1.0 Introduction

1.1	Rationale
1.2	Objectives
1.3	Background
1.4	Projects Included in this Summary

2.1	Green Plan Agricultural Stakeholders Forum
2.2	Current State of the Art on Manure/Nutrient Management
2.3	Ontario Agricultural Services Coordinating Committee

List of Appendices

List of Tables

1.0  INTRODUCTION

1.1 Rationale

Issues related to the management of manures, and the nutrients they contain, continue to be of prime concern within rural Ontario. Certain sectors of the livestock industry are growing very rapidly in parts of the country, and the size of livestock operations is ever increasing. There is much concern about the potential environmental impact of livestock operations and the manure that they generate. Unfortunately, there has been no clear answer to many of the questions that have been raised about livestock manures and the environment. A number of the projects undertaken with funding from the Research Program of The Canada-Ontario Agriculture Green Plan addressed issues related to manure and manure/nutrient management and much useful information and experience were obtained. To help resolve some of the issues related to management of livestock manures, the findings from these studies need to be transferred to extension personnel and the farmers that they serve, to the decision makers within the various levels of government, and to some degree, to the general public.

1.2 Objectives:

1.3  Background

Canada's Green Plan lists three objectives vital to achieving sustainable agri-food systems:

• To conserve and enhance the natural resources that agriculture uses and shares.

• To be compatible with other environmental resources that are affected by agriculture.

• To be proactive in protecting the agri-food sector from the environmental impacts caused by other sectors and factors, external to agriculture.

The Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) similarly identified the parallel goals of achieving environmental sustainability while maintaining an economically competitive agricultural industry.

The authors of the report, Phase I Evaluation of the Canada-Ontario Agreement on the Agricultural Component of the Green Plan: Evaluation Assessment, (Deloitte and Touche Management Consultants and Apogee Research International) state:

"The (Treasury Board) approval (for the Green Plan) also specifies that Green Plan effectiveness is to be judged on:

• the contribution to the intended reduction in severity of environmental problems;

• the related impact on the agricultural productivity and economic viability of the natural resource base for agriculture, and:

• the contribution to increased knowledge on the parts of all partners in the sector about environmental sustainability and solutions to current problems" (page 32)

"The ultimate Green Plan goal, stated clearly in the Treasury Board evaluation requirements, is to improve environmental conditions and the viability of the agricultural resource base. These improvements will occur only if farmers change their current practices and adopt the more environmentally sustainable ones being encouraged by the Green Plan activities." (page 33)

In October of 1991, a group of approximately 50 stakeholders met at the Green Plan Agricultural Stakeholders Forum, held at the Kempenfelt Conference Centre near Barrie Ontario, to identify issues affecting the environmental sustainability of agriculture in Ontario and to suggest strategies for addressing each issue.

From the 30 recommendations crafted at the Stakeholders Forum, the Agreement Management Committee of Green Plan identified nine program areas for Green Plan activities. The Research Sub-Program of Green Plan was comprised of three program areas, one of which was Manure/Nutrient Management and Utilization of Biodegradable Organic Wastes.

The summary presented here of Green Plan projects related to manure management included eight research projects funded through the Green Plan Research Program, one research project funded through the Land Management Assistance Program and four demonstration projects funded through the Rural Conservation Clubs program. The Executive Summaries of the research project reports can be accessed from links provided in the next Section 1.4, "Projects Included in this Summary".

1.4 Projects Included in this Summary

1.4.1 Green Plan Research Program

Current State of the Art on Manure/Nutrient Management.

COESA Report: RES/MAN-001/94
M. J. Goss, J. R. Ogilvie, E. G. Beauchamp, D. P. Stonehouse, M. H. Miller and K. Parris, University of Guelph, Guelph, ON

Nitrogen and Carbon Transformations in Conventionally-Handled Livestock Manures.

COESA Report: RES/MAN-002/97
G. Kachanoski, D. A. J. Barry and D. P. Stonehouse,
Environmental Soil Services, Arkell, ON

Manure Composting Techniques: Understanding Nitrogen and Carbon Conservation.

COESA Report: RES/MAN-003/97
R. St. Jean, Ecologistics Ltd, Waterloo, ON

Transformations in Soil: Crop Response to Nitrogen in Manures with Widely Different Characteristics.

COESA Report: RES/MAN-004/97
E. G. Beauchamp, J. Buchanan-Smith and M. Goss,
University of Guelph, Guelph, ON

The Effects of Livestock Manure Application Methods on Water Quality, Focussing on Nitrogen and Bacteria Transport in Soil.

