Combined Fertilization Could Increase Crop Productivity and Reduce Greenhouse Gas Intensity through Carbon Sequestration under Rice-Wheat Rotation

Quantifying greenhouse gas intensity (GHGI) and soil carbon sequestration is a method to assess the mitigation potential of agricultural activities. However, the effects of different fertilizer amendments on soil carbon sequestration and net GHGI in a rice-wheat cropping system are poorly understood. Here, fertilizer treatments including PK (P and K fertilizers); NPK (N, P and K fertilizers), NPK + OM (NPK plus manure), NPK + SR (NPK plus straw returning), and NPK + CR (NPK plus controlled-release fertilizer) with equal N input were conducted to gain insight into the change of soil organic carbon (SOC) derived from the net ecosystem carbon budget (NECB), net global warming potential (GWP), and GHGI under rice-wheat rotation. Results showed that compared with NPK treatment, NPK + OM significantly increased wheat yield and NPK + SR caused significant increase in rice yield. Meanwhile, NPK + SR and NPK + CR treatments reduced net GWP by 30.80% and 21.83%, GHGI by 36.84% and 28.07%, respectively, which suggested that improved grain production could be achieved without sacrificing the environment. With the greatest C sequestration, lowest GHGI, the NPK plus straw returning practices (NPK + SR) might be the best strategy to mitigate net GWP and improve grain yield and NUE in the current rice-wheat rotation system.

Finding Optimal Nutrients With Farming Techniques to influence Maize Productivity, and Mitigate Global Warming Potential Under Water-saving Agriculture in Semi-arid Regions

Background and aims: Effective nutrients management under various farming techniques is critical for improving maize productivity and ensuring the long-term protection of water-saving agriculture under semi-arid regions. However, the impacts have not been well documented in determining the features of soil greenhouse gas intensity (GHGI) emissions and the driving factors of nutrients fertilization is important for optimizing crop-land nutrients management under various farming techniques.Methods: The nutrients with farming techniques strategies were investigated under water-saving agriculture of maize during 2019-20 years, using the following nine treatments: BF: ridges covered with biodegradable film; CF: soil crust ridges; TF: conventional flat planting; 0: N:P at 0:0 kg ha-1, 1: N:P at 120:60 kg ha-1, 2: N:P at 280:140 kg ha-1. Results: Our results showed that the nutrients fertilization with various cultivation strategies had a significant influence on the GHG emissions. The BF2 treatment considerably increase soil water storage, soil respiration rate as a result of decreased ET rate and GHG emissions compared with the other treatments. The BF1 treatment significantly mitigated GWP, CH4, N2O, and CO2 emissions, changes in CH4, N2O, and CO2 cumulative emissions. The GHGI differently responded to nutrients with farming techniques strategies. Under the BF2 improved (25.0%) the average net GWP than that of TF2, but reduced GHGI, due to improved (18.5%) biomass productivity. The BF2 and BF1 farming methods results in greater N2O, CO2 emissions, GWP, and changes in cumulative CH4, N2O, and CO2 emissions, as a result, have an adverse effect on the soil than that of CF and TF treatments. Conclusions: However, obtained the higher area-scaled GWP (42.1%), WUEg (96.7%), WUEb (65.4%), and (41.1%) grain yield under the BF2 which may offset the negative environmental effects linked with climate change. Thus, it is recommended to use the BF2 treatment in water-saving agriculture under semi-arid regions for cleaner and more efficient maize production.

Biochar and DMPP Regulated Root-Zone CO2, N2O and CH4 Emissions of Soil-Ridged/Substrate-Embedded Cultivation Sweet Pepper in Chinese Solar Greenhouse

Northern China is a major production area for off-season vegetables in Chinese solar greenhouse. Usually, greenhouse gas emission flux and coefficient in Chinese solar greenhouse are higher than those in the open field. The reason for this phenomenon is heavy nitrogen (N) fertilization (esp. chemical N and organic manure N) and frequent irrigation during year-round cultivation. A novel substrate cultivation method for vegetable production in Chinese solar greenhouse, called soil-ridged/substrate-embedded cultivation (SSC), was put forward to reduce environmental pollution and increase use efficiency of nutrients. To clarify the characteristics of SSC root-zone greenhouse gas emissions, and the regulation effects of biochar and DMPP addition, five treatments were designed in Chinese solar greenhouse under the same nitrogen application level, including soil-ridge cultivation (SC, as a control), SSC (peat: vermiculite: perlite (v/v = 2:1:1), SSC-B50% (biochar: vermiculite: perlite,v/v = 2:1:1), SSC-B25% (biochar: peat: vermiculite: perlite, v/v = 1:1:1:1), and SSC-DMPP (SSC supplemented with 1% (w/w) DMPP of N fertilizer). Results showed that SSC improved fruit yield of sweet pepper of by 10.99% compared to SC. SSC-B50% and SSC-DMPP significantly improved sweet pepper growth compared to SSC. Moreover, SSC-DMPP increased sweet pepper yield by 10.30% compared to SSC treatment, while SSC-B50% and SSC-B25% treatments lowered the yield by 47.1% and 13.7% separately. Five treatments presented various root-zone temperature features. Also, substrate pH of SC, SSC-B50%, and SSC-B25% is alkaline, while SSC and SSC-DMPP treatments is acidic. Besides, the Global Warming Potential was significantly mitigated in the SSC cultivation compared with the SC. Similarly, the greenhouse gas intensity decreased from 0.074 to 0.038 kg CO2-eq kg− 1 yield. Compared with the SSC treatment, cumulative N2O emissions were significantly reduced in the SSC-DMPP treatment. The greenhouse gas intensity also decreased from 0.038 to 0.033 kg CO2-eq kg− 1 yield. Thus, we concluded that SSC was a promising method characterized with reduced greenhouse gas emissions and increased fruit yield. Application of DMPP in SSC cultivation significantly reduced N2O emissions. We recommend SSC method use in Chinese solar greenhouse with DMPP addition in substrate to optimize greenhouse gas mission.