After feeding corn stalks, probably the lowest cost way to feed cattle in the fall and winter is to stockpile forages. Stockpiling means to make the last harvest by clipping or grazing of a hay field or pasture and then let it grow for grazing latter; in this situation, in the fall or winter. While most predominantly cool season grass based fields will work, fescue works the best as it maintains quality into and throughout the winter better. Many studies have demonstrated that one way to improve the quality and yield is to apply nitrogen (N) when stockpiling is initiated. Urea is the most common form of N used for stockpiling in most areas, but the biggest risk is applying the urea, then not getting a rain allowing much of the nitrogen to be lost by or evaporating (volatilizing) in warm, dry conditions before it has a chance to react with the soil.
One product available to reduce nitrogen loss is Agrotain®, a urease inhibitor. Several universities have done research on urease inhibitors and the University of Kentucky has an excellent factsheet on Nitrogen Inhibitors (http://www2.ca.uky.edu/agc/pubs/agr/agr185/agr185.pdf).
In Southeast Ohio, studies and demonstrations have been conducted to evaluate quality and quantity of stockpiling cool season grasses such as fescue with no nitrogen (N), 100# of urea (46# N), and 100# of urea with Agrotain; at a rate of 4 quarts of the product applied per ton of urea. There are lower rates that can be used but we chose the high rate which would provide up to 14 days protection.
Stockpiling began on August 8, 2014 for the replicated plots with the fescue clipped to six inches and the treatments applied. On August 11th, the site received over a half an inch of rainfall (0.59"), with more on August 12 (0.56"). Previous research indicated that a half an inch of rainfall within 48 hours of application would help prevent the urea form volatizing back into the atmosphere and in this trial; rainfall was received within 72 hours of application.
Plots were harvested on December 3, 2014 with yields averaging 2369# dry matter (DM) per acre for the plots with no N, 3147# DM/acre for plots with 100# of urea, and 3210# DM/acre for the plots with 100# of urea with Agrotain. While there is no significant difference in the treatments (P>0.05), there was a trend (P>0.1) of higher yields with the treatments.
There was a significant difference (P>0.05) in crude protein (CP) with urea and urea with Agrotain. CP averaged 6.77% for the plots with no urea; 8.53% for the plots with 100# urea/ acre and 8.32% for the plots with urea and Agrotain. This and other studies confirm that urea and urea with Agrotain improves yield and quality.
What happens if we go for a longer period of time with no rainfall? One of the biggest problems with using urea to stockpile cool season grasses is the uncertainty of a timely, adequate rain in the late summer. In the study I just discussed, we had rain within 72 hours, but in 2013, we began stockpiling on August 5 and there was not a soaking rain for seventeen days (there were three days of .05-.15" rain) then there was 1.5" of rain on August 22. On October 14, samples were harvested from one set of plots and the plot with no N had 2003#/dry matter (DM) acre, the 46# of N had 2904# of DM/acre, and the 46# of N with Agrotain; had 4141# of DM/acre (unfortunately, cattle broke through the fence and cleaned up the plots before we could make a final harvest of the plots). However, the one set of results indicated a higher yield for the plots with urea and Agrotain, compared with urea alone and no urea.
So, what do I recommend? As a farmer and an Extension Educator, I recommend stockpiling cool season grasses to reduce our need for stored forages. In many cases it is higher quality than the hay we make. I also recommend adding nitrogen, approximately 50 #/acre when stockpiling is initiated. Finally, if there is any doubt about rainfall after applying urea, a urease inhibitor such as Agrotain is a good option. Several cattle producers in our area have tried it with success and research from University of Kentucky confirms it improves yields.