Irrigation
Most crops can utilize about 2.5–3 feet of soil profile to extract moisture. This gives a growing plant about 2.5–3.5 inches of available water to carry it without additional rainfall. Emerging crops use very little moisture early in the season, and a good profile of moisture will carry these plants for about a month without supplemental moisture.
As the crops get larger and begin to canopy, a full profile will only last about 8–14 days. This typically begins to occur in early June through August. Rainfall is the best hope for supplemental moisture since it is free, but it is not 100 percent effective. As soils seal over from rain or irrigation, they take water slower, thus making rainfall less effective. Determining how effective a rainfall is should be done with a soil probe, shovel, or some type of device to determine how deep the moisture soaked. Hard, fast rains can run-off as much as 75 percent of the water, where a slow steady rain can soak as much as 90 percent. The type of rainfall event will determine its effectiveness as well as the amount of moisture already in the soil.
Tillage will often dry out the soil surface as deep as 2–3 inches, but doesn't really effect the deeper moisture. Rainfall is the best choice for replenishing the shallow moisture early in the year, but irrigation may be required during the summer months. Supplemental irrigation is not typically needed until mid to late June on most crops under normal rainfall conditions. However, it is never too early to get prepared for irrigation, even if it is early, because it will certainly be needed in July and August to meet crop demand.
Common Conversions:
450 GPM = 1 acre inch per hour or 1 cubic foot per second (cfs)
1 gallon = 8.33 pounds
1 cubic foot = 7.48 gallons = 62.4 pounds
1 acre-inch = 27,000 gallons = 1 acre flooded one inch deep
1 acre-foot = 12 acre-inches = 43,560 cubic feet = 325,900 gallons
1 gallon = 3.785 liters = 0.003785 cubic meters
1 cubic meter = 1000 liters = 264.2 gallons
A column of water 2.31 feet high exerts a pressure at the base of one psi
1 psi = 2.31 feet of vertical elevation change for water.
1 atmosphere = 14.7 psi = 33.95 feet of water
1 inch of mercury = 1.13 feet of water
Publications
News
PINEY WOODS, Miss. -- Mississippi producers will receive training on irrigation practices during an April 20 field day.
The Alliance of Sustainable Farms will hold its Drip Irrigation and Plastic Mulch Laying field day on the National Center for Appropriate Technology demonstration farm at the Piney Woods School. The workshop will provide information on ecologically sound and profitable production practices.
Along with drip irrigation and plastic mulch laying, the workshop will also include transplanting demonstrations.
RAYMOND, Miss. -- Agricultural professionals, educators and service providers are invited to attend a training session on irrigation, water management and related technologies.
Two identical sessions will be offered. The first is March 6 at the Small Farm Training Center in Carriere. The second is March 7 at Jumpertown High School in Booneville.
Topics include production of specialty crops on small farms and application of federally funded cost-share programs and technical assistance for small farms.
STONEVILLE, Miss. -- Alternating wet and dry production is a radical new way to grow rice, and some Mississippi producers are finding the idea not only seems feasible in theory, but also works well in practice.
Jason Krutz is an irrigation specialist with the Mississippi State University Extension Service and a researcher with the Mississippi Agricultural and Forestry Experiment Station. He said the technique, known as AWD, grows rice without standing water, which reduces water use by about a third while also maintaining yields.
STARKVILLE, Miss. -- With spring around the corner, gardeners and farmers are beginning to plan for the upcoming planting and growing seasons.
One important way to ensure success during the Mississippi growing season is to have a plan for irrigation. Water keeps plants alive during the hot Mississippi summers, so irrigation is often vital during times of limited rainfall.
STARKVILLE, Miss. -- Dry September weather has Mississippi soybean producers on opposite ends of the irrigation spectrum: Some are done, while others want to water one more time.
Jason Krutz, irrigation specialist with the Mississippi State University Extension Service, has a question for them: What do the soil moisture sensors say?