黄土高原淤地坝土壤性质剖面变化规律及其功能探讨

为分析淤地坝土壤性质的剖面变化规律及其在非点源污染工程治理方面的可能性,采用经典统计学方法研究了黄土高原典型淤地坝土壤性质在5.20 m剖面上的变化规律,并探讨了淤地坝作为碳储存库以及养分富集库的独特功能.结果表明,①坝前土壤剖面容重、砂粒含量低于坝尾,而土壤含水率、有机碳、粘粒、粉粒、速效磷、硝态氮以及铵态氮均大于坝尾;容重随剖面的变异情况为弱变异性,其余指标为中等变异性;除坝前砂粒含量和坝尾土壤含水率外,其余指标均呈正态分布;②坝前和坝尾剖面土壤含水率随土层深度的增加均呈锯齿型变化趋势,在剖面上的分布表现为波动型;土壤有机碳、速效磷、铵态氮随剖面的变化规律与土壤水分的趋势相同;③除坝尾容重与硝态氮、铵态氮及速效磷与铵态氮的相关性未达到显著水平外,土壤含水率、有机碳、容重、粘粒、粉粒、砂粒、速效磷、硝态氮以及铵态氮之间的相关性均达到了显著水平(p＜0.05),并且坝前与坝尾剖面土壤各个性质之间所表现的正相关性或负相关性是一致的;④淤地坝作为黄土高原的一个重要碳储存库,坝前有机碳储量高于坝尾,且坝前在400～520 cm储量最高,坝尾在0～100 cm储量最高;⑤淤地坝对速效养分具有富集效应,坝前储量大于坝尾,且2个剖面上的储量大小顺序均为:铵态氮＞速效磷＞硝态氮;淤地坝对铵态氮、硝态氮的富集系数分别为1.132和1.956;⑥淤地坝作为土壤养分的富集库,对区域碳平衡以及小流域非点源污染工程措施有效治理具有重要的理论意义,对黄土高原坝系建设及其生态功能的深入认识具有一定的参考价值.

Profile Variability of Soil Properties in Check Dam on the Loess Plateau and Its Functions

To understand the profile variability of soil properties of check dam and its possibility of engineering control over non-point source pollution, we used classical statistics to characterize the profile change of soil properties of a 5.20 m depth soil profile in the typical check dam on the Loess Plateau. The roles of check dam as organic carbon storage and available nutrients storage were discussed. The results showed that: 1) The bulk density and sand content of dam-head were lower than dam-tail, while, soil water content, silt, loam, organic carbon, available P, NO3(-) -N and NH4+ -N were higher than dam-tail. The bulk density for both dam-head and dam-tail showed weak variability while other properties showed moderate variability. All variables followed a normal distribution except sand in dam-head and soil moisture in dam-tail. 2) The change pattern of soil moisture on the soil profile for both dam-head and dam-tail was saw-tooth type. The change trends of soil organic carbon, available P and NH4+ -N were comparable to that of soil moisture. 3) The correlations among soil water content, organic carbon, bulk density, silt, loam, sand, available P, NO3(-) -N and NH4+ -N were significant (p < 0.05) except the relationship between bulk density and NO3(-) -N, NH4+ -N and relationship between available P and NH4+ -N in dam-tail. The positive or negative correlation of soil properties both in dam-head and dam-tail were coincident. 4) The check dam can be an important carbon storage on the Loess Plateau, and the organic carbon storage in dam-head was higher than dam-tail. The storage of organic carbon in 400-520 cm depth was the biggest for dam-head, in 0-100 cm depths for dam-tail. 5) The check dam is an enrichment sink of available nutrients. The storage of available P, NO3(-) -N and NH4+ -N in dam-head were higher than dam-tail, and the range of storage was: NH4+ -N > available P > NO3(-) -N. The coefficient of enrichment for NH4+ -N and NO3(-) -N were 1.132 and 1.956, respectively. 6) As the sink of soil nutrients, check dam has an important theoretical value for region carbon balance, ecological environment reconstruction and the effective control over non-point source pollution.