Jim McGrann, Texas Agricultural Extension Service, Department of Agricultural Economics, Texas A&M University, College Station, 77843.
Research is funded by the E. Paul and Helen Buck Waggoner Foundation, Inc., USDA/NRICGP Agricultural Systems Grant # 9404256 and the Texas Agricultural Experiment Station.
The Waggoner Ranch lies just south of the Red River midway between Dallas and Amarillo. It covers some 500,000 acres spanning six counties. The land is gently rolling plains, well covered with grass, has a liberal presence of mesquite and a fair share of nodding oil jacks. With an average annual rainfall of 26 inches and a good mixture of warm and cool season midgrasses, it is one of the best cow-calf range areas in the nation. The ranch is currently stocked at 28-30 acres per cow compared to the recommended NRCS stocking rate of 18-20 acres per cow. Range condition is fair to good and grass is abundant even in times of drought. Most of the land is rangeland but a significant area is planted to wheat in fall to graze home grown stockers prior to shipping them off to feedlots for finishing. The large size of the operation gives them some economy of scale and when judged by the Standardized Performance Analysis (SPA)(National Cattleman's Association, 1992) they come out as one of the least cost cow-calf operations in the nation (McGrann et al., 1993).
The Waggoner ranching enterprise was founded by Dan Waggoner in 1837 near Clarkesville, Texas. In 1868, his son Tom earned enough money in the Texas cattle drives to Kansas, to purchase 56,000 acres of farmland near Electra, Texas. As the free range era came to an end in the late 1880s, Tom sold this land and purchased the current ranchland along the
Beaver Creek, south of Vernon. Shortly after this, oil was discovered in the region and it transpired that there was a good deal of it on the land purchased by Tom. The Waggoner organization thus became significant in both the oil and ranching economies of Texas.
Although the ranch has a lot going for it, they have one big problem, shared by many ranchers in the Rolling Plains of Texas and beyond, that of mesquite brush. There is so much brush that on much of the ranch, many cattle cannot be gathered without using a helicopter. Not only does thick mesquite increase the cost of working cattle but it also reduces total grass production and density of the most desirable grass species. However, mesquite is not all bad. At low or moderate densities it improves wildlife habitat and provides the right conditions for some cool season grasses to prosper, providing green grass in winter that reduces winter feeding costs substantially.
Mesquite poses the most serious problem where it grows as multi-stemmed thickets. Prior to man's attempts to kill it with chemical or mechanical treatment, mesquite existed mostly as a few-stemmed plant that posed much less of a problem (Figure 1). The Waggoner ranch
has treated many thousands of acres since the 1950s but the brush has grown back as multi-stemmed thickets everywhere except where the brush was removed by root-plowing and follow-up grubbing. Due to high costs, most of the treatments to reduce mesquite have been terminated. By 1992, when this research project was planned, the management of Waggoner
ranch realized that they had to resume with some means of reducing the mesquite. By doing nothing the number of stock they could run was decreasing, reducing earning power and costs were escalating.
The grass prairies of North America evolved under periodic defoliation by grazing and fire. It is believed that fire was a major factor in preventing woody plants from dominating on grasslands because grasses can recover quickly following fire. Woody plants are less protected and take longer to recover from fire (Daubenmire, 1986; Archer & Smeins, 1991). Lightning initiates many fires every year in the prairies and Indians used fire extensively to aid their hunting activities (Daubenmire, 1986).
Prior to fencing of the land, grazing was also very different. Grazing by migrating bison
herds was intense but infrequent. The bison herds followed rainfall and fires to select choice
grazing but moved on when forage became scarce. Areas that were ungrazed became rank
and unpalatable and therefore candidates for wildfires. With the introduction of fencing in the
mid 1800's, ranchers confined large numbers of domestic livestock to certain areas and altered
the frequency and intensity of grazing when compared to that of the bison. This continuous
and often heavy grazing pressure, reduced the fuel load needed to carry wildfires and the
ability of grasses to compete with brush. Ranchers also actively reduced the incidence and
extent of fire to protect their grazing and property. This situation had devastating results
especially after the severe droughts in the 1920's and 1930's during the dust bowl era.
In past efforts to control brush populations, most producers and researchers focused on chemical and/or mechanical treatments. It is estimated that about 1.5 million acres of Texas rangelands were treated annually between 1956 and 1977 (Soil Conservation Service, 1988). Table 1 gives the approximate costs of clearing mesquite in north central Texas. Many of these practices are combined to achieve the desired outcome. Therefore, one could easily spend over $100/acre. These options may decrease in the future because of soaring costs and environmental concerns. In addition, many agricultural analysts are predicting that within the next ten years, many of the currently available chemical treatments will be unavailable.
Research with prescribed fire in north Texas has indicated that fire could potentially control mesquite more cheaply than any other treatment. The challenge was to develop a management system that allowed us to incorporate fire on a regular enough basis and still produce beef profitably. Most fire research has shown that fire does not root-kill mesquite, but if fire could be used frequently enough in an appropriate grazing system, mesquite could be kept low enough to reduce competition with grasses and not interfere with working livestock.
