江苏省种植业碳排放的测算及达峰分析

在实现“碳达峰、碳中和”的目标背景下,明确农业温室气体排放现状,模拟预测峰值,为促进江苏省农业低碳减排提供科学依据。基于农业物资投入和农田土壤利用2类碳源,采用IPCC碳排放系数法和清单法综合测算江苏省1990—2020年间种植业碳排放量,运用Tapio脱钩模型对农业碳排放量与农业经济增长的脱钩关系进行分析,并根据灰色预测模型GM(1,1)对2021—2060年碳排放量进行预测。结果表明:(1)2020年江苏省种植业碳排放为1999.53万t,1990—2020年间呈现先增加后降低再增加然后趋于平稳的趋势;种植业碳排放主要来源于农田土壤利用,农田土壤利用碳排放占比为77.73%~86.95%,农资投入碳排放占比为13.05%~22.27%;(2)化肥是农资投入碳排放源中最主要的排放源,其占比为69.15%~79.20%,其次是农药和农膜,农机、灌溉、翻耕占比均较低;(3)水稻是农田土壤利用排放源中最主要的排放源,其占农田土壤利用碳排放的79.76%~87.23%,其次是小麦和蔬菜,大豆、玉米、棉花占比均较低;(4)脱钩关系以弱脱钩和强脱钩为主,表明随着种植业生产总值的提高,农业种植碳排放呈缓慢增长或递减的趋势;(5)分别以1990—2020(近30年)和1999—2020(近20年)年农业种植碳排放量数据为样本,预测2021—2060年江苏省农业种植碳排放呈持续增长趋势,2060年仍未达峰;以2010—2020(近10年)年农业种植碳排放量数据为样本预测,2021—2060年江苏省农业种植碳排放呈持续降低趋势,种植业碳排放已于2020年达到峰值,表明近年来江苏省在低碳绿色农业发展已初见成效。

Effect of Rice-Based Cropping System on Organic Matter Status in Soils

A long-term simulation experiment was carried out to study the effect of rice-based cropping system,green manure and ground-water level on soil organic matter. Soil organic matter content increased when upland soil was puddled and cropped under submerged conditions. Among all treatments, soil organic matter contents in the treatments of rice-rice-flooded fallow in winter (WF) were the highest, those in the treatments of rice-rice-astragalus (WG) came the second, and those in the treatments of rice-rice-rape (WR)were the lowest. At the same rate of green manure application, the degrees of organo-mineral complexing in soils of treatments WG and WR were higher than those of treatment WF. After 9-year rice cultivation, the state of combination of humus in heavy fraction varied with treatments. The relative content of loosely bonded humus decreased in the order of WR > WG > WF, and it correlated significantly with Se availability.