Precision Agriculture’s New Frontier: Irrigation By Lowell Catlett, MS, PhD

Precision agriculture in water-deficient areas focuses on water and chemical application technologies. As GPS allows for precise field mapping, water, nutrients and chemicals can be adjusted for each area, which results in the most productivity that has existed in agriculture’s 10,000-year history.

Precision agriculture is a farming-management concept based on observing, measuring and responding to inter- and intra-field variability in crops.

Early systems of ditches and field flooding have evolved to sophisticated subsurface drip irrigation and center pivot machines. Lucky for modern day irrigation professionals, the benefit of these technologies is that chemicals and fertilizer can be applied along with water delivery, providing plants the proper nutrients and plant protection via chemicals.

For most of the western United States, irrigation is a necessity accounting for 40% of the nation’s agricultural sales. The 17 contiguous western states account for 75% of all of the nation’s irrigated agriculture.

Natural Resources Conservation Service data states that more and more states east of the 100th meridian are moving away from 100% rain-fed agriculture and are supplementing with some form of irrigation. Concentrated efforts improve yields; molecular ge- netics and precision equipment allow for better seeding rates and varieties as the planter moves through the field. Planting windows are often short, so equipment is larger and easier to use. Addition- ally, chemical and nutrient application equipment becomes more complex, and all of the equipment from planting to harvest is linked via GPS so that precision agriculture is possible.

Top producers in both types of agriculture embrace precision farming — each area within a field is different and needs to be handled differently. Yet, non-irrigated agriculture has been slow to adopt irrigation. Why? The short answer is that there is ample water for crop growth and health and irrigation is an added and

unnecessary expense. But is the short answer correct? Maybe, but probably not in the new world of precision agriculture.

Non-irrigated areas do not have the right water conditions to extract the most from precision agriculture. Either they have too much (requiring drainage), or they get the moisture at non- optimum times during the growth stages of crops.

Numerous studies show that moisture is the limiting factor in opti- mum plant growth. For example, corn is most vulnerable to mois- ture stress during pollination, grain development and early leaf growth. Ample rain after pollination doesn’t make up for the lack of optimum moisture at the right time. A yield of 150 bushels of corn might be considered acceptable, but the potential that year with moisture not being a limiting factor might have been 300.

Since moisture is a major factor in crop yields, it is imperative that irrigation be front and center in developing and refining precision agriculture. Studies are all over the map on what optimum water can do. Generally the low is around 20% improvement to 100% (a few even put it higher than 100%).

Several top producers both in the U.S. and in Europe (in non- irrigated areas) are using irrigation as the backbone of their highly sophisticated operations to make sure that moisture is not the limiting factor. Some are experimenting with large water guns to add moisture during a critical stage while others are using both drip and center pivot systems to control as much as they possibly can of the plants’ moisture environment.

The cutting edge, of course, with all of the different types of irriga- tion possibilities is that remote sensing for moisture, insects, salt buildup, chemical runoff and deep percolation, just to name a few, can be integrated into an automatic algorithm that controls the crop’s health without human interaction.

Dr. Catlett was the keynote speaker at the 2014 Irrigation Show and Education Conference.

Dr. Lowell Catlett is Regents Professor and Dean, Emer- itus, College of Agricultural, Consumer and Environ- mental Sciences, New Mexico State University.

36 Irrigation TODAY | July 2016

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