More bang for your buck Application tools and principles can help farmers get more out of their applied nutrients. by Erica Rogers
Fair guidelines to follow The first R is right source. In order to determine the right source, the following should be taken into account: • Are the fertilizer nutrients being used (commercial or manure) available for immediate uptake, or is it delayed? • Is there a combination of fertilizers that can be utilized best? • What nutrients are already available in the soil? The next R is right rate: • Match the amount of fertilizer applied to the crop nutrient uptake. What is the crop nutrient demand? • Perform a soil analysis (manure analysis as well if using this as the fertilizer source) to appropriately match the amount of fertilizer needed for crops based on individual
field fertility. • Make sure the equipment being used to spread the fertilizer or manure is calibrated properly for appropriate distribution. • Be sure operators of the equipment spreading the fertilizer or manure are trained properly in using the equipment and know the appropriate rates and paths. • Consider crop yield goals. • Remember the law of diminishing returns: The unit of nutrient applied equals the crop yield increase generated (see Figure 1). The third R is right time: • Plan for fertilizer nutrients to be available during crop demand — many times this is close to the time
$0.60 $1 $2
Economic optimum The amount of input where: $1 input returns $1 worth of output
$4 $10
Overall @ EOR Spent $5 Return $42 $8.40 return / $1 spent
$25 10 lb/a 20 lb/a 30 lb/a 40 lb/a 50 lb/a 60 lb/a
$1
$1
$1
$1
$1
• Biological response • Cost of input • Value of output
$1
$ Growth factor (nutrient) Courtesy of Douglas Beegle, Penn State University.
18 | Journal of Nutrient Management | August 2020
F3 18-19 Aug 2020 More Bang.indd 1
of planting. • Consider the weather and seasonal conditions. There is potentially more nutrient runoff during the winter, and saturated fields are unable to retain nutrients effectively. Application of fertilizer immediately before a large rainfall could contribute to nutrient runoff. Michigan EnviroImpact is a runoff risk decision support tool to help with short-term planning of nutrient applications. Other regional runoff risk decision support tools can be found in Wisconsin, Ohio, and Minnesota. • Include mitigation of potential odors, mainly with manure. Consider location of neighbors, timing
Figure 1: There are economic benefits — up to a point
$ Plant response
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he four R’s of nutrient stewardship, or nutrient management, are commonly referred to when talking about proper nutrient application. The four R’s stand for right source, right rate, right time, and right place. This recommendation serves to guide farmers to the practices that help keep nutrients on and in the field. Implementation of the four R’s helps to align the economic, environmental, and social components of nutrient management. The Nutrient Stewardship 4R Pocket Guide (bit.ly/JNM-4r-guide) helps to explain what the components are for each of the four R’s.
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