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Superintendent
David Davis
21262 Genoa Road
Linneus, MO 64653
Phone: 660 895-5121
FAX: 660 895=5122
Email: DavisDK@missouri.edu

Forage Systems Update
Vol 13, No. 1

During the fall of 2003, I was often asked if fertilizing pastures in the fall with nitrogen was worth the time and effort and/or do I really need to fertilize with nitrogen if pastures contain a strong legume component (30-40%). Most of these questions were probably in response to the very dry conditions we experienced throughout the region during the summer of 2003 (not to mention 2001 and 2002). Most cow-calf producers in our region were short of pasture and many were already feeding hay in early August. However, the questions they asked are important questions to be answered for anyone interested in reducing winter feed costs-especially in dry years when forage supply is limited.

Most pastures at FSRC are a mixture of tall fescue and other cool season grass and legumes (predominantly red clover). We always apply nitrogen to some of the pastures in the late summer for stockpile production so that we can graze well into winter, regardless of how dry it has been. The form of nitrogen we apply is ammonium nitrate. Although urea is less expensive precipitation within a day of application is necessary in order to avoid excessive N loss to volatilization. Most years we receive enough fall precipitation to produce some stockpile production. The peak period for tall fescue stockpile production occurs in September and October. This year we received over ten inches of rain from late August through October, helping to promote stockpile production (Table 1). We also observed a slightly warmer than normal fall that helped promote fescue growth. I believe that if we had received more rain during the fall we would have observed better stockpile production.

Some continuing studies being conducted at the Center are helping us better understand stockpile production and are helping define answers to some of the stockpile questions posed earlier. One study designed to investigate yield and quality of stockpile in response to nitrogen application (see Forage Systems Update Vol 12, No.3, July 1, 2003), Dr. Kallenbach et al. reported that even in dry years (2001 and 2002) and regardless of whether plots contained red clover, they observed a nearly linear response to N rates up to 100 lb/acre. In 2003, preliminary results indicate that stockpile yield response was similar to what was observed during the first two years of the study, but November dry matter yields in 2003 were less than those observed during the previous two years. The lower yields in 2003 were probably due to the lack of soil moisture during the fall. Although we received significant rainfall during the fall we needed more precipitation. November stockpile yields in another study currently being conducted at FSRC ranged from approximately 3200 to 6200 pounds DM per acre (Table 2). The protocol for this study called for 60 lbs of N to be applied in early August.

To answer the question 'does it pay to grow stockpile in dry years' we need to estimate the value of the additional forage produced by fall applications of nitrogen. The value of applied nitrogen (as measured by forage yield) can be estimated by the difference in forage yield between plots receiving nitrogen and the plots receiving no nitrogen. Looking at stockpile yields from Dr. Kallenbach's study averaged across three years and staying within the linear phase of the yield response (from 0 to 100 lbs of applied N), the application of 50 lbs N produced approximately 1250 lbs. of additional forage while the application of 100 lbs N produced an additional 2250 lbs of forage. The value of this additional forage can be set to the value of hay (presuming you would feed hay instead of grazing pasture) or any supplemental feed you would need to purchase in order to make up the shortage in available forage. Using hay and nitrogen prices commonly observed in our region this fall as an example ($40/ton for hay and ammonium nitrate at $0.30/ pound N), the application of $15 of N (50 lbs N/acre) returned $25 worth of forage-a $10/acre profit! Applying $30 of N (100# N/ac) returned $45 of forage-a $15/acre profit! This of course assumes no stockpile waste, but if stockpile is allocated on a "as needed basis" utilization of 75% or more of the stockpile is easily accomplished. We try to allocate no more than a three day supply of stockpile at a time.

New data regarding the contribution of red clover to stockpile dry matter yield is also being collected. It appears that the inclusion of 25-30% red clover into pastures receiving no nitrogen in the fall will produce less dry matter yield when compared to pastures comprised of fescue without a legume and receiving as little as 50 lbs N/acre suggesting that fescue-red clover pastures selected for stockpile production would produce more yield with a fall application of N. FSRC continues to recommend applying 75-80# of N around the 10-15 of August even if you have a strong clover component in your pastures.

Most years producers make hay too late in the growing season for optimum quality. Stockpiled forage can be better quality than the 'average' dry hay made in the summer. We are following stockpile quality throughout the winter months as part of a stockpile feeding experiment. Typically our stockpile yields are greater than what we achieved this year, and high yielding stockpile is better able to cope with winter weather and maintain greater quality. As one would expect, stockpile quality was greatest in November and has slowly decreased over time (Table 2). However, stockpile quality in early January is still adequate to maintain dry spring calving cows. We are planning to calve half of our spring calving cows on stockpile again this year. For reference, our 'average quality' hay this year tested at 11.90% CP, 36.78% ADF, and 59.9% NDF. Stockpile quality in January was still as good as the hay we are feeding to the other half of our spring calving cows.

Table 1. 2003 Weather Data Collected at FSRC
Weather data has been collected at FSRC for over 25 years. Precipitation last year was about 10 inches below normal. What made the 2003 drought seem worse than the drought of 2002 is that in 2002 we had some sub-soil moisture. We made up some of our moisture deficit starting in late August, just in time for stockpile production.

Table 2. 2003 Yield and Quality of Stockpiled Tall Fescue Pastures Receiving 60 lbs N/acre in August at FSRC

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