The key to using prescribed fire is to manage the grazing to accumulate sufficient grass
fuel. Most rangelands managed under continuous grazing will not support frequently-planned
controlled burns because sufficient fuel to carry the fire does not accumulate and the fuel is
too patchy to have the desired effect. Also, many ranchers would have an added cost of
leasing pasture while their burned pasture was recovering. Rotational grazing, on the other
hand, has been shown in Africa (Trollope, 1984) to have the potential to manage for sufficient
fine fuel and allow for recovery after burning before it is grazed again. Fire has also been
used in the midgrass and tallgrass prairie to control brush and improve livestock nutrition and
wildlife habitat (Wright & Bailey, 1982). We believe that mesquite can be controlled in a
cost-effective manner with prescribed burning if managed in a rotational grazing system. This
led to the development of the Waggoner Kite Project.
In September of 1994, we as scientists with Texas A&M, in co-operation with the Waggoner Ranch began conducting a five year research project applying controlled burning by using rotational grazing. The objectives are to develop a profitable management strategy to reduce mesquite using fire, decrease chemical and mechanical inputs, improve grass composition and productivity, cope with drought, and enhance wildlife habitat (Teague, Ansley and Pinchak, 1995).
As researchers, we were concerned with the fact that much research is not adopted by producers and that most ranchers get their information from other ranchers (Merrill-Sands et al., 1991). We believe this results from most research being done "for" ranchers rather than "with" them and at a small scale. What ranchers really want to know is what happens under commercial ranch conditions at the ranch scale. To solve this problem we organized with the Waggoner ranch to have enough land and cattle that every treatment replicate would be at the ranch scale (3,000 to 5,000 acres) and to work with Waggoner staff using their skills and experience to carry out the day to day tasks of running the experiment.
The Kite project was an extension of an ongoing relationship between the Texas
Agricultural Experiment Station (TAES) at Vernon and The Texas Ranch Committee, an
autonomous, self constituted body of practicing ranchers. This committee was formed
following the drought of the 1950's by prominent north Texas ranchers who saw the need for
grazing management and animal nutrition research. As they had done in previous research
efforts, the Ranch Committee and TAES, along with the Waggoner Ranch, worked together to
develop and organize the Kite Project so that the results and procedures could also be
implemented by other ranchers at the ranch level. In addition to the Texas Ranch committee,
we get feedback from ranchers who are successfully using rotational grazing systems. We get
feedback from all these parties at least annually, to make sure that we are managing the way
an intelligent rancher would, to achieve the best possible outcome for each treatment. We
hope that this cooperative approach will give more credibility to our research and result in
more recognition and use of the information we generate.
The study includes four experimental treatments with two replications covering an area of about 34,000 acres. Replicate sizes range from 3,000 to 5,000 acres so results will apply to ranches of this size as well as larger ranches. A similar mixture of soils is present between treatments. All treatments were stocked with Hereford cows having the same age composition in September of 1995 at levels consistent with NRCS moderate stocking rates. These were calculated according to the acreage of each of the four major range sites in each pasture and the range condition in each.
Three different rotational grazing systems are being compared with continuous grazing.
These three different systems represent different levels of management intensity and are being
compared to provide the points for and against each, since different ranchers are likely to be
comfortable with different intensities of management (Figure 2). The treatments include:
Fire is used in years when there is sufficient fuel to carry the fire and produce the desired effect on mesquite. The whole area is grazed during the year but at least 1500 lb/ac of fuel is left in the areas to be burned that year. Prescribed burning is conducted in late winter to minimize negative effects on the soil and vegetation, increase the safety factor and achieve the desired effect on mesquite (after Wright and Bailey, 1982). In terms of frequency, the goal of the prescribed burning is to burn every 4 - 6 years.
Fire can have very different effects on mesquite depending on how it is applied. If a very hot fire is applied using high fuel levels and low humidity under moderately windy conditions, the entire above ground tree is killed. This is followed by regrowth of virtually all plants, which eventually creates a regrowth thicket. An alternative is to burn using less fuel and when weather conditions will result in a less intense fire. This will topkill small mesquite plants, but only kill growing points on the lower canopy of taller trees, creating a "savanna" effect (Ansley and Cadenhead, 1996). Compared to a complete topkill, a savanna fire burns only 45% to 70% of the lower positioned, secondary branches while leaving the very top branches alive.
Such low intensity fires result in mesquite trees that (1) have less foliage and
potentially compete less with grasses for water, (2) maintain apical dominance and do not
resprout, and (3) improve visibility for livestock management because the lower branches are
removed and there is no regrowth. Both high and low intensity fires are being applied in
each treatment to evaluate the relative merits of each (Figure 3).
