Crop Yield Response to Soil Organic Carbon Stock over Long-Term Fertilizer Management in Huang-Huai-Hai Plains of China

Abstract

Huang-Huai-Hai (HHH) plains of China account for 69.2 % of annual wheat (Triticum aestivum) and 35.3 % of annual maize (Zea mays) production in China, and are China’s principal crop production area. Thus, the understanding of crop yield response to increase in soil organic carbon (SOC) stock in different fertilizer managements, soil types, and the threshold of SOC stock in the HHH region is the key factor affecting the adoption of fertilizer managements. Thus, data from ten long-term experiments have been collated and synthesized in this article. These long-term experiments involved four groups of similar fertilizer managements: (i) no chemical fertilizer or organic as control (CK), (ii) chemical nitrogen (N) fertilizer applied without organic manure (UF), (iii) combined application of chemical fertilizer (N, P, K) without organic manure (CF), and (iv) integrated nutrient management (INM) based on use of manure/straw and chemical fertilizer (N, P, K). The results indicated that (i) Crop yield increased with increase in SOC stock in all sites across the HHH. Increase in SOC stock by one Mg ha⁻¹ increased crop yield (kg ha⁻¹ year⁻¹) from 66.9 in Changpin to 333.2 in XinjiA and 495.2 in XinjiB in sub-region 1, 1,031.4 in HengshuiA, 419.2 in HengshuiB, and 148.5 in Yucheng in sub-region 2, and 914.2 in ZhengzhouA, 1,116.6 in ZhengzhouB, 1,135.6 in Xuzhou, and 437.3 in Mengcheng in sub-region 3. (ii) The magnitude of increase in crop yield with increase in SOC stock varied among CK,UF,CF, and INM treatments for different sites across the HHH. A gradual but sustainable increase was observed through SOC-induced improvements in soil quality. (iii) The threshold value of SOC stock for sub-region 1 was 44.9 Mg ha⁻¹ in XinjiA with the corresponding crop yield of 12.3 Mg ha⁻¹ year⁻¹. The available data were not sufficient to identify the threshold level of SOC stock for sub-region 2. The threshold values of SOC stock(Mg ha⁻¹) for sub-region 3 were 27.5 in Xuzhou, and 44.6 in Mengcheng with the corresponding crop yield(Mg ha⁻¹ year⁻¹⁾ of 14.5 and 10.5, respectively. (v)The threshold value of SOC stock in response to crop yield for the entire HHH ranged from 25.0 to 41.0 Mg ha⁻¹, and the corresponding potential of increase in crop yield from 12.8 to 18.0 Mg ha⁻¹ year⁻¹. In comparison with a rapid yield response by application of chemical fertilizers, increase in SOC stock and improvement in soil quality result in a gradual but sustainable yield increase. Thus, restoration of the depleted SOC stock by conversion to a restorative land use and adoption of INM across the HHH can enhance soil quality and improve crop production.