| Evaluation of soil physical state in Guanzhong farmland |
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| DOI：10.7606/j.issn.1000-7601.2017.03.38 |
| Key Words: farmland soil arable layer soil density soil aggregate soil structure guanzhong area |
| Author Name | Affiliation | | WANG Jia-xu | College of Resources and Environmental Sciences, Northwest A & F University, Yangling, Shaanxi 712100, China | | WANG Yi-quan | College of Resources and Environmental Sciences, Northwest A & F University, Yangling, Shaanxi 712100, China | | LI Xin | College of Resources and Environmental Sciences, Northwest A & F University, Yangling, Shaanxi 712100, China | | LIANG Hua-xue | College of Resources and Environmental Sciences, Northwest A & F University, Yangling, Shaanxi 712100, China | | SHI Hong-ping | College of Resources and Environmental Sciences, Northwest A & F University, Yangling, Shaanxi 712100, China | | SHI Zong-lin | College of Resources and Environmental Sciences, Northwest A & F University, Yangling, Shaanxi 712100, China |
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| Abstract: |
| In the face of soil aeration and water permeability declining, the ability of resistance to harmful environment diminishing, and the productive cost increasing year by year in Guanzhong farmland, the farmland soil sample from 11 counties in Guanzhong was taken and the thickness of arable layer, the soil density and aggregate characteristics was determined to study the soil physical state and its degradation characteristics under the condition of modern utilization intensity and soil management. The results showed that the soil arable layer generally became thin because of the compaction of lower soil, although the thickness in Guanzhong area was very thick in soil genesis. The thickness of soil arable layer was 5～21 cm. The sample number of the thickness of about 20 cm accounted for only 18%, the sample for 10～15 cm accounted for 64%, the sample of less than 10 cm accounted for about 18%. The soil bulk density in 0～20 cm layer in Guanzhong farmland were 1.04～1.34 g·cm-3 and the average value was 1.21 g·cm-3, which is good physical state. However, the soil bulk density in 20～40 cm layer was from 1.46～1.70 g·cm-3 and the average was 1.58 g·cm-3. The soil density in subsoil layer for about 36% of farmland reached or exceeded the limit value of 1.60 g·cm-3. Soil aggregate composition was determined by dry and wet sieving. The proportion of optimum aggregates of 1～5 mm, GMD, NMWD and coefficient of soil structure (Kctp) demonstrated that soil aggregate in arable layer was in good state, and 64% of soil aggregate in subsoil layer was in poor state. The water-stability of aggregates in farmland was worse. The state and stability of soil aggregate differenced largely in Guanzhong farmland. The reason that the arable layer becomes thin might be the subsoil compaction happened in 20～40 cm layer and plow-pan moved up and thickened. The soil bulk density in 20～40 cm has increased to a limit value. In 0～20 cm layer, soil aggregates were in good condition, but its poor water stability was the important reason of subsoil compaction. Soil compaction in Guanzhong farmland was widespread and became more serious. The soil compaction was a concealed soil physical degradation. Thus, more attention should be paid to soilcompaction in subsoil. |
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