COESA Report: RES/MAN-005/97
G. J. Wall, B. A. Grant, D. J. King, and N. McLaughlin
Agriculture and Agri-Food Canada, Guelph, ON

Application of Composted Organic Waste to Agricultural Land

COESA Report: RES/MAN-006/97
V. Alder, R. W. Sheard, R. G. Kachanoski and M. J. Goss ,
Ecological Services For Planning², Guelph, ON

Assessment of the Influence of Manures for the Control of Soilborne Pests Including Fungi, Bacteria and Nematodes

COESA Report: RES/MAN-010/97
G. Lazarovits and K. Conn,
Agriculture and Agri-Food Canada, London, ON

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

COESA Report: RES/FARM-002/97
G. Schell and V. Alder, Ecological Services For Planning, Guelph, ON,
in association with R. Samson, REAP Canada and P.-Y. Gasser, AgKnowledge

1.4.2 Land Management Assistance Program

An Investigation into the Management of Manure-Nitrogen to Safeguard the Quality of Groundwater

COESA Report: LMAP - 013/95
M. J. Goss, W. E. Curnoe, E.G. Beauchamp, P. S. Smith, B. D. C. Nunn and D. A. J. Barry,  University of Guelph, Guelph, ON

1.4.3 Rural Conservation Clubs Program

Constructed Wetland Project, Belle River Conservation Club
Dignard Artificial Wetland, South Nation River Conservation Authority
Evaluation of Vegetative Filter Strips to Treat Beef Feedlot and Dairy Yard Runoff in Ontario, Ontario Cattlemen’s Association
Essex Manure Management Club

2.0 Identified Needs For Information

2.1 Green Plan Agricultural Stakeholders Forum

Recommendations 1 and 2 from the Stakeholders Forum addressed the issue of minimizing the impact of livestock manures on air and water quality, while improving the economic efficiency of farming operations, through more efficient use of manure nutrients.

1: "Develop alternative manure management systems appropriate for different soil and livestock management combinations."
2: "Improve utilization of nutrients by expanded use of soil and manure analyses."

Recommendation 4 from the Stakeholders Forum addressed the issue of "Closed Loop" recycling of urban or agricultural organic wastes, recognizing that a successful recycling system could turn waste products into useable resources, extend the life of current landfill sites and improve the organic matter content of soils.

4: "Conduct a pilot project in a small urban community to develop a workable ‘closed loop’ organic waste recycling system" (to demonstrate that it can work; to determine the costs and financial benefits; and to identify potential problems or barriers)

2.2 Current State of the Art on Manure/Nutrient Management (CSAMM)

The first project completed within the Green Plan Research Sub-program was the report, The Current State of the Art on Manure/Nutrient Management by Goss et al, 1994. (Hereafter, referred to as the CSAMM Report.) This project was undertaken to:

1: "identify the various areas of active research related to the management of manure systems and summarize the current knowledge base".
2: "identify areas of research needed to allow the efficient handling, storage, processing and utilization of animal manure on farms in Ontario."

In preparing their report, Goss et al consulted with The Expert Evaluation Panel for Manure Management, a multi-disciplinary group with producer, government, university and industry representatives.

This panel identified and ranked twelve priority areas for research and extension activities, related to manure management. In order of priority, their recommendations were:

Goss et al also conducted three workshops across the province, in March 1993, with representation from a broad cross-section of the agricultural industry. Participants in these workshops were asked to identify the main information needs for farmers and society to address manure issues. The main issues identified in this way are listed below.

• application rates and timing.
• the nutrient content of manure (including manure testing) and its value to crops.
• the economic benefits and environmental costs of manure.
• the relative merits of different manure handling and storage systems.
• methods and equipment to apply manure properly and uniformly.
• alternate uses for manure.

The CSAMM Report included a literature review summarizing the level of knowledge about manure/nutrient management as of 1993. It also identifies the major gaps in the information base or in technology transfer activities, regarding the influence of manure management and environmental conditions on either the utilization of manure nutrients by crops, or on the effect of manure on the environment, or both (summarized in Table 1). Thus, the CSAMM report can be used as a benchmark against which to compare the progress made within Green Plan. The various areas identified in the report which were addressed by specific Green Plan or Supplementary Projects are identified in Table 1. The contributions of Green Plan projects toward addressing specific concerns are summarized in Section 3 of this report.

