Spatial Variability of Physical Soil Quality Index of an Agricultural Field

Table 1

Threshold ranges of physical soil quality indicators for crop production.

Physical soil quality indicator	Threshold range	Comment	References
Clay, %	≤40	>40% impede soil water movement and redistribution	USDA staff [26]
Bulk density, g cm^−3	0.9–1.2	In fine textured soils bulk density <0.9 g cm^−3 may provide insufficient soil-root contact, water retention, and plant anchoring whereas bulk density >1.2 g cm^−3 may impede root elongation and reduce soil aeration	Reynolds et al. [27]
Porosity, %	≥50–65	10% (by volume) air filled porosity is considered limiting for plant growth. >50% of total porosity is considered quite adequate to provide 10% air filled porosity in silty clay and clay soils	Hall et al. [28]; Joshua and Rahman [29]
𝐾𝑆^‡, cm day^−1	≥8.64–43.2	In fine textured soil, 𝐾𝑆 < 8.64 cm day^−1 substantially reduced crop production by inadequate aeration in root zone, whereas 𝐾𝑆 43.2 cm day^−1 may consider ideal for rapid infiltration and redistribution of crop available water	Reynolds et al. [27]; McQueen and Shepherd [30]
MWD^#, mm	≥1–3	Soil aggregates with >1 mm MWD is considered moderately water stable	Rabbi et al. [31]

‡Saturated hydraulic conductivity; ^#mean weight diameter.