Agribusiness Management Series: The Effect of Grazing Past First Hollow Stem On Wheat and Stocker Profits

Background

In some years as much as two-thirds of Oklahoma’s winter wheat may be planted as a dual-purpose, grazing and grain crop (True et al.; Hossain et al.). A critical decision point in dual-purpose wheat profitability occurs near a physiological growth stage called first hollow stem (FHS). FHS occurs when stems of ungrazed plants begin to elongate and the stem above the roots and below the developing head becomes hollow. The wheat plant is said to be at FHS when the hollow stem portion of the plant is 5/8 inch long. The occurrence of FHS depends on climatic factors including temperature and precipitation and on wheat variety. (See Edwards and Horn for more details.)

 

For a given planting date and with a reasonable stocking density, grazing prior to FHS has limited effects on wheat yield, but extended grazing beyond FHS can greatly reduce wheat yields. Grazing, however, increases calf weights. So, if the value of weight gain exceeds the value of reduced wheat yields, extended grazing would be economically viable. The questions are (1) what are relative values of increased weights versus reduced wheat yields and (2) Under what circumstances is grazing wheat intended for grain harvest past FHS advisable?

 

Wheat Yields and Extended Grazing

Two field experiments have been conducted to determine the effect of grazing past FHS on Oklahoma wheat yields. A chart that shows the results of these experiments is included in Figure 1. Redmon et al. conducted experiments in 1990, 1992, 1993, and 1994. In 1992 and 1994, the wheat yield decline from grazing past FHS was dramatic. They found that on average grazing past FHS reduced wheat yields by 1.25 bushels (or 5 percent of yield) per day. They concluded that grazing should be terminated at or before FHS. The Fieser et al. study was conducted in 2003 and 2005. In 2003 they found only a small yield decline from grazing a week past FHS. They concluded that there may be a “safety zone” during which cattle can be grazed past FHS without damaging grain yield. The results of these field trials, as with almost all field crop experiments, were sensitive to weather prior to FHS and weather after FHS. In addition to the weather, wheat recovery after grazing is sensitive to the amount of green leaf area left after grazing.

 

Addressing the contradictory findings from these two studies, Taylor et al. revisited the grazing termination date issue. They combined data from the two studies, used a more precise statistical modeling approach, and assumed that conditions reflected in each of the six years was equally likely to occur. Whereas Fieser et al. assumed that 2003 conditions would occur half the time, and Redmon et al. assumed that 1992 conditions would occur a quarter of the time, Taylor et al. assumed that each of the six years for which data were available was equally likely. They assumed that the very favorable conditions of 2003 could be expected to occur only once in six years. Similarly, by assumption, the very unfavorable conditions of 1992 could be expected to occur only once in six years. As could be expected, the Taylor et al. results fall roughly half way between those of Fieser et al. and Redmon et al. Taylor et al. found an expected 3 percent reduction in grain yield for grazing one day past FHS, an 8 percent reduction at three days past FHS and an 18 percent reduction at seven days past FHS. Table 1 shows the expected percent reduction in wheat yield from extended grazing from each of the three studies.

 

Figure 1. Mean wheat yields relative to first hollow stem (FHS) Wheat yields relative to first hollow stem (FHS) and date of grazing termination for six production seasons at the Wheat Pasture Research Unit, Marshall, OK. Wheat yields in years 1990-1994 are from Redmon et al. and wheat yields in 2003 and 2005 are from Fieser et al.

 

Table 1. Estimated percent reduction in wheat grain yield from extended grazing.

Source: Adapted from Taylor et al.

 

Economics of Extended Grazing

Table 2 shows the impact, based on the Taylor et al. estimates, of extended grazing on wheat grain returns, feeder cattle returns, and total returns. ADG is set at 3 lb/day (Fieser et al. reported an ADG of 3.5 pounds in 2003 and 3.3 pounds in 2005. Redmon et al. estimated an ADG of 2.43 pounds.). Wheat grain yield is set at 35 bu/ac, stocking rate is 0.64 hd/ac (1.6 ac/hd), wheat price is $7.80/bu, calf price is $124/cwt and wheat pasture rental rate is $0.50 per pound of gain.The Redmon et al. data show the worst case scenario. Even a single day of extended grazing reduces profit. The combined data show a similar, although less pessimistic, result.

