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Research Report  2.3

A Comparison of the Environmental Effects of Conservation and Conventional Crop Production Systems, 1994-1996

Ms. Jane Sadler Richards, Ecologistics Ltd,
490 Dutton Drive, Suite 1A, Waterloo, ONT N2L 6H7
COESA Report No.:  RES/FARM-003/97

Objectives & Expected Outputs
Executive Summary
Table of Contents

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Objectives and Expected Outputs

Objectives: To determine on paired sites (8 pairs) with known histories of conservation and conventional crop production, the effects of the conservation or conventional systems on soil and water quality, focusing on pesticide and nutrient movement. Implicit in the goal is concern that by emphasizing erosion control, overland flow may be reduced at the expense of leaching and environmental filtering.
Expected Outputs: Comparisons of paired locations will be made, providing definition of inherent soil characters (landscape position, slope, soil profile, depth to impervious layer, particle size distribution) and dynamic characters (water release characteristics, infiltration rate, organic carbon, extractable nitrates, nitrites and P, microbial activity and extractable pesticides). Water quality measurements will be made on surface runoff waters, water from tile drains, and groundwater. It is expected that collection of water samples will be coordinated with pesticide and nutrient application and major rainfall events.
Type: Open Bid, Industry
Spending Profile: 93-94: $259.8 K,  94-95: $167.5 K,  95-96: $132.7 K, 96-97: $185.0 K, Total: $745.0 K
Status: Available March 1998

 

Executive Summary

The Canada-Ontario Green Plan agreement was designed to encourage and assist farmers with the implementation of appropriate farm management practices within the framework of environmentally sustainable agriculture. Under this agreement three research related areas were designated: nutrient management/closed loop recycling, on-farm research, and integrated monitoring capabilities. This project addressed the on-farm research component and compared the environmental effects of conservation and conventional crop production systems.

Concern about the overall environmental effects of conservation cropping systems relative to the effects of conventional cropping systems lead to the question: Are we solving one problem (i.e. soil erosion and phosphorus loading) by promoting conservation practices, while inadvertently creating another (i.e. nutrient and pesticide runoff and leaching)? Nutrients and pesticides may move through the soil profile and water system differently in a conservation system compared to a conventional system. If this does occur, what are the differences between the systems and do they have a positive or negative effect on soil and water quality?

This study was designed to obtain a better understanding of the possible answer to this question.
The main objective of the study was:

To determine the influence of conservation and conventional crop production systems on soil and water quality, focusing on pesticide and nutrient movement: by measuring the movement of nutrients and selected common pesticides through the soil profile and in off-site water within well established conventional and conservation tillage cropping systems.

Specific objectives were:

  1. to select paired conventional and conservation farms, fields and farm cooperators given specific criteria;

  2. to evaluate the cropping systems, which are intended to improve soil and water quality, for any trends or aspects which might be environmentally negative in the long term;

  3. to monitor the appropriate water routes of exit including surface, tile and groundwater flow and the soil profile;

  4. to document inputs/outputs, including pest management practices, to permit an economic comparison; and

  5. to select a study design that will allow the statistical analysis and scientific defense of the data.

Fields were selected from farms which represented viable production systems where respective conservation or conventional crop production systems were in place for a minimum of four years. The compared production systems included a conservation no-till system and a conventional tilled (moldboard plough) system with a corn/soybean/winter wheat rotation. Eight paired fields (16 fields total) were selected based on their similar soil type, drainage, slope, geographic area, crop rotation, crop inputs and cooperator willingness to participate.

Selected soil and water quality indicators (total phosphorus, nitrate, nitrite, metolachlor, 2,4-D, water infiltration, water holding capacity, microbial biomass carbon) were monitored with a focus on pesticide and nutrient concentration and movement through the soil/water continuum. Monitoring occurred on a seasonal and rainfall event basis for three growing seasons. Data to support an economic analysis was also compiled for the two productions systems involved.

A sampling protocol for the above soil and water quality indicators was developed at the initial stage of the project, prior to the commencement of sampling tasks. This protocol was supported, where appropriate, by documented standard operating procedures (SOPs). The principles of Good Laboratory Practices (GLP) standards were incorporated into the field portion of the study. This approach has been particularly useful in studies involving analyses for chemical residues in various media where the potential for inadequate handling and/or cross contamination of samples is relatively high.

