黄土区草被生长过程中土壤抗冲性及其与影响因素的关系

采用室内盆栽与原状土冲刷相结合的方法,设置了裸地对照(CK)、低种植密度黑麦草(H1)和高种植密度黑麦草(H2)3种处理,对3种处理在不同生长阶段的土壤理化性质和根系变化进行研究,分析了黄土区草被生长过程中土壤抗冲性及其与影响因素的相关关系。结果表明:(1)处理CK的容重、有机质含量和水稳性团聚体在4个生长阶段波动变化,但变化范围较小;随生长周期的延长,H1和H2处理的土壤容重呈下降趋势,有机质含量、水稳性团聚体、根表面积密度(RSAD,root surface area density)和根生物量密度(RWD,root weight density)呈增加趋势;在4个生长阶段,H1和H2处理各根径的RSAD表现为随根系径级的增大而减小。(2)CK和H2处理的土壤抗冲指数(ASI,anti-scourability index)在4个生长阶段无显著性变化;H1处理的ASI随生长时间的延长表现为逐渐增加的趋势,且在第16周,对ASI的影响最显著。(3)ASI与土壤容重呈幂函数递减关系,与有机质含量、水稳性团聚体呈幂函数递增关系,与RSAD、RWD之间均呈指数递增函数关系。(4)ASI与容重、水稳性团聚体、1.0~2.0,2.0~5.0,5mm径级的RSAD之间均无显著差异,与有机质含量、RSAD及RWD呈显著正相关(p0.05),与1mm径级的RSAD呈极显著正相关(p0.01)。

Soil Anti-scourability of the Growing Grass and Its Relationship with Influencing Factors in the Loessial Soil Area

By combining indoor pot experiment and scouring of undisturbed soil,three treatments were set up,i.e.bare land (CK),low planting density Lolium perenne L.(H1),and high planting density Lolium perenne L.(H2),to study the changes of soil physiochemical properties and root system at different growth stages.Soil anti-scourability of the growing grass and its relationship with influencing factors in the loessial soil area were analyzed.The results showed that:(1) Soil bulk density,organic matter content,and waterstable aggregates of CK fluctuated at four growth stages,but the ranges of changes were small.Soil bulk density decreased,organic matter content,water-stable aggregates,root surface area density (RSAD),and root weight density (RWD) showed an increasing trend with the extension of the growth cycle of H1 and H2.The RSAD of H1 and H2 treatments decreased with increasing root diameter at four growth stages.(2) Soil anti-scourability index (ASI) of CK and H2 were not significantly different at four growth stages.The ASI of H1 showed an increasing trend with the extension of growth time,and the effect of H1 treatment on ASI was the most significant at the 16th week.(3) ASI had a diminishing power function relationship with soil bulk density.ASI had an increasing power function relationship with organic matter content,and waterstable aggregates.ASI had an increasing exponential function relationship with RSAD,and RWD.(4) There was no significant difference between ASI and bulk density,water-stable aggregates,and 1.0 mm to 2.0 mm,2.0 mm to 5.0 mm,and ＞5 mm diameter class RSAD.There was a significantly positive correlation between ASI and organic matter content,RSAD,and RWD (p＜0.05).There was a highly significantly positive correlation between ASI and ＜1 mm diameter class RSAD (p＜0.01).