Systems for sustainability of alfalfa production on acid, Coastal Plain soils using various harvesting strategies
Preliminary observations from beef cattle grazing of alfalfa varieties and livestock response to grazing alfalfa in 2001 are reported. Yields of 12-percent moisture hay on five East Texas ranches ranged from 4.6 to 5.3 tons per acre. Net income from these alfalfa demonstration sites ranged from $360 to $440 per acre with alfalfa valued at $135 per ton and establishment costs prorated over five years. Field tours were conducted. Alfalfa production on Coastal Plain soils is described at the Internet site http://soils.tamu.edu. Production studies and subsoil aluminum detoxification studies will continue into 2002.
Development of soil amendment and nutrient management plans to enhance establishment and sustainability of alfalfa on acid, Coastal Plain soils.
Develop multiple-option defoliation strategies using hay, silage, greenchop, and/or grazing to improve stand survival and sustainability of alfalfa.
Develop risk assessment models to project economic benefits from alfalfa production on Coastal Plain soils.
Use a variety of the latest technologies to transfer best management practices to stakeholders in the southern US.
Field studies at Overton and Nacogdoches, Texas and a greenhouse experiment were established to evaluate the effectiveness of gypsum and calcium sulfite, a flue gas desulfurization by-product, for reducing phytotoxic subsoil aluminum levels in strongly acid soils. Alfalfa was harvested four times at both locations during the 2001-growing season. Yield data and samples for chemical analysis were collected. Plant tissue analysis has been completed on all but the last harvest. Data from plant samples collected in 2000 failed to indicate any consistent treatment effects. Soil samples were taken at both the Rusk and Nacogdoches County sites in April 2001. Soil samples were collected to 48-inches deep and separated at 0-6, 6-12, 12-24, 24-36, and 36-48 inches. Analysis has been completed on the Nacogdoches County samples. Analysis of Rusk County samples is currently in process. Data will be analyzed to determine if surface treatments applied in 1999 are affecting sub-surface properties. Preliminary analysis of data from samples collected in 2000 indicated no treatment differences for subsurface pH or soluble aluminum levels. Soil from cylinders in the greenhouse study was separated every three inches to one-foot deep and every six inches from 1 to 4-feet deep. Analysis of soil samples was completed in 2001. Analysis of plant tissue has also been completed. Statistical analysis of these data has not been completed at this time.
Organic analyses of alfalfa samples collected (frozen in liquid nitrogen) from aluminum detoxification studies in the greenhouse and field is continuing. Preliminary results from analyses of plant samples from the greenhouse study indicate that aluminum is not toxic to the glutamate dehydrogenase isoenzymes in the absence of boron and gypsum, but boron application in the absence of gypsum was toxic to the glutamate dehydrogenase isoenzymes. Application of 4.46 tons of gypsum per acre in the absence of boron induced all of the glutamate dehydrogenase isoenzymes. Application of calcium sulfite in the absence of boron and without liming was unsuitable because it suppressed the glutamate dehydrogenase isoenzymes. Fructose biphosphatase activity was insensitive to all the soil treatments. Total chlorophyll decreased with increasing boron application in the absence of gypsum. At 2.23 tons of gypsum per acre, 4 lb of boron per acre induced highest chlorophyll contents. At 4.46 tons of gypsum per acre, increasing boron rates decreased the alfalfa chlorophyll content. Calcium sulfite in the presence or absence of lime treatment was unsuitable as it decreased total chlorophyll content.
Organic analyses of alfalfa samples from the Nacogdoches field study indicated that increasing rates of gypsum increased chlorophyll content. Based on chlorophyll content of the alfalfa samples, the calcium sulfite sludge appeared to cause phytotoxicity at high rates. As in the greenhouse study, fructose biphosphatase was insensitive to gypsum and sludge amendments on the Nacogdoches and Overton field sites. Glutamate dehydrogenase activity was low on both field sites indicating the existence of a nutrient imbalance in both soils.
Six varieties of grazing-tolerant alfalfa were established in six replications on two 1.5-acre sites that were divided into three pastures each in fall 1997. Alfalfa was harvested for hay during the first year of production. During the following three years in this southern region SARE program, these six varieties of alfalfa were test grazed. The six alfalfa varieties that a were established in six replications for evaluation of stand maintenance and sustainability under different grazing regimens included Alfagraze, GrazeKing, Amerigraze 401+Z, HayGrazer, Amerigraze 702, and Cimmeron 3I. Grazing regimens included 1) continuous stocking with grazing to a stubble height of three-inches or more; 2) rotational stocking, with grazing initiated at stage five or 10-percent bloom and grazed to a three-inch stubble height: 3) rotational stocking, with grazing initiated at stage three or pre-bud and graze to a three-inch stubble. The duration of stocking on rotational treatments was three days or less. Testers were stocked for grazing during each month beginning in April and continuing through September.
On Nov. 5 and 6, 2001, final plot readings for plant count, stems per plant, stand height, and percent stand were conducted. Except for a few isolated plants, alfalfa was not sustainable in plots that had been continuously stocked. The grazing treatment of rotational stocking as plants reached stage three resulted in nearly complete loss of stand in one block of three replications, and about 50 to 100-percent loss of stand in the other block of three replications. The only grazing treatment that had substantial, sustainable alfalfa stand was the rotational stocking when plants reached stage five or about 10-percent bloom. The most detrimental factors contributing to significant stand loss during this grazing experiment were summer drought and the invasion of common bermudagrass. By nature of the grazed-deferred treatment of rotational stocking when plants reached stage five, the alfalfa canopy reduced the extent of plot invasion by bermudagrass. A preliminary conclusion from this study is that alfalfa is not sustainable as an exclusive summer-grazing pasture plant on Coastal Plain soils in the southern US. For alfalfa to be sustainable on Coastal Plain soils, our research indicates this crop should be used primarily for hay, and grazed only during early spring and or late fall after a hard freeze when defoliation by animals would not be detrimental to the stand.
