Responses of Soil Carbon Pools and Carbon Management Index to Nitrogen Substitution Treatments in a Sweet Maize Farmland in South China

Abstract

In China, excessive nitrogen fertilizer application in sweet maize fields contributes to greenhouse gas emissions. This study used maize straw (MS), cow dung (CD), biogas residue (BR), and straw-based biochar (CB) to substitute the mineral nitrogen fertilizer at 20% and 50% ratios in the Pearl River Delta in China. In comparison with a conventional amount of mineral nitrogen fertilizer (CK), the soil organic carbon (SOC) storages of the different treatments increased by 6.5–183.0%. The CB treatment significantly improved the inert organic carbon pool in the soil, while other types of organic materials promoted the formation of activated carbon pools. The treatments increased the soil carbon pool management index by 21.1–111.0% compared to the CK. Moreover, the CB treatments increased the soil carbon sequestration index by 78.3% and 155.8% compared to the CK. In general, substituting the mineral N fertilizer with BR, CB, and CD could improve the SOC accumulation in sweet maize farmland in South China. The CB at the high substitution level was the best measure for stabilizing carbon sequestration in the sweet maize cropping system. This experiment provides valuable information for ensuring the clean production of sweet maize in a typical subtropical area in East Asia.

Effect of Chemical Fertilizer and Tobacco Stalks-derived Biochar on FCV Tobacco Yield, Nutrient Use Efficiency and Carbon Management Index in a Light Textured Alfisol

“…The treatments increased the soil carbon pool management index by 21.1-111.0% compared to the control. Moreover, the straw based biochar treatments increased the soil carbon sequestration index by 78.3% and 155.8% compared to the control" [88].…”

Improvement of Active Organic Carbon Distribution and Soil Quality with the Combination of Deep Tillage and No-Tillage Straw Returning Mode

“…The incorporation of straw into the soil can regulate the metabolic activity of soil microorganisms [5,6], and its metabolic products are an important source of soil organic matter, such as enzymes, polysaccharides, and proteins [7]. The increase in this type of soil organic matter creates favorable conditions for improving soil quality and fertility and can potentially replace a portion of chemical fertilizers in the long term [8,9], thereby reducing production costs and increasing crop yields. Although long-term straw return can improve soil quality and enhance soil fertility [10,11], in the initial years of straw return, the large amount of organic carbon entering the soil within a short period can significantly alter the original soil carbon-nitrogen balance [12].…”