Research offers long-term solutions for conserving water on the farm
By Rachel Alexander
A Texas Agricultural Experiment Station researcher is helping growers in the Rio Grande Basin find long-term solutions for conserving water on the farm.
“The goal is to develop strategies for using limited irrigation water while achieving the maximum yield,” said Texas A&M University Assistant Professor Dr. Giovanni Piccinni, who is determining coefficients regarding water use for crops grown in the Rio Grande Basin and the Winter Garden.
Crop coefficients are used in calculating the optimum amount of water needed by a crop – and, not a drop more.
“We’ve found that some crops yield well with only 75 percent replacement of their water needs,” he said. “That saves 25 percent of the water.”
Initially, Piccinni is working with corn, onions and cotton, and he’s planting them in weighing lysimeters to determine their crop coefficients. Weighing lysimeters are large open-top boxes, buried to ground level and filled with undisturbed soil. The boxes rest on scales, which measure changes in weight as crops grow in them and extract water from the soil.
“Exact measurements of plant water use are determined by measuring weight losses,” Piccinni said. “The lysimeters are sensitive to changes in weight as small as a coin the size of a quarter.”
The research complements an existing network that already delivers irrigation recommendations to the Texas High Plains.
Because crop coefficients vary for different crops and stages of development, as well as for the region crops are grown in, construction of lysimeters in Uvalde, Texas, will enable Piccinni to provide crop coefficients for local conditions.
He said the existing model for potential evapotranspiration – a standard estimate of water requirements – is being calibrated with the new coefficients, and daily water requirements for crops will soon be widely available.
Weather stations for other networks will be used to extend irrigation recommendations based on the crop coefficients to counties throughout the Rio Grande Basin.