A second replicated study was established at Hope, Arkansas to evaluate beef cattle performance on grazed alfalfa compared to grazed common bermudagrass. The field data collection planned for this trial was completed in fall 2001. Two years of animal performance data have been collected and preliminary analysis is completed. A graduate student has begun laboratory forage nutritive value analysis of samples collected during the trial and will also conduct an economic evaluation of the grazing comparison data collected. Plans are to extend grazing comparison data collection into 2002 because the alfalfa stand is still in fair to good condition. Procedures will be altered slightly. Because there has been some stand loss of alfalfa, all pastures were overseeded with annual ryegrass in fall 2001. Annual ryegrass should fill the gaps in alfalfa stands, and ryegrass overseeded on bermudagrass permits a comparison of alfalfa/ryegrass with the bermudagrass/ryegrass mixture that is frequently used in southern regions for late-winter and spring grazing.
Observations and some preliminary conclusions from this study at Hope, Arkansas are as follows: It is possible to establish an excellent stand of alfalfa on borderline-suitable Coastal Plain soils properly treated with the right soil amendments. This site was limed to raise soil pH to 7.0 in the surface followed by incorporation of gypsum. Stocker calves having free access to a bloat preventive showed no signs of bloat at any time while grazing alfalfa. Grazing alfalfa required greater attention to management than grazing bermudagrass without large improvements in grazer performance. Difficulties encountered when using alfalfa as a primary grazing crop may be different in the South than in northern regions. In this study, aggressive summer weeds and herbicides applied to control these weeds required grazing withdrawal periods that are incompatible with timely grazing. A similar situation occurs with insects and insecticide applications. Periods of high rainfall that necessitated pulling cattle off alfalfa to avoid trampling damage interfered with timely grazing and damaged alfalfa in low spots that became waterlogged for extended periods. Alfalfa reached flower stage rapidly during hot summer weather and often before pesticide withdrawal periods were over. Stocker calves did not effectively grazed alfalfa once it passed the late bud growth stage, leading to poor utilization of the standing crop with resultant poor calf performance, especially in summer. Alfalfa went dormant during late summer drought. Some of these problems incurred with grazing could be eliminated if alfalfa were grown by producers who have the capability to harvest the crop as hay when it outgrows the ability of grazers to consume it. Also, adult cattle would probably utilize the mature alfalfa stands more effectively than stocker calves in the summer.
In cooperation with five stakeholders, alfalfa production demonstrations totaling 32 acres were maintained and harvested in 2001. Sites located in Gregg, Rusk, Cherokee, Anderson, and Smith Counties in Texas were treated with best management practices developed for alfalfa production by TAMU scientists and were harvested for hay by stakeholder-cooperators. Yield estimates were made from meter-square quadrant samples before each harvest. All stands survived the prolonged drought in 2000. Yields in 2001 ranged from 4.6 to 5.3 tons of 12%-moisture hay/acre. Economic analysis of the alfalfa hay valued at $135 per ton projected a net income ranging from $360 to $440 per acre on four of the five initial sites established. The fifth site located on a deep sandy soil in a creek bottom rapidly declined this year and was terminated at the end of the 2001 production season. Net income from this terminated site approximated $60 per acre in 2001. Five educational meetings and tours of stakeholder alfalfa demonstrations were organized by County Cooperative Extension Agents, principal investigators, and stakeholders and were attended by approximately 200 interested producers and clientele. Details for production of alfalfa, the value of alfalfa as forage for livestock, and the economics of alfalfa production were discussed at these field tours. At each field tour, stakeholders hosted and shared their experiences and alfalfa management expertise with participants. One news article for general release was written describing alfalfa production practices and economic benefits of growing alfalfa for hay. Approximately 15 telephone calls/e-mail contacts were received during the year from persons interested in planting alfalfa. Slides of alfalfa production practices are being used in an Internet Web site that details production techniques for success with alfalfa production on Coastal Plain soils. The Web site address is http://soils.tamu.edu, then click on Publications. Digital video of alfalfa production practices is being captured for development of a video that details the practices essential for successful production of alfalfa on Coastal Plain soils.
Impacts and Contributions/Outcomes
Results from this research and demonstration project offer producers high-quality alternative forage for production on carefully selected soils on farms and ranches in the Southern Region. Grazing alfalfa in this region may not be as attractive of an alternative as is alfalfa planted for hay production. Environmental problems such as excessive rainfall or prolonged drought and layout periods required due to chemical applications for pest control interfered with effective grazing management. Alfalfa stand reductions due to continuous grazing and to rotational grazing before the 10-percent bloom stage of growth were shown particularly harmful to alfalfa stands. Intensive grazing of first growth alfalfa during a time when environmental conditions are not conducive to hay production and grazing of final growth alfalfa following a hard freeze may be the best grazing alternatives for this region.
Economic analysis of hay yields from demonstration sites projected that net income ranged from $360 to $440 per acre during the second year of production when hay was valued at $135 per ton. Income in this range exceeds that from most other forages produced in the Southern Region, and can be used to greatly improve the standard of living of farmers, ranchers, and local and regional communities.