水保所知识产出(1956---)知识库

依据毛细管理论，土壤水分特征曲线实际反映的是土壤孔隙状况和含水量之间的关
系，所以一切影响土壤孔隙状况和水分特性的因素都会对土壤水分特征曲线产生影响。
植物根系是土壤中普遍存在的成分，根系在生长过程中对土壤的穿插、挤压、伸展，势
必会对土壤大小孔隙的分配、分布和连通情况产生重要影响。
本试验采用室内土柱试验，分层测定了 0-40 cm 土层小麦不同种植密度下的土壤水
分特征曲线，以及土壤饱和含水量、毛管水含量等水分特征参数，并用 Gardner 模型对
土壤水分特征曲线进行拟合。探讨了不同处理对土壤持水能力、供水能力以及土壤孔隙
分布的影响。主要结论如下：
1） 土壤水分特征曲线形态变化
水吸力在 100 kPa 左右时曲线出现明显的转折，水吸力小于 100 kPa 时，曲线比较
平缓，而水吸力大于 100 kPa 时，曲线形态明显趋于陡直。各处理与对照之间均存在明
显差异。在土壤水吸力小于 100kPa 时，不同处理间曲线斜率差异显著；而当水吸力大
于 100kPa 时，不同处理土壤水分特征曲线近似平行，仅 0-20cm 土层处理 E 与其他处理
相比更为陡直。
相同种植密度下，不同土层的土壤水分特征曲线也有一定的差异，且较大种植密度
下（330 万株/hm 2 ，330 万株/hm 2 ，330 万株/hm 2 ）各土层土壤水分特征曲线的差异更为
明显。
2）土壤持水能力
总体上来看，各土层土壤持水能力呈现出相似的变化规律。即随着种植密度的增加，
持水能力呈现出先减小后增加的趋势。另外，同一种植密度下浅层土壤持水能力差异更
为显著，而深层土壤差异相对较小。
3)土壤供水能力
总体上看，0-20cm 土层，随便种植密度的增加，土壤供水能力依次减弱。而 20-40cm
土层，随着种植密度的增加，土壤供水能力则呈现先减弱后增强的趋势。另一方面，相
同种植密度下，浅土层土壤的供水能力更弱。
随着土壤水吸力的增高，比水容量迅速降低。水吸力增高到 0.4bar 时，比水容量已
经降低到 10 -2 数量级（cm 3 /cm 3 ·bar）。土水势高于-0.4bar 时土壤比水容量大，释水量大；
土水势降低到-2.5bar 时，土壤的比水容量明显变小，土壤的释水量明显减小。当土水势
处于-10bar~-15bar 时，此时虽仍属于有效水范围，但土壤的释水量己经很小了。4） 土壤当量孔隙容积变化
与对照处理相比，各处理土壤大孔隙（>0.05mm）均有较大程度增加，而小孔隙
（0.0002mm 关键词：土壤；土壤水分特征曲线；小麦；种植密度；孔隙

According to capillary theory, soil water characteristic curve (SWCC) actually reflects
the relationship between soil pore condition and soil water content. So any factor which
influences soil pore will lead to the change of SWCC. Root widely exists in the soil. Root can
insert, push the soil and stretch in it. This will significantly affect different size soil pore’s
distribution and connectivity. Laboratory soil column experiment planted wheat with different
densities was conducted. Soil water characteristic curve, saturated water content and capillary
water in 0-40 cm soil layers were measured layer-by-layer. Gardner model was used to
describe SWCC. SWCC, water-holding capacity and water-supplying capability of different
planting densities were studied. The results showed that:
1) Soil water characteristic curve
There is an obvious inflection point of SWCC when soil water suction is about
100kPa.The curve is relatively flat when soil water suction is less than 100kPa, while it
become steeper when soil water suction is greater than 100kPa.There are significant
differences between the treatments and the control. When the soil water suction is less than
100kPa, there is significant difference of the slop of the curve between each treatment. When
soil water suction is greater than 100kPa, only treatment E is steeper than others in 0-20cm
soil layer.
With the same planting density, there are some differences between different soil layers.
The difference is more obvious with larger planting density.
2) Soil water- holding ability
Water-holding capacity of different soil layers showed similar trends. Soil water-holding
capacity decreased minimum and then increase with increasing planting density of wheat. In
addition, with the same planting density, the differences of soil water holding ability in
shallow layers are more obvious.
3) Soil water-supplying capacity
In 0-20 cm soil layers, soil water-supplying capacity decrease with increasing planting
density of wheat. In 20-40cm soil layers, soil water supplying capacity decreased minimum
and then increase with increasing planting density of wheat. On the other hand, with the same
planting density, soil water supplying ability in shallow layers is weaker.  With the increase of soil suction the specific water capacity was sharply decreased and it
had already reduced to 10-2 cm3/cm3·bar at soil suction -0.4bar. When soil water potential is
larger than -0.4bar, the specific water capacity is larger and soil can supply a large amount of
water. When soil water potential reduced to -2.5bar, the specific water capacity became
smaller obviously, water amount which soil can supply became less. When soil water
potential is smaller than -10bar and larger than -15bar, the water content still belongs to
available water, while it can be used difficultly.
4) Equivalent pore volume
Compared with the control treatment, macrospores (d> 0.05) increased greatly,
micropores（0.0002mm extent.
Key words ： soil; soil water characteristic curve(SWCC); wheat; planting density; pore