基于长期试验资料对中国农田表土有机碳含量变化的估算

Estimation of the change of topsoil organic carbon of croplands in China based on long-term experimental data

分析了文献报道的我国26个长期试验站点29个长期试验的农田土壤有机碳变化情况,并据此分析了近20年来我国农田土壤表层有机碳储量的可能变化范围。收集的长期试验涉及水稻土、红壤、黑土、棕壤、潮土等15种土壤类型。选择每一长期试验的不施肥对照(0类)、有机碳含量增长最慢或下降最快(I类)、增长最快或下降最慢(II类)、纯化肥NPK平衡施肥(III类)4种处理进行分析,分别代表极端耗竭、不合理施肥、增长潜力和常见施肥情景下的土壤有机碳含量(储量)变化。结果表明,对照土壤的有机碳含量变化速率平均为-0.06g·kg-1·a-1;I、II、III类处理情景下土壤有机碳含量变化率分别为-0.008g·kg-1·a-1、0.29g·kg-1·a-1和0.05g·kg-1·a-1。据此推算,在极端耗竭情景下,过去20年全国农田表土有机碳贮量减少419Tg;在I、II或III类处理情景下,农田表层土壤有机碳储量变化分别为下降99Tg、增加1.56Pg和增加208Tg。II类和III类处理情景的有机碳储量变化量差值表明,我国农田表层土壤具有较大的固碳潜力。

This paper looked up 29 long-term experimental data about the change of soil organic carbon content （SOC） of cropland at 26 long-term experimental sites, and analyzed the changable scope of topsoil organic carbon pool of China in recent 20 years. There are 15 soil types like paddy soil, red soil, brown soil, and Chao soil et al. in the references of 29 long-term experimental data. Ⅰn this paper, the treatment of no fertilizing CK（0）, the treatment of the lowest increasing or highest decreasing of SOC（Ⅰ）, the treatment of the highest increasing or lowest decreasing of SOC（Ⅱ）, and the treatment of NPK balanced-fertilizing（Ⅲ）in long-term experiments was selected for the SOC change at most exhausted, irrational fertilizing, increasing potential, and usual fertilizing scenario respectively. The results indicated that the average value of annual change velocity of SOC in the treatment of CK（0）was -0.06 g·kg^-1·a^-1, and that in the treatment of Ⅰ, Ⅱ, and Ⅲ was respectively -0.008 g·kg^-1·a^-1, 0.29 g·kg^-1·a^-1 and 0.05 g·kg^-1·a^-1. According to the annual change velocity of SOC and national cropland area, the topsoil organic carbon store of croplands in China's Mainland would have decreased 419 Tg in passed 20 years under the extremely exhausted scenario; and it would have respectively decreased 99 Tg, increased 1.56 Pg and 208 Tg under the scenario of Ⅰ, Ⅱ and Ⅲ. The great difference of SOC pool change of croplands between Ⅱ and Ⅲ model indicated that there would be great potential of carbon sequestration of agricultural topsoil in China.