New technology helps growers improve

“The decision to combine knowledge of plant systems and water needs with intensive irrigation management is the single most important decision I’ve made in our operation, ” said Rob Knorr, co-owner of Knorr Farms, Maricopa, Ariz. “The system allows Knorr Farms to be a top producer of high-quality produce with lower inputs.”

Only an estimated 10 percent of growers are currently managing crop production in this way. “That will have to increase due to the lack of water and the need for agriculture in general to be more competitive on a global scale,” Knorr said. Green and red peppers are produced primarily under center pivot irrigation across the chili belt of the desert Southwest that includes acreages in Texas, New Mexico and Arizona. Efficient irrigation management is crucial to high production and competitiveness at Knorr Farms, and understanding efficient irrigation management is becoming increasingly important to the agricultural industry.

Knorr Farms specializes in jalapeno peppers, and grows 200 to 400 acres of both sweet and hot jalapenos. Jalapenos are forward contracted for sale about a year in advance. About 130 acres of paprika red peppers, 130 acres of edible dry beans and additional acreages of potatoes for chipping are also grown.

Additionally, watermelon, cantaloupe and honeydew melons, as well as wheat and cotton, are grown on the farm. Melons are marketed through partnerships with melon shippers. Knorr emphasized the benefits of working with a growing/marketing partner rather than a broker. He said, “Our growing/marketing partners actually have an interest in the crop rather than just marketing our crop on a fee basis. Both partners bring something to the table. Our growing expertise and their marketing skills make for a strong relationship.”

Most of the jalapeno peppers are used in salsas, with paprika peppers primarily used in chili powder and seasonings. Potatoes are grown for chip operations. Garbanzo, pinto and black beans are grown for seed and commercial production, varying with market needs. While most melons are marketed in the Southwest, some are shipped throughout the U.S.

Rob Knorr checks soil moisture by hand in a recently transplanted pepper field.

Irrigation management increases in importance

Arid lands make up half the world’s agriculture production land, and irrigation is an increasingly important issue for U.S. growers. Irrigation is assuming a larger role in non-arid land production. Growers once raised crops only for subsistence or local markets, but many now depend on regional, national and international markets. These growers must compete not only in their own and neighboring states, but also in the international marketplace, as imports play increasingly important roles in the competitive market.

Irrigation technology has increased in complexity and intensity from simply getting water onto fields to micromanagement of a small land area. Crop production systems that can help growers reduce inputs and increase profit margins have been established. Establishing consumptive water use (CU) knowledge into Arizona vegetable production came about to a significant degree from work in cotton production. Incorporating CU into production can help growers reduce inputs of not only water, but also fertilizers, which helps assure profits as production costs continue to rise.

While irrigation is essential and efficient irrigation crucial to profits in the arid Southwest, more and more growers are incorporating irrigation into their operations. Even where rainfall is ample for crop production in the eastern half of the nation and across the rainy Northwest, irrigation is becoming the norm. Irrigation helps assure consistency and reduces inputs, helping growers to be more competitive in an increasingly competitive industry.

Rob Knorr discusses transplanting progress with Dimas Flores, labor contractor with AZ Hand Harvesting LLC.

Establishing Southwest operation

Knorr Farms is family-owned and operated. The Arizona operation was established in 1994. Knorr is a partner with his father, Bob Knorr. Bob Knorr and his other son, Steve Knorr, operate the North Dakota farming operation, growing primarily corn, wheat and pinto beans.

“We wanted to expand our operation, and we could buy land here at that time for about the same cost as in North Dakota,” Knorr said. “Down here, we can grow more than one crop annually; we have 12 months of sunshine, and we have access to irrigation water from the Colorado River.” The Central Arizona Project (CAP) distributes water to municipalities, tribal lands and agricultural customers through local irrigation districts. Arizona is one of a seven-state compact that originally negotiated water interests in 1922. The Maricopa Stanfield Irrigation and Drainage District (MSIDD) delivers water onto Knorr Farms’ lands via canals and irrigation ditches, or channels, that carry water throughout the farms. Wells located on the farms are leased to the irrigation district, which blends local well water with Colorado River water to produce the lowest-cost water before distributing it to local growers.

