The conversation in agriculture is turning from irrigating crops more efficiently to not irrigating them at all.
Irrigated agriculture is a key contributor to our economic fortunes, pumping billions into our economy (to see exactly how much, and the toll that drought conditions have taken on farm production, read page 10 of the Texas Water Report: Going Deeper for the Solution (PDF)).
However, a growing population will place increased demands on already slim water sources, meaning that farmers may have to revert to techniques used before irrigation came to the Plains. How does dryland farming work?
A typical dryland planting schedule might involve a three-year cycle producing two crops.
- Wheat, for instance, could be planted around October 1 of year one and harvested in July of year two.
- The land then remains fallow until June of year three, when sorghum or cotton is planted and harvested in November. Once this is harvested, the land again remains fallow until the following October 1, when the cycle repeats.
- As long as the land remains mulched in fallow periods, it can retain moisture
Farmers might also switch to producing feed for livestock, growing lower-grade corn, or wheat or sorghum for forage and silage.
- Forage is grain grown directly for livestock. Silage makers harvest the crop and ferment it in anaerobic storage before feeding it to livestock, a process that improves its digestibility.
- Forage and silage crops require considerably less water since livestock will eat the whole plant, not just the human-consumable portion.
“No-till” planting methods also reduce water usage by improving the soil’s ability to retain moisture. In a field that is not tilled, or plowed, stalks or straw from a previous crop are left on the ground as mulch. A farmer then can plant a crop after the land has been left fallow for almost a year.
The obvious drawback is economic.
- Irrigation — when available — allows some farmers to produce two crops for human consumption a year.
- Dryland farming on the Plains could be expected to yield two crops every three years.
- A recent study by Texas Tech University and Texas AgriLife Research indicates that a shift to dryland farming in the Texas High Plains could reduce the region’s economic output by $1.6 billion and lead to a loss of nearly 7,300 jobs.
Continued improvement in water use efficiency may ease this impact somewhat, however, through the greater use of methods such as:
- irrigation audits, sometimes offered by groundwater conservation districts, which can provide producers with critical information about their irrigation systems’ efficiency and identify problems before they affect the entire system;
- variable rate irrigation, in which individual sprinklers on a center-pivot system
can be turned on and off to vary the amounts of water applied in various sections of a field;
- soil moisture sensors, wireless nodes that collect soil moisture data; and
- irrigation scheduling, which employs soil moisture measurements to make decisions on when to irrigate.