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Research Report  2.2

 Investigating Methods of Integrating Liquid Manure into a Conservation Tillage Cropping System

Mr. David Charlton, Ecolog. Services For Planning,
361 Southgate Drive, Guelph, ONT N1G 3M5
COESA Report No.:  RES/FARM-002/97

Objectives & Expected Outputs
Executive Summary

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Objectives and Expected Outputs
Objectives: To examine in cooperation with farmers the effectiveness of several methods and rates of liquid manure application within conservation farming systems; and to investigate techniques for retaining the nutritive value of manure within the rooting zone.
Expected Outputs: Evaluations of the prescribed rate of manure, determined by soil test for N, as a source of nitrogen, in comparison with mineral fertilizer; the effectiveness of the manure from different types of livestock; and the importance of timing of the manure application relative to the stage of growth where the comparisons are directed to the feasibility of soil injection, side dressing or top dressing of liquid manures.
Type: Open Bid, Industry
Spending Profile: 93-94: $85.6 K,  94-95: $133.0 K,  95-96: $136.1 K, 96-97: $144.9 K,  Total: $499.6 K
Status: Available Fall 1997


Executive Summary

This research project was funded by the Canada-Ontario Green Plan. Green Plan research activities were designed to promote environmentally sustainable agriculture within the farming community. The objectives of this project were established by the Green Plan Agreement Management Committee and included:

  • Objective A - to determine the influence of the source (cattle, swine, poultry), amount and method of manure application on the nutrient status in the soil and availability to crop growth in a conservation tillage system; and

  • Objective B - to investigate techniques of retaining the nutritive value of manure within the rooting zone in a conservation cropping system.

While the objectives of the project were focused on an investigation of methods of integrating manure management in a conservation tillage system, an important secondary goal was to produce information which would be directly relevant and of immediate use to a wide range of farmers. This was the underlying purpose behind conducting on farm research. The direct and significant involvement of farmers in designing, implementing and interpreting the research was seen as key to wider application of results and significant impact on the goals of the Green Plan.

Research experiments were conducted on field length plots at six farm sites in southwestern and eastern Ontario in the growing seasons of 1994, 1995 and 1996. The farms sites included two dairy farms, three hog farms and a poultry farm, which provided a range of manure types. The conservation cropping systems in place at the six farms included three different modified no-till systems, an aeration tillage system using an Aerway™ implement, a chisel tillage system and a ridge tillage system. This broad range of tillage activities provided wide scope for testing manure application practices under a range of field conditions and timing requirements.

The experimental treatments included the application of 100% of the estimated nitrogen requirement from manure, 100% from inorganic fertilizer and a combination of approximately 75% of the nitrogen requirement from manure and 25% from inorganic fertilizer. The effect of the timing of manure application was evaluated through comparisons of treatments involving pre-plant and side-dress manure applications, and different side-dress application timings.

The effect of the treatments on the nutrient status of the soil was evaluated through soil fertility and soil N tests in spring and fall. The effect of the treatments on agronomic and crop productivity was evaluated using corn yield and weed counts at some of the sites. The effect of the treatments on farm management activities was evaluated by the farmer co-operators. Farmer impressions and comments were used extensively to evaluate the operational and economic feasibility of treatments.

As would be expected in a broad ranging field research program, results varied widely from year to year and from site to site. Difficult weather patterns, weed and pest pressures and changing farmer requirements posed challenges to the conduct of the research and the interpretation of results. However, within the statistical limits of field research, several conclusions were reached.

First, the research confirmed that liquid manure is an effective substitute for inorganic fertilizer in conservation tillage corn production. Manure application rates should be based on the nitrogen content of the manure and the nitrogen response of the field as indicated by the nitrate soil test. A wide range of manure volumes (2000 to 9000 gallons per acre) and total N applications (100 to 200 kg/ha) were evaluated. Where the total N applied was close to the maximum economic rate (MER) for the field, yields were similar for manure and mineral N sources. Calculating manure application rates was a straight forward matter based on manure analysis and soil nitrate. Delivering the required volumes of manure to the field under conservation cropping systems was not always straight forward. However, with typical farmer ingenuity, equipment was modified, practices were refined such that the manure was effectively and efficiently applied in most cases. Highly concentrated poultry manure and highly dilute dairy manure were extreme situations that tested farmer ingenuity and equipment flexibility. Yet even in these challenging situations, methods were developed to deliver the volume of manure necessary to provide the appropriate nitrogen amount to the corn.

Second, the research demonstrated that there is flexibility in the timing of the application of manure under conservation tillage. Pre-plant broadcast of manure and application of substantial volumes of manure to standing corn crops were both shown to produce similar yields as mineral N sources, with no un-surmountable operational difficulties. Once again equipment modification and farmer ingenuity played an important role in getting the manure nutrients to the crop at the right time and without crop damage.

Third, the research suggests that the groundwater implications of using manure in a conservation cropping system are similar to using mineral N sources. Residual soil nitrate levels after harvest were measured as an indicator of nitrate volumes potentially available to leach to groundwater. The results of these measurements varied widely from site to site, and some high, and potentially detrimental, levels were detected. However, the levels were similar whether the nitrogen was from manure or mineral sources. Based on the reasonable assumption that conservation tillage provides water quality benefits beyond conventional tillage, the use of manure in conservation systems is as environmentally sound as the use of mineral nitrogen, and seems to offer water quality benefits over the use of manure in conventional systems.

Fourth, the research showed conclusively that manure can be integrated in to conservation tillage in an effective and efficient manner that will be acceptable to farmers. All the farmers involved in the research were able to solve their problems and develop a manure management/conservation tillage system that worked for them. Based on their own whole farm accounting, taking into account all the costs and benefits specific to their own situation, 5 of the 6 farmers saw reasons to invest time and money in the systems. One farmer abandoned conservation tillage during the course of the experiment, but this decision seems to have been based on a wide range of issues not specifically related to difficulties with manure applications. Following three seasons of data collection, it is evident that no single system of manure application tested was the most efficient in terms of corn yield and minimizing residual N left in the soil profile in the fall. Conditions vary from farm to farm and it is essential that the manure application system be tailored to the requirements at each site. Ongoing on farm research and demonstration sites should be used to promote the concept of conservation tillage to a wider group of livestock producers.


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