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In soil nutrient management, simple isn’t necessarily better

Alan Blaylock Published on 26 September 2015
Environmental

I’m sitting here looking at my “smartphone.” I’ve heard it said there is more technology and computing power in that phone than went to the moon on Apollo 13. But some days it doesn’t make me feel so smart.

I also haven’t figured out how to use the entire “technology package” on the car I purchased three years ago. Yet the features I do use on my smartphone and my car are very useful and have changed how I do things.

It wasn’t necessarily simple to figure them out, but once I did, some things in my life are now simpler. I used to study the maps to determine how to get to a destination – learned a lot of geography that way. My family wonders how I know where all these places are.

Now I just type the address into my phone or car guidance system and follow the directions. I don’t learn as much as studying the map, but figuring out how to get somewhere becomes simple. It’s still nice to know what’s on the map because I’ve learned the GPS guidance systems are not infallible.

Growers are constantly faced with changing conditions and new challenges. New technologies are also continuously introduced to the marketplace that can help growers face the challenges.

Sometimes technologies can simplify decisions and operations; sometimes those technologies themselves can make decisions more complex. What to choose? How do we best take advantage of technology? How do we make sense out of the myriad choices?

My experience – through formal focus groups, grower surveys and informal interactions – is that growers want less complication and more simplicity. The growers’ search is for the intersection of simplicity in a forest of complexity and the need to continually improve amid shrinking margins, greater regulatory pressure and information bombardment – some of it relevant, some of it not.

Take the new technologies for guiding in-season nitrogen applications using active crop sensors. These are great new tools with considerable science behind them and lots of field validation.

They do, however, require a higher level of management, greater agronomic knowledge and more trips across the field to apply nutrients according to the in-season diagnosis.

In other words, technologies for in-season nitrogen applications are a great tool, scientifically sound, but add complexity (versus a traditional single application based on a guess of anticipated crop need). Can these be compatible with the growers’ desire for simplicity? There’s a little bit of a disconnect. How will this be adopted in practice? And will it be adopted on a wide basis or just for certain high-end innovators?

New technologies provide many opportunities for improvement, yet are not always so readily adopted. Sometimes these technologies, while improving the outcome, complicate growers’ operations.

Nutrient management is a great example. We know that recommended nitrogen best management practices commonly recommend applying nutrients in-season close to the time of greatest crop need – sometimes multiple times during the growing season. Yet this isn’t always convenient, practical or sometimes even possible. What is a grower to do?

There are many factors that affect crop response to nutrients. Responses to some nutrients may be dramatic if the nutrient is deficient. For others, such as micronutrients, responses are often incremental yield increases or even only maturity or quality improvements.

Nutrient chemistry in the soil is complex, and there are numerous interactions with other nutrients and environmental conditions. Nutrient responses can be improved by considering the nutrient interactions with some of the factors affecting crop nutrient response. Management of some inputs can only be simplified to a certain degree.

Oversimplification increases the risk that management will not be site- and situation-specific enough to reap the full benefits of the nutrient inputs, correspondingly reducing economic return and creating greater environmental risk.

One system being extensively adopted around the world to help deal with nutrient management complexity is “4R” nutrient stewardship, which simply means:

  • Using the right nutrient source

  • At the right rate

  • At the right time

  • In the right place with regard to all outcomes – productivity and profitability, social needs and environmental impact

Sounds simple, right? 4R nutrient stewardship recognizes that complexity exists and there are multiple paths to achieve the desired outcomes. What 4R nutrient stewardship does is organize the decision-making process so that it is methodical, considers the inter-relationships among management factors and seeks to match nutrient applications to site- and situation-specific needs.

4R stewardship seeks to apply sound agronomic and soil science principles to real-world nutrient management.

Consider soil testing to determine the “right rate.” How many growers regularly soil test? The data says “too few.” Nutrient need is evaluated first by soil testing.

Appropriate soil testing provides an indicator of the probability of crop response to a given nutrient, but because of the complexity of nutrient interactions with other production factors, the predictability of nutrient response to fertilizer is sometimes less than perfect. A low soil test does not guarantee crop response when other factors are limiting.

Conversely, responses to nutrients can sometimes be observed when soil test levels seem adequate. Nevertheless, soil test information should not be ignored. Crop history and field scouting records help to pinpoint previous problem areas and gain some insight as to how the crop responded to nutrient applications.

Interpreting soil tests in the context of other management variables can greatly improve the probability of making correct decisions. Soil test information alone is valuable; soil tests combined with cropping history, field scouting, weather conditions and other management variables are invaluable.

Nutrient source, placement and timing may depend on available equipment, desired application method and time of year. For example, there are a variety of nitrogen fertilizers available. Each has unique properties. If urea is chosen as the N source, placement and timing need to also be managed to prevent volatilization losses.

Placement can be used to improve nutrient availability of immobile nutrients and to prevent losses. For nutrients particularly susceptible to losses, such as nitrogen, timing of application close to the time of crop demand can reduce exposure to loss events and improve N-use efficiency.

With so many choices, can simplicity be found in the complexity that is modern agriculture? I’m not sure it’s going to get simpler. The more we learn, the better we are able to deal with new problems and challenges. With knowledge comes more options and the ability to make better decisions, but knowledge brings more complexity.

If I don’t really know how complex nutrient management is and all the things I should consider, I probably make one application of some shotgun mix of nutrients and hope the weather makes a good crop. Simple, right?

But if I can understand how the nutrients behave, how the crop responds, what is needed, when it is needed and how to provide it, I have the ability to improve the result and make adjustments when needed. It’s more complex but yields better outcomes.

So while everyone likes simplicity, better results are usually achieved not necessarily by simplifying but by learning to manage the complexity in a systematic manner. This is what 4R nutrient stewardship is designed to do. It just makes a lot of sense to me as a practicing agronomist.

So if I can draw on the car guidance system analogy, use the nutrient management “guidance system” but know where it is you want to go so you can know if the system is taking you down the right road.  FG

Alan Blaylock
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