Northeast Region Certified Crop Adviser (NRCCA) Study Resources

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In This Section

• Introduction
• PO 25 Plant nutrient sources
• PO 26 Form and analysis of nitrogen sources
• PO 27 Form and analysis of phosphorous sources
• PO 28 Form and analysis of potassium sources
• PO 29 Form and analysis of calcium or magnesium sources
• PO 30 Commercial fertlizer terms
• PO 31 Nutrient terms
• PO 32 Calculating fertilizer application rates
• PO 33 Calculating manure application rates
• PO 34 Fertlizer placement methods
• PO 35 Certifiable organic nutrient sources
• Summary

Competency Area 4: Nutrient Sources, Analyses, Application Methods

Introduction

If the typical northeast dairy farm ships 1 lb of N and P in milk for every 3-4 lbs of N and P imported, why do we need to worry about adding fertilizer at all?  Doesn't the rest come out in manure?

Manure nutrients are not 100% available.  Many get lost to the environment, runoff, etc.  To maximize plant growth and yield, the correct amounts of nutrients must be supplied when the plant needs them.  Using manure is hard because there is too much volume being produced to be able to apply it to the plants at the "right" time.

Appropriate use of fertilizer allows achievement of optimum yields.  For example:

• N banded on corn often results in a 1-2 ton corn silage response
• N can be sidedressed on corn if needed, promoting efficient nutrient uptake
• P can be banded on very low to medium soil test corn fields, promoting efficient nutrient uptake
• P can be banded P on legume seedlings
• N can be topdressed on grass at spring green-up to give a boost

There is no one "correct" balance – the "right" answer is based on a particular farm's resources and goals.