2.3 Ontario Agricultural Services Coordinating Committee

Within Ontario, responsibility for coordination of agricultural research and services is assigned to the Ontario Agricultural Services Coordinating Committee (OASCC). The eight committees that report to OASCC and their sub-committees (Appendix B) have the responsibility to identify issues for which additional research is required. Several of these committees have identified the need for research or service programs to reduce the impact of livestock production and manure use on the environment. (Their recommendations are listed in Appendix C.) Many of the recommendations made by these committees were generic in nature, calling for additional research directed toward finding affordable and environmentally sustainable methods for managing manures and associated environmental contaminants. More specific recommendations tended to mirror the concerns identified in the CSAMM report.

The recommendations made between 1992 and 1997 identified the following areas as being those which should be given priority for additional research.

• affordable systems to minimize contamination of surface and groundwater by livestock wastes.
• effects of livestock housing alternatives on the environment.
• effects of manure handling methods on the environment.
• innovative methods of treating milkhouse washwater and other contaminated water.
• long-term effectiveness of earthen storage structures for liquid manures.
• movement of contaminants from manure through soils into tile drainage water or groundwater.
• reducing, detecting and dealing with hazardous gases associated with livestock operations.
• reducing odours associated with livestock operations.
• protecting steel and concrete from corrosive manure gases.
• reducing the effect of livestock operations through management of livestock feeds.
• nutrient management extension programs.
• integrated management systems for using nutrients from fertilizers, crop residues, manures and organic wastes, in the agro-ecosystem.
• investigating the ability of manure application equipment to apply manure uniformly.
• manure application practices suitable for conservation tillage systems.
• economic analysis of manure handling systems.

Table 1: Green Plan Activities Providing Information Related to Needs Identified in The Current State of the Art on Manure/Nutrient Management.

3.0    Progress Made Within Green Plan Towards Addressing Information Needs Related to Manure/Nutrient Management

3.1 Introduction

As outlined in Section 2, OASCC and the CSAMM report identified many areas related to manure management for which there were gaps in the knowledge base. The projects considered in this report provided information on many of these topics. The following sub-sections summarize the key findings of these projects as they relate to the areas listed in Table 1. Because the results are organized by issue area, information from individual projects may be presented in several sub-sections.

 3.2 Areas of identified needs not directly addressed by Green Plans projects

• Contamination of surface water by runoff from fields after manure application.

• Generation of odours and toxic gases (other than ammonia) in barns and storage.

• Release of odours and toxic gases (other than ammonia) during spreading.

• Deterioration of structures by corrosive gases released from manure.

• Environmental costs and benefits of manure management practices.

3.3 Control and treatment of contaminated water including milkhouse wash water and runoff from barnyards, feedlots or manure storages

3.3.1  Identified Needs
3.3.2  Summary of Green Plan Research Results
3.3.3  Observations from Green Plan Rural Conservation Club Demonstration Projects
     3.3.3.1  The Belle River Conservation Club
     3.3.3.2  The South Nation River Conservation Authority
     3.3.3.3  The Ontario Cattlemen’s Association

3.3.1 Identified Needs

In 1992 to 1997, inclusive, OASCC annually recommended that research be supported to assess the impact of different manure handling and milkhouse wash water disposal systems on the environment. Although not formally recorded as such, the need for economical ways to manage runoff from solid manure storages has also been frequently expressed.

3.3.2 Summary of Green Plan Research Results

Two research projects provided information related to the control or treatment of contaminated water.

• Nitrogen & Carbon Transformations in Conventionally-Handled Livestock Manures (Kachanoski et al)

• On-Farm Manure Composting Techniques: Understanding Nitrogen and Carbon Conservation (St. Jeann)

Runoff from a storage pad holding solid beef manure system from a cow-calf operation contained 2% of the manure N delivered to the pad ((Kachanoski et al). Since this was mostly mineral N, it represented roughly 25% of the final available N. The concentration of NH₄-N in the runoff storage tank averaged 112 mg kg^-1 in the summer and 256 mg kg^-1 in the winter.

There is significant loss of moisture from manure by evaporation during composting (St. Jean). Solid beef cattle manure had a net moisture loss of 43.2% when composted outside, and 69.6% for the covered control process. Thus, the process appeared to have potential as a means to treat contaminated water (e.g. barnyard runoff and milkhouse waste water). However, moisture loss from composting processes manipulated for nitrogen conservation was not sufficient to make them suitable for treatment of farm-generated liquids. There was a trend, that was not statistically significant, towards higher nitrogen and organic matter losses as a result of the addition of barnyard runoff to composting manure. (See Section 3.7.3.2)

3.3.3 Observations from Green Plan Rural Conservation Club Demonstration Projects

Three conservation clubs provided information related to the control or treatment of contaminated water.

