More crop per drop

Written by Allison Jenkins on June 01 2023.

Whether irrigating with center pivot sprinklers, pictured here, or surface methods such as furrow or flood irrigation, the ability to provide crops water throughout the growing season is a distinct advantage in producing higher yields—as long as it’s managed effectively.
A center pivot with sprinklers
On the farm of Robert Lange, right, in Randles, Mo., the use of a surge valve helps improve the efficiency of his furrow irrigation systems. This apparatus hooks to the well head, and a butterfly valve inside alternates the flow of water in timed intervals. As irrigated furrows dry, the top layer of soil consolidates and seals the surface, allowing the next round of irrigation to be more evenly distributed through the entirety of the row. Jesse Surface, left, MFA district agronomist who works with Lange, says this technology lowers water usage and helps growers be better stewards.
In furrow irrigation systems, the crop is planted in elevated beds, and collapsible poly pipes distribute water through channels created between those beds. Software programs such as PHAUCET and Delta Plastics’ Pipe Planner can help growers calculate the best hole size for uniform water application and improve timeliness of irrigating fields. Surface and Lange say they use a tool called a Poly Piranha to punch various-size holes in the tubing according to the computer-generated plan.
In furrow irrigation systems on corn.
This aerial view of a center pivot irrigation system shows how it covers fields of both corn and soybeans. Center pivots are best suited for large, regular-shaped fields that are free of obstacles. In addition to irrigation, center pivots are often used to apply fertilizers and crop protection products, and many modern systems also allow for variable-rate irrigation.
MFA District Agronomist Jesse Surface shares information and advice on managing furrow irrigation at MFA Incorporated’s Winter Agronomy Meeting in January. In his agronomist’s role, Surface works with growers throughout the Missouri Bootheel and Northeast Arkansas, where most of the irrigation systems are the furrow type.
Jesse Surface

Whether irrigating with center pivot sprinklers, pictured here, or surface methods such as furrow or flood irrigation, the ability to provide crops water throughout the growing season is a distinct advantage in producing higher yields—as long as it’s managed effectively.

On the farm of Robert Lange, right, in Randles, Mo., the use of a surge valve helps improve the efficiency of his furrow irrigation systems. This apparatus hooks to the well head, and a butterfly valve inside alternates the flow of water in timed intervals. As irrigated furrows dry, the top layer of soil consolidates and seals the surface, allowing the next round of irrigation to be more evenly distributed through the entirety of the row. Jesse Surface, left, MFA district agronomist who works with Lange, says this technology lowers water usage and helps growers be better stewards.

In furrow irrigation systems, the crop is planted in elevated beds, and collapsible poly pipes distribute water through channels created between those beds. Software programs such as PHAUCET and Delta Plastics’ Pipe Planner can help growers calculate the best hole size for uniform water application and improve timeliness of irrigating fields. Surface and Lange say they use a tool called a Poly Piranha to punch various-size holes in the tubing according to the computer-generated plan.

This aerial view of a center pivot irrigation system shows how it covers fields of both corn and soybeans. Center pivots are best suited for large, regular-shaped fields that are free of obstacles. In addition to irrigation, center pivots are often used to apply fertilizers and crop protection products, and many modern systems also allow for variable-rate irrigation.

MFA District Agronomist Jesse Surface shares information and advice on managing furrow irrigation at MFA Incorporated’s Winter Agronomy Meeting in January. In his agronomist’s role, Surface works with growers throughout the Missouri Bootheel and Northeast Arkansas, where most of the irrigation systems are the furrow type.

FARMERS CAN’T SET MARKET PRICES for their crops. They can’t stop government from creating new regulations. They can’t control the cost of inputs or keep land values from rising.

But they can make rain—with irrigation, that is.

“So much about farming is out of our hands, but irrigation is one thing you can control. It takes away a lot of the risk,” said Robert Lange, who raises corn and soybeans on 400 irrigated acres in the Missouri Bootheel, just outside Cape Girardeau. His grandfather, also named Robert, graded all the fields, installed wells and started farming with furrow irrigation here in the mid-1980s. The younger Lange took over a portion of the farm from his uncle, David, when he retired in 2020.

With water being one of the biggest factors in determining yield, irrigation can help improve both productivity and profitability in crop production. Only about 15% of harvested land in the U.S. is irrigated yet those acres contribute 40% of the country’s agricultural production, according to the 2017 Census of Agriculture, the latest figures available. Data from the 2022 census will likely show an increase in those numbers, although cost, water availability and suitability of the land for irrigation are barriers to more widespread adoption.

