White clover in dairy pastures in the Northeast is known to improve forage quality and yield and decrease or eliminate the need for N fertilization. Unfortunately, white clover survival can be a problem. Field trials were conducted on Tom Miller’s dairy farm at Dryden, NY in 1993-95 to determine the seasonal growth pattern and times of stress for white clover in grazed pastures as well as the effect of moderate and heavy grazing pressure on white clover performance. In 1994-97, white clover cultivars and experimental lines were evaluated under grazing on the Miller farm and at the NRCS Plant Materials Center at Big Flats New York. In 1996-98, extension information describing the pasture ecosystem was prepared as a basis for improving farmer and student understanding of pasture management. Finally, in 1997-98 enterprise budgets of pasture renovation with improved white clovers were prepared to summarize the economic implications of the field work. It was found that white clover in the Northeast is most vulnerable and most stressed in the summer, especially after drought. This contrasts to reports from other places (New Zealand, UK) where white clover management requires special precautions in the spring. More frequent grazing in the spring has been successful in other climates in increasing grass tiller density. Higher tiller density more effectively shades white clover in hot and dry summer periods and can improve survival. However, our studies showed that current recommendations for orchardgrass-white clover pastures are about optimal. We could not increase orchardgrass tiller density by grazing more frequently than recommended (2100 vs 2400 kg of DM/ha at start). In fact, there was some evidence that such a practice increased invasion of weeds. Nevertheless, more frequent grazing of the pasture in the spring did improve white clover performance later in the season in one of our trials. This was probably because of less shading of the clover in the spring leading to higher photosynthesis and better capacity to survive summer stress. The white clover variety most commonly used in New York State is called “Ladino” (technically ‘California Ladino’). Our field trials showed that ‘Milkanova’ (from Denmark) was more drought tolerant and that ‘Brown Loam’ (Syn #2) (a US experimental line) established better than Ladino. Thus, better white clover cultivars may soon be available. Assuming that an improved white clover cultivar would increase both pasture yield and quality, the gross value of such an improvement depends upon the market value of the feeds replaced by pasture. We found that a 1 ton/acre and 5% NDF gain would be worth about $115/acre. The corresponding market value for good alfalfa hay was $100/ton. With pasture renovation costs calculated to be about $40/acre, finding and growing better white clovers is economically sound. The ecological summary of this work identified five ecological principles that can be demonstrated in a typical pasture in the Northeast: (1) everything that is organic is food (energy flows), (2) nothing is wasted (matter circulates), (3) there is a premium on protecting the soil, (4) there is always a substitute (biodiversity), and (5) there are always animals under natural conditions. These principles can be applied to good pasture management as well as general education about the ecological basis of sustainable agriculture.
The overall objective was to increase the sustainability of dairying and pasture-based agricultural systems in the Northeast through better management of white clover, a key pasture species. The study was done on a commercial dairy farm and involved the following sub-objectives: (1) detailed characterization of the seasonal growth pattern of white clover in order to understand when it is most vulnerable and how it survives the stresses of pasture, (2) evaluation of alternative varieties (cultivars) in terms of productivity and persistence, (3) testing of different grazing managements for effects on (1) and (2), and (4) extension of information about the pasture ecosystem and superior white clover varieties to farmers who could make better use of pastures.
The research was conducted primarily on the Tom Miller dairy farm. About 45 dairy cows were rotationally stocked on 50 acres of orchardgrass-white clover pastures that were seeded in 1988. The soils are Phelps and Howard gravelly loams on rolling topography with moderate to good drainage. The climate is typical of central New York State with a Cornell weather about 10 miles from the site.
Findings and Accomplishments
Objective 1. The seasonal growth pattern of white clover in rotationally grazed pasture on the Tom Miller Farm at Dryden, NY showed relatively low levels of leaf density and bud activity in the spring that increased through the season. Mortality of complete white clover plants was very low throughout the season, although stolon decay and break-up into separate plants was observed. White clover plants were not smaller or less complex in branching pattern in the spring than later in the season. However, at the end of a hot and dry period in the summer of 1995, white clover plants occupied a smaller area and were less complex than plants in the spring. This contrasts with studies in milder climates where plants were smaller and less complex in the spring. Reduced size and complexity is interpreted as a response to stress. Thus, summer drought appears to be the most important stress for white clover in our climate. Therefore, we recommend that farmers decrease grazing frequency and closeness for a short period after a summer drought in order to maintain the productivity and persistence of white clover. In contrast to white clover, the leaf-density and tiller-density of orchardgrass and bluegrass decreased toward the end of the growing season. After the drought period of 1995, the leaf density of dandelion and other weeds was higher than they had been in the spring.
