砒砂岩改良风沙土物理和养分特征的大田试验

Physical and nutrient characteristics of sand soil improved by Pisha sandstone via field experiment

砒砂岩与沙土复配可以有效提升沙土的物理结构和养分特征,利用大田试验的方法,将不同体积比例(0、30%、50%、80%和100%)的砒砂岩添加到库布齐沙漠的风沙土中混合均匀,研究不同掺入比例条件下砒砂岩对风沙土的物理结构和养分特征的改良效果。结果表明:随着砒砂岩掺入比例的增加,黏粒含量、粉粒含量、毛管孔隙度、田间持水量、土壤团聚体、有机质、速效氮和有效磷含量逐渐增加,说明砒砂岩对风沙土具有明显的改良效果;在同一砒砂岩添加比例下,随着土层深度(0~30 cm)的增加,黏粒、粉粒、土壤有机质、速效氮和速效磷含量呈降低趋势,但土壤密度、毛管孔隙度及田间持水量的垂直变异特征较小,呈现明显表聚性,且50%的掺入比例可以作为改良的分界值;土壤颗粒及团聚体结构与土壤毛管孔隙度、有机质含量、田间持水量、速效氮含量及速效磷含量极显著正相关,说明砒砂岩与风沙土粒径的互补性较为明显。该研究成果将会为砒砂岩改良库布齐沙漠风沙土的大规模推广应用提供参考依据。

[Background]Pisha sandstone is a kind of interbedding generated in Mesozoic rock that is mainly distributed in Shanxi,Shaanxi and Inner Mongolia.Due to its special properties of collapsing easily encountering water,it is eroded seriously.Additionally,Aeolian sandy soil and Pisha sandstone are complementary in structure,and the both can be transformed into useful composite soil and be effectively utilized for planting through effective combination.However,the related research on improvement of soil structure and nutrients is mainly carried out in laboratory conditions and the systematic research of field test is rare,especially in the Kubuqi Desert.[Methods]The research was conducted by the field test method(each is 6667 m2)to study the improving effect by adding different proportions of Pisha sandstone on the physical structure and nutrient characteristics of the Aeolian sand soil from the hinterland of Kubuqi Desert in the northwest of Ordos Plateau.In the experimental test field,the different volume ratios(0%,30%,50%,80%and 100%)of Pisha sandstone were added and mixed evenly.Additionally,the Haloxylon ammodendron and Glycyrrhiza uralensis were inter-planted.One month later,the evaluation indexes include mainly soil capillary porosity,field water holding capacity,organic matter,available nitrogen and available phosphorus were tested.[Results]With the increase of the adding proportion of Pisha sandstone,the contents of clay,silt,capillary porosity,field water-holding capacity,soil aggregate,organic matter,available nitrogen and available phosphorus increase gradually and the sandy soil is improved significantly.Under the condition of the same proportion of Pisha sandstone,with the increasing soil depth(0-30 cm)of the improved soil,the contents of clay,silt,soil organic matter,available nitrogen and available phosphorus decrease,but the vertical variation characteristics of soil bulk density,capillary porosity and field water-holding capacity are small.And the variation is smaller with the increase of mixing proportion,showing the phenomenon of obvious surface aggregation.According to multiple indexes,the mixing ratio of 50%has the best improvement effect,which can be used as the boundary value for improving the Aeolian sand soil.Additionally,the structure of soil particle and aggregate is positively correlated with soil capillary porosity,field water-holding capacity,organic matter,available nitrogen and available phosphorus content,which shows that the particle size of Pisha sandstone and Aeolian sand soil is complementary.[Conculsions]This is the first time to study the composite soil by the field test in Kubuqi Desert.The physical and nutrient characteristics of sand soil are improved by Pisha sandstone.It can provide a reference for the large-scale popularization and application of Pisha sandstone to improve the Aeolian sandy soil in Kubuqi Desert and promote the desertification control.