4R’s: The Right Source

Optimizing the 4R framework is a balanced approach of the Right Source, Right Rate, Right Time, and Right Place. The Right Source is often taken for granted and can have visible and unintentional consequences if not speculated. Agronomic and economic performance depend on a thorough study of the right nutrient source. Keep in mind, the right source is not always the cheapest option; multiple characteristics must be considered in the decision-making process.

Essential characteristics to consider:

Supply plant available nutrients

Nutrient water solubility is essential to plant uptake. Since plants do not chew their food, to be absorbed by the roots, nutrients need to dissolve into solution.
Beware of efficiency ratio micronutrient claims. These additives typically only supply a fraction of the nutrient required (see Efficiency Ratio Facts). Review closely with your crop consultant.
Know the make-up of your micronutrient. For example, Zinc Sulfate Monohydrate is water soluble vs Zinc Oxide which has a very low solubility. Which product can your crop use now?

Correlate soil physical and chemical properties
Multiple characteristics can affect nutrient availability (soil type, pH, organic matter, climate)

Mobile nutrients like boron may be at higher risk of leaching if applied to sandy soils.
Orthophosphate starter fertilizers are more effective in colder climates where low soil temps are slow to convert polyphosphate to the plant available orthophosphate.

Recognize compatibility

Know the chelating agent as not all are the same. Citric, EDTA, and Ortho-Ortho EDDHA are well known chelates with different attributes, compatibilities and price points.

Mode of action

Nitrogen stabilizers are a great tool for nutrient management, but their application is not a blanket approach. Know the active ingredient and its mode of action. For example- if nitrogen is knifed below the soil surface/strip tilled, a product containing NBPT would not be necessary because the nitrogen is not subject to volatility.
Is the active ingredient AAPFCO approved? NBPT and DCD are defined by AAPFCO as acceptable urease and nitrification inhibitors for enhancement activities such as CSP 590.