Variation of least limiting water range with compaction for divergent textured soils
2009
Choudhary, K.K. | Aggarwal, P. | Singh, A.K.
Least limiting water range (LL WR), an indicator of soil structural quality is dynamic in nature and varies inversely with bulk density (BD) changes; its effects are further modified by variation in soil texture. Hence, in order to relate LL WR with compaction and soil type, a column study was carried out with three soil types i.e. sandy loam (SL), loamy sand (LS) and clay loam (CL), five soil water contents (Sw) (5, 10,15,20 and 25% by weight) and three compaction levels (10, 20 and 30 blows). Components of LLWR i.e. soil water content at soil penetration resistance (PR) of 2MPa (S2MPJ were obtained by drawing soil resistance curve (SRC) and also soil water contents at field capacity (SfJ, permanent wilting point (Spwp-) and at 10% aeration porosity (Sap) determined by drawing soil water release curve (SWC). The SRC showed that as compared to higher BD, at lower BD the magnitude of PR was low and its reduction with increase in Sw was appreciable. Computed S2MPa from SRC was higher for CL than for LS and SL. Among all four parameters of LL WR, Sfc and qpWP did not vary much, whereas Sap reduced significantly and S2MPa increased appreciably with increase in BD. Trends of LL WR-BD curve showed that LL WR was more than 20% (m3m-3) at lower BD, which is indication of good structural condition and decreased with increase in BD. At BD 1.75 Mg m3for LS and SL and at BD 1.68 Mg m-3 for CL the value of LL WR became less than 10% (m3m-3) which indicated poor structural conditions. For all soil types, available water capacity (A WC) did not vary appreciably with BD, whereas LLWR decreased appreciably with increase in BD, which indicated that LLWR was a true indicator of soil structural condition.
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