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The ultimate spoon-fed nutrient plan

Drip irrigation provides the potential for precise fertilizer application and offers in-season potential to make yield corrections.
A program built around drip irrigation is showing dramatic yield improvements when nutrient delivery is matched to actual plant need.

For the corn and soybean producer, the investment in a drip irrigation system can be a challenge. The upfront cost of these systems can be intimidating; yet, once farmers start seeing the yield potential, the investment question may become easier to answer with a “yes.”

“When I worked with onion producers and drip irrigation, we saw amazing yield results,” recalls Jim Hunt, market segment leader for corn and soybean, Netafim. “Corn and soybeans are not as easy as some crops, so we focused on unlocking information about the crops to bring those yield deltas up to justify the expense of a drip system.”

The key is not to think of the system simply for irrigation, but as a nutrient application system — Netafim calls it Nutrigation. But that’s the question: what to deliver, and when? Working with Fred Below, plant physiologist and professor, University of Illinois, Netafim was able to develop a kind of nutrient delivery plan based on actual plant nutrient uptake.

Below has spent several years characterizing how corn and soybean plants use nutrients through the growing season, and when they need it most. Turns out that need comes at different times for different nutrients.

And what started with nitrogen, phosphorus and potash has also expanded to include sulfur and micronutrients.

“What we wanted to do was to create solid yield deltas for those crops, and repeatable results,” says Hunt. “This brings a higher level of irrigation management, including measurement of soil moisture, weather data, crop imagery — and also paying attention to what the crop needs fertility-wise depending on the growth stage.”

With Below’s information, Netafim agronomists were able to start developing plans to impact crop yields in season. For the past two years the company has been working more closely with growers to collect that information, to better quantify the results and show the impact on yield.

Surprising numbers

“With a lot of crop management approaches, you can get a 2- or 3-bushel-per-acre improvement,” Hunt says. “Sometimes you can get as much as 20 bushels per acre.” He explains that with timely application of nutrients through the drip system, the yield increases are a lot higher.

For example, one producer near Denison, Iowa — with odd-shaped fields and an 80-foot elevation change — saw about 230 bushels per acre for the dryland portion of the field. Where drip irrigation was installed, and with timely nutrient application, that part of the field produced 289 bushels per acre. That 59-bushel-per-acre difference was a one-year number, but a big “yield delta.”

In that field N, P, K, S and micronutrients were applied to optimize the return per seed, per unit of fertilizer per acre of land, and per dollar invested. And the field only used 2.5 inches of water in season to apply nutrients.

The list of examples like this is long, and Hunt says his company has worked with a lot of growers to validate this approach to fertilizer application and show the true system payback.

The results make sense when you consider the fact that the crop is never starved for water, and nutrients are delivered as the plant needs to take them up for proper growth. Add in the in-season ability to make changes, and the approach has other advantages.

In-season capability

“With the sensors we currently have, along with tissue sampling, we can monitor the crop and trigger any needs that it has, and deliver [proper nutrients] in smaller bites,” says Tim Wolf, crop agronomic support, Netafim. Daily, or weekly, a drip irrigation system can deliver what the plant needs at the right time, which has implications for the environment and water quality, too.

Perhaps one of the biggest challenges of precision agriculture tools is that many are postseason systems for diagnosing the year, with little in-season activity possible to boost yields. With a drip system in place, Wolf explains that it’s possible to see a problem and take action.

Wolf explains that farmers can use imagery like Normalized Difference Vegetation Index (NDVI) or a thermal image, along with ground-truthing stressed areas, to determine crop needs. Based on that information the farmer can take action right away with a drip system in place.

Adds Jim Hunt, market segment leader, corn and soybeans, Netafim: “Years ago, we were working the crop season with nutrients delivered upfront. Now we can be very precise about delivery of the nutrients.”

Wolf and Hunt shared numerous examples of fields where drip-irrigated fields topped dryland yields by 60, 70 and more bushels per acre. And in their multiyear testing, they’re seeing repeatability.

“In one [Oregon, Ill.] field in 2015, there were some dry patches during the season. For the drip-irrigation part of the field versus the rain-fed areas, the difference was 169 bushels per acre. In 2016, when he [the farmer] had plenty of rainfall, the difference was 70 bushels per acre. However, in both years the drip field yielded 300 bushels per acre,” Hunt says. “The system provided yield stability for that field, improving his yield and stabilizing income.”

Running the numbers

Hunt is clear that his company works with farmers to run the numbers. The upfront drip-system cost can be a stalling point until growers really dig into the potential. “That’s what we do, and we can show a payback on a $1,500- to $2,200-per-acre investment in drip irrigation,” he says. “If you’re talking about an area that’s not traditionally irrigated, but has easy access to water — shallow wells or waterways where they can build ponds — it’s easy to run the numbers.”

Wolf explains that they work out amortization of the system over 15 years, though it can last more than 25. “We do that just to be conservative for our grower estimates,” he says. “Actual payback, even with these low commodity prices, ranges from three to six years in most cases. Throw in a drought year, and payback can be in one to two years.”

Delivering fertilizer through an irrigation system, whether pivot or drip, can show a payback. Matching fertilizer delivery more exactly to plant needs and uptake is showing that the precision payback is real, with big per-acre yield improvements.

If you want to learn more about the Netafim system, visit

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