Before they plant fence row to fence row to take advantage of high commodity prices, producers need to develop realistic expectations of their irrigation capacity, said a Texas AgriLife Extension Service expert.
Leon New, AgriLife Extension irrigation specialist, told producers at the High Plains Irrigation Conference held recently in Amarillo that there is only a certain amount of water available for commodity crops.
"We may want to plant all the wheat and corn we can and maybe some soybeans and cotton," New said. "One of the limiting factors may not be money, as in the past, but water."
There are a number of tools available that will help producers identify how much water they have available and when to apply it to address peak water-use periods, he said.
"You need to know your seasonal irrigation capacity and then you're going to make a decision on where your water is going," New said.
The Texas High Plains Evapotranspiration Network of weather stations can help producers determine how much water a crop needs throughout the growing season, as well as how much is being derived from rainfall, he said.
Corn may need 20 inches or more water from June to August. A 5.5 gallons-per-minute-per-acre well can only produce 17.5 inches running full-time during that period, so producers will need some stored water in the 6-inch soil profile, New said.
"We want to do more with less, but just how much can you do?" he asked. "You don't want to plant corn with only four gallons per minute per acre available from your well. You are better off with sorghum."
Sorghum requires 12 to 12.5 inches of moisture from mid-July to the end of August, and a four gallon-per-minute-per-acre well can produce somewhere between 9.5-10 inches, New said. That risk can be made up with a full soil-moisture profile.
Also, grain sorghum will do without moisture longer than corn before it starts stressing.
Cotton is another option where water is limited, he said. A three gallon-per-minute-per-acre well can support the production of three to four bales per acre of cotton.
"Every crop-water-use chart indicates we don't have the water to meet the demand throughout the growing season," New said. "What we try to meet is the demand during peak parts of the season.
"On most crops, you are betting on some free moisture in the form of rainfall, but you don't want a wreck."
Utilizing tools such as soil moisture probes and the weather station network, he advised, wait as long as possible, but be prepared to put on water to fill the 6-inch soil profile for this year's crop.
"You know as well as I know, every year is different," New said. "Wait as long as you can. If you can only put on an inch a week, it takes six weeks to fill the soil profile. So keep that in mind when planning water for critical water-use stages.
"If you have to quit watering on one of these stages, it will hurt you at harvest," he said.