Evaluating Productivity of Various Pasture Species by Utilizing Comsec Pasture Gauge and Bulk Density Plates

Final Report for FNC93-033

Project Type: Farmer/Rancher
Funds awarded in 1993: $3,920.00
Projected End Date: 12/31/1994
Matching Non-Federal Funds: $8,040.00
Region: North Central
State: Minnesota
Project Coordinator:
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Project Information


The research area includes the farms of roughly 100 members of the Southeast Minnesota grazing groups which meet at their neighbors’ farms throughout the year to examine members’ pastures and farming operations, discuss management methods and techniques, and network. The farms are very diverse in themselves, as well as the geographic area that encompasses the grazing members. Farms vary from flat, prime crop land to extremely rough, hilly land and farms range from small to large. Cropping systems vary from corn, small grain and hay rotations to all pasture and hay land. The grazing enterprises include dairy cows, dairy heifers, dairy and beef steers, beef cow-calf, sheep and pastured poultry. A few grazers are doing contract heifer grazing.

Many of the grazing club members have been experimenting with and have applied sustainable practices. In addition to management intensive grazing, other practices are being used, such as reducing use of synthetic fertilizers and chemicals, planting cover crops, diversifying cropping systems to include other crops in rotations, and adapting new practices which replace purchased production inputs.

The practice of management intensive grazing is in itself a process. Grazing members are gradually applying it to their own farms and learning through practice. The grazing objectives and methods vary by type of livestock species being managed.

A core group of farmers, who serve as “unofficial” leaders of the five neighborhood grazing clubs, provided overall leadership in organizing the pasture walks and coordinating other parts of the project.

Mike Watson, Animal Nutritionist with Wayne Feeds, provided assistance with interpretation of forage lab results and attended the October pasture walk. Ron Bressemann, Grazer and Dairy Consultant, attended the October and November pasture walks and provided information on forage quality.

The Minnesota Dairy Initiative, Land Stewardship Project, the Cannon River Sustainable Farming Association and the Southeast MN Sustainable Farming Association were sponsors for one or both of the two field day field in conjunction with this project.

Allan Savory, Founding Director for the Center for Holistic Resource Management, provided the keynote address at the large group field day held at the Art Thicke farm near La Crescent, MN on June 24th. Savory shared with the group his concepts and views on “rational” grazing and “planned” grazing systems, and how grazing management, holistic thinking and decision making, apply to the holistic approach to resource management and biodiversity. He also emphasized and demonstrated the need to do recordkeeping and monitoring on the farm to look at the long term effects of our planning and decision making.

Members were assisted with plant identification and forage species management by Dr. Craig Sheaffer, Forage Agronomist, University of Minnesota, at the May pasture walk and September Field Day at the Dave Minar Family Farm. Br. Hugh Chester-Jones, animal Scientist at UM Southern Experiment Station, Waseca, provided on-farm research findings for grazing management and economic costs for heifers on pasture at two pasture walks.

The Hiawatha Valley Resource Conservation and Development (RC&D) Council and Roger Lenzmeier, RC&D Coordinator, cooperated by providing partial funding support for the work to be performed by the project intern.

Initially, the Grazing Clubs decided to have the large group meet once monthly and the five small groups to meet once or twice a month on their own. Pasture walk location and dates were established and announcements were mailed to all members on the Grazing Club mailing list. The purpose of these meetings is to examine members’ pastures through pasture walks. At these pasture walks; the Comsec Pasture Gauge and a Bulk Density Plate were used to assess pasture quantity and productivity of different pasture cuttings in order to calibrate these tools to the pasture swards and to determine their reliability. Forage samples were also taken and analyzed by Dairyland Lab to determine quality.

In addition to the pasture walks, two public field days were held to promote management intensive grazing and to increase understanding of proper grazing management.

The barrier to getting farmers to measure and monitor their own pasture yields and pasture quality in order to effectively balance their livestock rations and manage their pastures is that the farmers themselves are not wiling to spend the time to do this, and they don’t wee a need for it in their own operation. Most farmers who are grazing have more available acres than are needed for the number of livestock they pasture. Therefore, pasture balancing and rationing are not a high priority, or not enough of a problem yet at this point, so they don’t feel pushed to learn new skills.

Even though forage availability is the most variable quality factor of the pasture, the farmers are, for the most part, not ready to pay attention to balancing pasture rations through yield measurements and estimates. More education over time, and going through the “growth curve”, will help farmers to overcome this barrier.

The Grazing Club purchased a Comsec Pasture Gauge and a few grazers constructed their own bulk height plates to use on their own pastures to measure pasture quantity. The design for the Bulk Height Plate as taken from Andre Voisin’s Grass Productivity, which is also described by Dr. William Murphy, noted grazer, researcher and educator at the University of Vermont and author of Greener Pastures On Your Side of the Fence.