• Constructed Wetland Project (Belle River Conservation Club)

• Dignard Artificial Wetland (South Nation River Conservation Authority)

• Evaluation of Vegetative Filter Strips to Treat Beef Feedlot and Dairy Yard Runoff in Ontario (Ontario Cattlemen’s Association)

3.3.3.1 The Belle River Conservation Club, in conjunction with the Essex Region Conservation Authority, conducted a four year demonstration project to test the feasibility of using a constructed wetland to treat barnyard runoff and milkhouse wash water from a 200 head dairy operation. The treatment system consisted of a storage pond, a serpentine wetland area, in which a variety of native aquatic plants was transplanted, and a polishing pond. Barnyard runoff and milkhouse wastes were directed into a collection tank and then pumped into the storage pond. The system was sized based on average rainfall and evapotranspiration data for the area with additional provision for a 1:100 year storm event. Liquids were held in the storage pond from November through April, and released into the wetland when average water temperatures exceeded 6 C. On average, the operating period was 180 days. The wetland was designed for a retention time of at least 14 days. Excess water from the polishing pond was irrigated on an adjacent pasture when necessary. No water was released into surface watercourses.

On average over the two years, contaminant concentrations in the polishing pond were reduced by 88% to 99%, relative to samples taken at the transfer pump, depending on the parameter (Table 2). Over ninety percent of the removal of E. coli and Biochemical Oxygen Demand (BOD₅) occurred in the storage pond. Sixty percent of the phosphate removal occurred in the wetland complex. Removal of suspended solids was equally divided between the storage pond and wetland area.

Piezometers were installed around the wetland site to monitor ground water quality. Over the two operating years of the project, there was no conclusive evidence of ground water quality impairment.

Additional information about this project can be obtained from The Essex Region Conservation Authority, 360 Fairview Avenue West, Essex, Ontario N8M 1Y6

Table 2 : Artificial Wetland System Treatment Efficiencies, Belle River Conservation Club

3.3.3.2 The South Nation River Conservation Authority conducted a three year demonstration project to evaluate an artificial wetland for the treatment of milkhouse wash water and runoff from a solid manure storage and an exercise yard. The system consisted of a previously existing lagoon in which manure runoff was collected and held temporarily, a stabilization pond, an initial wetland cell, an aerobic pond, a second wetland cell and a vegetated filter strip for overland flow. The wetland system was designed to operate between May 1 and September 30. During the rest of the year, the runoff was stored in the lagoon which was sized to hold the wash water, manure runoff and precipitation from a "wet winter" (amount expected to be exceeded once in ten years).

The stabilization pond was designed to accommodate a BOD₅ loading of 100 kg/ha/day. The wetland was designed for a BOD₅ loading of 75 kg/ha/day and a total nitrogen loading of 3 kg/ha/day. Pollutant concentrations were monitored at each stage of the system. Relative to the concentrations in the lagoon, concentrations at the end of the wetland were reduced by 98.7 % for BOD₅, 97.8 % for nitrogen and 95.3 % for total phosphorus (P). Additional polishing occurred on the vegetated filter strip. Shallow ground water piezometers were installed around the site for the second year. However, because of low soil moisture conditions, there was insufficient water in the sampling tubes for regular monitoring.

Additional information about this project can be obtained from The South Nation River Conservation Authority, Box 69, Berwick, Ontario K0C 1G0

3.3.3.3 The Ontario Cattlemen’s Association coordinated demonstration projects on five farms to evaluate vegetative filter strips for the treatment of runoff from beef feedlots and dairy yards. The treatment systems consisted of the following elements:

• a settling area, usually the feedlot or yard, to allow solids to settle and to serve as a holding area in the case of large storm events.

• a filter box to remove debris.

• a gravel spreader to distribute flow over the entire width of the filter strip.

• the vegetative filter strip.

