黄土高原农田土壤碳和养分库分布及稳定性

发布时间：2019-01-12 12:32

【摘要】：针对当前黄土高原农田土壤碳储量低这一薄弱环节,以黄土高原典型X土、黑垆土、黄绵土为研究对象,研究有机碳和养分库构成分布及稳定性,为黄土高原农田土壤碳储量估算及合理施肥提供参考,结果如下:(1)颗粒有机碳占相应土壤总有机碳的比例在上层(0-20cm)土壤高于下层(20-40cm),上层土壤有利于颗粒有机碳的积累,而下层土壤则有利于矿物结合态有机碳的累积;颗粒有机碳及其占总有机碳的比例与土壤有机碳含量呈正相关关系,土壤有机质的积累主要以颗粒有机碳积累为主。(2)土壤层次(0-20cm、20-40cm)有机碳难降解指数(RIc)在50-89%之间,上层(0-20cm)土壤有机碳难降解指数(RIc)显著大于下层(20-40cm)的,并且黑垆土RIcX土RIc黄绵土RIc。难降解性组分的变化可以改变土壤结构的稳定性。(3)黑垆土剖面有机碳、全氮大致呈“S型”分布,耕层土壤有机碳、全氮含量较高,耕层以下呈明显下降,而在垆土层出现一个小峰值,以下土层又继续下降。全磷含量表现为“中低型”分布,在古耕层中全磷含量最低,耕层土壤全磷含量最高。全钾含量在整个剖面分布表现为耕层含量高于古耕层高于垆土层高于钙积层。无机碳含量分布呈“高—低—高”型,黑垆土耕层无机碳含量较高,随着土层深度的增加(0-110cm)无机碳含量开始降低,至垆土层无机碳含量最低,垆土层以下层次(110-320cm)又随剖面深度的增加而开始上升。(4)有机碳及养分在X土剖面中表聚现象明显,并呈现相似变化趋势,表现为:耕作层(0-20cm土层)有机碳及养分含量最高,随着土层深度的增加,含量逐渐降低,表现为耕作层含量高于黏化层高于钙积层高于母质层。无机碳含量分布呈“高—低—高”型,其中X土覆盖层无机碳含量较高,随着土层深度的增加,至粘化层时无机碳含量最低,至钙积层时又迅速升高。(5)X土、黑垆土剖面颗粒有机碳及颗粒有机碳比例随着剖面深度的增加而明显减少,剖面土壤有机碳难降解指数(RIc)在42-89%之间,并且随着剖面深度的加深而减少。因此本研究表明矿质结合态有机质比颗粒有机质对X土、黑垆土、黄绵土土壤有机碳的积累作用大,以及表层土壤有机碳较易矿化、周转期较短或活性高,稳定程度低,而剖面下层土壤有利于矿物结合态有机碳的累积,多以稳定形式存在,是重要的惰性碳汇库,随土壤有机质的积累,颗粒有机碳比例越高,有机碳中不稳定部分也越高,因此可以用颗粒有机碳比例反应土壤结构的稳定性。难降解性组分变化也可以反应土壤结构的稳定性。
[Abstract]:In view of the weak link of low carbon storage in farmland soil on the Loess Plateau at present, the distribution and stability of organic carbon and nutrient pool were studied with typical X soil, black loessial soil and yellow soil on the Loess Plateau. The results are as follows: (1) the ratio of particulate organic carbon to soil total organic carbon in the upper layer (0-20cm) is higher than that in the lower layer (20-40cm). The accumulation of particulate organic carbon in the upper soil was beneficial to the accumulation of particulate organic carbon, while the accumulation of the mineral bound organic carbon in the lower soil. Particulate organic carbon and its proportion in total organic carbon were positively correlated with soil organic carbon content. The accumulation of soil organic matter was dominated by particulate organic carbon accumulation. (2) soil level (0-20 cm). The organic carbon index (RIc) of 20-40cm was 50-89%, the (RIc) of 0-20cm soil was significantly higher than that of 20-40cm, and the RIc RIc. of RIcX soil in black loessial soil was higher than that of 20-40cm. The change of refractory components can change the stability of soil structure. (3) the organic carbon in the section of black loessial soil is approximately "S-type", the total nitrogen content of the topsoil is higher, and the content of total nitrogen is obviously decreased below the tilling layer. However, a small peak occurred in the loessial soil layer, and the following soil layer continued to decrease. The distribution of total phosphorus in the paleoplough was the lowest, and the total phosphorus content in the topsoil was the highest. The total potassium content in the whole section was higher than that in the paleo-cultivated layer and higher than that in the loessial soil layer than in the calcium accumulation layer. The distribution of inorganic carbon was "high-low-high". The content of inorganic carbon in cultivated layer of black loessial soil was higher, and the content of inorganic carbon began to decrease with the increase of soil depth (0-110cm), and the lowest content of inorganic carbon was found in soil layer of loessial soil. (4) the accumulation of organic carbon and nutrients in X soil profile was obvious and showed a similar trend. The content of organic carbon and nutrients in cultivated layer (0-20cm soil layer) was the highest. With the increase of soil depth, the content of organic carbon and nutrients in tilling layer decreased gradually, which showed that the content of cultivated layer was higher than that of clay layer and calcium accumulation layer was higher than that of parent material layer. The distribution of inorganic carbon is of "high-low-high" type, in which the content of inorganic carbon in the cover layer of X soil is higher. With the increase of soil depth, the content of inorganic carbon in the clay layer is the lowest, and the content of inorganic carbon in the layer of calcium accumulation increases rapidly. (5) the content of inorganic carbon in the cover layer of X soil increases rapidly with the increase of the depth of soil layer. The ratio of particulate organic carbon and particulate organic carbon in the section of black loessial soil decreased obviously with the increase of depth of section, and the (RIc) of soil organic carbon in section was between 42-89%, and decreased with the depth of section. Therefore, the results showed that the mineral bound organic matter had a greater effect on the accumulation of organic carbon in X soil, black loessial soil and yellow cavernous soil than granular organic matter, and the surface soil organic carbon was easily mineralized, with shorter or higher turnover period and lower stability. The soil in the lower layer of the profile is favorable to the accumulation of mineral bound organic carbon, which exists in a stable form and is an important inert carbon sink. With the accumulation of soil organic matter, the higher the ratio of particulate organic carbon is, the higher the unstable part of organic carbon is. Therefore, the particle organic carbon ratio can be used to reflect the stability of soil structure. The change of refractory components can also reflect the stability of soil structure.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S153.6;S158

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