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Soil Moisture

  • Soil Health

  • Physical


Soil moisture represents a key driver of vegetation characteristics, operating at both species and community levels. It has a substantial influence on crop yields in agriculture. The quantification of soil moisture content gives insights into critical aspects of soil dynamics, encompassing its water storage capacity, hydraulic properties, and chemical and biological activities (Le Roux et al., 2013; Soil Testing Methods Global Soil Doctors Programme, FAO).

Water availability within the soil is a pivotal determinant of microbial activity, and there is a well-established relationship between water availability and microbial activity. Constraints imposed by limited water resources can significantly impact soil microbial functionality and synthesis and mineralization of soil organic matter. This can have repercussions for biogeochemical cycles. It is important to note that distinct microbial groups within the soil exhibit different sensitivities to water restrictions, with bacteria exhibiting higher water requirements while fungi, benefiting from lower water thresholds, can readily explore air-filled pores (Cardoso et al., 2013).

Methodology summary

The oven-dry method is the standard laboratory method for determining the water content of soil.

The FAO Soil Doctor guide provides a standardized methodology for soil moisture, for calculating the gravimetric water content with high accuracy:

  • Using the normal procedure for soil sampling, obtain a soil sample from a desired depth.
  • Place the soil samples in sealable sample paper bags, and label the samples
  • Measure the weight of the field wet soil
  • Oven dry the soil for about 24 hours at 105 degrees Celsius or air dry the soil for 7 days
  • After drying, weigh the soil in order to obtain the dry weight of that soil
  • The difference between the wet and the dry weight is the amount of water in the soil

Detailed methodology on determining soil moisture can be found at Soil Testing Methods from FAO pg. 24-34.

Detailed information on soil sampling such as where to take the samples from, how many, the best time to sample, and depth of sampling, can be found at the Farm Carbon Toolkit.

Metric threshold or direction of change

Thresholds are context (habitat, land use, etc) dependent.

Technological innovations

The cosmic-ray neutron sensing (CRNS) is a promising technique for estimating soil moisture at an intermediate scale in a passive and non-invasive way (Li et al., 2023).

The development of smart soil sensors using IoT (Internet-of-Things)-based systems for analysing and monitoring soil nutrients in agriculture is a promising tool for monitoring soil health. These systems utilize a network of digital sensors that can provide real-time measurements. They are capable of quickly determining the nutrient content of the soil, including nitrogen, phosphorus, and potassium levels. The network of sensors can provide real-time measurements of other soil properties such as moisture, pH, electrical conductivity, and other plant properties at the same time as providing a NPK (nitrogen, phosphorus, and potassium) content in the soil (Pyingkodi et al., 2022; Ramson et al., 2021; Soetedjo & Hendriarianti, 2023).


  • Agricultural
  • Forest
  • Grassland
  • Peatland
  • Saltmarsh
  • Wetland


  • Community


  • Low


  • Tier 1

Technical expertise

  • Low

Standardised methodology

  • Partial