This demonstration project indicates there are viable alternatives to the continuous use of fumigants in potato production on the Fort Hall Indian Reservation. The mustard green manure amended area produced yields higher than the metam sodium treated areas. The mustard area returned more US #1 potatoes than all other treatments. On an economic return basis, the mustard, control and carbofuran areas returned more net dollar per acre than the metam sodium. In comparison, the radish treated area performed poorly on yields and economic returns. The reason for this weak performance is not known. Additional monitoring of the effects of green manure crops on potato yields in future years is needed to determine if these patterns represent a real difference..
The objectives for this project are to:
Manage, monitor and assess progress on the Shoshone-Bannock Tribes’ sustainable agriculture demonstration project;
Begin to Assess Economic Issues/Impacts of Management Changes for the Tribes and leaseholders.
Assess the applicability of World Wildlife Fund and Wisconsin Potato and Vegetable Growers Association IPM program to the management of Shoshone-Bannock agricultural lands;
Conduct an outreach program that will reach Tribal members and leaseholders, as well as the broader community, with information about the demonstration project and sustainable agriculture;
Continue to identify potato farmers on and off the Reservation who are using sustainable practices and highlight those practices; and
Secure continued funding for the Shoshone-Bannock Tribes’ sustainable agriculture demonstration project.
After the detection of nitrate- and pesticide-contaminated wells in the late 1980s on the Fort Hall Indian Reservation in eastern Idaho, a report of potential actions was prepared by the USDA Natural Resources Conservation Service (formerly the Soil Conservation Service) (USDA SCS, 1991). In this 1991 report, agricultural chemical usage was listed among the most likely contributing factors to the water quality problem. The potential for contamination of ground water with other agricultural chemicals was noted, due to the excess nitrates appearing in numerous Reservation wells. To address this potential future contamination source and reduce the threat, the 1991 study recommended that alternative crops and crop sequences be explored. In response to this recommendation, Shoshone-Bannock Tribal leaders initiated a demonstration field project on the Reservation to study the effectiveness and feasibility of alternative cropping practices.
After a period of growth, green manure crops are turned into soil to improve soil fertility and overall soil characteristics. Leguminous green manure crops are selected for their ability to build soil nitrogen, while other crops are selected for their ability to suppress diseases, pests and weeds or to stimulate beneficial bacterial and fungal populations. Of particular concern to Idaho potato growers is Verticillium dahliae, which is suppressed by a number of different green manure crops (Davis et al., 1994; Davis et al., 1996). Green manures are grown for different lengths of time; some grow all season, while others are utilized only during the spring or fall.
Due to Reservation potato growers’ interest in maintaining the existing two-year wheat-potato rotation, green manures that could be added to the current rotation without extending the rotation were selected. Two green manures crops, mustard and radish, were selected for their ability to grow during the cooler temperatures and shorter days of fall in southeastern Idaho (Finnigan et al., 2003).
Radish, cultivar Colonel, was selected for use in this demonstration project due to its biomass accumulation during fall and suppression of plant-parasitic nematodes. Idaho farmers have been adding radish to their sugar beet rotations for years, while potato farmers have recently begun utilizing radish in their cropping sequence. The radish green manure has been shown to be an effective control of cyst nematode in sugar beets. When turned into the soil, radish suppresses the cyst nematode by stimulating cyst nematode egg hatching, but not supporting cyst nematode growth (Hafez, 1999). Radish has also been shown to reduce Columbia root-knot nematode levels and increase potato yields and quality compared to fallow (Al-Rehiayani and Hafez, 1998).
Mustard green manure crops have been grown by potato farmers in Washington state. Recent studies by Washington State University Cooperative Extension Educator, Andrew McGuire, and a central Washington potato farmer have documented the use of mustard as an alternative to metam sodium (McGuire, 2002; McGuire, 2003). The mustard improved soil quality as determined by higher infiltration rates and produced yields similar to fields treated with metam sodium.
Mustard and radish green manure crops were added to the standard wheat-potato rotation on the demonstration field. The effectiveness and economics of using green manures versus fumigant and the timing of green manure management on the farm were assessed.
The sustainable agriculture demonstration project was located on a 160-acre field near Fort Hall, Idaho, on the Fort Hall Indian Reservation. The land is leased to a local potato farmer who participated in this project.
Following winter wheat harvest in August 2002, 40 acres of the demonstration field were planted with mustard (Sinapis alba and Brassica juncea blend Caliente Brand 119) and 40 acres were planted with radish (Raphanus sativus cv. Colonel). After 9 weeks of growth, the mustard and radish were incorporated into the soil. The effects of the radish and mustard green manures were compared to a 40-acre metam sodium treatment, a 30-acre carbofuran treatment and a 10-acre nontreated control. The 160-acre field was planted with standard Russett Norkotah potatoes in April 2003. Potatoes were harvested in early September 2003.
