Final Report for EW99-013

A Community Based Approach to Extension In Organic Agriculture

Project Type: Professional Development Program
Funds awarded in 1999: $10,000.00
Projected End Date: 12/31/2002
Region: Western
State: Idaho
Principal Investigator:
Mir M. Seyedbagheri
University of Idaho, Elmore County Extension
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Project Information


Demonstration trials were conducted using organic amendments (compost and rapeseed meal) on fields of organic and conventional potatoes. Field tours were conducted during the growing season with growers and agricultural professionals in attendance. Data from demonstration trials was discussed and interpreted in terms of crop ecology and soil science principles. After each growing season, this information was presented at local workshops and regional meetings to reach a wider audience. Because of this program, several conventional growers are integrating the use of organic amendments into their cropping systems and organic growers are making more efficient use of these products

Project Objectives:
  • Objectives:
    To educate agricultural professionals about the special needs of organic growers.
    To demonstrate the use of organic amendments to provide nutrients and biological pes control.
    To educate growers and agricultural professionals about natural cycles related to organic agriculture.
    To foster a more sustainable agriculture by integrating some of the cultural methods used by organic growers into conventional cropping systems.
    To make a dialogue between the community of conventional growers and the community of organic growers.
    To measure the impact of PDP training on agricultural professionals and growers.

    Performance Targets:
    For those involved with organic production, an increased level of understanding of ecological principles in crop production, especially with respect to the use of organic amendments.
    For those involved with conventional production, an increased knowledge of the possibility to integrate ecological principles and organic amendments used in organic production systems into conventional systems.
    Grower adoption of improved crop management practices based on information presented during this program.


Organic agriculture is a small but increasing segment of the agricultural economy. Since organic products command substantially higher prices than conventionally grown products, organic farming is a lucrative niche in the market for the grower willing to put forth the extra effort needed to integrate natural cycles into the management system. Agronomic management of the organic crop is more complex since chemical fertilizers and pesticides are not allowed. The agricultural community of southern Idaho consists of two major groups-the growers and the agricultural professionals that serve them. The latter group includes extension personnel, fieldmen from produce companies and dealers of agricultural products and agricultural consultants. Since the vast majority of growers use a conventional system, agricultural professionals tend to be more knowledge about the needs of this group. These people have a high degree of technical competence but often do not have experience with crop management solely by natural cycles. In recent years a small but dedicated group of organic growers have been producing crops within the constraints of certified organic regulations. This has led to the development of cultural practices that work for producing organic crops under southern Idaho conditions. It has also led to management problems such as providing nitrogen at the right time to satisfy plant demand and controlling pests without chemicals. As growers have wrestled with these problems, investigators in the scientific community have been elucidating details of natural cycles responsible for the complex interactions observed in organic crop production. An important concept that has emerged is that of the soil food web. The natural cycles that constitute the soil foodweb are vitally important to organic crop production since they are largely responsible for the release of inorganic nutrients from organic sources and control of pests and pathogens. A related line of investigation has demonstrated that certain green manure crops and organic amendments suppress nematodes in certain crops.
The research group of Dr. Elaine Ingham has conducted extensive in soil ecology in several ecosystems including grassland, forest and cropland. They have found that an intact soil foodweb is an excellent indicator of soil ecosystem health and is responsible for efficient nutrient cycling and biological suppression of plant pathogens and parasites. To date no such studies have been done in irrigated potatoes grown under southwest Idaho conditions. (Coleman, 1985; Coleman et al, 1992; Ingham, 1994; Ingham et al, 1986; Ingham et al, 1985; Lal and Stewart, 1992.) Studies have been conducted in several areas to evaluate the use of compost as a nutrient source. However, little work has been done on potatoes and none have compared potatoes growing under different production systems (i.e.: organic or conventional). We have conducted compost trials in potatoes for the last three growing seasons on an organic field. In the 1997 growing season mineralization bags were placed in a conventional potato field that had been composted. We are currently analyzing and summarizing data from these trials. Several investigators have studied compost mineralization with other parts of the country. No studies other than our own have been done on compost mineralization in southwest Idaho soils. Stieber
et al 1994 reported a general study of nitrogen mineralization in Treasure Valley soils. (Berner et al, 1995; Hadas and Portron, 1994; Paul and Beauchamp, 1994; Stieber et al, 1994; Tyson and Cabrera, 1993.) Pest control benefits from compost. Hoitink and Fahy, 1986, reported that compost suppresses several soil borne plant pathogens. This is believed to be a result of microbes in compost that antagonize pathogenic microbes and parasites. In the 1997 growing season, we collected soil samples from composted and non-composted fields and from our 1997 compost trial in organic potatoes. These samples were sent to the UI Nematology Lab. Data is currently being analyzed and summarized. No replicated trials have been done to specifically address the effect of compost on plant parasitic nematodes in irrigated potatoes under southwest Idaho conditions. (Hoitink and Fahy, 1986; Hader et al, 1992; Stockdale et al, 1992.)

