For many of us, the rain in June was greatly appreciated and provided very "effective precipitation." I use the term effective precipitation to mean precipitation which is actually captured in the soil profile and available for plant growth. Luckily, the June rains came with modest temperatures and winds, cloudy days and high humidity, which are ideal conditions for water retention in the soil. Too often, our summertime rains are immediately followed by high temperatures, windy days and sunny skies that increase the rate of evapotranspiration.
Do we have any control over how "effective" the limited summertime rains are in regard to plant growth? I believe we do. If pastures are closely grazed, they are much more exposed to the elements (wind, temperature, humidity, sunlight, etc.). As a result:
- Evapotranspiration increases.
- Movement of water into the soil (infiltration) decreases, thus increasing runoff and the probability of erosion.
- Soil temperature increases due to the exposure of the soil surface to sunlight.
If pastures are properly grazed, and we have an average grass height of 6 inches or greater, we stand a much better chance of the limited summertime rains being "effective." Having the ground covered is beneficial in many ways:
- Standing forage disperses and slows the raindrops upon impact, reducing soil compaction.
- It shades the ground, reducing the temperature of the soil.
- It increases the rate of water infiltration into the soil, as well as movement of water through the soil profile (percolation).
However, there is one negative impact of keeping the ground covered you should be aware of less runoff means less water for your ponds and surface streams. But, under most circumstances in southern Oklahoma, pasture health and forage production are the primary concerns for most producers in mid to late summer.