“We have four primary types of irrigation in Arizona,” Knorr said. “We have furrow, level basin flood, overhead sprinkler and subsurface irrigation.” Furrow irrigation is the oldest type of irrigation and was used by the ancient Hohokam Indians who farmed the valley in prehistoric times, followed by flood, overhead sprinkler and the newest, most efficient, subsurface irrigation. Knorr Farms has used all four types of irrigation, initially using furrow, which depended on gravity flow to move water through an unlevel field. Flood irrigation is used on laser-leveled fields, and overhead center-pivot or linear sprinklers are used additionally as a more efficient method than furrow and flood irrigation.

Knorr Farms changed to the efficient (95 percent-plus efficiency) subsurface irrigation for growing peppers about six years ago. Knorr said, “Peppers are an extremely water-sensitive crop needing approximately 70 to 96 inches of water annually. The fruit is 92 percent water, and, therefore, growing them in the arid Southwest, where we receive less than 7 inches of rainfall annually, is difficult. The need to produce high tonnage and quality peppers is what drove us to subsurface drip irrigation. The subsurface allows more intense management of water, allowing us to micromanage our fields.”

Water is pumped from the irrigation ditch through a filtration system into the belowground irrigation system, where PVC pipe carries water to the flexible drip tape that is buried 8 to 12 inches under each row of plants. Fertilizers and chemicals can be added to the irrigation water before it enters the subsurface portion of the drip system. Peppers have the greatest need for nitrogen, phosphorus and potassium. A NetaJet irrigation and fertigation controller, manufactured by Netafim Corp., is used. Systemic insecticides can also be chemigated through the underground system. Although Knorr is currently using drip tape and system components from multiple manufacturers, he prefers the Typhoon drip tape from Netafim Corp. and stainless steel filters from Everfilt Corp.

Efficient management

Employing techniques to monitor plant consumptive water use at various stages of plant growth is an essential component of crop management. To efficiently manage irrigation, the consumptive water use for the crop at different growth stages must be understood and mapped. Extensive research has been conducted to determine these specific requirements, and a number of tools can be used. Tensiometers, that measure soil moisture, and soil probes that are used to remove soil cores for moisture checks, help in measuring soil moisture.

Knorr says that simply picking up a handful of soil is an effective way to check moisture. He said, “Even with the newest technologies available today, simply ribboning the soil to feel the moisture level can be an effective way to monitor soil moisture.”

Established crop coefficients combined with evapotranspiration (ET) rates help in determining the amount of irrigation water that the crop needs at specific stages of growth.

“The concept is to reduce stresses on plants and be more productive in the arid Southwest by delivering water in the right amounts at the right time,” Knorr said. “Drip irrigation is a tool that allows us to reduce other inputs, such as fertilizer. It allows us to reduce costs, producing a big savings in water and even more savings in fertilizer, by placing water at the root where it is most efficient.”

Everfilt Corp. stainless steel sand media filters that prevent larger particles from entering drip tape and plugging small emitters.

The precise management of fertilizer delivery through the irrigation system is a significant advance in delivering only the amount of fertilizer needed to the root system. Knorr’s fields are designed on a small-scale basis and mapped for precise fertilizer needs based on soil testing and yields. Different amounts of fertilizer are delivered as needed to specific blocks rather than one amount of fertilizer over an entire field.

Knorr said, “In the past, produce in Arizona was grown in large fields, perhaps 80-acre blocks. In reality, we are growing in 10-acre mini blocks that allow us to tailor water and fertilizer needs to soil types in those small 10-acre mini blocks versus large 80-acre blocks that contain different soil types. By utilizing subsurface drip irrigation as a tool, combined with the knowledge of the complete plant and soil systems, we can produce greater quantities and qualities of crops.”

He added, “I believe that for us to be sustainable and profitable on a local and global basis, we have to be competitive on a cost per unit basis.”

Knorr Farms is a member of the Western Growers Association, a trade organization of Arizona and California growers. The Western Growers Association serves the interests of members on a wide range of issues that include water, transportation, science and technology, and supports a foundation that promotes education on food production.

Nancy Riggs is a freelance writer. She resides in Mount Zion, Ill.