Growing a productive crop is a science. It’s more than just planting a few seeds and hoping for the best. It’s a delicate balance of applying the right nutrition to get the most out of the seeds you plant, while not wasting a dime of that fertilizer budget by overapplying.
Part of understanding how much fertilizer to apply is understanding what those nutrients do in the plant - for health and yield, how the plant best utilizes those nutrients and how you can get the most efficiency from the plant nutrients you put down
Primary Nutrients in Your Crop
The robust stands and high yields start with the right balance of essential nutrients, which are the nutrients needed by the plant to complete its full lifecycle. Nutrients that the plant uses in high quantities are called primary nutrients, providing the nutrition that the plants need to thrive. NPK are most commonly referred to as the primary nutrients
Nitrogen (N) is a critical component of proteins and chlorophyll. Plants require large amounts of N, and they can only take it up through their roots. Most nitrogen is taken up during the vegetative stage of growth, and most is utilized during the reproductive stages. Nitrogen is mobile in the plant, so deficiency shows in the older leaves. A common symptom of nitrogen deficiency is a yellowing of the lower leaves due to reduced chlorophyll production. In most areas, nitrogen is the most limiting crop nutrient. Nitrogen helps promote phosphorus uptake.
Phosphorus (P) plays an important part in early root and cell growth throughout the growing season. It’s the base element of compounds that drive many cell processes, such as respiration. Phosphorus deficiency in corn can often be seen as purpling in older leaves. Phosphorus is also mobile in the plant. However, unlike nitrogen, it is fairly immobile in the soil.
Potassium (K) is key to establishing strong roots and stalks. Strong roots improve the plant’s ability to take up other nutrients and increase its resistance to drought, insects and disease. Stalk strength is dependent on the amount of lignin in the cell walls and potassium is the key component of lignin. Corn plants deficient in potassium will often lodge or break, making a real mess at harvest. As with N and P, K is mobile within the plant, meaning it will pull from the older leaves to feed the newer growth. It is also generally immobile in the soil, except in sand, where it can leach.
How Much NPK Does Your Crop Need
Every bushel you grow requires a specific nutrient amount. So it is important to feed your crop for what you hope to make, while also understanding your field’s yield potential, as overestimating your fertilizer needs can mean wasted nutrients and wasted money.
Nutrient removal rates can help determine the amount of nutrients you’ll need to replace what your previous crop utilized and removed.
Nutrient removal = Per bushel removal rates X actual yield
Nutrient removal amounts can vary, but this table from Michigan State University shows their research results.
Nutrient Removal Rates by Crop
Crop | N (lbs./bu) | P2O5 | K2O (lbs./nu) |
Corn | 0.9 | 0.37 | 0.27 |
Soybean | 3.8 | 0.80 | 1.40 |
Wheat | 1.2 | 0.63 | 0.37 |
Source: Michigan State University
It takes a certain about of NPK to make a crop, but you also have to consider your yield environment, your soil testing results and an understanding of your soil’s actual nutrient availability to assess what you should be putting down.
Understanding a Soil Test
Ensuring your crop has what it needs starts with a soil test. The best time to pull soil samples is in the late summer or early fall when K is most available. The test report will show if the soil has a sufficient or deficient amount of each nutrient, and provide a recommendation of what it will take to bring your soils back to the sufficient range. The mobility of N makes it very hard to test for; thus, an N rec is based on various additional factors, including the crop being grown and potential yield goals.
Getting the Most From Your NPK Investment
Fertilizer prices are high this year, leading farmers to wonder what they can do to squeeze more from their fertilizer budget.
Here are a few ways you can cut fertilizer without sacrificing yield:
1. Utilize the Nutrients Already in Your Soil
Some nutrients - especially P and K - can get tied up in the soil. Improving microbial activity can play an important role in making those nutrients more available. If you want to grab those trapped nutrients, healthy soil microbes are the key.
2. Wake Up Microbes
Sadly, the majority of soil microbes are dormant, thanks to less than ideal soil conditions. Those microbes need a catalyst to get them working to improve your soil health, soil nutrient availability and overall plant health.
3. Turbocharge Microbial Activity
Once the microbes are awake, they might need a jumpstart. Microbial activity can be measured by the amount of CO2 being respirated in the soil. Increased microbial activity means more CO2 is being released.
4. Invigorate the Rootzone
An in-furrow product that motivates the microbial activity ensures that nutrients closest to the plant and its early growth will be easier to take up. This boost can also mean faster emergence.
5. Focus on Chemistry
Microbially available chemistry can further improve the release of tied-up nutrients. Microbes do the work, but some chemistries can make it easier to break those chemical bonds that keep nutrients such as N from being readily available.
Agnition Knows that Fertilizer Efficiency is Important
Agnition’s patented Microbial Catalyst® technology increases enzymatic activity, helping break down plant matter by stimulating the dormant soil microbes.
Generate® from Agnition uses Microbial Catalyst technology to help microbes drive more efficient nutrient utilization. Using Generate to wake up the microbes in your soil leads to improved emergence and early season vigor, healthier plants and higher yield opportunities.