Degree of soil compactness is highly correlated with the soil physical quality index S

Abstract

The soil physical parameter S (S-value or S-index) has been proposed as an index of soil physical quality. Soil physical quality is negatively affected by soil compaction (e.g. caused by agricultural field traffic). It has previously been shown that S decreases with increasing soil bulk density. This study investigated whether the relationship between S and soil compactness can be described by a single function that is valid across soil textures when soil compactness is expressed in terms of the degree of compactness (DC), which is relative density expressed as the ratio of bulk density to a reference density. This would provide an alternative measurement for soil physical quality that is more easily obtained than S. We also evaluated different methods for deriving reference density and tested whether reference values for S suggested in previous studies correspond to critical levels of DC reported in the literature. The relationships between S and DC were investigated for the 12 FAO/USDA soil textural classes based on pedo-transfer functions, and compared with data reported in the literature. A strong positive correlation was found between DC and ln (1/S), and a unique function was found between S and DC that is valid across soil textures, with the possible exception of poorly sorted soils with a high sand or silt concentration. Experimental data on S obtained from the literature supported these findings. The reference value of S (0.035) previously proposed as a boundary between good and poor soil physical conditions was found to agree well with the level of DC (87%) reported in the literature as critical with respect to plant growth. Proctor density was found to be the most useful measure of reference density, better than Håkansson reference density, which introduced some texture dependency into the relationship between S and DC. Our findings indicate that 1/S is a good measure of soil compactness and support the usefulness of S as a soil physical quality index. 3 However, our findings suggest that DC can also be used as an index of soil physical quality, and is much easier to obtain than S.

Long‐Term Soil Structure Observatory for Monitoring Post‐Compaction Evolution of Soil Structure

“…The degree of compactness, DC, given as the ratio of the actual bulk density to ρ Proctor , increased due to compaction from 78 to 90% at the 0.1‐m depth, and from 88 to 94% at the 0.3‐m depth. Critical limits of DC with respect to crop yield reported in the literature are 84 to 87% (Carter, 1990; Håkansson and Lipiec, 2000; Naderi‐Boldaji and Keller, 2016). Using the relationship between DC and the Dexter (2004) soil quality index S developed by Naderi‐Boldaji and Keller (2016), the DC values of the 0.1‐m depth (topsoil) translate into S values of 0.044 (uncompacted) and 0.027 (compacted), indicating a shift from “good” soil physical quality to “poor” soil physical quality.…”

“…Critical limits of DC with respect to crop yield reported in the literature are 84 to 87% (Carter, 1990; Håkansson and Lipiec, 2000; Naderi‐Boldaji and Keller, 2016). Using the relationship between DC and the Dexter (2004) soil quality index S developed by Naderi‐Boldaji and Keller (2016), the DC values of the 0.1‐m depth (topsoil) translate into S values of 0.044 (uncompacted) and 0.027 (compacted), indicating a shift from “good” soil physical quality to “poor” soil physical quality. These estimations suggest that the compaction inflicted in the SSO created soil physical conditions that are considered poor and expected to be limiting for crop development.…”

<b>Soybean productivity in Rhodic Hapludox compacted by the action of furrow openers

“…This system consists of stirring up the soil only in the sowing furrow (Palma et al, 2010;Botta, Tolon-Becerra, LastraBravo, & Tourn, 2010). It is also marked by the intense traffic of machines and equipments, which results in serious problems with soil compacting that may cause a loss in production (Moraes et al, 2016;Naderi-Boldaji & Keller, 2016;Botta et al, 2016).…”

Traction force demand of soybean planting in compacted Oxisol

“…However, it also involves the intense traffic of machines and implements, causing soil compaction and a subsequent drop in production (Moraes et al, 2016;Naderi-Boldaji and Keller, 2016). Studies developed in Paraná affirm that around 45% of farm areas with clayey soil and cultivated with soybean/corn show levels of compaction in the 0.1 -0.2m layer, which is restrictive to root and aerial development of the plants (Franchini et al, 2011).…”