Education & Outreach Initiatives



In 2000 demonstration trials were established on 2 organic and 2 conventional potato fields. These fields are designated as follows:

Location County Cropping System
1 Elmore Conventional
2 Elmore Conventional
3 Lincoln Organic
4 Twin Falls Organic
At locations 1,2, and 3 composted manure was applied 0, 5, 15, and 25 T/A to small plots. At locations 1 and 3 the treatments were arranged in a randomized complete block design with 4 replications while at location 2 treatments were applied in nonreplicated strips. Treatments were applied by opening up the hills, spreading compost by hand and raking the hills back. Potatoes were planted by the grower. At location 4, rapeseed meal at 0, 500, 1000, 1500, and 2000 lb/A were applied to small plots arranged in a randomized complete block with 4 replications. Treatments were applied by hand to the sides of recently planted hills and were incorporated by the grower. At locations 1 and 3, soil samples for determination of soil foodweb structure were taken shortly before treatment application. At locations 1, 2, and 3 nonreplicated mineralization plots were established shortly after treatment application using the buried bag method in the 0, 5 and 25 T/A rates of compost. Mineralization bags were pulled on a monthly basis and mineralization was determined by subtraction from the N values for the initial soil sample. At harvest, plots were harvested by hand for determination of yield.
In 2001, mineralization trials were established on three potato fields, 1 conventional and 2 organic. The locations are designated as follows:

Location Cropping System County
1 Organic Lincoln
2 Organic Elmore
3 Conventional Elmore

Early in the growing season, soil samples were taken and nonreplicated mineralization plots were established using the buried bag method. Mineralization bags were pulled at monthly intervals. At location 1, mineralization bags were placed in two fields designated fields 2 and 3. Field 2 had been treated with 1 pass of chicken compost while field 3 had been treated with 2 passes of dairy compost. Compost was applied by the grower to the entire field prior to planting.

Outreach and Publications

Field tours were held on July 5, 2000 and August 7, 2000 with 32 people in attendance including 27 growers, 2 extension personnel, 2 fieldmen, and 1 master gardener. Small group tours in 2001 were attended by 11 people, including 3 fieldmen, 3 growers from the Gooding/Shoshone area and 4 growers from Elmore and Owyhee counties.
Winter 2001 presentations were attended by 375 people. Response was excellent. Discussions with attendees indicated that they intended to use the information presented. As a result, one grower subsequently took a 5 credit upper division course in sustainable agriculture and assessing soil quality. The Elmore County extension educator has been following up with these participants as they apply what was learned to their individual farming operations. As this occurs, further outreach occurs by work of mouth within the agricultural community as growers share experiences and agricultural professionals such as fieldmen work with their clients.
Publication that resulted from the research is: Seyedbagheri, M.M., and J.M. Torell. 2001. Effects of humic acids and nitrogen mineralization on crop production in field trials. Humic Substances Structures, Models and Functions. Pp. 355-359. Royal Society of Chemistry (eds. Ghabbour, E.A., and G. Davis).

Outcomes and impacts:

