Soil Fertility Strategies on Organic Vegetable Farms

Soil Fertility Strategies on Organic Vegetable Farms

Summary

Organic growers in general—and organic vegetable growers in particular—rank soil fertility as a top research priority. There have been no comprehensive and detailed studies that document and compare fertility strategies across organic vegetable farms in the north central region. This project will document the soil fertility practices employed by organic vegetable growers in Wisconsin and Illinois, gather specific grower information needs and research questions, generate a set of cases studies highlighting contrasting fertility management strategies, and provide a framework for instituting organic research plots on University of Wisconsin and University of Illinois research farms. Growers will be major participants in developing, implementing and evaluating the project.

Methods will include a survey and development of case studies. Publications, field days, and workshops will be used to communicate results and solicit feedback.

Outcomes will include increasing the knowledge base of growers and University specialists, changes in grower practices based on an increased understanding of soil fertility management options and their cost and impacts, and increasing organic research acreage on University research farms.

The evaluation plan will entail tracking publication requests and feedback, grower involvement, field day/workshop participation, and documenting the development of organic plots and trials at University research stations. A follow-up questionnaire one year after the project will measure changes in fertility management practices.

Objectives/Performance Targets

This project will document the soil fertility practices employed by organic vegetable growers in Wisconsin and Illinois, gather grower information needs and research questions, generate a set of cases studies highlighting contrasting fertility management strategies, and provide the framework for instituting transitional organic research plots and fertility trials on University of Wisconsin and University of Illinois research farms. Short-term outcomes include:

-Increase the knowledge base of growers and University specialists on the range of soil fertility strategies employed by organic vegetable growers and
-Increase awareness among organic growers of soil fertility options available to them and the cost and benefits of different practices and strategies.

Intermediate-term outcomes include:

-Changes in grower practices based on an increased understanding of soil fertility management options and their impacts and
-Increasing organic acreage on University research farms

Long-term outcomes include:

-Enhancing the sustainability of organic farming and
-Engendering future organic research and programming at Land Grant Universities.

Accomplishments/Milestones

In 2005, we began the process of conducting a grower survey to quantify the types and prevalence of different soil fertility practices. The survey instrument questions will address all aspects of soil fertility management including use of inputs like fertilizers, manure and compost, as well as on farm composting, rotations, intensity of land use, tillage, and the use of cover crops. The survey will have four basic sections:

1. General information about each farm and farming operations—such as farm size, soil type, farming history, types of crops and/or livestock grown/raised, etc.
2. Soil fertility practices and strategies—including types of rotations used, cover crop types and types of soil amendments used (fertilizers, manure, composts, teas, microbial inoculants or other biological preparations, biodynamic amendments, etc.)
3. Attitudes and perceptions—what is their perception of interactions between soil fertility and weed, pest, and disease pressure on their farms? How important is soil fertility in the overall management of their farm? Do they feel that they have a good working knowledge of how to manage soil fertility optimally on their farm?
4. Questions and research needs—what kinds of resources and research do they need to increase their knowledge and soil fertility management practices?

Within the context of these general survey sections, several issues will be probed in particular, including:

Issue 1 — Composting and compost use: If they use compost, in what parts of their farming operation do they use compost—field application, greenhouse growing medium, other? How do they use compost in each aspect of their farming operation, including: timing, frequency, application rates, and whether it is used with or without a cover crop. Do they use compost as a primary nutrient source (fertilizer substitute) or as a way to build soil organic matter? Do they make it themselves or do they purchase compost? If they make compost, what kind of feedstocks do they use and how do they manage compost piles? Have the NOP Standards for composting affected the way they produce compost? If they purchase compost, where do get it from, what characteristics are they looking for in the compost and do they request information from the compost producer to demonstrate that the compost meets the NOP rule requirements?

Issue 2 — Soil testing: Do they soil test? If no, why not? If yes, from how large an area are samples collected? How frequently to do they analyze their soils? What kind of analyses do they have run? Where are samples tested? Does the testing lab provide interpretation of test results that are useful? Do they use test results with or without interpretation to make soil fertility management decisions? If so, how? If they don’t use soil test results to make fertility management decisions, what would they consider is needed to make soil testing and test results more meaningful?

Issue 3 — Manure, other organic fertilizers and soil amendments. Is manure used as a fertility source? If so, how do they decide application rates and timing of application? What types of manure do they use? Is manure generated on the farm or purchased from off-farm sources? If purchased from off-farm, how much do they pay (per ton or cubic yard) and how far away does it come from? What kinds of organic fertilizers or soil amendments do they use? How do they decide methods, timing, and rates of application? How do they evaluate the efficacy of soil amendment products?

Issue 4 — Rotations. How would they describe the management philosophy they use to design their rotation? What is the rotation duration? What kind of crops and cover crops are included? Do they use permanent perennial vegetation for part of the rotation? Is livestock grazing part of the rotation? What strategies do they use to transition land into organic production?

Issue 5 — Tillage. How frequently are soils tilled and what kind of tillage equipment and methods are used? What is their perception about interactions between soil tillage and soil fertility?

Both certified organic growers and growers who follow organic practices but are not certified will be included in the survey sample. “Non-certified organic” growers represent a large and important group due to the prevalence of direct marketing in the upper Midwest including farmers’ market and community supported agriculture (CSA). Many of these growers rely on direct interaction with customers rather than on third party certification to satisfy consumer concerns about food safety and farming practices.

Working with the advisory board, the survey instrument will be tested by growers in early 2006 before being administered. A database of growers is being created by using lists from organic certifiers, grower groups and networks, and existing databases managed by project collaborators. We estimate that 200-300 surveys will be mailed.

2005 was also when we original planned to select a group of case study farms for a more in-depth look at specific soil fertility management approaches and practices. A key goal is to describe the costs and benefits of contrasting fertility management systems. We plan to monitor soil nutrient levels, percent organic matter, pH, aggregate stability, and other characteristics over a three-year period on 8 farms.

The case study farms will feature different combinations of fertility practices so that contrasting approaches can be monitored and evaluated. Originally, we planned to select the farms at the very beginning of the project based on advice from a grower advisory board. We changed our plans, however, because we felt it best to utilize the survey data to identify common and intriguing management practices as well as broaden the potential pool of case study candidates beyond the farms with which the project coordinators were already familiar.

Impacts and Contributions/Outcomes

Given the early stage of our project, there is not much to report in terms of impacts and outcomes. We can report that growers are pleased to learn about our project and enthusiastic to lend support and guidance on developing the survey instrument.

Likewise, University collaborators are looking forward to working more closely with organic growers and to utilize them as expert informants as they develop research programs.

Collaborators: