Objectives and Expected Outputs
||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.
||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.
||Open Bid, Industry
||93-94: $259.8 K, 94-95: $167.5 K,
95-96: $132.7 K, 96-97: $185.0 K, Total: $745.0
||Available March 1998
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
Specific objectives were:
to select paired conventional and conservation farms, fields
and farm cooperators given specific criteria;
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;
to monitor the appropriate water routes of exit including surface,
tile and groundwater flow and the soil profile;
to document inputs/outputs, including pest management practices,
to permit an economic comparison; and
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:
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.
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:
||comparable or better
||comparable or better
|water holding capacity
|microbial biomass carbon
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.
In general the crop type and the year in which it was grown did
not have a significant affect on the findings.
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
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.
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.
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.
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.
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:
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
analyze soil and water samples still in storage i.e. 30 -
45 cm soil depth, ground water, rainfall
explore data for relationships not readily apparent between
specific combinations having a significant impact on the findings
e.g. microbial biomass carbon content
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
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
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.
May 16, 2011 08:57:39 PM