litter derived C in a corn (Zea mays L) production system in northern Mississippi USA. The corn field was fertilized with poultry litter (18,000 kg ha(-1) yr(-1)) or NO3NH4 (202 kg ha(-1) N yr(-1)) applied in the spring or fall over 3-yr. The results showed that simulated CO2 emissions from soil fertilized with litter averaged across years was approximately 0.8 times higher than soil fertilized with NH4NO3. Simulated CO2 emission loss from fall-applied litter was 16% higher than spring-applied litter when averaged across three years. The emission 59% of added litter C was lost as CO2 over the 3 yr course of the experiment, with an average loss rate of 7.53 kg C ha(-1) d(-1), implying 41% of C added remained in the soil profile. Relative to NH4NO3, litter increased soil total C by an average 1882 kg C ha(-1) yr(-1). The results overall show that, although the majority C applied to corn soil in the form of poultry litter may be lost as CO2, about 41% of it is stored in the soil in the short term may be contributing to the soil organic matter pool. (C) 2018 Elsevier Ltd. All rights reserved.