Objective 2. The most widely sown white clover cultivar in the Northeast is California Ladino (or simply Ladino). It is in the giant cultivar group and originated in Italy. Winter survival often has been associated with place of origin and increased stolon production. Thus, we compared Ladino to cultivars that were supposedly more stoloniferous and/or came from regions of colder climate. Three such cultivars (Milkanova, Ranger, and Will) were hand established as clones and repeatedly sampled under grazing conditions on the Miller Farm. Milkanova produced more than Ladino following the 1995 drought. Ranger had higher visual ratings than Ladino in 1995, but there were no detectible differences in winter survival and performance by 1996 under grazed conditions. Twelve cultivars and breeding lines (including Ladino) were also established with orchardgrass in ungrazed research plots at the NRCS Plant Materials Center at Big Flats, NY in 1995. ‘Brown Loam’ out yielded Ladino in both 1995 and 1996. ‘Olwen’ also out yielded Ladino in 1996. ‘Blanca’ and ‘Sonja’ (which yielded similar to Ladino) showed better resistance to virus infection in the fall of 1996. Ladino, Brown Loam, and Will were seriously damaged by virus and survived the winter poorly. Milkanova survived the winter better than Ladino at Big Flats in 1996-97, but not as well as Blanca, Olwen, Ranger, and Sustain. These results do not clearly identify a cultivar better than Ladino. However, they do show that lines are available with better drought tolerance and virus resistance. Therefore it is possible to improve white clover varieties for the Northeast.
Objective 3. Survival and recovery of white clover following summer drought was identified as an important problem under objective 1. Increasing grass tiller density by more frequent spring grazing has helped reduce summer stress in white clover under conditions in New Zealand. The apparent mechanism is through increased shading and lower soil temperatures during summer drought. The work in New Zealand was done with perennial ryegrass as the companion grass species. Grass tiller density (number of tillers per unit area of ground surface) is known to show an inverse relationship with tiller mass. Thus, more frequent or closer grazing should increase tiller density. We tested this hypothesis with orchardgrass on the Miller Farm in 1993 by grazing the test plots by the calendar (every 7 days), which was about 3 days ahead of the farmer, and in 1994 and 1995 by grazing at a starting pasture mass of 2100 kg/ha compared to the farmers starting mass of about 2400 kg/ha, again achieved by grazing a little more frequently than the farmer. The different grazing systems were applied only through June. Our results showed that we did not increase orchardgrass tiller density. In fact, the most aggressive system in 1993 appeared to weaken the orchardgrass and allow weed invasion of the test areas. White clover leaf numbers were increased by more aggressive grazing, and following the 1995 summer drought, white clover recovered more quickly on the plots that had been grazed more frequently in the spring. Orchardgrass is apparently weakened by grazing before it has about 2400 kg/ha of available forage. This weakening can benefit white clover if it is stressed by drought, but one must manage to optimize the pasture (not just one species). We concluded that the present recommendations for grazing white clover and orchardgrass pastures should not be changed.
Objective 4. Many of the practices of sustainable agriculture can be understood and refined in terms of ecological principles. If fact, some have argued that the way to make agriculture more sustainable is to make agroecosystems more like natural ecosystems. The grazed pasture is a relatively natural agroecosystem. We prepared a publication entitled “Concepts of Sustainability and the Pasture Ecosystem” as background information for a field trip to a pasture. It highlights five principles and presents quantitative and relational information about these principles in the context of a Northeast dairy pasture. The five principles are statements of (1) energy flow, (2) matter circulation, (3) soil protection, (4) biodiversity stabilization, and (5) animal contributions. The definition of sustainable agriculture, the pasture food web, the biomass pyramid, the carbon cycle, and species composition are presented for new as well as experienced visitors to the pasture ecosystem. The publication has been used with a laboratory field trip for the introductory course in sustainable agriculture at Cornell University.
Dissemination of Findings
A Ph.D. dissertation was prepared based on the studies at the Miller Farm. Two scientific papers and four presentations at regional or national scientific meetings based on that work have been presented. An additional manuscript on white clover ecology is being prepared for the journal Grass and Forage Science. There were also two local seminar presentations. In addition, a departmental teaching publication on the pasture ecosystem has been published and several articles are planned for What’s Cropping Up, the departmental extension publication for New York State. Two tours, including one by NE-SARE, visited the farm and learned about the experiment.
Publications or abstracts of publications previously submitted with progress reports are not included with this final report. However, the citations of all publications partially supported by this project are listed here:
Fick, G.W., and D.L. Emmick. 1996. Changes in botanical composition of orchardgrass and perennial ryegrass pastures in New York. p. 7. In Invited papers and abstracts of contributed papers, northeastern branch meetings. Am. Soc. of Agron., Madison, WI. [Only partially supported by this project]
Karsten, H.D. 1996. Improving the persistence and productivity of white clover (Trifolium repens L.) in rotationally stocked pastures in the northeastern U.S.A. Ph.D. thesis, Cornell Univ., Ithaca, NY, 198 p.
Karsten, H.D., and G.W. Fick. 1994. Investigating white clover growth in rotationally-grazed dairy pastures. Abstracts for the 10th Annual Symposium on Agricultural Ecology, 23 April 1994, Div. of Ecology and Systematics, Cornell Univ., Ithaca, NY.