In Missouri, irrigation is found on some 1.5 million acres, representing about 10% of the state’s total cropland. Around 800,000 of those acres are set up for surface irrigation—furrow or flood—while center pivot sprinklers make up most of the rest.

“It costs a lot and is a lot of work, but it by far pays for itself,” MFA District Agronomist Jesse Surface said. “In general, irrigating soybeans gives you an increased yield of 10 to 20 bushels per acre over dryland beans. In corn, we see a 50- to 60-bushel increase. And the biggest benefit is yield stabilization, knowing from year to year what your production will be. That allows growers to more confidently market their crops.”

As an MFA agronomist, Surface works with growers throughout the Missouri Bootheel, where more than 85% of the state’s irrigated acres are located. Furrow irrigation is the most common system in the region. This gravity-powered method works by creating furrows between elevated crop beds and pumping water into these sloping channels through poly pipes with strategically placed holes. This system requires relatively level land that can be precision-graded to allow for the ideal flow of water.

On the other hand, center pivots, the second-most prevalent irrigation system in Missouri, offer the ability to water fields where surface irrigation is impossible or impractical. In this method, an overhead sprinkler system rotates around a central point connected to a water supply. Pivots are best suited for large square-, rectangular- or circular-shaped fields free of obstacles such as trees, fences, roads and power poles.

No matter what type of system, making every drop count through proper irrigation scheduling is both environmentally and economically important. However, determining when to irrigate and how much water to apply during the growing season can be a challenge. With too little water, the crop is stressed. With too much water, plants are stunted and fertilizer leaches below the root zone. Either way, the crop suffers.

“People talk about the science, but irrigation is truly an art form,” Surface said. “The biggest thing to understand is when crop needs its water the most, especially when we talk about soybeans. They almost use more water than corn when they get to the grain fill stage. Knowing when the crop really starts ramping up water intake helps you stay on top of it. And sometimes, you have to just trust your gut.”

From emergence to maturity, corn typically uses around 26 inches of water, with peak demand during reproductive stages from tassel (R1) to beginning dent (R4). Similarly, soybeans will use nearly 23 inches of water during the growing season, needing the most moisture from beginning bloom (R1) to pod fill (R5-R6). Unless the soil is extremely dry, supplemental irrigation is generally not needed during germination or vegetative growth stages.

When soil moisture becomes limiting, that’s the time to turn on the water for the first time each season, Surface said. In making that decision, growers must not only consider the soil moisture but also factors such as crop stage, soil type and weather forecast.

“Nobody likes to get started until they have to, because the general rule is, once you start irrigating, you don’t stop,” Surface said. “A lot of guys will wait too long on this step, and it hits them in the back end. Once you get behind on irrigation, there’s no catching up. You’re just behind all year.”

One of the biggest mistakes growers make, he added, is trying to make irrigation decisions by the “window farming” method.

“You can’t evaluate soil moisture from the highway,” Surface said. “You have to get out there and dig with a shovel. It may look dry, but is it really? You need to know how deep the moisture is in the soil profile.”

Knowing the soil type can also help. The water-holding capacity varies with the soil’s texture, structure and infiltration. For example, coarse-textured and sandy soils hold less water and need to be irrigated more frequently than loam and clay soils.

The weather forecast should also be considered when scheduling irrigation. If precipitation is expected in the near future, the first watering could be delayed without detriment to the crop, Lange said.

“You don’t want to be watering the crop right in front of rain,” he said. “You’ll just waste water and oversaturate the field, and that’s never a good thing.”

Along with when to start irrigating, the second-most common question is when to stop, Surface said. While this decision, too, can be subjective, he said the rule of thumb is, “You don’t want to keep watering after your crop is already made.”

In corn, the timing is relatively cut-and-dried. When the kernels reach black layer, irrigation can be stopped. Soybeans take a little more work. Surface suggests walking fields, pulling a few pods from the top three nodes and opening them.

“Inside, there will be a membrane that should peel off the beans,” he explained. “When it does, you know a majority of moisture is already in that bean. At the most, you’ll only need one more watering at that point. Corn is easier. You just break open a kernel, and when it’s at black layer, it’s done. Corn is very distinct on when to quit irrigating.”

Despite its benefits, Lange warns that growers can’t count on irrigation to be a crop’s savior when conditions are extreme. He said last year was the driest since 2011 on his farm. Irrigation started early, and there were no breaks. Yields reflected the challenges.

“The biggest thing we learned from last year is that Mother Nature still holds the cards,” he said. “I wouldn’t want to farm without irrigation, yet it doesn’t alleviate all the risk.”

MFA agronomists and crop consultants can help growers in making irrigation decisions. Check with your local MFA for more information.

Created on June 01 2023.
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