 

Although not shown in Table 2, there is an additional adverse effect due to calf prices. Both seasonal trends and price slide reduce expected returns from extended grazing. Seasonally, prices for heavier weight cattle (700+ pounds) tend to decline from February through March. The effect is typically $8 to $10 per cwt for 700+ pound feeder calves.

 

For most expected weather and price conditions, extending grazing beyond FHS for wheat intended for grain harvest is not likely to generate more net income than terminating grazing at FHS. If an additional day of grazing adds 3 lbs to calves and calf price is $124/cwt with a $6 slide, stocking rate is 0.64 head per acre and wheat pasture rental rate is $0.50 per pound of gain, added calf returns are only about $0.61 per acre. That translates into a breakeven yield loss of 0.08 bu/acre at $7.80/bu for wheat. Any wheat grain yield loss greater than 0.08 bu/acre/day will reduce profit given these prices, ADG, and stocking rate.

 

Table 3 provides a worksheet to determine if extended grazing is advisable for your situation. A computerized decision aid is also available to assist producers with economic evaluation of extended grazing. 

 

Table 2. Effect of extended grazing on cattle return, wheat grain return and total returns.

Note: Assumes a 35 bu/ac wheat grain yield, a stocking rate of 0.64 hd/ac, average daily gain = 3.0 lb, wheat price = $7.80/bu, calf price of $124/cwt, a $6 slide and wheat pasture lease rate of $0.50 per lb of gain. Adapted from Taylor et al.

 

Table 3. Extended grazing worksheet to determine the expected change in net return from grazing past First Hollow Stem (FHS).

 

Table 3

 

References

Edwards, J. and G. Horn.  “First Hollow Stem: A Critical Wheat Growth Stage for Dual-purpose Producers,” Oklahoma State University, Oklahoma Cooperative Extension Service Fact sheet PSS-2147, 2010.

 

Fieser, B.G., G.W. Horn, J.T. Edwards, and E.G. Krenzer, Jr.  “Timing of Grazing Termination in Dual-Purpose Winter Wheat Enterprises.”  The Professional Animal Scientist 22(2006):210-216.

 

Hossain, I., F.M. Epplin, G.W. Horn, and E.G. Krenzer Jr.  “Wheat Production and Management Practices Used by Oklahoma Grain and Livestock Producers.”  Oklahoma State University Agricultural Experiment Station.  Bull. No. B-818, 2004.

 

Redmon, L.A., E.G. Krenzer Jr., D.J. Bernardo, and G.W. Horn.  “Effect of Wheat Morphological Stage at Grazing Termination on Economic Return.”  Agronomy Journal 88(1996):94-97.

 

Taylor, K.W., F.M. Epplin, B.W. Brorsen, B.G. Fieser, and G.W. Horn. “Optimal Grazing Termination Date for Dual-Purpose Winter Wheat Production,” Journal of Agricultural and Applied Economics 42(2010): 87-103.

 

True, R., F. Epplin, E. Krenzer, Jr., and G.W. Horn.  “A Survey of Wheat Production and Wheat Forage Use Practices in Oklahoma.”  Oklahoma State University Agricultural Experiment Station.  Bull. No. B-815, 2001.

 

For more information contact:

 

Eric DeVuyst

Oklahoma State University

530 Ag. Hall

Stillwater, OK 74078-6026

405-744-6166

eric.devuyst@okstate.edu

 

Eric A. DeVuyst
Department of Agricultural Economics

 

Francis M. Epplin
Department of Agricultural Economics

 

Karen W. Taylor
Farm Credit Canada

 

Gerald W. Horn
Department of Animal Science

 

Jeffrey T. Edwards
Department of Plant and Soil Science