Last week, I wrote about how you can and frankly, why you should utilize soil testing to enhance your fertility plan. For the second installment of “A Hands-On Approach to Fertility” I am going to dive into the fundamentals of a fertility plan and share a polarizing view on utilizing starter fertilizer.
Starter Fertilizer is NOT a Significant Crop Fertility Input
I like to think of fertility applications in a couple different ways, and the first one is by separating out the application of starter fertilizer from the fertility plan entirely. It’s why I consider starter fertilizer a crop starter and not a significant crop fertility input. Before I dive into the crop starter component, let me define what I consider to be a significant crop fertility input.
A significant crop fertility input is one where you are applying fertilizer in a high enough quantity to make a difference on the overall soil balance or crop need. For example in the case of phosphorus you might use an application of 3 gallons of 10-34-0 in a starter fertilizer application, and while you are adding nearly 12 pounds of phosphorus, it’s unlikely you will see any change in your soil fertility when you pull samples next time. On the other hand, if you make an application of 5 tons of compost with an analysis of 45 pounds of phos per ton, you can count on seeing some movement in your soil test phosphorus levels and as a result some real results in the grain bin the next time you harvest.
Starter fertilizer applications have one purpose: to get the plant off to a better start (hence my desire to put this into the crop starter bucket). This application feeds that seedling a highly concentrated band of nutrition because often these nutrients are not as highly available this early in the growing season. And because we’re not enhancing what’s already there, instead supplementing with what is not, I don’t consider starter fertilizer as a part of the overarching fertility plan.
So what should you be including in your fertility plan? Read on to find out!
The Building Blocks of a Fertility Plan
For years the main emphasis has been on N, P, and K which are considered the macronutrients, but are they really the most important? Don’t get me wrong, N and P are important pieces, but since for the past several decades most fertility plans have focused solely on these two nutrients in our area, we have lost our efficiency of application. In testing we are finding more often that additional applications of N and P are becoming less efficient, even showing no significant economic impact to your crop. And that’s why diving deeper into the results and looking at pieces like Sulfur, Zinc, Base Saturations, Soluble Calcium, and many other levels may be worth your time.
The applications that should be included in your fertility plan are those that are going to enhance your soil’s composition or directly feed the crop to ultimately increase yield. I generally break these down into two types of applications: non-mobile and mobile applications.
Non-Mobile Applications
When planning to apply non-mobile nutrients your fertility application’s goal is to impact the overall soil balance of that nutrient. For example, if you apply phosphorus, you’re not only increasing the total amount of this nutrient within the soil but also making it easier for the microbes within the soil profile to cycle phosphorus for plant uptake. Other non-mobile nutrients like Zinc are needed by the crop in much smaller amounts, increasing the overall soil balance of the nutrient may be an option here along with foliar application. Foliar applications can be much more efficient because you eliminate the issue of soil tie up which is especially common of micronutrients in our high pH soils. But they can be trickier also because you need a healthy plant and weather conditions that allow effectiveness of application. Anytime it’s too hot, foliar application can be a waste because plants are in a more defensive mode and wont take in the nutrients, or they will quickly dry on the leaf surface before having a chance to translocate through the leaf.
Mobile Applications
When applying a mobile nutrient like nitrogen, you’re impacting the balance of how much nitrogen is available in that soil for the current crop, not necessarily the overall soil profile. While our soils are better at holding nitrogen than many, storing nitrogen in the soil is also not the best practice. Soil water drains from the bottom of the rooting profile and anytime a soil reaches greater than 60% of field capacity, that soil water draining carries mobile nutrients into the depths of the soil profile never to return.
The timing and type of nitrogen application is also important because every nutrient application must undergo a biological process before becoming available as plants simply don’t use fertilizer in the synthetic form in which they are commonly applied. Thinking through these processes, and the weather events necessary to make the nutrient available, helps establish what both the right product and right timing is for each application.
The combination of non-mobile and mobile nutrient applications is what ultimately comprises your fertility plan. And it’s best to look at this from a multi-crop, multi-year perspective. For example, loading your soil with phosphorus is a part of your plan if you commonly use compost or manure applications. Understanding how a compost application will impact this crop and the crops for several years to come on your farm helps create the overall Max Yield System fertility plan. Similarly, making an application of elemental sulfur would be a long-term fertility strategy to increase sulfur content of your soil and buffer soil pH over the course of multiple years. Whereas using 12-0-0-26 Thio-Sul as a component of your liquid nitrogen applications can enhance the efficiency of your nitrogen application and more quickly impact this years crop sulfur needs.
The fundamentals of a fertility plan that produce a top crop require farmers to rethink starter fertilizer and break the exclusivity of an NPK mindset. Even still, I often hear farmers talk almost exclusively about Nitrogen when it comes to fertility plans, which is why in our last and final installment we will discuss this important input.
This concludes Part II of our three-part series, “A Hands-On Approach to Soil Fertility.” If you missed last week’s post click here, and don’t forget to check back next week for the third and final installment!
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