Pecan (Carya illinoiensis) production in the southwest US requires 1.90 m (75 inches) to 2.5 m (98 inches) of irrigation per year depending on soil type. However, for many growers, scheduling irrigation is an inexact science. Currently, there are several options available to growers, and some, such as soil moisture sensors and computerized data-collection devices have become inexpensive. With more growers using computers in their business, there is potential to improve irrigation efficiency using these new soil moisture monitoring tools. The objectives of this project were to introduce 2 low-cost soil monitoring instruments to a group of pecan producers, provide instruction on the use of internet-based irrigation scheduling resources, and provide assistance in utilizing these tools to improve their irrigation scheduling and possibly yield. The Dona Ana County Extension agent selected 5 small to intermediate-scale pecan farmers based on their expressed interest in improving soil moisture monitoringand whether they used a computer. Farmers were instructed on the use of the instruments and associated software, and received instruction on the use of climate-based irrigation scheduling resources found on the internet. All participants understood thatbetter management of water inputs may translate into higher yields that could offset instrument costs. Three out of five growers indicated they used either the granular matrix sensors (GMS) or tensiometer to schedule irrigations, but compared to the climate-based irrigation scheduling model, all growers tended to irrigate later than the model’s recommendation. Graphical analysis of time-series soil moisture content measured with the GMS showed a decrease in the rate of soil moisture extraction coincident with the model’s recommended irrigation dates. These inflection points indicated the depletion of readily available soil moisture in the root zone. The findings support the accuracy of the climate-based model and suggest that the model may be used tocalibrate the sensors. Four of the five growers expressed interest in continued use of the tensiometer, but only one expressed a desire to use the GMS in the future. None of the participants expressed interest in using the climate-based irrigation scheduling model. A series of nomographs relating time of years to days between irrigation bas on multiple years of climate and the irrigation scheduling model were then produced to try and simplify the irrigation scheduling process. These nomgraphs are currently be evaluated by a focus group to determine if this solution will overcome the limitations of soil moisture sensors or internet climate based irrigation scheduling The nomograph approach to irrigation scheduling is simpler but information is lost using average weather data than real time climate data.
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