Soil is formed partly from the effects of wind and rain. Throughout soil’s lifetime, it continues to be affected by the same elements. The effects of moisture on soil are determined by the moisture content for a given region and by taking into account the topography of the land. Current climate conditions have a significant impact on soil as land and sea temperatures continue to rise.
Erosion is a natural occurrence, yet when human-related activities (agriculture and development) change the structure of the land and therefore the soil, consequences take place. Determining whether an area is experiencing a drought or will experience one is measured by the soil’s moisture content. If the moisture content is too high, the risk of soil compaction rises. Soil that is dry or in arid climates may experience drought although that may change as climate does.
What Is Soil Moisture?
The level of moisture in the soil is often determined by variables in climate systems. Surface temperatures affect moisture levels through precipitation and evaporation. Drought and floods have severe impacts on soil moisture content in addition to the effects of climate change. As these conditions affect moisture content, they also indicate vulnerability to runoff and erosion.
Jamali Baruti, in a recent study of soil moisture in relation to soil erosion, explains: “Available water capacity (AWC) is the amount of water that the soil can store. It is the amount of water that is available for use by plants and is normally expressed as volume fractions or percentage.’ People have an adverse effect on soil’s AWC. Activities such as compacting soil with heavy equipment will decrease the amount of water soil can hold. Lower AWC makes soil more prone to drought.
Climate Change and Soil Moisture
The moisture content of soil has increased over the last 30 years: a trend that has coincided with rising temperatures due to climate change. As temperatures rise and rainfall increases, there is less chance for evaporation or for the soil to dry enough to lessen its water content.
Changes to the climate drive the global hydrologic cycle and intensify it. This cycle starts with oceanic evaporation that is lifted and cooled, then condensed into water vapor to forms clouds. Moisture is carried until it is deposited back to earth in the form of precipitation. As this cycle is disrupted, it opens the door for increases in ET or evapotranspiration which is the process of moisture up — then down — in the hydrologic cycle.
What Is Soil Erosion?
Soil erosion takes place when one or more contributing factors are in place, water not being the least. Soil erosion from water can be devastating as it strips the top layer of soil while diminishing the integrity of underlying soils. Debris and sediment are carried away and can change the soil’s composition resulting in loss of fertility or new plantings.
Soil Moisture and Erosion Combined
A combination of soil moisture and soil erosion can work to create a superlative amount of damage to an area. Erosion accounts for economic, environmental, and human health risks.
”Soil erosion rates vary widely over the landscapes, over a field and even along a slope profile within the field. To understand soil erosion over a particular area it is necessary to assess erosion at different landscapes for which various techniques are available,” says Mr. Baruti.
Understanding moisture content is imperative to know what the health of the soil is at any given time and if steps can be taken to avoid drought or erosion. Testing soil for its moisture content with various soil moisture testing devices or techniques is recommended to minimize the impacts of erosion and moisture imbalances.
How to Test Soil Moisture
By far the oldest method to measure soil moisture, the gravimetric process is lengthy and time-consuming. Soil samples are collected and weighed, then dried in an oven and weighed again, and compared for differences to estimated water content. The gravimetric method may prove difficult to apply if samples need to be taken from greater depths. Disruptions in the soil might also account for soil compromise as numerous samples might need to be collected for analysis.
These devices come with shaft extensions and are commonly used for deeper samples. Augers can be applied to depths up to 55 feet. The auger is turned by its handle which pushes its cylinder into the soil. The auger is then raised, and the cylinder’s barrel is emptied by striking it to free the sample. The gravimetric method can then be applied to the deeper sample.
This device determines how much force a growing plant needs to absorb moisture from the soil. A tensiometer consists of a ceramic cup (porous point) connected to a measuring device. The cup is filled with water, and the water in the cup finds its balance with the soil. As the soil dries, water flows out of the cup to indicate greater tension. As soil becomes wet and its tension reduces, water flows back into the cup. Changes in these tensions are indicated on the instrument’s measuring device. Temperature can affect tensiometers as the gradients between the device’s porous point and the soil might cause variations in its measurements.
Moisture sensors or probes
Soil moisture sensors test for moisture volume through electrical resistance, dielectric constant, or through interactions with soil neutrons. These instruments run the spectrum from a low-end do-it-yourself type up to more sophisticated devices that can also measure soil pH and determine soil temperature. Simply insert the probe into the soil, and the instrument does the rest.
Soil erosion is a serious consequence of agriculture and development. A warming planet is disrupting its cycles to create balance in soil’s moisture content. As these imbalances increase or fail to stabilize, drought, runoff, or erosion might result.
Testing soil for its moisture volume is one way to find out what’s coming. Take measures to increase soil’s ability to infiltrate or drain to avoid conditions that contribute to adverse consequences. Working to prevent problems now can positively affect two important factors — agriculture and development.