The goals of 4R Nutrient Stewardship strategies are to maximize economic productivity and limit offsite nutrient losses that cost both the grower pocketbook and society.
The 4 R’s include: ‘right’ rate to meet crop needs and minimize offsite movement, ‘right’ source selected for location and timing of application, ‘right’ time based on source and crop needs and ‘right’ placement so the nutrients are available to the crop and stay on site.
The 4 Rights are interconnected and work with each other in the overall agronomic production system.
As we enter the fall, there are a few reminders of 4R principals to apply:
Determine the right rate of phosphorus, potassium and lime, by collecting a representative soil test. The investment in a representative soil testing program is well worth the expense.
Once a rate is determined, attention needs to be given to source, placement and timing of the nutrient. In Ohio, both phosphorous and nitrogen are nutrients that can have offsite consequences to water quality. They need to be kept in place from an economic standpoint for the crop you want to grow. No sense sending dollars down the ditch.
Whether phosphorus is from a commercial fertilizer or organic source such as manure, broadcast surface applications have the greatest risk of offsite movement. In fall 2011, high phosphorous levels in tributary water samples seemed to coincide with periods where broadcast fertilizer applications occurred followed by rainfall events. Shallow incorporation tends to reduce phosphorous losses has been shown during rainfall simulator studies. However, caution is warranted to tillage practices that increase soil exposure and erosion losses. Alternatives such as row starter fertilizer or strip tillage should be considered in erosion loss situations.
Ohio State University does not recommend fall applied anhydrous ammonia as a preferred method of nitrogen application. Years of field research shows fall applied anhydrous ammonia can be susceptible to loss and can result in significant corn yield decreases of as much as 30%, but generally 10-15%. Shallow, poorly drained soils with systematic subsurface drainage, cause fall anhydrous ammonia applications to be risky. Late winter and early spring warm weather periods lead to conditions where ammonium is converted to nitrate via nitrification. Nitrogen in the form of nitrate can be lost by leaching (under cool, excessively wet conditions) or by denitrification (under warm, excessively wet conditions).
Did you know that there are 351,000 acres of cropland in Darke County which is the most of any county in Ohio? Richland County is number 2 at 295,000 and Mercer County is third at 293,000 acres.
For more information visit our web site at http://darke.osu.edu/ or contact Sam Custer at 937.548.5215.
Sam Custer is the Extension Educator for Agriculture and Natural Resources at the Darke County OSU Extension office. He can be reached at 937-548-5215 or by email at firstname.lastname@example.org. Viewpoints expressed in these opinion pieces are the work of the author. The Daily Advocate does not endorse these viewpoints or the independent activities of the author.