Surface Hardness as an Indicator of Soil Strength of Agricultural Soils

Abstract

Soil strength is an important quality of agricultural soils prone to traffic. Surface hardness (SH) measured by the clegg impact tester (CIT) was evaluated as an indicator for assessing soil strength. Proctor tests were performed on a diverse range of soils to examine the relationships between bulk density (BD), penetration resistance (PR), SH and water content. All three indices showed typical response curves with increasing water content, with notable differences among the soils. Maximum dry bulk density (MDBD), peak penetration resistance (PPR) and peak surface hardness (PSH) showed values of 1.98 Mg·m −3 , 8.2 MPa and 248 Cmax for Piarco, River Estate and Piarco respectively. Corresponding critical moisture contents (CMC) were much greater for MDBD compared to PPR and PSH. SH showed a significant positive correlation with PR, but not BD. Further divulgence into the relationships between SH and other soil properties as well as crop response will facilitate greater use of the CIT.

Bulk soil properties as determinants of the compression strength of puddled lowland paddy soils in Sri Lanka

“…As explained by Bhagat (2003) initially lowest BD (1.62 g/cm 2 at 1WAT) was due to the submergence prior to tillage and it increased with time up to 1.81 g/cm 2 (12 WAT) which recorded as the highest, when the puddled soils undergo desiccation because of soil shrinkage. As reported by Eudoxie, et al (2012), this may be due to the MC variation of the field which showed the highest significant correlation (r = -0.893).…”

Comparative Evaluation of Common Savannah Grass on a Range of Soils Subjected to Different Stresses II: Root Zone Physical Condition

“…Christians [5] noted that the leaves of ZG are stiff, due to their high silica content [42], which could buffer the compactive force applied to the surface [43]. Eudoxie et al [44] also reported that the type of turfgrass cover influenced the effects of compaction on the bulk density of the underlying root zone. Statistically, root zone BD under ZG was similar for all stress treatments, supporting the argument that the root system of this grass may also be responsible for this result.…”

Bulk soil properties as the determinants of soil surface shear strength of puddled lowland rice soils of Sri Lanka affected by weed controlling methods

“…As reported by Bhagat et al (1999) initially lowest BD (1.323 g/cm 3 at 1WAT) is due to the submergence prior to tillage and it increased with the time up to 1.7 g/cm 3 (12 WAT) which recorded as the highest, when the puddled soils shrink due to desiccation. As indicated by Eudoxie et al (2012), this may be due to the MC variation of the field which showed the significant correlation (r = -0.574) at 0.05 α level. As discussed by Grossman and Reinsch (2002), this average BD is in the reference range of agricultural soils.…”

“…3, the predicted and measured SS values show higher linear relationships (R 2 =0.695 in T 3 and 0.794 in other treatments). As reported by Eudoxie et al (2012), MC is identified as the determinant of surface soil strength of upland soils and Weerasooriya et al in (2015); MC and BD are identified as the determinants of surface compression strength of low land pudddled soil. These are partially supportive findings to this result.…”

“…However it is not adequate for accurate assessment of overall soil SS because, assessing by one direct index may mislead the results and give relatively great spatial variation due to the point measurement (Hillel, 1971). Hence Eudoxie et al (2012) suggested using bulk soil parameters for overall estimation of soil strength. Soil moisture content, bulk density, soil compressibility, soil structure, soil texture and organic matter content are the potential nonpoint (bulk) soil indices of soil strength (IRRI, 1994).…”