The filter strips were designed such that liquid flowed in a shallow sheet (< 1.3 cm) and infiltrated into the soil. The strips were sized to accommodate a 2-year, 2-hour storm event. The slope of the various strips were between 0.3 to 4.5 percent; lengths were 70 to 180 m.; and widths were 8.0 to 24 m. No event of runoff flowing off the end of any strip was observed. Grab samples were collected for analysis at the point of farthest flow of the liquid. Relative to samples collected from the yard runoff, the system reduced contaminant concentrations by: nitrate - 45.2%, total phosphorus - 31%, total dissolved solids - 29.1%, faecal coliforms - 40.6% and BOD₅ - 51.3%

Results showed no accumulation of nutrients in the soil profile and no change in the quality of ground water samples from preconstruction levels. Surface removal rates, soil profile results, and groundwater monitoring results when taken together, establish that the vegetated filter strip system is an environmentally sound treatment system for feedlot and barnyard runoff.

Additional information about this project can be obtained from The Ontario Cattlemen’s Association, 130 Malcolm Road, Guelph, Ontario N1K 1B1

3.4 Contamination of surface water through macropore flow to tile drains

3.4.1 Identified Needs

A 1992 recommendation from OASCC identified the need to "study the movement of bacteria, toxins and nutrients through soil and to examine the quantitative and physical processes involved as well as the development and evaluation of best management systems to reduce the potential for ground water contamination".

A recommendation submitted annually between 1992 and 1996 stressed the need to "investigate management systems to minimize contamination of air, surface and groundwater by nitrogen originating from fertilizers, legumes, manures and other organic sources, and by bacteria from manures and organic wastes applied to soils."

The CSAMM report cited studies documenting the frequent impairment of the quality of tile drainage water from the spreading of liquid manure. The report noted the difficulty of determining an acceptable rate of application of liquid manure due to the numerous factors involved (e.g. manure type and composition, time and method of application, tillage system, soil conditions and weather). The importance of soil macropores for the rapid transport of bacteria to tile drains was highlighted.

3.4.2 Summary of Green Plan Research Results

In the study, The Effects of Livestock Manure Application Methods on Water Quality, Focussing on Nitrogen and Bacteria Transport in Soil, Wall et al conducted field scale studies to evaluate liquid manure application technologies in no-till corn cropping systems, in terms of sustainable crop productivity and subsurface water quality (nitrogen, bacteria), and to identify pathways and processes of nutrient and bacteria transport to tile drains and ground water with special consideration to preferential flow.

Side-dressed applications of liquid manure, at the four-leaf stage of corn, resulted in water quality impairments to tile drainage water if tile drains were flowing at the time of application. Water quality guidelines for bacteria, ammonia and phosphorus were exceeded for several hours. Manure was confirmed as the source of this contamination and macropore pathways contributed to tile flows even under unsaturated soil moisture conditions. Simulated rainfall on the day following manure application also resulted in impairment of tile drain water quality. Tile water contamination occurred both immediately following the manure application and after the simulated rainfall event, regardless of the method of liquid manure application. Compared to surface application, contamination was generally less when the manure had been injected, especially if the system was modified to till the soil before injection.

Based on the results of this study, Wall et al offered the following recommendations for the application of liquid manure in no-till cropping systems:

i) Liquid manure nutrient testing is required immediately prior to manure application to establish accurate manure application rates.
ii) Side dress injection or surface application of liquid manure at soil test recommended rates, at the fourth leaf stage, will produce corn yields equivalent to conventional inorganic N fertilization.
iii) Conventional and modified injection equipment are recommended for use on medium to coarse textured soils.
iv) Side dressed injection applications should be considered to reduce impacts on tile water quality relative to surface applications especially on medium and light textured soils.
v) Apply liquid manure to tile drained land when the tile drains are not flowing to reduce impacts on tile water quality.

3.4.3 Additional Information from Specific Studies

3.4.3.1 The Effects of Livestock Manure Application Methods on Water Quality, Focussing on Nitrogen and Bacteria Transport in Soil   (Wall et al)

Trials were conducted at locations representing the following soil textures: sandy loam, silt loam and silty clay loam. Liquid hog manure was side dressed with a 6,800 L tanker around the fourth leaf stage of corn using surface application and two injection techniques (conventional injection and injection modified by slight tillage in front of the injectors).

Tile flow rate volumes increased within 30 minutes of liquid manure application and returned to base flow conditions within three hours. Flow increases represented <3% of the applied manure on average. The greatest increases in flow rates occurred when the tiles were flowing prior to the manure application. Following simulated rainfall events, one day after manure application, tile flows increased significantly and did not return to base flow rates for several days. Tile drain flow increases represented about 10% of simulated rainfall volumes at the sandy loam and silt loam sites and under 5% at clay loam site.