This project has resulted in the integration of the use of organic amendments into conventional crop management to produce more sustainable crop production systems. For example, five conventional growers in Elmore County on irrigated conventional row crop farms of 600-5500 acres each, have begun to use compost to enhance soil quality. In consultation with the Elmore county extension educator, these growers have designed more sustainable conventional cropping systems utilizing organic amendments and rotational crops that return organic matter to the soil. The conventional growers are using cultural practices of organic agriculture to increase sustainability and long term profitability of their farm enterprises. Organic growers in Elmore County and neighboring counties are using the results of this project to fine-tune their management practices for better nutrient and pest management. Workshops presented by the Elmore County Extension Educator and his colleagues have extended this information beyond our area, resulting in the adoption of improved crop management by growers in other areas.
This project has shown conventional growers that organic amendments have a place in conventional cropping systems. Organic growers have learned how to better utilize organic amendments for improved nutrient and pest management within the constraints of organic production. Farmer adoption as detailed in item 11 is resulting in increased sustainability of irrigated agriculture in Elmore county as well as neighboring counties. For conventional production, long-term impacts will be reduced reliance on off farm inputs such as fertilizers and pesticides, reduced loading of water resources with chemicals and fertilizers and increased profitability. These may be the greatest impacts of this project since most of the irrigated acreage in Elmore county is managed in a conventional cropping system.
The Elmore County extension educator has worked with local growers to produce crop enterprise budgets for various alternatives involving use of organic amendments in conventional cropping systems. He has developed an internet counseling program whereby growers can receive crop management advice from the Elmore County extension educator, including crop enterprise budgets for economic analysis.
Results of demonstration trials showed the uses of organic amendments in organic and conventional production systems. Soil foodweb data demonstrated ecological principles that may be applied in either cropping system. Mineralization data showed one of the benefits of organic amendments-that of providing a controlled release source of N for the crop. This is important in organic systems because it is the main N source for the crop. In conventional systems, knowledge of mineralization is useful as growers seek to optimize returns from applied nutrients and minimize adverse environmental effects of excess nitrates. (Tables 1-9)

Table 1. Soil Data for Location 1 2000

Soil Foodweb Analysis————————————————————————
Treatment Active BacterialBiomass mg/g Total BacterialBiomass mg/g Active FungalBiomass mg/g Total FungalBiomass mg/g
Check 7.5 16.3 29.9 59.3
Compost 5 T/A 7.8 15.3 22.8 76.5
Compost 25 T/A 7.6 21.0 12.8 73.7

Table 2. Soil Data for Location 3 2000

Soil Foodweb Analysis————————————————————————
Treatment Active BacterialBiomass mg/g Total BacterialBiomass mg/g Active FungalBiomass mg/g Total FungalBiomass mg/g
Check 10.5 21.2 21.6 64.0
Compost 5 T/A 12.8 19.7 28.7 27.5
Compost 25 T/A 12.0 23.3 31.6 140.0

Table 3. Effects of Compost on Yield: Organic Farm, Location 3 2000

Yield (CWT/A)—————————————————————————————
Treatment 0-4 oz 4-8 oz 8-12 oz > 12 oz Culls Total
Check 21.8 66.3 20.3 13.1 7.0 128.5
Compost 5 T/A 33.9 62.9 25.6 4.8 1.4 128.6
Compost 15 T/A 31.5 37.3 15.5 7.3 3.3 94.9
Compost 25 T/A 37.3 55.6 25.2 1.0 2.4 121.5

Table 4. Effects of Compost on Yield: Conventional Farm, Location 1 2000

Yield (CWT/A)—————————————————————————————
Treatment 0-4 oz 4-8 oz 8-12 oz > 12 oz Culls Total
Check 35.8 161.2 140.8 128.3 64.4 530.5
Compost 5 T/A 26.1 160.2 149.6 101.6 23.7 461.2
Compost 15 T/A 28.6 157.3 131.2 96.3 68.2 481.6
Compost 25 T/A 31.5 140.8 153.9 96.3 57.6 480.1

Table 5. Effects of Compost on Yield: Conventional Farm, Location 2 2000

Yield (CWT/A)—————————————————————————————
Treatment 0-4 oz 4-8 oz 8-12 oz > 12 oz Culls Total
Check 24.2 121.0 169.4 242.0 56.5 613.1
Compost 5 T/A 28.2 112.9 129.1 250.1 96.8 617.1
Compost 15 T/A 40.3 137.1 137.1 209.7 64.5 588.7
Compost 25 T/A 48.4 129.1 137.1 217.8 121.0 653.4

Table 6. Effects of Rapeseed Meal on Yield: Organic Farm, Location 4 2000

Yield (CWT/A)—————————————————————————————
Treatment 0-4 oz 4-8 oz 8-12 oz > 12 oz Culls Total
Check 36.3 92.9 94.4 97.8 13.1 334.5
500 lb/A 30.0 65.3 82.8 85.7 31.5 295.3
1000 lb/A 37.3 97.8 71.1 82.3 13.1 301.6
1500 lb/A 33.9 87.1 101.6 114.7 15.5 352.8
2000 lb/A 32.4 111.3 108.9 106.5 7.3 366.4

