Percent soil moisture data estimate the percent soil moisture within the plant’s root zone (1 m depth or less). Plant roots may have a depth of less than 1 m as a result of shallow/impermeable soil layers that may prevent root growth or in early growth stages. These data are most useful for monitoring an established crop. Crop development is best with soil moisture between 50-80%. At soil moisture <40%, crop stress occurs.

January 01, 2021 - January 03, 2021 Percent Soil Moisture (%)

Surface soil moisture measurements are most useful for planting/harvesting activities. The top-layer surface depth depends on soil texture, but the surface is assumed to hold a maximum of 25 mm of available water. Surface soil moisture levels of 20-25 mm are beneficial for germinating and emerging a new crop but may damage newly seeded crops if these conditions last for an extended time; these conditions may also hinder fieldwork. Levels of 15-20 mm are best for vigorous field activity. Levels <10 mm cannot support seed germination or early growth potentials for a recently emerged crop.

January 01, 2021 - January 03, 2021 Surface Soil Moisture (mm)

Subsurface soil moisture measurements provide an estimate of the available water within a plant’s root zone (1 m depth or less) and are most useful for monitoring an established crop. The subsurface soil is assumed to hold 0-275 mm/m of water, depending on the soil’s water-holding capacity and the available water. Subsurface soil moisture levels >100 mm are favorable. Levels <100 mm indicate that subsurface soil moisture is short but can still support a well-established crop. Levels <25 mm can severely stress/reduce crop yields, especially at a critical stage for a crop’s growth; these effects are worsened if the surface layer also has low soil moisture at the same time.

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