Soil samples were collected prior to green manure planting, post green manure incorporation, during the potato growing season and following potato harvest. The effects of the five treatments on soil biological parameters, including total fungi and bacteria levels, beneficial nematodes, plant parasitic nematodes and Verticillium dahliae, were measured. The harvested potatoes from each treatment were inspected and graded by a USDA inspector and sold through a local warehouse.
Objective A: Manage, monitor and assess progress on the Shoshone-Bannock Tribes’ sustainable agriculture demonstration project.
Net yields from 5 acres of each treatment were highest in the carbofuran, mustard and metam sodium treated areas, respectively, while the nontreated control and radish produced fewer potatoes. The highest percent of US #1 potatoes was found in the mustard, metam sodium and carbofuran treated fields, respectively. Gross economic returns from a September 24, 2003, sale showed the best returns for the carbofuran, mustard and metam sodium treated fields, respectively. No major differences were found between treatments in soil beneficial or plant pathogenic nematodes, Verticillium levels or total fungal levels. A slight stimulation of total bacteria and predatory nematodes in mustard and radish amended soils was found. Sampling of potato petioles and soil nutrient levels showed that no nutrients were limiting. This demonstration project tracked a single rotation sequence of green manures compared to other soil chemical treatments, so some caution must be taken in placing significance on these findings.
This project did show that it is feasible for farmers to add a mustard or radish green manure crop to their wheat-potato rotation on the Fort Hall Indian Reservation. Mustard and radish crop management fits into the timing of fall activities of the operation.
Soil sampling was conducted to determine if beneficial soil organisms were stimulated in green manure amended fields. No overall stimulation of beneficial soil microorganisms was found in this demonstration. This may be an indication that several years of soil building with green manures is necessary to realize such a change.
A positive net return was found in the nontreated control, which was not treated with metam sodium or amended with green manure. With the reduced production costs from not fumigating with metam sodium, the nontreated control provided a net return of $95 per acre more than metam sodium treatment. When soil samples indicate that plant pathogenic organism levels are low, metam sodium treatment may be unnecessary.
Mustard or radish can be grown for less than treating with metam sodium, due to the high cost of metam sodium. Consequently, if the mustard and radish crops produce yields similar to metam sodium, the green manure crops can be a viable economic alternative. Gross returns were greater from mustard, but less for radish as compared to metam sodium. In this demonstration project, net returns from mustard amendment resulted in $280 per acre more than metam sodium treatment, while radish amendment resulted in $240 per acre less than metam sodium treatment.
Objective B: Begin to assess economic issues/impacts of management changes for the Tribes and the leaseholders.
The original plan for the demonstration project was to extend the rotation to three years by growing a green manure crop for the whole growing season between the wheat and potato crops. The Tribes and leaseholders determined that this was not an economically viable solution. Instead, a green manure crop was grown during the fall in between wheat harvest and potato planting. The mustard and radish green manure crops were grown instead of treating with metam sodium, which did not increase production costs. The mustard and radish green manure can be grown for less than the cost of metam sodium treatment. In this demonstration project, net potato returns from mustard amendment resulted in $280 per acre more than metam sodium treatment, while radish amendment resulted in $240 per acre less than metam sodium treatment.
Objective C: Assess the applicability of World Wildlife Fund and Wisconsin Potato and Vegetable Growers Association IPM program to the management of Shoshone-Bannock agricultural lands.
An assessment of the World Wildlife Fund and Wisconsin Potato and Vegetable Growers Association IPM program and its applicability to the Shoshone-Bannock agricultural lands indicated that such a program must come from the potato growers in order to be successful. No further direct action was taken regarding this IPM program and the demonstration project. Of interest, though, is the recent action by the Potato Growers of Idaho, an association representing potato growers’ interests with government, regulatory agencies and industry. The Potato Growers of Idaho is working with University of Idaho potato researchers to develop an IPM program similar to the one in Wisconsin.
Objective D: Conduct an outreach program that will reach Tribal members and leaseholders, as well as the broader agricultural community, with information about the demonstration project and sustainable agriculture.
Regular coverage on the project progress has been obtained in the Shoshone-Bannock News (newspaper on the Fort Hall Indian Reservation), the Fort Hall Extension Newsletter and area newspapers. In addition, a field day was held for leaseholders and the community when the green manures were growing on the demonstration field. Presentations have been given for the past two years at Shoshone-Bannock Tribes’ annual leaseholders meeting. A brochure and poster were developed and presentations were given at district meetings on the Reservation to share information about the demonstration project with Tribal members.
Objective E: Continue to identify potato farmers on and off the Reservation that are utilizing sustainable practices and highlight those practices.
