- Agronomic: peanuts, grass (misc. perennial), hay
- Animals: sheep
- Animal Production: parasite control, preventive practices, range improvement, grazing - rotational, feed/forage
- Education and Training: extension, farmer to farmer, networking
- Farm Business Management: budgets/cost and returns, feasibility study, agricultural finance
- Pest Management: biological control, economic threshold, field monitoring/scouting, physical control
Traditional alfalfa weevil management relies heavily on the use of insecticides that target alfalfa weevil larvae. Insecticides are applied when populations reach the ‘economic threshold,’ which locks producers into an insecticide application during years of high crop damage or high hay values. Research conducted at Montana State University demonstrated that prescriptive sheep grazing during winter and spring months can reduce alfalfa weevil populations up to 70%, prior to the growing season, without negatively impacting the quality or quantity of harvested hay. This represents a new paradigm in pest management by using strategic sheep grazing to prevent high alfalfa weevil populations and subsequent damage the growing season after grazing cessation. However, research funds are needed to determine the effectiveness of fall grazing in Montana and address information gaps in the current winter/spring grazing system for better on-site implementation. Funding the proposed research meets Western SARE goals by: 1) reducing pesticide usage, 2) creating low capital opportunities for rural development, 3) partnering two of Montana’s vital agricultural enterprises in a mutually beneficial program, and 4) creating change in the current paradigm by shifting grazing from a cost to an income without requiring ownership of land. Additionally, the proposed study will be ready for producer implementation upon completion of research. Objectives of the proposed research include: 1) Scientifically measure sheep grazing as a viable tool for managing alfalfa weevil damage in Montana while monitoring weed densities and soil compaction in response to the grazing system, 2) Develop grazing timetables, based on the alfalfa weevil degree day model, to maximize alfalfa weevil mortality, 3) Develop an economic model to assess long-term cost-benefits to producers and 4) Conduct multi-farm demonstrations. The proposed research will fall over a two-year period using sound scientific protocols to establish the methodology and experimental design. Treatments will compare various intensities of sheep grazing against traditional insecticides. Our results will reflect the ability of sheep grazing to manage alfalfa weevil and weed populations while developing a grazing protocol that adapts itself to different climatic and regional conditions. A search of the SARE-funded projects database and Agricola 1979-present indicates that no projects have been funded or published with similar research objectives. We will incorporate our findings into existing sheep, crop, IPM, and economic extension programs using a variety of communications methods. Educational tools such as those found at http://www.montana.edu/extensionecon/livestockdownloads.html will result from this research. Our team’s short-term outcomes are to scientifically address the informational gaps of the current grazing system and increase acceptance in the agricultural community. Medium-term outcomes focus on a long-term PI commitment to increasing sustainable agriculture practices. With over 300,000 sheep in Montana, and numbers of sheep increasing, integrating sheep into farming systems has the potential to reduce pesticide usage while creating new entrepreneurial, non-capital opportunities for rural families. Producer participation in this research is high with 3 of the 4 research sites located on stakeholder property using stakeholder livestock. The evaluation plan will focus on means of increasing producer acceptance and use. Feedback will be gathered before, during, and after presentations and panel discussions at producers meetings.
Project objectives from proposal:
1) Compare various intensities (0-125 alfalfa weevil degree days) of sheep grazing (fall and spring), insecticides and a no-input control in a multi-farm study on:
a) alfalfa weevil larval numbers
b) alfalfa yield and nutritive characteristics
c) total biomass including alfalfa aftermath and broadleaf and grass weed species
d) change in soil in soil bulk density
2) Develop a specific fall and/or spring sheep grazing timetable, based on the alfalfa weevil degree day model, to maximize alfalfa weevil mortality.
3) Develop an economic model to evaluate long-term cost-benefits of sheep grazing and insecticides in alfalfa production.
4) Develop and conduct large, multi-farm demonstrations. Communicate results to producers, students, scientists, and the public on the advantages of incorporating prescriptive sheep grazing into alfalfa production systems.
Methodology and Experimental Design.
This research will be conducted at 4 sites in Montana. Three of these sites will be located on stakeholder property using stakeholder livestock. One site will be located on Montana Agricultural Experiment Station (MAES) land using MSU livestock. Based on previous work conducted by the PI, study site size will vary between 100 and 350 hectares. This is a replicated research project conducted on a commercial scale, not small plot.
1) fall/winter grazing (i.e., grazing to 0 alfalfa weevil degree days),
2) winter/spring grazing to 25 alfalfa weevil degree days,
3) winter/spring grazing to 50 alfalfa weevil degree days,
4) winter/spring grazing to 75 alfalfa weevil degree days, and
5) winter/spring grazing to 100 alfalfa weevil degree days,
6) winter/spring grazing to 125 alfalfa weevil degree days
7) Warrior 1EC applied at the recommended rate of 11.2 gai/acre, and
8) no input control.
