Abstract

Soil hydraulic properties are often influenced by agricultural activities. Knowledge of such properties is needed to understand the effect of agricultural practices on the soil water regime and catchment hydrology. In the present study, we investigated the effects of three land use types including orchard field, OF (without plowing), annual cultivated field, ACF (with seasonal plowing), and perennial alfalfa field, PAF (without plowing) on the soil’s water-conducting porosity at equivalent pore radius interval a to b, ε(a, b), sorptivity at applied tension ψ, S_ψ, and macroscopic capillary length at tension interval ψ_i to ψ_i+1, λ(ψ_i, ψ_i+1) of calcareous soils. The mentioned hydraulic attributes were calculated from infiltration data obtained from tension-disk infiltration measurements at six tensions of 0–15 cm at 75 experimental locations (25 replications per land use). In general, it can be concluded that more macropores are present in the soils of PAF than in those of ACF and OF land uses, probably due to high organic matter content, long-term no-till conditions, positive effects of alfalfa root systems, low machinery/livestock traffic, and low soluble sodium content. In ACF, conventional tillage and high machinery traffic, and in OF excessive use of Na-rich manure fertilizers and high livestock traffic resulted in less macropores compared to PAF.

摘要

土壤水力特性经常受到农业活动的影响。需要了解这些特性，以了解农业实践对土壤水分状况和流域水文的影响。在本研究中，我们调查了三种土地利用类型，包括果园地 OF（不耕地）、一年生耕地 ACF（季节性耕地）和多年生紫花苜蓿地 PAF（不耕地）对土壤水分的影响——在等效孔隙半径间隔 a 到 b 下的导孔隙率，ε(a, b)，在施加张力 ψ，S _ψ下的吸附性，以及在张力间隔 ψ _i到 ψ _i+1下的宏观毛细管长度，λ(ψ _i , ψ _{i+ 1}) 石灰质土壤。所提到的水力属性是根据在 75 个实验地点（每种土地使用 25 次重复）在 0-15 厘米的六个张力下的张力盘渗透测量获得的渗透数据计算的。一般来说，可以得出结论，PAF 土壤中的大孔比 ACF 和 OF 土地利用的土壤中存在更多的大孔，这可能是由于有机质含量高、长期免耕条件、苜蓿根系的积极影响，机械/牲畜交通量低，可溶性钠含量低。在 ACF 中，与 PAF 相比，传统耕作和高机械流量，以及在 OF 过度使用富钠肥料和高牲畜流量导致大孔较少。