Advanced Agrilytics

Does Organic Matter, Matter?

Four Keys to Unlock Potential with Nitrogen Management

As growers, we can often find ourselves in conversations bragging about how much — or lamenting about how little — organic matter we have based on our soil testing reports. While the importance of organic matter is generally understood, we continue to struggle as an industry to put that knowledge into action.

So, how do we use organic matter to make better decisions and improve productivity?

Here are four key concepts to consider:

  1. LANDSCAPE POSITION

Research shows higher landscape positions often achieve canopy later. Additionally, they have higher soil temperatures during the mid-to-late-vegetative stages and have less available water throughout the growing season. These are key factors that help us understand mineralization rates and total nitrogen supply, but more importantly can lead to prediction of available nitrogen for the crop.

  1. NITROGEN USE EFFICIENCY (NUE)

Regardless of the per unit cost, the effective use of applied nitrogen is important every growing season. For generations, research has shown that substantial amounts of nitrogen can be mineralized by organic matter for crop production. For this reason, understanding environment is critical to optimizing nitrogen input decisions.

  1. QUANTIFYING NITROGEN CONTRIBUTIONS

Another common industry practice is to place more nitrogen on better producing soils, rationalizing that with higher yield potential comes a greater nitrogen requirement. If we assume these better producing soils also have an organic matter of >3.5%, we could mineralize upwards of 120-140 lbs N/acre. Now with that information, would we still place more nitrogen on these higher organic matter soils? In that same vein, the rationale of “cutting back” on acres that are going to yield less may seem economically sound. However, knowing that these acres will mineralize less than half the nitrogen compared to the lower landscape acres, is this decision agronomically sound?

  1. PLANNING NITROGEN TIMING FOR SUCCESS

While more nitrogen does need to be added to the lower organic matter acres, adding the higher rate earlier in crop development — at planting or just prior to — is key. The increased availability of nitrogen will promote increased plant growth to get the crop to canopy faster, decreasing soil temperature and increasing mineralized nitrogen.

The higher organic matter soils do have a greater potential yield. However, they already have an advantage with increased organic matter. They also have a greater potential for saturation and thus leaching and denitrification. Applying foundation nitrogen applications early (fall, preplant, or very early side-dress) should have a nitrogen stabilization product added to protect against nitrogen loss in these more saturated environments.

Planning with understanding

A good plan is more than just applying higher amounts of nitrogen to the lower organic matter acres and less to the higher organic matter acres. While practices like variable rate nitrogen have been in the industry for years, associating nitrogen rate to yield potential was not getting us to the best answers. Incorporating knowledge of the environment, organic matter, and other interactions can lead growers to a more robust nitrogen program. The team at Advanced Agrilytics is ready to assist in your ability to get the right rates on the right acre, increasing the likelihood of consistent yield and return on your nitrogen investment. Connect with our team at: advancedagrilytics.com/contact-us

 

Contributing factors to the mystery of organic matter are its variability across fields, the dependence of mineralization on moisture and temperature, and the Carbon to Nitrogen ratio.

*True sand, OM < 0.5% & CEC < 5

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