裸岩石砾地客土土体结构对水肥渗漏的影响

针对裸岩石砾地利用客土法整治后新增耕地存在失水失肥的现象,以秦岭北麓某荒石滩新增耕地客土耕层作为模拟研究对象,将供试土壤以不同容重分层填装试验土柱,并对其进行了水分入渗试验,分析了裸岩石砾地人为耕作层结构的水分、养分渗漏特征。通过对5种耕作层结构的模拟渗漏试验,结果表明:(1)人为耕层土壤初始渗漏能力和渗漏速率与模拟心土层容重呈负相关关系,其入渗过程可用修正后的Kostiakov入渗模型进行模拟;(2)心土层土壤容重对累积入渗量、入渗速率及养分流失量均有较大影响,并呈负相关关系;(3)分析养分总渗漏量显示,存在一个最优耕层结构,在此耕层结构具有较好的保肥效果。通过综合分析水肥渗漏状况,确定最优耕层结构自下而上容重分别为1.5,1.3,1.2g/cm3。

Analysis of Water and Nutrients Leakage on Barren Gravel Land with Different Structure of Topsoil

Aiming at the problems such as poor effect of water and nutrient retention, instability and leakage in barren gravel land at the northern foot of Qinling Mountain, raw soil in Shaanxi Province was chosen as the tested soil to study the characteristics of water and nutrient leakage in topsoil with different structure. By filling the soil column hierarchically with different bulk density, five kinds of topsoil structure were set to analyze the leakage characteristics of water and nutrient in the artificial plough layer. The results showed that: (1) The initial leakage ability and the attenuation degree showed a negative correlation relationship with the underlying soil bulk density, and the infiltration process could be simulated by the modified Kostiakov infiltration empirical formula; (2) The underlying soil bulk density greatly affected the cumulative amount of leakage, water leakage rate and nutrient loss amount, and they showed negative correlation relationships; (3) From the perspective of the total nutrients leakage amount, there was an optimal structure of topsoil, which had the best effect of retaining fertilizer. By analyzing the leakage of water and nutrient comprehensively, the optimal structure of topsoil was that the bulk densities of the soil layers from the bottom to up were 1.5, 1.3 and 1.2 g/cm3, respectively.