Grazing School

Workshops

Research

Faculty

News

Weather

Contact us

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 10, No. 3

Stockpiling tall fescue pastures for winter grazing is an increasingly popular low-cost wintering strategy among livestock producers across Missouri as well as many other states. Research and producer experience has found grazing stockpiled pastures to be about one-third the cost of feeding hay to dry, pregnant beef cows. The typical recommendation for growing a productive, good quality stockpile has been to apply 40 to 60 pounds N/acre about 75 days before the end of the growing season. Many producers who have a good stand of legumes in their pastures frequently ask if N fertilizer is necessary or will legumes provide enough nitrogen for the stockpiling grass crop.

We conducted two studies at FSRC to address this question. The first study began in 1991 and was terminated prematurely in 1993 due to extremely wet conditions. The second was similar to the first and ran from 1996 through 1998. The 1991 to 1993 study will be referred to as Study 1 and the 1996- 1998 project as Study 2.

Research approach: Both studies included perennial and annual legumes interseeded into well established Ky31 tall fescue with and without N fertilization. Experimental design was randomized complete block in three blocks with N and legume treatments in 2 X 6 factorial arrangement. Individual plots were 20 ft X 15 ft in Study 1 and 20ft X 20 ft in Study 2. The width of the plot was designed to allow five harvests during the winter stockpile utilization period allowing us to measure change in forage availability and quality through the winter. Legumes and N treatments for each study are presented below.

In Study 1, one set of plots was established in 1990 and a second set in 1991. Austrian winter peas, crimson clover, and hairy vetch were no-till drilled into clipped tall fescue sod on September 5, 1990 at 20, 10, and 20 lbs/acre, respectively. All winter annual plots were allowed to go to seed in spring of 1991 and were clipped after seed had matured. Our objective was to evaluate winter annual legume stand maintained through natural reseeding. Alfalfa, birdsfoot trefoil, and red clover were no-till drilled on April 17, 1991, at 10, 5, and 8 lb/acre, respectively. Perennial legume plots were clipped twice during May when grass height was deemed to be overly competitive for the seedling legumes. The second set of plots were established by the same process with seeding date for the winter annual legumes being September 24, 1991, and seeding date for perennial legumes being April 12, 1992. Seeding rates and establishment management were identical to the first set of plots.

Plots were harvested twice during the growing season (early July and mid August) and either two or three times during the dormant season (November, December, January) in the year of establishment. In the year following establishment, plots were harvested three times during the growing season (May, July, August) and two or three times during the winter following stockpiling. Each harvest consisted of taking a 3 ft X 12 ft strip with a Carter Harvester. The remainder of the plot was clipped and removed at growing season harvests. During the stockpile period, only the harvest strip was removed and the remainder of the plot was left undisturbed.

In study 2, only one set of plots was used during the entire study period. Plots were seeded on May 31, 1996 with birdsfoot trefoil, kura clover, and red clover at 6, 13, and 8 lb/acre, respectively. Seeding was done so late because of extremely wet conditions through April and early May. Crimson clover and hairy vetch were seeded on September 17 at 10 and 20 lb/acre, respectively. Marion lespedeza was seeded on March 31, 1997. Due to poor stand establishment with the late seeding in 1996, birdsfoot trefoil, kura clover, and red clover were reseeded on March 31 at the same rate used the previous spring. Spring fertilization was as urea and summer fertilization was as ammonium nitrate.

First harvest was made on May 28, 1997 when the crimson clover and hairy vetch had mature seed. After the harvest strip was taken, the remainder of the plot was clipped with a rotary mower in an attempt to shatter seed from the plants and removed from the plots after drying for two days. Subsequent harvests were made in early July and mid-August.

Rainfall for each project year is shown in Table 2 along with the long-term mean for FSRC. July, August, and September are the three critical months for determining fall stockpile production. Good subsoil moisture in midsummer allows tall fescue and companion legumes to make rapid growth at the beginning of the stockpile period. Interseeded winter annual legumes should also have greater likelihood of successful establishment at normal to slightly above precipitation levels. Rainfall in September sustains growth while October precipitation may come too late to produce significant growth, particularly in north Missouri where low nighttime temperature may already begin to reduce growth rate. Precipitation during this three-month period was normal in 1998, 26% below normal for 1991 and 1997, and 44% above normal in 1992. Rainfall had significant impact on stockpile yield relative to deviation from normal precipitation amounts.

Results and discussion: Neither legume species nor N rate were significant factors in determining stockpile forage yield in 1991 (Figure 1). Winter annual establishment was poor due to very dry conditions in August and September. Stockpile yield in the year of legume establishment was much greater in 1992 and was significantly affected by N rate (Figure 2). First year stockpile forage yield from plots established 1991 was approximately one-third of the first year stockpile yield from 1992 establishment. The difference is likely due to the large rainfall differences between the two years in August and September (Table 2). Even though crimson clover and hairy vetch established adequately in 1992, neither made significant contribution to stockpile yield. Only the very top seedling leaves extended above harvest height. Austrian winter peas established poorly in both years. A strong volunteer red clover component in all 0 N plots tended to even out the stockpile yield among treatments.

