Rainfall effectiveness measured

Rain gauges across Shackelford County measured well above average rainfall during 2018, and that trend is continuing in 2019. 

Residents reporting totals to the -USDA-Service Center office showed anywhere from 34 inches to over 40 inches of rainfall in various parts of the county during 2018, even though there were several months when less than 25 percent of the expected normal was reported. 

“These numbers give us a quantifiable report on the amount of rainfall, but what about the quality of that rainfall?” said district conservationist Troy Reinke. “How can you measure the effectiveness of all this rainfall?” 

Reinke said that an understanding of the water cycle is the key to determining how effective a rainfall event was on specific land. 

“The water cycle is the never-ending movement of water from clouds to soil, through plants and to clouds again,” he explained. “Influencing those parts of the cycle that affect crop and rangeland is paramount to how effective each rainfall event was.” 

He added that the cycle begins when precipitation strikes the land and ends when the water leaves that land either through runoff or evapotranspiration. 

“During this time, a livestock producer or crop farmer should store as much water as possible within the soil for use in forage or crop production,” said Reinke.  

On many farms and ranches, water is usually the limiting factor for crop and forage productivity. 

“The moisture in every raindrop, snowflake, or hailstone may be used productively on the site where it falls,” said the conservationist. “Or it may go downstream as clean water, or it may carry parts of soil that it fell on. When runoff water is dirty, it is taking a little of the potential of the land with it.” 

There are three main factors that determine how each raindrop is utilized, either to the benefit or detriment of the landowner and his downstream neighbors. 

IMPACT: When falling raindrops strike bare soil, the impact causes both splash erosion and soil compaction. This results in faster runoff and increased erosion. 

A good plant cover breaks the force of the raindrops and allows the water to move into the soil. This plant cover can be in the form of living plants or residue from the past growing season. 

The soil affords a large reservoir for the moisture storage – reducing flooding, enhancing water quality, and promoting a greater and more consistent supply of forage or enhanced annual crop yields. 

SOIL: Coarse-textured soil (sand) takes in water faster than fine-textured soil (clay) but stores less of the water within the root-zone of most perennial and annual plants. 

Water that moves below the root zone of the plants recharges groundwater and sometimes may appear downslope in a spring or in the creek. 

Because this movement through the soil is slow, the water supply downstream is cleaner and its flow occurs over a longer period. Where the surface is bare, less moisture enters the soil, and much of the water stored may evaporate during hot, windy days instead of being used for plant growth. 

By increasing organic matter, those parts of the plant that were not harvested by grazing or gleaning, a landowner can improve the infiltration rates on his fine-textured soils and improve the water-holding capacity of his course-textured soils. 

“This in turn will increase his land’s ability to store each raindrop for future growth of his desired plant communities, whether that be perennial grasses or annual crops,” said Reinke. “And when those raindrops must move in the form of runoff across the soil surface, the resulting downstream flow will be cleaner.”

He asked if readers noticed the common factor minimizing the impact of the raindrop and the effectiveness of the raindrop? 

PLANTS: Plants and the litter/organic matter they produce affect the water cycle in many ways. 

“Plants are the key to armoring the soil against the destructive power of a falling raindrop and improving a soil’s function to capture and store vast quantities of rainfall,” said Reinke. 

A healthier, more productive water cycle is the result of a landowner’s properly managed plant communities. The proper management of the plants leads to the breaking of the impact of raindrops on the soil surface. 

Plants also serve as small windbreaks to hold snow. 

Litter/organic matter acts as a sponge and slows runoff, giving moisture more time to move into the soil. 

Plant roots increase soil porosity so water moves more readily into and through the soil. They also hold the soil particles in place and reduce erosion.  

“A vigorous plant cover is an important part of influencing the water cycle and making effective use of the precipitation falling on your land,” said Reinke. 

Landowners who want to increase their land’s effective rainfall by improving the water cycle can implement a variety of conservation practices, he said. 

“Whether you are grazing livestock, managing wildlife habitat or farming cotton, your local Natural Resources Conservation Service field office can help,” Reinke concluded. “We have the conservation technical assistance that can tailor conservation practices to fit your goals and your land.” 

Call 325-762-2552 or stop by 584 US Hwy. 180 E to visit with conservation planners.

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