Farmers utilizing sustainable practices on and off the Reservation were interviewed and highlighted in The Farmer Exchange newsletter. Two issues a year were produced in 2000, 2001 and 2003. The Farmer Exchange has reached a broader audience beyond the project mailing list through collaborations with potato industry leaders. Potato Growers of Idaho (PGI) reprinted an issue of The Farmer Exchange in its October 2003 bulletin to Idaho’s 600 potato growers and PGI has expressed interest in reprinting others.
Objective F: Secure continued funding for the Shoshone-Bannock Tribes’ sustainable agriculture demonstration project.
Several proposals have been submitted. The demonstration project has been funded through the end of 2004 with an Environmental Protection Agency Regional Geographic Initiative Grant.
The participating producer who farms the demonstration project decided to forego metam sodium treatment on half of his 2004 potato acres (representing approximately 1700 acres). The participating producer manages one farm in an operation with 15,000 acres. Other farm managers in this operation have modified practices and one planted a mustard green manure on 150 acres.
A survey of leaseholders attending the annual leaseholder meeting showed a growing interest in green manures. Over three-fourths of the leaseholders had considered growing a green manure crop and a quarter had previously grown a green manure crop. Prior to 2003, 615 acres were planted to green manures. Leaseholders are planning to plant over 2000 acres with green manures in 2004 and at this time 670 acres are to be planted in 2005. If the leaseholders replace metam sodium treatment on the 2000 acres with a green manure crop, this would represent a reduction of 260,000 lbs of pesticides used on the Reservation.
Due to the results of the demonstration project, the Shoshone-Bannock Land Use Commission is currently working with leaseholders to implement the alternative crop rotation.
It is expected that in the future there will be an increase in soil biological sampling on the Reservation and subsequent reduction of metam sodium use based upon the information provided by the sampling. It is also expected that the number of fields planted to green manures on the Reservation will increase.
Educational & Outreach Activities
“Potato Possibilities” project brochure – Sept 2002
“Mustard and Radish Green Manure Use in a Wheat-Potato Rotation” project final report – Dec 2004
“Improving Farm Balance and Performance Leads to Radish Experiment” in The Farmer Exchange volume 5 – Summer 2001
“Stewardship passion drives Shoshone farmer to innovate” in The Farmer Exchange volume 6 – Fall 2001
“Marketing Crucial for Middleton Area Herb Farm” in The Farmer Exchange volume 7 – Summer 2002
“Knowledge is Power for Blackfoot Area Potato Farmer” in The Farmer Exchange volume 8 – Winter 2002
“Compost Tea: Restoring Soil Life” in The Farmer Exchange volume 9 – Summer 2003
“An Exploration into Eco-labeling” in The Farmer Exchange volume 10 – Fall 2003
A field day was held for leaseholders, area farmers, agricultural professionals and Tribal members in October of 2002 when the green manure crops were growing on the demonstration field. Presentations on green manures and the demonstration project have been given for the past two years at the Shoshone-Bannock Tribes’ annual leaseholders meeting. A brochure and poster were developed and presentations were given at district meetings on the Reservation to share information about the demonstration project with Tribal members. A presentation on the project findings was also given to regional tribes at the Northwest Intertribal Agricultural Council Conference in March 2004.
Cost benefit analyses were conducted to compare the expenses and revenue of using a mustard or radish green manure crop instead of metam sodium. Expenses and revenue were tracked from wheat harvest in August 2002 to potato harvest in September 2003. The added expenses from producing the mustard, $117, or radish, $130, green manure crop were offset by the savings from not treating with metam sodium $135. While this cost-benefit analysis reflects only one year’s data from the demonstration trial and conditions specific to Cedar Farms, higher gross returns were earned from the mustard amended field as compared to the metam sodium treated field resulting in a positive net change of $280 per acre. In this one-year demonstration trial on Cedar Farms, the radish amended field showed lower gross returns as compared to the metam sodium treated fields, resulting in a negative net change of $240 per acre.
Information on this demonstration project reached all 130 Reservation leaseholders. In addition, area potato farmers learned of the project through a field day and newspaper articles.
A survey of leaseholders attending the annual leaseholder meeting showed a growing interest in green manures. Over three-fourths of the leaseholders had considered growing a green manure crop and a quarter had previously grown a green manure crop. Prior to 2003, 615 acres were planted to green manures. Leaseholders are planning to plant over 2000 acres with green manures in 2004 and at this time 670 acres are to be planted in 2005.
Areas needing additional study
From this demonstration project, questions emerged regarding the input requirements to grow the green manure crops. Of particular concern are the water requirements, fertilizer levels and need for control of volunteer wheat. The long-term goal of this work is to develop a low-input alternative crop rotation on the Reservation. Questions on input use need to be addressed.