How Crop Fertility Removal Rates Impact Rotational Crops

Categories: PLANNING, CORN, SOYBEANS
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Common biomass (stover) removal via stalk baling

Fertility can be one of the highest crop input costs, so it’s important to keep it top-of-mind to maximize your profits. Numerous resources are available for alfalfa, corn, soybean and wheat fertility removal rates and the subsequent impact on a rotational crop’s fertility needs. The topic of crop nutrient removal may appear complex, but the good news is that crop fertility removal rates are very consistent from source to source, and many online resources and local experts can be consulted to make an informed fertility plan. Read on to learn more about crop nutrient removal rates, nutrient removal impact on rotational crops and additional resources.

Crop Nutrient Removal Rates

Soil nutrient removal rates are dependent on many factors. For example, simply harvesting grain removes part of the total nutrients from the field and slowly returns what is remaining in the crop residue to the soil. But bailing the crop stubble or harvesting the whole plant for silage will make the overall nutrient removal rates much higher. Calculate nutrient removal rates based on management practices.

One of the most concise nutrient removal charts was produced by the International Plant Nutrition Institute [IPNI]:

Source: IPNI Table 4.5

To use this chart, multiply the yield of the crop by the “Removal, lb/unit” number.

Calculation examples: 
1. If corn grain yield was 230 bu/A, multiply 230 by 0.38 to get 87.4 lbs of P2O5/A.
2. If soybean grain yield was 60 bu/A, multiply 60 by 1.3 to get 78 lbs of K2O/A.

Nutrient Removal Impact on Rotational Crops
After calculating the crop’s nutrient removal rates, it is important to consider the fertility needs of the rotation crop the following year. Not only should the previous crop nutrient removal rates be considered, but also the soil type and its ability to retain and supply nutrients. This is why it is important to soil sample at least every 3 years to correlate crop nutrient removal rates with current soil nutrient test values.

Farmers will often spend more on corn fertility than soybean fertility. Average nutrient application rates in a corn year of a corn-soybean rotation trend around 90 lbs/A of P2O5 and 100 lbs/A of K2O. Soybeans require about 4x more potassium than phosphorus for a yield of 60 bu/A. Potassium is usually not the limiting nutrient in a rotation due to corn removing higher amounts of phosphorus per bushel than potassium. Research indicates that due to a large removal of phosphorus from the soil for corn grain, increasing corn yields, and the current average farmer phosphorus and potassium application rates, we may be mining the soil of phosphorus during the course of a corn-soybean rotation. Research has shown that applying extra phosphorus may increase soybean yields by 3.5 bu/A if your fertility program hasn’t been keeping up with removal rates.

Resources on Nutrient Removal
In the digital age, numerous applications have been developed that allow farmers to input their crop and crop yield, and the application provides the nutrient removal rate for the desired crop. Ohio State University Extension consolidated many nutrient removal rate calculators along with numerous other management application tools.

For more information on nutrient application rates for your field, contact your local Golden Harvest Seed Advisor.

Photos are either the property of Syngenta or used under agreement.

Syngenta hereby disclaims liability for third-party websites.


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