Changes in soil properties have been reported under several long-term no-till (NT) studies, however, the magnitude of changes in soil hydraulic properties with the use of new generation heavy machinery under NT farming is not widely documented on a long term basis. Therefore, a site under long-term NT production system was selected, where a known compaction force of 0 Mg axle load (control, C-0), two (C-2) and four (C-4) passages of 2.5 Mg water wagon axle load was applied to cover the entire plot for 20 consecutive years to assess changes in soil hydraulic properties at a site in the Central Ohio, USA. The field was under NT-based corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotation since 1997. An additional three plots were established in a natural woodlot (30 m adjacent from the compaction field plots) as the baseline to compare the impact of compaction under a NT managed agricultural soil. Total of 24 (three per treatment for each depth) undisturbed soil cores was collected in November 2016 from 0 to 10 cm and 10 to 20 cm depths by using a hammer based manual core sampler for determination of soil hydraulic properties (soil water retention-SWR, plant available water), and to measure pore size distribution and air porosity. Results revealed that vehicular traffic induced significant changes in SWR at 0 and -6 kPa soil water potential (ψ). A reduction of SWR by 7.9 to 3.2% under C-2, by 6.6 to 0% under C-4 and by 2.4 to 0.8% under C-0 was observed at -6 to -300 kPa compared to that for the wooded soil. The soil under C-4 treatment had the lowest air porosity. Furthermore, the volume of pores with diameter >10 μm under C-4 was reduced by 8.3% compared to C-0 and by 7.6% compared to the wooded soil. Soil water content (transmission, plant available and residual water) followed a trend similar to that of the pore volume distribution for soil subjected to vehicular traffic-induced compaction. The data supports the conclusion that two or four passages of 2.5 Mg axle load of vehicular traffic under NT farming moderately changed SWR, plant available water, pores size distribution and air porosity compared to that of the wooded soil. However, the magnitudes of changes in soil hydraulic properties due to vehicular passages of 2.5 Mg axle load were not consistent under the NT production system. Thus, further monitoring of the impacts of compaction on soil hydraulic properties particularly on some other properties (e.g., water infiltration and air permeability) across the years is needed for better assessment of the relationships between crop production and soil hydraulic properties as well as soil resilience.

在一些长期免耕研究中已报告了土壤特性的变化，但是，长期以来，关于农耕条件下使用新一代重型机械的土壤水力学特性的变化幅度并未得到广泛记录。 。因此，选择了长期使用NT生产系统的工地，其中已知压实力为0 Mg轴重（控制，C-0），两次（C-2）和四次（C-4）通过2.5 Mg水在美国俄亥俄州中部某地，连续两次使用货车轴荷覆盖整个样地，以评估土壤水力特性的变化。田地位于基于NT的玉米（Zea mays L。）-大豆下[ Glycine max自1997年以来（L.）Merr。]的轮作。在自然林地（与压实田地相邻30 m）中建立了另外三个样地作为基线，比较了NT管理的农业土壤下压实的影响。2016年11月，使用基于锤子的手动岩心取样器确定了土壤的水力特性（土壤保水率-SWR），从0至10 cm和10至20 cm的深度收集了总共24个（每个处理深度三个）未扰动的土壤核心，植物可用水），并测量孔径分布和空气孔隙率。结果表明，在0和-6 kPa的土壤水势（ψ）下，车辆通行引起SWR的显着变化。与林木土壤相比，在-6至-300 kPa下，在C-2下SWR降低了7.9％至3.2％，在C-4下降低了6.6％至0％，在C-0下降低了2.4至0.8％。经过C-4处理的土壤的空气孔隙率最低。此外，与C-0相比，C-4下直径> 10μm的孔的体积减少了，与林木土壤相比，减少了7.6％。土壤含水量（传输，植物可利用的水分和残留水）的变化趋势与行车引起的压实土壤的孔体积分布相似。数据支持这样的结论，与林木土壤相比，NT耕作下车辆通行的2.5 Mg轴载荷的两个或四个通道适度改变了SWR，植物可用水，孔尺寸分布和空气孔隙度。但是，在NT生产系统下，由于2.5 Mg轴重的车辆通过而导致的土壤水力学性质的变化幅度不一致。从而，