Improved Irrigation Scheduling for Freshwater Conservation in Pecan Fields of EL Paso, TX.

Pecan (Carya illinoinensis Koch) is a major irrigated crop in the El Paso region of Texas. El Paso County has about 9,000 acres under pecan production and has third highest acreage among pecan producing counties in Texas. Pecan trees require large amounts of water for their growth and depth of irrigation water applied varies widely within the region, ranging from 5 to 10 feet per year. Border irrigation, a type of flood irrigation wherein water is applied from a field irrigation ditch at its highest elevation end to leveled tabs divided by earthen berms, is the oldest and most common irrigation method followed in the region. At present, most pecan growers base their irrigation scheduling on intuition or by counting the calendar days since the last irrigation. This method of irrigation scheduling can lead to over irrigation. Over-irrigation not only results in loss of water to deep percolation but also increases leaching of salts/nutrients into groundwater.  Studies on consumptive water use of pecan trees suggest that considerable amount of water can be saved by improving the water use efficiency. Conserving freshwater is the top priority in rapidly urbanizing extremely arid regions such as El Paso, Texas. Due to elevated salinity of irrigated soils in the region, there is very little scope for adopting other efficient methods of irrigation such as sprinkler or drip to conserve freshwater. Thus, improved irrigation scheduling can be the main method to improve water use efficiency and promote on-farm water conservation. Instead of counting number of days, growers can improve water use efficiency by better timing of their irrigation using soil moisture sensors. Currently, many types of sensors that can provide real time continuous soil moisture data are available in the market. In the recent years, some of these sensors and the data loggers that facilitate automatic data acquisition from these sensors have become inexpensive, making them affordable to many growers. About 57% of the growers in the region use computers for farm business and many of these growers have access to internet. Soil moisture data from some of these inexpensive sensor systems can be downloaded wirelessly within the radio range (typically 1-3 miles), making data acquisition much easier for busy growers. This can make using soil moisture sensors to time irrigation practical for many growers and help in development of  improved irrigation scheduling in pecan fields.