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Soil Moisture: Types of Measurements and the Impact of Temperatures

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In agriculture, the productivity of crop production significantly depends on the quality of the soil. To ensure sufficient yield, the soil must be saturated with moisture. The problem is either a lack of moisture or an overabundance of it, which in turn is detrimental to the plant’s health and growth.

Soil quality surveys start with controlling the topsoil. Controls can determine the timing of seed sowing and harvesting. However, in the field of precision farming, it is difficult to estimate the moisture index, because it depends on the correct application of the data obtained. The data provided for analysis must have reliability about the condition of the topsoil. Replacing manual labor (application of the laboratory method) with automation via using modern technologies leads to improved productivity and reduced time for soil analysis, including information on moisture and soil temperature data.

What Soil Moisture Means

Ultimately, soil moisture is seen as a percentage measurement of the amount of water the soil contains. However, soil moisture can be described depending on different parameters:

• Soil moisture tension — measurement of tightness with which water is attached to the soil. Drier soils possess greater water potential, complicating the process of drawing water from them.
• Soil water content — the amount of water in a particular amount of soil (percentage of water to weight or volume of soil or inches of water per foot of soil).
• Plant available water — the amount of moisture in the soil between the soil’s field capacity. Measured in inches of water available per foot of soil.

The importance of soil moisture lies in:

Supplying water to plants
Affecting air content, salinity, and toxic substances
Supporting soil structure, plasticity, and density
Influencing the soil temperature regime and heat capacity
Prevention of soil weathering
Determining the readiness of the land for agricultural and agrotechnical activities.

Measuring Soil Moisture

To assess growing conditions and crop yield formation, soil moisture is taken into account at agrometeorological stations and posts during the whole vegetation period. Observations are made in the root zone differentiated by depth since due to limited mobility of soil moisture significant differences in soil moisture in its vertical profile can be created.

There are direct and indirect methods of field measurements of soil moisture. Direct methods directly measure the amount of water present in the soil. Indirect methods determine changes in one or other physical properties of soil, which depend on the degree of its moistening.

The Importance of Soil Temperature

Soil surface temperature is another important environmental factor affecting physiological processes. Soil temperature maps can be highly variable, especially in spaces where unshaded soil surfaces are exposed to large amounts of solar radiation. In addition, the temperature is more variable at the surface than deeper in the soil or air profile.

Temperature represents a critical control of physiological processes. For example, when soil moisture is constant under laboratory conditions, carbon losses from soil increase dramatically with increasing temperature in most ecosystems. Similarly, heated soils release more carbon than unheated soils. Both temperature and current soil temperature have been proved to be important environmental variables and sensors that can accurately capture soil surface climatic conditions can clarify how they affect the physiological processes of organisms on the soil surface.

Measuring Soil Moisture From Space

Today, agrarians use various observation methods to determine the plants’ irrigation requirements: manual observations of crops, data from soil moisture sensors, aerial photography, and satellite imagery. Using soil moisture data is an advanced method, but this solution does not scale well when we are talking about large land banks or continuous crops. Irregular UAV inspections of fields, to determine symptoms of plant water stress, also do not provide enough information.

Monitoring fields with remote sensing satellites is a technology that is easily scalable and provides data at a high frequency. However, the low spatial resolution of the images makes it impossible to make optimal crop irrigation decisions. To solve the problem, scientists suggest combining different satellite monitoring data with modeling technologies into one integrated product.

There are now different software products offering abundant data necessary for smart farm management, including soil moisture data. For instance, EOSDA Crop Monitoring provides two types of critical moisture data: soil surface and root zone levels. The platform is based on AI-powered satellite imagery analytics. And apart from soil moisture data, the tool offers all kinds of the necessary information on vegetation state, precipitation, weather, crop growth stages, and more. Therefore, users can retrieve all insights in one place to make effective decisions.

Aquifers do not have time to regenerate, and plant irrigation rate needs to grow along with average annual temperatures. The shortage of water for crop production is a problem that scientists and farmers will have to solve to ensure the efficiency of the industry in the face of growing demand for food. And modern tech like satellite monitoring can help doing so by providing necessary data for smart water distribution, based on the current needs of the soil and its moisture content.

 

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