FAQs - AG WATER CONSERVATION PRACTICES

Q: What are Phreatophytes and what can producers do to manage or control their impact at the farm level?
A: Phreatophytes are plants such as Russian Olive, tamarisk, willows and cottonwood, that obtain water from the water table or the unsaturated zone just above it. Often found along water supply canals, phreatophytes can consume significant quantities of water through evapotranspiration, reducing the availability of water to a cropping system and its users. Producers usually engage in management of phreatophytes to preserve water reserves for crop intake. Methods of control include mechanical, chemical, and biological treatments or a combination of all three in order to remove, reduce, or manipulate unwanted communities.  Populations of phreatophytes are more common in areas where precipitation or water availability is not a limiting factor.

 

Q: How do conservation (reduced) tillage practices aid water conservation efforts?
A: Conservation or reduced tillage refers to the practice that supports continuous crop production on a field with 30% residue from the previous crop on the soil surface. Low pressure center pivot irrigation, subsurface drip irrigation, furrow irrigation, and dryland farming systems are all farming practices where conservation tillage could be adapted. No-Till and ridge tillage strategies are also considered conservation practices. Concerns related to irrigation timing and uniformity have discouraged many producers from adopting conservation tillage practices however they are known to conserve water in arid and semi-arid environments where water is the limiting factor.

Water savings in conservation tillage systems include reduced runoff, increased soil moisture especially in the winter months when crop residue will trap snow, and reduced evaporation. Because of increased infiltration rates, soils with low and medium intakes will benefit as irrigation applications decrease with frequency. Furrow firming will also steady infiltration rates in soils with high intake. Additional changes may be necessary depending upon how the soil responds, for example, changes in furrow stream size which determines advance time. Management of the amount of crop residue, set times, length of run, surface conditions at the trough of the furrow, and furrow size together will increase water savings. Conservation tillage in conjunction with monitoring soil moisture particularly in the spring after sufficient winter precipitation, may allow a producer to conserve one to two irrigation applications per year.

           

Q: What are drought tolerant crops and how do they achieve more efficient water use?
A: Climate, elevation, season, and market are four determining factors that dictate which crops to plant and when. Depending on the soil conditions and precipitation, some crops are drought and saline tolerant while others may flourish in a cooler or warmer climate. Pasture is a good example of this, where warm-season grasses perform better in Texas while cool-season fescue grows better in high altitude and cool temperatures. One of the best ways to manage water resources is by choosing specific plants for specific eco-agro purposes and by appropriate plant rotation such as planting and interchanging crops at specific times in order to improve soil moisture, nitrogen fixation, and reduce soil erosion.

Cool-season, short-growth crops such as brown mustard, canola and camelina have become an essential component in on-farm agricultural water conservation strategies. They are known to use less water and allow more time to accumulate water prior to planting wheat, for example, to replace fallow in the High Plains of western United States. The High Plains is a particularly volatile agricultural area due to dependence on a declining water resource, the Ogallala aquifer. Farmers are forced to face water conservation decisions. Choosing crops based on their plant-water requirements as well as crop rotation and fallow periods contribute to agricultural water conservation at the micro and macro level of farming systems.