Effect of organic amendments (manure, compost, green manure) on soil quality and nutrient cycling in the North Central Region

Effect of organic amendments (manure, compost, green manure) on soil quality and nutrient cycling in the North Central Region

Summary

Manure, compost, and green manure have been used systematically for more than two thousand years to sustain crop production. An initial search produced more than 3500 Journal articles, Conference proceedings, book chapters, and Extension bulletins. We narrowed the literature to 438 references relevant to the North Central region. A detailed bibliography with over 1200 different keywords was assembled. Development of educational materials is underway.

Objectives/Performance Targets

Our objectives are:1) to compile information on the topic; 2) to synthesize the information into the following educational products: a) scientific and popular articles; b) a slide show with documentation; c) a poster display; d) self-study material; e) a Web-page

Accomplishments/Milestones

Objective 1): accomplished.
Our initial search produced more than 3500 Journal articles, Conference proceedings, book chapters, and Extension bulletins. This field was narrowed down to 438 pieces of literature we deemed relevant in the context of our work.
A classification by state of origin of the published literature and the NCR SARE projects is shown in Figure 1. Within the north Central region of the US most work on the topic was done in Iowa (56 references) followed by Minnesota (51 references). The least reports were available from South Dakota (5 references) and North Dakota (12 references). Most of the NCR SARE projects were conducted in Iowa and Illinois (8 projects in each state) and least of the projects in South Dakota (0 project) and Missouri (1 project). There was general consistency between the activities published in the literature and NCR SARE Projects. States with high research activities on the topic in general received more NCR SARE projects than states with low research activity.
A classification by area of emphasis of the published literature and the NCR SARE projects is shown in Figure 2. The largest category of reports described effects of manure utilization (204 references) followed by effects of sludge application (94 references). The largest categories of NCR SARE project were on manure (12 projects) and green manure utilization (11 projects). There was quite a bit of discrepancy between the areas of emphasis in the published literature and the activities of NCR SARE projects. More than 70% of the published literature dealt with biosolids (manure, compost, and sludge), whereas in the NCR SARE projects this area only was dealt with in less than 25% of the projects. On the other side, almost 50% of the NCR SARE projects dealt with management of covercrops and green manure, whereas this area of emphasis was covered by only about 15% of the published literature. In our opinion there may be several possible reasons for these discrepancies. Farmer involvement is great in design of the NCR SARE projects. In fact, in our study are also included farmer-conducted projects. Our observations are that the segment of farmers and ranchers involved in NCR SARE activities generally have already quite sustainable enterprises and are looking to increase this sustainability and reduce the amount of off-farm inputs. Hence, a lot of NCR SARE projects deal with utilization of cover crops and green manure to reduce fertilizer and herbicide inputs and to increase soil quality. They appear not to have large animal based enterprises where disposal of manure is a major problem. Another reason for the magnitude of the published research conducted with biosolids may be the availability of funding for projects. Negative impacts of inappropriate handling of biosolids, such as nitrate contamination of surface and ground water and phosphorus loading, have received a lot of attention and then in turn also a lot of funding to research and solve these problems. The area of cover crops and green manure has not received the same public attention and, hence, the same amount of funding for research.

Objective 2): work in progress

We reviewed the 438 pieces of literature and assembled a detailed bibliography with more than 1200 keywords that allow rapid and detailed access to the information contained in the literature. A hardcopy and/or a electronic copy ( Procite-file (ISI ResearchSoft, Berkeley, CA)). is available upon request. These materials will also be made available to the NCR SARE office and on the web page. Development of educational products is ongoing.

Impacts and Contributions/Outcomes

The bibliography, we assembled, has several potential contributions. It is the most comprehensive compilation of work in the topic area done in the North Central region of the US and can be used as a initial point of reference by persons and entities interested in the topic area. This information can be valuable in directing further research and bridging gaps on the knowledge about organic soil amendments.

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