The questions we are asking in this project include which treatment(s) provide;
In order to critically evaluate the advantages and disadvantages of each grazing treatment, many scientific measures will be taken. Environmental measurements taken in each treatment include rainfall, soil moisture, soil organic matter, infiltration rate, litter cover, bare ground, sign of soil erosion, forage decomposition rate and forage production. In addition, changes in plant species composition are measured 3 times each year. Aerial photography and ground transects are used to quantify mesquite densities and canopy cover and the effects of fire on mesquite. Wildlife population estimates for white-tailed deer and bobwhite quail are also taken to assist in evaluating treatment effects on wildlife habitat (Figure 4).
Body condition scores are estimated and fecal samples collected for each herd monthly. These are used to monitor the nutritional status of each herd and determine the level of supplementary feeding necessary in winter and spring to maintain the cows in the desired condition. Target body condition scores are 6 at the beginning of calving in December and 5 when the bulls are put in with the cows in April. The fecal samples are analyzed by Dr Jerry Stuth's "Grazingland Animal Nutrition Laboratory" in College Station. Supplementary feeding levels are calculated using the "NUTBAL" feeding decision aid system (Stuth and Lyons, 1995). It uses expected cow performance, cow condition, stage of lactation, vegetation conditions and current weather to calculate the required level of feeding.
The grazing impact is assessed monthly using "THE GRAZING MANAGER" grazing decision aid system developed by Dr Mort Kothmann in College Station (Kothmann and Hinnant, 1994). This program uses current grazing use level, the normal amount of growth expected in an average year and the sum of actual growth that has taken place to determine if sufficient grass will be available through the rest of the season. It gives an early warning of 3-6 months if there is likely to be a shortage of grazing in the future so that management can plan ahead for any drought problems before they become unmanageable.
In addition to environmental and animal performance measures, a full economic
analysis of each treatment will be conducted using Standardized Performance Analysis (SPA)
(National Cattleman's Association, 1992). Cow-calf pairs are used to evaluate all treatments
and animal performance is assessed in terms of beef produced and profit per acre.
Pre-treatment historical records will be used as a baseline against which to compare treatment
differences for both land and animal resources. One of the most important results will come
from the unburned controls. In this treatment, the cost of not controlling mesquite or not
implementing other treatments will be taken into account when calculating profit. In this way
the cost of not maintaining the natural resources on which production depends will be taken
into account to calculate true profit.
What ranchers often want to know from research information is, what would happen if I did different things on my ranch with different soils, slopes, vegetation, cattle and rainfall? In order to answer such questions on a ranch-specific basis, we are developing and testing a computer model called SPUR (Simulation of Production and Utilization of Rangeland). It is a grazingland ecosystem model that has the potential for long-term trend forecasting. It contains much of the science that is known on hydrology, soil fertility, soil-plant relations, plant growth, animal selection of plants, and cow-calf or steer performance.
Before the model can be called a useful tool, it has to be tested against the
measurements we make in this project and other relevant research. Once calibrated for a
particular location, SPUR can be run for more than one hundred years to predict the outcome
of different management and different weather sequences, to assess best management
strategies and combinations of management practices. The output from SPUR can be selected
to include rainfall runoff, soil loss, grass production, soil organic matter, forage harvested by
livestock and wildlife, animal weight and gain, and estimates of net return. It has the
advantage of being able to assess the results of managing in a certain manner for decades,
rather than just 2-3 years which happens with most research.
We have completed 2 years of grazing and 1 year of burning to date. Highly unusual weather was experienced in these 2 years. Rainfall in spring and summer 1995 was well above normal while winter 1995 and spring and early summer 1996 were the driest this century. This resulted in very low forage quality during winter 1995, and spring and early summer 1996. We increased stocking rate by 1-2 acres per cow in fall of 1995 to take advantage of the abundant grass growth. Even though the fall and winter of 1995 were dry we burned according to plan because soil moisture was still high from the heavy summer rains.
Only half of the planned burns were completed in 1996 because of the drought and supplementary feeding was much higher than normal. We were unable to graze the burned pastures until late summer because we received no spring rain. These drought conditions also resulted in the need for early weaning and destocking by 35% in October 1996. Below are listed some of the points we have learned in the process thus far:
We hope that this facility and method of conducting research will improve the applicability of the information we generate. Results will be published in Rangelands as they become available in the future. We will be glad to show the experiment to any interested party.
| Table 1. Approximate costs of treating mesquite in north Texas | ||
| Treatment | Cost per treatment* | Treatment interval |
| Chemical spray** | $ 15 - 25/acre | Retreat every 10-12 years |
| Spray + chain (as above) | $ 25 - 40/acre | Chain after 2 years then as above |
| Roller chopping | $ 50 - 100/acre | Retreat every 8-10 years |
| Root plowing + reseed | $ 80 - 90/acre | Grub every 12 years |
| Fire | $ 5 - 7/acre | Burn every 5 years |
* All costs are estimates and will vary with the size of the equipment, density and size of the brush, fuel costs, and number of acres to be treated and regrowth rate.
** Reclaim + Remedy
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