Effects of Mulching and Application of Organic and Chemical Fertilizer on Greenhouse Gas Emission and Water and Nitrogen Use in Summer Maize Farmland

Abstract

To explore the effects of mulching and the application of organic and chemical fertilizer on N2O, CO2, and CH4 emission; maize yield; water use efficiency (WUE); and nitrogen fertilizer use efficiency under the conditions of the same nitrogen fertilizer input in summer maize farmland, an experiment was conducted in the Guanzhong Plain of China. In this experiment, the two main experimental factors were mulching (M) and no-mulching, and the secondary experimental factors included no fertilizer application (CK), organic fertilizer substituting chemical fertilizer at 0% (T0, 0.00 kg·hm-2 organic fertilizer and 225.00 kg·hm-2 chemical fertilizer), 25% (T25, 56.25 kg·hm-2 organic fertilizer and 168.75 kg·hm-2 chemical fertilizer), 50% (T50, 112.50 kg·hm-2 organic fertilizer and 112.50 kg·hm-2 chemical fertilizer), 75% (T75, 168.75 kg·hm-2 organic fertilizer and 56.25 kg·hm-2 chemical fertilizer), and 100% (T100, 225.00 kg·hm-2 organic fertilizer and 0.00 kg·hm-2 chemical fertilizer), for a total of 12 treatments. The results showed as follows:1 both mulching and fertilizer application (with or without mulching) factors significantly increased soil N2O and CO2 emissions and reduced soil uptake of CH4(P<0.05). Compared to chemical fertilizer treatments, the organic fertilizer treatments reduced soil N2O emission by 11.8% to 52.6% and 14.1% to 68.0% and increased soil CO2 emission by 5.1% to 24.1% and 15.1% to 48.7% under mulching and no-mulching conditions, respectively (P<0.05). Compared to that under no-mulching, the global warming potential (GWP) under mulching increased by 140.7% to 206.6%. Compared to that in the CK treatment, the GWP of fertilized treatments increased by 36.6% to 67.6% and 31.2% to 89.1% under mulching and no-mulching conditions (P<0.05), respectively. Combined with the yield factor, the greenhouse gas intensity (GHGI) under the mulching condition increased by 103.4% to 166.2% compared to that under the no-mulching condition. Therefore, GHG emissions could be reduced by increasing yields. 2 The mulching treatments increased maize yield by 8.4% to 22.4% and WUE by 4.8% to 24.9% (P<0.05). Fertilizer application significantly increased maize yield and WUE. The organic fertilizer treatments increased yield by 2.6% to 8.5% and WUE 13.5% to 23.2% under the mulching condition compared to that in the MT0 treatment and increased yield by 3.9% to 14.3% and WUE 4.5% to 18.2% under the no-mulching condition compared to that in the T0 treatment. 3 In the 0-40 cm soil layer, the total nitrogen content of mulching treatments was increased by 2.4% to 24.7% compared with that of the no-mulching treatments. Fertilizer application treatments increased the total nitrogen content by 18.1% to 48.9% and 15.4% to 49.7% under the mulching and no-mulching conditions, respectively. Mulching and fertilizer application promoted nitrogen accumulation and nitrogen fertilizer use efficiency in maize plants (P<0.05). Compared to that in chemical fertilizer treatments, the organic fertilizer treatments increased nitrogen fertilizer use efficiency by 2.6% to 8.5% and 3.9% to 14.3% under mulching and no-mulching conditions, respectively. Combining ecological and economic benefits, the MT50 under mulching conditions and T75 under no-mulching conditions can be recommended as planting models to guarantee stable yield and achieve green and sustainable agricultural production.