不同耕作方式对灌溉农田土壤有机碳组分的影响

Effects of Different Tillage Methods on Soil Organic Carbon Fractions in Irrigated Farmland

为探究引黄灌区不同耕作方式下有机碳及有机碳组分的分布特征,在甘肃省农业科学院白银沿黄灌区农业试验站设置田间试验。运用重铬酸钾外加热法、333 mol/L高锰酸钾溶液氧化法、六偏磷酸钠提取法、密度分组、酸水解法等方法,研究旋耕(RT对照)、免耕(NT)、深松(ST)、深松 + 秸秆还田(STS)处理对0~40 cm土层有机碳及有机碳组分的分布。结果表明,在0~40cm土层,不同耕作方式下,土壤有机碳含量(SOC)在8.53~12.64 g/kg之间,易氧化有机碳(ROOC)含量在3.72~6.69 g/kg之间,颗粒态有机碳(ROC)含量在1.29~3.56 g/kg之间,矿质结合态有机碳(MOC)含量在2.86~5.64 g/kg之间,轻组有机碳(LFOC)含量在0.82~2.61 g/kg之间,重组有机碳(HFOC)含量在5.93~10.38 g/kg之间,惰性有机碳(RPC)含量在5.20~7.87 g/kg之间。有机碳含量及有机碳各组分含量的变化呈现随深度增加而影响逐渐减弱的垂直分布规律。与旋耕相比,秸秆还田显著增加了SOC、ROOC、ROC、MOC、LFOC、HFOC、RPC的含量,深松显著增加了ROOC、ROC、LFOC的含量,免耕显著增加0~20cm的ROOC、ROC、HFOC的含量。不同类型的有机碳之间存在着一定的转换关系,秸秆还田对不同类型的有机碳含量均存在一定的促进作用,深松和免耕也能对少部分类型有机碳含量呈促进作用。保护性耕作措施对维持土地生产力具有重要意义。

In order to explore the distribution characteristics of organic carbon and organic carbon components under different tillage methods in the Yellow River irrigation area, a field experiment was set up in the Agricultural Experimental Station of Baiyin Yellow River Irrigation Area of Gansu Academy of Agricultural Sciences. The potassium dichromate external heating method, 333 mol/L potassium permanganate solution oxidation method, hexametaphosphate extraction method, density grouping, acid hydrolysis method and other methods were used. The distribution of organic carbon and organic carbon fractions in the 0~40 cm soil layer was studied by rotary tillage (RT control), no-tillage (NT), subsoiling (ST) and subsoiling + straw returning (STS). The results showed that in 0~40 cm soil layer, under different tillage methods, soil organic carbon content (SOC) ranged from 8.53 g/kg to 12.64 g/kg;the content of readily oxidizable organic carbon (ROOC) ranged from 3.72 to 6.69 g/kg;the content of particulate organic carbon (ROC) ranged from 1.29 to 3.56 g/kg, and the content of mineral-bound organic carbon (MOC) ranged from 2.86 to 5.64 g/kg. The light fraction organic carbon (LFOC) content ranged from 0.82 to 2.61 g/kg, and the heavy fraction organic carbon (HFOC) content ranged from 5.93 to 10.38 g/kg;the content of inert organic carbon (RPC) was between 5.20~7.87 g/kg. The change in organic carbon content and the content of each component of organic carbon showed a vertical distribution law that the influence gradually weakened with the increase of depth. Compared with rotary tillage, straw returning significantly increased the contents of SOC, ROOC, ROC, MOC, LFOC, HFOC, RPC, LP1-C and LP2-C. Subsoiling significantly increased the contents of ROOC, ROC and LFOC. No-tillage significantly increased the content of ROOC, ROC and HFOC in 0~20 cm. There is a certain conversion relationship between different types of organic carbon. Straw returning had a certain promoting effect on different types of organic carbon content. Subsoiling and no-tillage can also promote the content of organic carbon in a small number of types. Conservation tillage measures are of great significance to maintain land productivity.