At all sites, application of liquid manure when the tile drains were flowing usually resulted in water quality impairments to tile drainage water for 2 to 3 hrs following manure application. There was visual evidence (change in turbidity) of tile water contamination within 7 to 30 minutes from the time of application. Although the total volume of manure reaching the tile was small (<2%), water quality guidelines for bacteria, ammonia and phosphorus were exceeded for several hours. The presence of the tracer bacteria and chemicals in the tile water samples after manure application provided verification of manure as the source.

The simulated rainfall events resulted in increased levels of ammonia, tracer bacteria and phosphorus in tile drainage water within 30 minutes. Levels peaked within 60 minutes, but at concentrations lower than those observed on the day of manure application. Loadings, however, were significantly greater due to the larger volumes of water coming through the tile drains. Since the bacteria and chemical tracers were not detected in the tile water a few days after the rainfall event, it appears that the impact of the manure application on the tile water quality is relatively short-lived.

Chemical tracers added to the manure mirrored the bacteria movement to the tile drains both in time and concentration. The percentage of applied non-reactive tracers (bromide, chloride) reaching the tile drains (<2%) was similar to the percentage of the applied manure volume measured in the tile drains. Although <1% of the applied reactive tracer (strontium) was recovered in the tile water, its presence provided evidence that the macropore pathways contribute to tile flows even under the unsaturated soil moisture conditions of the experiment.

Background nitrate (NO₃) levels in the tile water ranged from 7.0 mg/L to 25 mg/L. Liquid manure application did not immediately affect the NO₃ concentration of the tile water since the mineral N in the manure was predominantly present as NH₄-N. Any increase in NO₃ levels of tile water associated with manure application did not occur until 1 to 2 weeks following manure application.

While there was no significant difference between application methods at sandy loam and silt loam sites, the manure injection techniques tended to have less water quality impairment than the surface applied treatment. At the clay loam site, surface applied manure resulted in significantly greater levels of nutrient and bacteria contamination than the injection methods. However, tile water contamination occurred both immediately following the manure application and after the simulated rainfall event, regardless of the method of liquid manure application. In this no-till system, it may only be possible to stop tile water contamination by applying liquid manure during growing season periods when soil moisture content is low and tile drains are not flowing.

The tile drainage model (DRAINMOD 4.0) provided statistically good predictions of tile flow for both years compared to measured flow values. Further study of the water quality components of the model that are currently under development appear warranted.

3.5 Contamination of ground water by nutrients, pathogens or solids from manure through leaching from manure storage, processing or treatment

3.5.1 Identified Needs

The CSAMM report noted concerns related to the leakage or leaching of manure from storage into the soil and hence, into the groundwater. Leakage from concrete storages was thought to be minimal. The greatest concern related to the potential for leaching from improperly sealed earthen storages. Although, it was not identified in CSAMM, similar concerns presumably exist for uncontrolled runoff or leachate from solid manure storages.

3.5.2 Summary of Green Plan Research Results

Two research projects provided information related to the potential for leaching during manure storage, processing or treatment.

• Nitrogen & Carbon Transformations in Conventionally-Handled Livestock Manures (Kachanoski et al)

• On-Farm Manure Composting Techniques: Understanding Nitrogen and Carbon Conservation (St. Jean)

Kachanoski et al. analyzed soil cores taken at various depths and distances from a poultry manure pile on a field site that had been used for several years for manure storage. Soil mineral N concentrations in the top 0.15 m were 88 mg kg^-1 within 2.5 m of the pile, but averaged around 20 mg kg^-1 at 5.0 m and farther from the pile. Most of this increase in soil mineral N near the pile was from NO₃, which was also evident at greater depths. While the field storage site did appear to be a point source of NO₃, it was not certain that this NO₃ was contaminating ground water. It may have been denitrified in a saturated zone, perhaps because of soluble C also leaching from the manure.

St. Jean found that the potential for leaching of nutrients from solid beef cattle manure during the composting process was low whether it was done outside or inside. The drying action of the sun caused a hard crust to form on the surface of manure being composted outside. This crust effectively shed water and reduced the potential for N leaching during the process despite the exposure to rainfall.

Sect 3.6 - 3.10 | Sect 3.11 - 5.0

Report 1.12 Summary |  Research Report List | Green Plan Research

Last Updated: May 16, 2011 02:33:51 PM