Fall grazing, treatment 1, will be conducted on stakeholder property. Each fall, stakeholder field will be identified and six non-grazed exclosures (treatment 8), measuring 9 x 12 m, will be established within each experimental field. The exclosures are designed to keep sheep out of non-grazed, no-input control areas. Sheep will have access to the entire field with the exception of the six non-grazed plots. Sample collection will be from non-grazed, no-input control plots and their paired grazed area.
Spring grazing and insecticide applications (treatments 2-7) will be conducted on MAES property. It is necessary to conduct this portion of the research on MAES property near to the MSU campus due to it being labor intensive. It would be very difficult to carry out the necessary work on stakeholder properties, which are all 70 to 150 miles from MSU, and guarantee any level of accuracy. Degree days, for grazing treatments 2-6, were derived from work completed and published by the PI. Grazing exclosures will measure 9 x 12 m. Treatments 7 and 8 will be fenced off prior to introducing sheep to the experimental field. Sheep will be introduced and allowed to graze the entire experimental field while the PI monitors weather conditions and calculates degree days. When the degree days for treatment 2 (25 dd) have been reached, a 9 x 12 m portion of the experimental field will be fenced off to exclude sheep from further grazing that area. When the degree days for treatment 3 (50dd) have been reached, again a 9 x 12 m portion of the field will be fenced off, excluding sheep from further grazing that area. This process will continue, as degree days accumulate, until exclosures have been established for all degree day grazing treatments (i.e., 25, 50, 75, 100, and 125). Sheep will have access to the entire field during this time with the exception of those areas fenced off at the appropriated degree day mark. Proposed research will be implemented over a 24-month (two field season) period.
Experimental design for the fall grazing portion of this research is a randomized block with six replicates per site. Experimental design for the spring grazing/degree day portion of this research is a randomized complete block with six replicates per site. Statistical analyses will consist of GLM procedures of SAS used to compute least squared means to make within date comparisons of treatment variables and, where appropriate, time based treatment responses.
Objective 1: Compare various intensities (0-125 alfalfa weevil degree days) of sheep grazing (fall and spring), insecticides and a no-input control in a multi-farm study on:
a) alfalfa weevil larval numbers. Alfalfa weevil adult and larval densities will be determined by collecting one sample, consisting of 20 (180°) sweeps with a 38 cm diameter sweep net, per plot per sampling date. It is anticipated that, based on previous work of Goosey et al. (2004) there will be 4 weekly sampling dates prior to first cutting harvest which tentatively takes place during the first week of July of each year.
b) alfalfa yield and nutritive characteristics. To determine yield, 3 (50 x 50 cm) quadrats will be hand harvested from each plot using a Stihl HS 75 gas hedge trimmer by cutting and bagging all above ground alfalfa biomass. Forage samples will be dried at 48° C for 72 hours to determine dry matter yield.
Three tillers per yield sample will be collected at harvest and bagged separately for plant nutrient analyses (dry matter (%), crude protein (%), acid and neutral detergent fibers (%) conducted at the Montana State University Oscar Thomas Nutrition Center. Crude protein will be calculated using the AOAC Leco combustion method 990.03 and acid and neutral detergent fibers will be calculated using methods of Van Soest.
c) total biomass including alfalfa aftermath and broadleaf and grass weed species. Total biomass samples will be completed by collecting all above ground biomass from 3-0.25 m2 quadrats per plot pre and post grazing. Broad leaf and grass weed species biomass will be determined by collecting all above ground weed biomass from 3-0.25 m2 quadrats per plot 48 hours prior to harvest. All biomass samples will be dried at 48° C for 72 hours and weighed to determine dry matter.
Additionally, weekly numerical data will be collected on weed abundance during the growing season. Weed density will be collected by counting weed abundance in 3-0.25 m2 quadrats per plot per sampling date. It is anticipated that, based on previous work of Goosey et al. (2004) there will be 4 sampling dates prior to first cutting harvest.
d) soil compaction. Three soil bulk density samples will be taken from each plot pre- and post-treatment. Each sample will consist of all soil from a 91 cm3 compaction core sampler. Samples will be dried at 105° C for 48 hours and weighed to determine soil bulk density.
2) Develop a specific fall and/or spring sheep grazing timetable, based on the alfalfa weevil degree day model, to maximize alfalfa weevil mortality
3) Develop an economic model to evaluate long-term cost-benefits of sheep grazing and insecticides in alfalfa production
4) Develop and conduct large, multi-farm demonstrations. Communicate results to producers, students, scientists, and the public on the advantages of incorporating prescriptive sheep grazing into alfalfa production systems