In both establishment years, tall fescue with interseeded red clover produced stockpile yields comparable to tall fescue receiving 60 lb N/acre. In 1992 stockpile yield of plots interseeded with alfalfa were similar with or without applied N, but were significantly lower than the plots interseeded with winter annuals. With the red clover component in the alfalfa plots, the tall fescue:legume ratio was very similar between tall fescue+red clover and tall fescue+alfalfa. The heavy growth of legumes in the red clover and alfalfa treatments resulted in reduced tall fescue presence compared to plots interseeded with winter annuals which were largely non-competitive during the fall growing period. The significantly higher stockpile yields noted for plots without strong legume components in 1992 may be due to the higher level of grass present in the sward compared to red clover and alfalfa seeded plots.

Total forage yield in the year of establishment was significantly affected by legume component with red clover interseeded treatment being significantly higher yielding than several other N X legume combinations (Figure 3). The total forage yield shown in Figure 3 underestimates actual forage production as the spring growth was clipped each year to manage grass competition and was not included in the total yield determination.

In the year following establishment, N level significantly affected stockpile yield while seeded legume did not (Figure 4). One reason why the legume effect was non-significant was the presence of volunteer red clover in almost all plots (Table 3). While the red clover seeded plots with 0 N contained 68% red clover when harvested in November, the other legume treatments and no legume treatment contained an average of 37% red clover in the sward. Red clover content in red clover seeded plots was 62% even with 60 lb N applied in August. The only other legume making a significant contribution to stockpile yield was alfalfa, which was present at 27% and 25% with 0 or 60 lb N, respectively. None of the winter annual legumes were present at levels greater than 5% during the stockpile period. Crimson clover had been present in spring growth at levels up to 70% and seedlings were present in the stockpile period, but no forage was harvested in the stockpiled mixture. Austrian winter peas and hairy vetch were present in the first fall of establishment but were weak and uncompetitive in the tall fescue mixture.

Stockpile yield of tall fescue interseeded with red clover and receiving 0 N was not significantly different from tall fescue receiving 60 lb N/acre with or without red clover in Study 1. Overall, applying 60 lb N/acre resulted in about 600 pounds of additional forage/acre or 10 pounds of forage per pound of N applied. If N price were less than 23¢/lb, applying N to tall fescue would be a cost effective alternative to feeding hay. At today's N price of 33¢/lb, N to forage conversion rate needs to be greater than 20 lb forage/lb N to be cost effective. We have achieved N conversion rates in excess of 20 pounds of forage per pound of N applied in the past so it is a realistic possibility in years with normal to above normal rainfall.

Results from Study 2 were similar in trend to Study 1, but stockpile yield was much lower in Study 2 (Figure 5). Applying 60 lb N/acre produced about 750 pounds more forage/acre compared to unfertilized mixtures. Legume species did not affect stockpile yield, probably due to the presence of red clover in all plots. Individual legume species were not sorted in 1997, but in 1998, red clover was present at 25% in non-red clover, unfertilized plots but only 5% in fertilized plots seeded to other legume species (Table 4). The reduced yield observed in Study 2 is probably a combination of less rainfall during the study period compared to 1991-92 and lower level of red clover. Birdsfoot trefoil was a significant contributor to stockpile yield with 27% presence in 1998 during the stockpile phase. Kura clover failed to establish in the tall fescue sward. Once established, kura clover is a very aggressive and persistent legume. However, it is weak seedling and slow to establish legume. The addition of 60 lbs N/acre in the spring likely made establishment even more challenging.

As in Study 1, neither crimson clover nor hairy vetch made significant contribution to stockpile yield even though both were very productive in the spring. Marion lespedeza contributed nearly 50% of stockpile yield in the year of establishment but less than 5% in the following year. Seed was produced by Marion lespedeza, but spring fertilization may have created too much competition for reestablishment in the second year.

Practical conclusions: Red clover appears to be the legume of choice in stockpiling situations. In the first study, tall fescue interseeded with red clover and receiving no N fertilizer provided stockpile yield comparable to applying 60 lb N/acre at lower cost per acre. Maintaining annual legume presence between 30 and 50% provided this level of production. While tall fescue stockpile yield with red clover as the legume was significantly lower than N-fertilized stockpile in the second study, the cost per pound of dry matter produced was still lower for the red clover interseeding. In both studies the total annual forage yield for tall fescue interseeded with red clover was similar to fescue alone receiving either 60 or 120 pounds of N annually. Historically N fertilization of tall fescue pastures with 40 to 60 lb N/acre has been a good investment, but when N prices exceed 25¢/lb N fertilization becomes a more marginal practice. In the long term, managing pastures for high red clover content may be the most cost effective stockpiling strategy.

Site maintained by people at AgEBB
agebb@missouri.edu