Karsten, H.D., and G.W. Fick. 1994. Methods for describing white clover growth in pastures. p. 3-4. In Invited papers and abstracts of contributed papers, northeastern branch meetings. Am. Soc. of Agron., Madison, WI.
Karsten, H.D., and G.W. Fick. 1995. Seasonal growth of white clover in rotationally-stocked dairy pasture in the northeastern U.S. Proc. Am. Forage and Grassl. Council. 4:209-213.
Karsten, H.D., and G.W. Fick. 1996. Effect of frequent grazing on orchardgrass and white clover in a rotationally-stocked New York pasture. p. 115. In Agronomy abstracts. Am. Soc. of Agron., Madison, WI.
Karsten, H.D., and G.W. Fick. 1997. Winter-hardiness and pasture productivity of some white clover cultivars in New York. p. 22:89-90. In Proc. 18th Int. Grassl. Congr., Winnipeg and Saskatoon, Canada, 8-19 June 1997. XVIII Int. Grassl. Congr. ’97, P.O. Box 4520, Station C, Calgary, Alberta, Canada.
Unruh, L.J., and G.W. Fick. 1997. Concepts of sustainability and the pasture ecosystem. SCAS Teaching Series No. T97-1. Dep. of Soil, Crop and Atmos. Sci., Cornell Univ., Ithaca, NY. 11 p.
Impacts of Results/Outcomes
Potential Contributions and Practical Applications
Increased use of pasture would reduce the amount of cropland in feed crops such as corn and soybean. Corn and soybean production uses more biocides and exposes the soil to more accelerated erosion than does pasture. Thus, increasing the profitability and reducing the risks associated with pasture production has important indirect benefits for the environment and for agricultural sustainability. Our studies have shown that grazing management recommendations for orchardgrass-white clover pastures are nearly optimal. However, the cultivar studies with white clover show that there is a good possibility of improving this species by giving it more productivity in dry summers and increasing its resistance to virus diseases. Those changes would improve pasture yields and forage quality and reduce the risk low pasture production. The economic analyses mentioned above show that these are very positive outcomes.
The most important finding of this study is that there is very strong economic justification to search for or develop improved white clover cultivars for Northeast pastures. Virus resistance, drought tolerance, and winter survival capacity must be added to high yield and forage quality of a optimal cultivar. The study also showed that drought stress, when it occurs, is an important limitation for white clover production and survival. It may be possible to improve management recommendations for white clover under hot and dry summer conditions.
The economic questions raised by the field work in this project boil down to the costs and benefits of improving the white clover component of orchardgrass pastures in the Northeast. Our results indicate that reseeding improved cultivars may be more successful than attempting to refine the grazing management system. Thus, we prepared enterprise budgets for pasture improvement including reseeding. We did not collect data on the likely responses, but have chosen to look at cases where such practices would increase yields by 1 or 2 tons per acre with 1.5% higher crude protein and 5% less fiber (NDF) than the unimproved pastures. Those numbers are consistent with results from other studies done by NRCS or that have been reported in the literature. The Cornell FORVAL model was used to calculate the value of the pasture produced given its forage quality and the market prices of alfalfa and timothy hays that would be used to replace the pasture should it not be available. Two scenarios were considered: low feed prices ($100/ton alfalfa hay) and high feed prices ($200/ton alfalfa). At low feed costs, increasing the yield and quality of a Northeast pasture by planting an improved white clover cultivar would increase the value of the pasture produced from $120 to $130/acre. With the expense of renovation being about $40/acre, pasture reseeding would be a profitable practice.
Changes in Practice
Wide dissemination of the results of this study have not yet been made, but our findings strengthen confidence in present recommendations for orchardgrass-white clover pastures in the Northeast. From the farmer’s perspective, our results emphasized the importance of grazing control. The economic analyses also help demonstrate the economic value of using pastures as a main source of summer feed.
Farmers making pasture seedings should be experimenting with improved white clover cultivars, especially those with virus and drought resistance. Blanca, Milkanova, Olwen, Ranger, and Sonja are already available and may do better than Ladino on some farms. Having surplus pasture is probably the best way to deal with drought, using the surplus for hay in an average year. Avoiding overgrazing of orchardgrass may also be important in reducing weed encroachment into pastures.
Farmer Evaluations (from Tom Miller)
It was not too much trouble for me. Cornell supplied all the materials and most of the work. On-farm research has more validity for farmers, especially in grazing research. With the assistance of farmers, you can save a lot of time in setting up the research. The researcher can draw on the experience of the farmer. I really encourage on-farm research to be continued, especially with cows and grass. Research takes a lot of time and we need researchers and research organizations to do it, but the farmer can really help out. The farmer can supply the cows, the grass, and the experience.
Areas needing additional study
Plant breeding applied to white clover cultivars for the Northeast is presently not being emphasized by anyone. In addition, the ecological and physiological aspects of the survival of pasture plants under stress is receiving very little attention. To develop better pasture management systems, we need to understand how the white clover stolons become tolerant of heat, cold, and desiccation. Finally, we need to know more about the viruses that infect pastures, how they are spread, and how the plant becomes resistant to them.