Table 7. Effects of Compost on Mineralized Nitrogen: Conventional Farm, Location 2 and Organic Farm, Location 3 2000
Mineralized Nitrogen (lb/A)———————————————————–
Treatment July 2000 September 2000

Check 54.4 116.0
5 T/A Compost 41.2 90.0
25 T/A Compost 83.2 144.4

Check 61.2 136.8
5 T/A Compost 47.6 131.6
25 T/A Compost 56.4 164.4

Table 8. 2001 Nitrogen Mineralization

Location Field Cropping System May June July Aug September
1 2 Organic 42.4 62.8 60.4 84.8
1 3 Organic 39.2 65.6 86.8 104.4
2 1 Organic 25.2 56.0 77.6 120.4
3 1 Conventional 89.2 111.2 147.6 225.6 147.6

Table 9. 2001 Soil Foodweb Data

Location Field Active Bacterial Biomass(mg/g) Total Bacterial Biomass(mg/g) Active Fungal Biomass(mg/g) Total Fungal Biomass(mg/g)
1 2 26.2 135 25 722
1 3 31.1 117 12 209
1 5 29.0 134 28 182
3 1 17.6 130 6.7 7.3
Desired Range 10-25 150-300 10-25 150-300

Project Outcomes

Project outcomes:

Demonstration trials using organic amendments were used in an extension program for organic and conventional irrigated row crop farmers consisting of a series of field tours and workshops. A major accomplishment for this project was bringing together members of the agricultural community with differing approaches to farming (organic and conventional production) to achieve a useful dialogue.. This resulted in the development of improved crop management practices for both organic and conventional growers. For organic growers, the fine-tuning of their use of organic amendments was an accomplishment. For conventional growers, the greatest accomplishment was the integration of organic amendments into conventional cropping systems to achieve greater sustainability.
As detailed in item 12, more work needs to be done to ascertain the effects of organic amendments on nutrient and pest management for irrigated cropping systems. In terms of extension, more work needs to be done to extend these results throughout the area and adapt them to fit the needs of individual growers.


Potential Contributions

This project increased understanding of the use of organic amendments in irrigated row crops for both agricultural professionals and growers. Growers and agricultural professionals involved with organic production gained a deeper understanding of the use of natural cycles and organic amendments while conventional growers gained an understanding of the potential for integrating organic amendments into conventional management to achieve more sustainable cropping systems.


In terms of research, more work is needed to determine the course of mineralization for organic amendments used in different cropping situations. This is a complex problem since numerous factors affect the function of the soil foodweb such as rotational crops, type and rate of organic amendment, fertilizer and chemicals (conventional system). There is also a need for more information relative to the effects of organic amendments for management of soil borne pests and pathogens. More detailed economic analysis needs to be done for the use of these materials in organic and conventional cropping systems.. We need to know the economic results of substituting organic amendments for other inputs. For example, in a conventional system, what is the economic benefit of replacing some of the nutrient need from fertilizers with an organic amendment, taking into account the long-term benefits of organic amendments on soil quality deriving from the action of humic substances. In organic cropping systems, we need to compare economics of using different types and rates of organic amendments in combination with other alternatives such as green manure crops and forages in rotation.

In terms of extension, the results of this project need to be extended to a wider audience of growers and agricultural professionals in the area and the region. Benefits of the adoption of these sustainable agriculture practices on a large scale need to be presented to personnel involved in other aspects of resource management. To this end, the Elmore County extension educator has presented the results to meetings of personnel from agencies including the United States Forest Service, Natural Resource Conservation Service, United States Bureau of Land Management, Idaho Department of Agriculture, and Idaho Department of environmental Quality. In these presentations, Professor Seyedbagheri emphasized implications of sustainable for reducing nonpoint source pollution.

Potential Contributions

This project increased understanding of the use of organic amendments in irrigated row crops for both agricultural professionals and growers. Growers and agricultural professionals involved with organic production gained a deeper understanding of the use of natural cycles and organic amendments while conventional growers gained an understanding of the potential for integrating organic amendments into conventional management to achieve more sustainable cropping systems.

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.