Farmer Ron Rayner left ATumblingT Ranches Goodyear Ariz and Cash Veo WilburEllis Buckeye Ariz have worked together to improve farm productivity for four years

Farmer Ron Rayner, left, A-Tumbling-T Ranches, Goodyear, Ariz. and Cash Veo, Wilbur-Ellis, Buckeye, Ariz., have worked together to improve farm productivity for four years.

Variable rate fertilization can maximize alfalfa efficiency, profitability

A one alfalfa field trial focused on variable rate fertilizer applications in alfalfa. The process included guiding a Veris soil-sensor system implement across the field to determine soil type and relative salinity. The data and GPS recorded soil sample data were downloaded to Wilbur-Ellis’ AgVerdict software to determine which field areas had too much and too little phosphorous.

The Rayner family farms year round near Phoenix in the Arizona desert, double cropping 4,500 acres of alfalfa, cotton, wheat, and forage sorghum.

The family embraces new technology across the farm to maximize the farm’s productivity and efficiency. Yet there’s always room for improvement.

“With all of our yield gains in our crops, alfalfa is the one that has been lagging yield wise,” said Ron Rayner, who along with his brothers Robert and Earl are partners in ‘A-Tumbling-T-Ranches’ based in Goodyear.

“We’d like to get more production out of alfalfa.”

Current farm alfalfa yields average 8.5 tons to 9 tons per acre annually. Rayner farms alfalfa stands for three years. The entire farm is irrigated with groundwater.

The Rayners are busy growers, like many others, and turn to local agricultural service providers for suggestions on better ways to farm and new applicable technology. Rayner works closely with Cash Veo, branch manager of Wilbur-Ellis in nearby Buckeye.

Adding phosphate, magnesium, and sulfur are important to a healthy alfalfa stand in the desert. For about the last 20 years, Rayner has applied about an average of 300 pounds of fertilizer per acre annually to the alfalfa fields.

Last year, Veo approached the Rayners about conducting a one-field trial in the fall using the latest precision technology to use variable rate to apply fertilizers in alfalfa.

Information gathering

The Rayners gave the go ahead. The first step in the single field trial was gathering information.

Veo guided a tractor-pulled Veris soil-sensor system implement across the field. The onboard sensors gathered electrical conductivity (or EC) readings to determine soil type and relative salinity across the field.

This spring, Veo downloaded the data and GPS recorded soil sample data to Wilbur-Ellis’ new AgVerdict software program which interpreted the data to determine nutrient variability in the soil and learn which areas of the field had too much phosphorous and the areas which had too little.

The program allows soil texture, variability, and nutrient data to be seen and evaluated in one location.

“The findings showed the field had a large phosphate variability ranging from 11 parts per million (ppm) to 29 ppm,” Veo said.

The phosphate target for the Rayners’ alfalfa is 15-20 ppm to maintain nutrient availability and crop demand.

This technology allowed Veo to create a prescription map for the field which was broken down into 2-3 zones. Veo used the farm data, university findings, and his experience as a field agronomist to determine the needed changes in applied phosphate as well as other nutrients needed in varying amounts.

Veo said, “We are putting a little bit more of the nutrient needs for the crop in the field where it really needs it and a little less where it doesn’t.”

Prescription fertilizer rates

The AgVerdict data and prescription fertilizer rates agreed upon by the Rayners and Veo was then downloaded to a Trimble GPS in a TerraGator air spreader which is equipped with a variable rate spreader. Reading data from the GPS, precise amounts of phosphorus were spread in the specific field zones.

Rayner owns the collected data.

In addition to wanting to increase alfalfa yield, the trial was conducted in alfalfa since it’s much easier to operate a Veris in an even alfalfa field.

Since the trial, Rayner and Veo have run the Veris and AgVerdict software on the farm’s entire alfalfa acreage and made the needed nutrient application changes field by field.

“We are aiming to increase the yield,” Veo emphasized.

“By applying the correct amount of fertilizer we should increase the yield without increasing the amount spent on the fertilizer. It is more about putting the right product in the right place within a field.”

Less phosphorus required

A second benefit is a slight reduction in the amounts of phosphorus needed in the field.

Rayner is pleased with the initial results from the trial. The next couple of alfalfa cuts showed an estimated increased yield of almost a quarter-ton-per-acre per cut, based on 100 percent dry matter.

“We’ve seen a pretty good increase in yield. Simply put, we cut more hay.”

Rayner added, “As a grower you incur some slight additional costs with this system. You want to make sure you’re getting a benefit from it and a return on your investment. So far we are.”

Future plans

In the future, Veo plans to repeat the field sampling process annually in January or February followed by a prescribed rate of nutrients in March.

Over the long term, Veo says an important part of this project is creating a fertilizer and soil history from year to year.

“So often a grower wants to track changes over time, especially given the speed at which agriculture is changing,” Veo said. “A three-year assessment allows the grower to get a good handle on the soil, see how the changes affect it, and make an accurate assessment of fertilizer use and needs.”

When the crop rotation shifts from alfalfa into the next crop, Veo believes the soil’s balanced fertilizer level should boost yields in the new crop.

Rayner added, “I think it will create more uniform fertile soil. With a uniform reservoir of nutrients, I believe it could help improve yields in future plantings of grain and cotton.”

Most of the Rayner alfalfa is chopped for haylage for a nearby dairy. The balance is usually baled for export.

Veo says other area alfalfa growers are also participating in a similar Wilbur-Ellis program and are achieving similar results to the Rayners. Several others have already moved forward for this fall and into next spring. 

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