Samples along with documentation (chain of custody, sample log and analysis request form) were forwarded to the Land Resource Science (LRS) Laboratory and the Environmental Biology Laboratory, both located at the University of Guelph. The LRS Laboratory conducted analyses of soil and water samples for nutrients, specifically total phosphorus and nitrogen (nitrate, nitrites), as well as soil fertility, particle size distribution, organic carbon and microbial biomass. The Environmental Biology Laboratory conducted analyses of soil and water samples for pesticides, specifically 2,4-D and metolachlor.

In cooperation with the Ashton Statistical Laboratory, University of Guelph, a mixed model including fixed and random effects was developed to statistically analyze the complete data set. An analysis of covariance using the general linear model was used to further examine the effect of individual crop on the concentration of metolachlor, nitrate, nitrite and total phosphorus in soil and water. The analyses were conducted using SAS software.

Communications programming and activities occurred at several different levels within the project to address the information compilation and dissemination needs of the cooperators (producers), and research and broader farm communities.

The conclusions from the research were as follows:

  1. This on-farm research program, as designed and implemented, was sensitive enough to allow a comparison of the environmental effects of conservation and conventional crop production systems.

  2. Based on a rotation of corn, soybeans and winter wheat and a monitoring period equivilant to the active growing season, a conservation no-till crop production system had a comparable or better effect on the soil and water environment than a similar conventional till crop production system with regard to total phosphorus, nitrate, nitrite, metolachlor, 2,4-D, water infiltration, water holding capacity and microbial biomass carbon content.
    Specifically the effect of a no-till versus a till crop production system on each indicator was as follows:

    Indicator Environmental Effect
    total phosphorus comparable
    nitrate comparable or better
    nitrite comparable or better
    metolachlor better
    2,4-D comparable
    water infiltration better
    water holding capacity comparable
    microbial biomass carbon comparable
  3. During the active growing season and regardless of crop production system, guidelines for the maintenance of freshwater aquatic life were regularly exceeded in surface and tile water runoff for total phosphorus, nitrate, nitrite, metolachlor and 2,4-D.

  4. In general the crop type and the year in which it was grown did not have a significant affect on the findings.

  5. Under either crop production system there were complex interactions of conditions which when combined in certain ways caused significantly different results. These findings indicated that while the above generalized conclusions hold, individual field conditions exist which may have a positive or negative impact on the environment regardless of the crop production system involved.

Based on the findings of this study the following recommendations are made:

  1. In Ontario the production of field crops using conservation no-till crop production strategies should continue to be encouraged since the environmental effect as characterized in this study, appears to be comparable or better than the effect from conventional till crop production strategies.

  2. In Ontario the effect of both conservation no-till and conventional till field crop production systems should continue to be examined for ways to decrease off-site impacts since the environmental effect as characterized in this study, appears to be negative with regard to water quality and the maintenance of freshwater aquatic life.

  3. Producers using either conservation no-till or conventional till crop production systems should examine their crop management strategies to ensure they are not over-applying input materials that may have a detrimental impact on the environment.

  4. A pilot project aimed at developing a low cost, practical on-farm water monitoring system (e.g. the McKague catchbasin) for use by those producers or organizations wanting to document the impact of their agricultural practices on tile and surface runoff, should be initiated. This system would provide both crop and livestock producers with an opportunity to track the results of changes to their crop management strategies. Such information could be described as a natural extension of the Ontario Environmental Farm Plan initiative and used to support a claim of due diligence in protecting the environment.

  5. The data generated from this study should be further examined to fully realize the scientific potential of the work. Specifically the following items should be pursued:

    1. report on data available but not analysed within the scope of this project:

      • water quality and quantity relationships using chemical indicator results and water flow hydrographs

      • predicting and validating agricultural watershed water quality and quantity under various crop management strategies using mathematical models and available data

      • concentration of metolachlor and 2,4-D in rainfall

      • ammonia content of soil and water

      • microbial biomass nitrogen content in soil

      • other effects not involving the till variable e.g. time, soil, rate of application, amount and timing of rainfall

    2. analyze soil and water samples still in storage i.e. 30 - 45 cm soil depth, ground water, rainfall

    3. explore data for relationships not readily apparent between specific combinations having a significant impact on the findings e.g. microbial biomass carbon content

    4. in order to further refine the procedure for choosing agricultural site pairs in future studies, conduct a statistical analysis and procedural review to evaluate the goodness of the match between site pairs in this study

    5. using the input/output data collected from these long term and well established no-till/till crop management fields, conduct a comparative economic analysis that includes on and off site environmental impacts

  6. The barrel and pump sample collection configuration (as described in this report) should be used where composite samples of an entire rainfall event are required. If however subsamples within a rainfall event are required, the ISCO system may be more advantageous than potential modifications to the barrel and pump configuration.

 


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