An intern was recruited to coordinate the use of the Comsec Pasture Gauge, demonstrate and take measurements at pasture walks, and assist members with on-farm sampling and use of the Pasture Gauge and Bulk Height Plate. Throughout the grazing season, measurements and clippings were taken and recorded at the monthly pasture walks and at additional farms where requested. In addition to measuring yields, forage samples were taken and sent to Dairyland Laboratory for analysis. Results of these measurements and lab results were sent as a follow up to members who attended that specific pasture walk. Discussion on the merit of measuring pasture yields, and comparison of methods and tools, was held in conjunction with the demonstration of the gauge and plate. An informational sheet on measuring pasture productivity was developed and distributed at the June pasture walk and used in subsequent mailings. An on-farm data collection sheet was developed to record relative grazing management information and the measurements from the methods used to measure pasture quantity on the individual farm.

In addition to the monthly pasture walks, the gauge and plate were demonstrated at two small group pasture walks and at a LSP-sponsored grazing class on-farm visit. One-on-one assistance was conducted with eight additional grazers at their farms. This assistance included demonstration of the pasture measuring tools and calibrating with the cut-dry-weigh method. Currently, four grazing members have constructed their own bulk height plates to use on their own pastures. One is using the “ISU Sward Stick” (developed by Jim Russell of Iowa State University).

Members were assisted with plant identification by Dr. Craig Sheaffer, Forage Agronomist, UM. Handouts on plant identification were made available at several pasture walks, as was continuing discussion and evaluation of plant species (i.e. methods of establishment, growth characteristics, impacts from different grazing/harvesting management etc.).

1) Many grazers are curious about the Pasture Gauge and Bulk Height Plate and how they work. Some are skeptical of the need to measure pastures and feel that visual observations and trial-and-error method of estimating pasture conditions for grazing and harvesting are sufficient. Some have made their own bulk height plate and report that they have found it useful in measuring their pastures and that after a period of use; they can “eyeball” the pasture amount while walking through their paddocks.
2) The key question grazing club members ask: “is the Pasture Gauge accurate”? Many feel the cost of the gauge ($1,200.00) is too prohibitive for one to purchase on their own , even it if it reliable
3) The Pasture Gauge appears to be very sensitive in different weather conditions. It did not function well with the presence of dew on the grass or during any wet, rain or fog conditions. The method of operating the gauge in the field seemed to be tricky at times, i.e. the timing of the probe placement to the ground, getting the program set up before taking measurements. Extra batteries need to be on hand, as the gauge seems to “eat up” batteries.
4) The bulk height plate was relatively easy to use. After initial construction, one can take it to the field and begin measuring immediately. Farmers can easily afford to construct their own pasture bulk height plate (one farmer made his for $4) and start measuring their own paddocks. For best results, the plate should be calibrated so that one can compare the bulk height readings to forage dry matter yields taken from clippings. Even though the clipping method is time consuming, the best part would be that the farmer is actually getting out there walking the paddocks, observing the density of the sward from a close-up view, and making some visual comparisons that will enhance and sharpen the farmer’s ability to observe and evaluate what’s going on in the pastures and what’s out there.
5) Through preliminary measurements during this first grazing season both the Bulk Height Plate and the Pasture Gauge values in pasture dry matter appeared to be closer to the actual clippings from the cut-dry-weigh method when the paddock heights were shorter (less than 12” pasture height). The yield measurements for the Pasture Gauge as compared to the Bulk Height Plate appeared to be more erratic when compared to the clippings, especially when pasture heights exceeded 12” or more. We have since learned from the distributor of the Pasture Gauge that the gauge loses its accuracy when pasture height exceeds somewhere around 16”, or when the plants start to lean. It is not intended for use in “hay” fields.
6) Some of the club members who used the gauge and bulk plate on their own indicated that they could easily see the difference in plant species with more dense swards, i.e. those containing white clover had higher values. Also, longer established paddocks yielded higher values in comparison to newer paddocks with similar pasture height. This is probably related to sward density.
7) Questions regarding identification of plant species seem to always be present at pasture walks. This may be an indication for more training or different tools to help the grazer ID plants on their own.
8) Few grazers are keeping detailed records of their grazing management. More emphasis on recordkeeping and “planned grazing” management may be helpful.
9) Though we feel we don’t have sufficient data at the end of this season to do a regressional analysis, a preliminary calibration with the figures we have shows the Pasture Gauge measures about 18% lower than the clipping method. One needs to take into consideration that these measurements were taken over several farms and at different times of the growing season. It is suggested by prior research and by the manufacturer that the Pasture Gauge needs to be calibrated to the individual farm. The same is suggested for the use of the Bulk Height Plate. Continued pasture yield measurements and comparisons throughout the second year of this project should provide us more information to calibrate these tools and to answer the question, “it this tool reliable”? Consistency and reliability are the two primary concerns that still nee to be answered.

Initially, a schedule of “1994 Grazing Days” was sent to all members on the grazing members list. This list includes others who have an interest in grazing as well as active grazers. Results of pasture walks were mailed to attendees. A news release was developed and used for the Allan Savory Field Day, which received news coverage. A special announcement for the Dave Minar farm Field Day was developed and sent to the list of grazer through the Cannon River Sustainable Farming Association.

Both field days had large attendance – over 200 attended the Savory Field Day and 100 attended the Minar Field Day. Monthly Large Group Pasture Walk attendance ranged from 10 to 32, with approximately 154 participants. Small group pasture walks were held once or twice monthly among the five small groups, which probably averaged 8 - 10 people.


Participation Summary
Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.