| while global climate change and food security have been paid much attention in the world, the cooperation from all over the world to tackle climate change and promote green and low carbon development has become the mainstream of the world. Agriculuture ecological system, as an important source of emissions of greenhouse gases, was paid more and more attention by the government, experts and scholars. The agricultural applications of crop straw, forestry waste and carbonized charcoal made from biomass has been recognized as an important technology to improve soil quality, ensure food production and tackle climate change. Treatments including NR (chemical fertilizer, no straw), SR (chemical fertilizer+straw), AR (chemical fertilizer, straw as ash), BR (chemical fertilizer, straw as biochar) and also fertilizer different levels were conducted to investigate the combined effects of straw and biochar compound fertilizer on soil quality, maize yield and GHG emissions in wheat-maize rotation system in dryland soil in North China Plain. Results were as follow.1. Straw return significantly affect on soil quality and maize yield. Results showed that maize yield for BR was higher by 4.3%,4.2% and 11.2%, respectively, compared with NR, AR and SR; agronomic N use efficiency for BR was higher by 18.6%,16.7% and 60.9%, respectively, compared with for NR, AR and SR. The SOC content under BR was higher by 12.0%,8.6% and 4.8%, respectively, compared with for NR, AR and SR. Although there is no significant difference between BR and AR, soil available P content under BR was higher by 20.1% and 9.1% compared with NR and SR, respectively. There is no significant difference in soil available K content between BR and NR, but the soil available K content for SR and AR were higher by 5.2% and 4.9% compared with NRO There is no significant difference in soil pH and total N among all treatments. Soil bulk density for BR was significantly lower by 9.8% compared with NR, and no significant difference was found among the other treatments.2. there was no significant difference in CO2, CH4 and N2O fluxes dynamic among straw return ways, but the difference of GHG cumulative emissions vaired with the type. CO2 emissions for SR were higher by 29.7%,17.5% and 31.7% compared with NR, AR and BR, respectively. N2O emissions for SR were higher by 78.1%,76.3% and 114.0% compared with NR, AR and BR, respectively. No significant difference in cumulative CH4 was found among all treatments. The GWP under BR was lower by 53.4% compared with SR, and no significant difference compared with NR. Cosidering the maize, the GHGI under BR was significantly lower by 20.0%,20.9% and 58.0% compared with NR, AR and SR, respectively. Therefore, biochar return was considered as an appropriate way for mitigrating GHG emissions and lower C production.3. Biochar compound fertilizer application impact on soil quality and maize yield. Results showed that there is no significant diffenrence in maize yield and agronomic N use efficiency among NN, CBF1+N1 and CBF1+N2, but the maize yield in CBF1+N3 and CBF2 was significantly higher by 5.0% and 6.0%, agronomic N use efficiency was significantly higher by 21.0% and 25.4% compared with NN, respectively. Compared with NN, the agronomic N use efficiency under CBF1+N1 and CBF1+N2 was higher by 7.3% and 19.9%, and significantly higher CBF1+N3 and CBF2 by 21.0% and 25.4%, respectively. However, Effects of biochar compound fertilizer on soil properties was different with above results. Although no significant difference was found between NN and CBF1+N1, total N for CBF1+N2, CBF1+N3 and CBF2 was higher by 4.7%,5.8% and 7.0% compared with NN, respectively. The SOC content for CBF1+N1 and CBF1+N2 showed no significant difference compared with NN, but higher by 3.0% and 6.8% under CBF1+N3 and CBF2, respectively. There is no significant difference in soil available P among NN, CBF1+N1, CBF1+N2 and CBF1+N3, but the soil available P under CBF2 was higher by 57.3% than that under NN. Although no significant difference was found between NN and CBF1+N2, the soil available K under CBF1+N1, CBF1+N3 and CBF2 was lower by 25.6%,20.9% and 14.2% compared with NN, respectively. Compared with NN, the soil bulk density was significantly decreased only under CBF2 among all the treatments.4. Biochar compound fertilizer had significantly effect on cumulative N2O and CO2 emissions. N2O emissions under the treatments added with N fertilizer was 2.84-3.30 times higher than that under CK. Compared to CBF1+N3, the N2O emissions were lower by 13.9% and 9.5% for CBF1+N1 and CBF2, respectively. Although there was no difference between NN and CBF2, the CO2 emissions were significantly higher by 25.2%,27.7% and 19.3% for CBF1+N1, CBF1+N2 and CBF1+N3 compared to NN, respectively. There was no difference in CH4 emssions among all treatments. The lowest EF value occurredin CBF2, with lower by 13.3% than that under CBF1+N1 and CBF1+N3. GWP was lowest in CBF1+N1 and CBF2, and lower by 14.1% and 9.6% compared to CBF1+N3, respectively, while there was no difference between NN and CBF1+N2. No significant difference was found in GHGI among all treatments.Therefore, biochar amendment could improve the soil properties and maize yield while decrease the total GWP, which is better way than conventional straw direct return and straw return as ash. Biochar compound fertilizer could improve the maize yield and matigrate the GHGs while reduce the N fertilization application by 20%, and it is an appropriate way to meet the low carbon agriculture. |
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