Effects of maize stover and its derived biochar on greenhouse gases emissions and C-budget of brown earth in Northeast China.

Concerns regarding rising population levels and the impacts of atmospheric greenhouse gas (GHG) emissions on world climate have encouraged effective alternative methods to increase agricultural production while mitigating climate change. Soil GHG emissions from maize (Zea mays L.) fields treated with stover and a stover-derived biochar amendment during two consecutive maize growing seasons were studied in a brown earth soil type in Liaoning, China. We considered three treatments: CK (basal application of mineral NPK fertilizer; 120 kg N ha-1, 60 kg P2O5 ha-1, and 60 kg K2O ha-1, respectively), ST (maize stover application; 7.5 t ha-1), and BC (7.5 t ha-1 of maize stover was charred, with a yield of 35% of the original biomass; 2.63 t ha-1). Both ST and BC treatments received the same fertilization as CK. Soil GHG emissions were monitored using the static chamber-gas chromatography method. The mean CO2 emissions of the two-year experiment indicated that ST and BC were significantly higher than CK by 131.0 and by 21.3%, respectively, and there was a striking difference between ST and BC treatments. The N2O-N emissions decreased in the following order, BC < ST < CK, and cumulative reduced CH4 emissions in BC and ST were 1.58 and 2.21 times higher than observations in CK, respectively. The total global warming potential (GWP) in 2013 and 2014 decreased in the following order: BC < ST < CK. For the yield average data of two-year experiment, compared to CK and BC treatments, ST treatment showed 7.9 and 4.5% reduction, respectively. The C gains in BC treatment were significantly higher than that observed in ST treatment by 7.3%. Compared with the stover incorporating, biochar application significantly decreased the total CO2 emissions and GHG intensity (GHGI), and it enhanced C-sequestration.