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SWEEP Report #61

Final Report of the
Technology Evaluation and Development (TED) Sub-program of the Soil and Water Environmental Enhancement Program (SWEEP)

Researchers: 

W.I. Findlay, Agriculture Canada, Harrow, Ont., and Ecological Services for Planning Ltd., Guelph, Ont.

Executive Summary

View / Download Final Report  [2327 KB]

(includes Literature Review "Soil Erosion and Phosphorus in Runoff from Agricultural Cropland in Southwestern Ontario",  by The Centre for Soil and Water Conservation, University of Guelph;  Principal Authors: W.T. Dickinson, R.G. Kachanoski, D.A. Lobb, J.A. Smithers, T.J. Vyn, M.H. Miller, Director - June, 1987)

 

 

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Completed: October, 1992

Executive Summary

In August of 1985, the Governments of Canada and the province of Ontario announced the beginning of a coordinated federal/provincial program to deal with soil conservation and water quality as part of the Canadian response to an international agreement with the United States to reduce phosphorus loads to Lake Erie. A Five Year Implementation Plan was developed which set out the program objectives of a 200 tonne annual reduction in P loads due to agriculture. This target was to be met by encouraging and assisting 8,000 farmers cropping 400,000 hectares of land to adopt appropriate conservation cropping practices. Allocating the 200 tonne objective over 400,000 ha meant that an average annual reduction of 0.5 kg of P per ha was required.

The Technology Evaluation and Development (TED) Subprogram of the Soil and Water Environmental Enhancement Program (SWEEP) ran from February of 1987 until September of 1992. This final report presents a summary of the subprogram.

The TED program was successful in responding to the research priorities identified during a detailed planning process. The planned research was implemented and completed on budget and on schedule making efficient use of a range of research capabilities throughout the province. The available research funds were equitably distributed between research institutions, such as the University of Guelph and the private sector. A number of productive joint ventures between research institutions, private sector contractors and active farmers were encouraged and supported Regular review of the program progress with the Technical Advisory Panel resulted in modifications and research enhancements which improved the focus and overall achievement of the program objectives. Communication of research results and opportunity for input was provided to a wide range of interest through the use of Progress Summary Bulletins and research conferences.

The TED subprogram of SWEEP was conceived, developed and delivered as a cooperative venture between farmers, research scientists and administrative personnel. Any success which the TED subprogram achieved was due to the tremendous cooperation of individuals within these different groups.

Of the 53 research projects funded by TED, 21 (40%) were awarded in response to the formal Request for Proposal procedure, while 32 (60%) were awarded as a result of unsolicited proposals. Work conducted as a result of unsolicited proposals had to be justified by a demonstrated need for the knowledge which the work would provide.

The TED subprogram was given a mandate to focus on research conducted at the farm scale. Nearly 78% of all the research money spent during the TED subprogram was spent on projects which were conducted on viable commercial farms. In addition, an additional 5.5% of the research money was spent on studies which used a combination of farm and research station resources. Two hundred and thirty-five farmers were directly contacted through the TED program. Of these 235 individuals, 148 were directly involved in some component of the TED research. One of the first projects awarded under TED was a survey of conservation practices being tested, revised and adopted by leading farmers in Ontario. This study was valuable to TED in refining the farmer position on research priorities and identifying a resource group of advisors and research cooperators.

In addition to supporting, strengthening and enlarging the network of farmer-to-farmer communication about conservation practices, the TED program assisted in the training and professional development of a number of technicians, researchers and research groups.

TED identified a need for tools which would assist farmers in reducing the risks associated with the transition from conventional to conservation farming. Means of providing these tools were explored to some extent at the TED Modelling Workshop held on November, 1988. An existing approach which showed the greatest promise was developed by ROBBERT ASSOCIATES, and derived from a five year program in Statistics Canada to develop a socioeconomic resource framework. The promise shown by the first phase of the project conducted under TED clearly indicates a potential for meeting the established guidelines outlined above.

 

RESEARCH

Farm Management Systems

A high priority research topic identified in the early planning stages of TED was the management of farm-field variability. The project arose out of the identified need to better understand the challenges involved in managing farm fields with complex topography, soils and drainage patterns. The main conclusions were that large amounts of soil and associated phosphorus are being moved within fields with complex topography in southwestern Ontario, and the amount of soil and phosphorus moved within a field does not necessarily relate to the amount of soil and sediment delivered to streams. Therefore the crop productivity impacts of soil movement in complex fields can be significantly greater than the environmental and water quality impacts.

A study was undertaken to investigate an alternative farm management system developed by a group of innovative farmers known as the Ontario Biological Aeration Tillage Association (OBATA). Over the three field seasons of the research, many of the OBATA treatments appeared to have little or no quantifiable agronomic benefits. Soil fertility, structure and compaction, and microbial biomass did not appear to differ between the OBATA and standard treatments. Rainfall simulation indicated that the practices did result in reduced soil and phosphorus losses when compared to conventional practices. While the TED studies did not show the OBATA system to be agronomically superior to the standard management system, it may be a viable alternative to conventional agriculture, offering comparable yields and net returns, while reducing soil erosion and phosphorus losses. Since pasture and manure management are readily included in the OBATA system, it may appeal more to farmers with livestock than those who grow strictly cash crops.

Cropping Strategies

The TED studies explored a range of management and species alternatives for cover crops and developed the establishment and elimination methods required to successfully incorporate their use into a farm system. The success of a succeeding crop often appeared dependent on using some degree of tillage in the spring prior to planting to provide an optimal seed bed environment in the presence of crop residues. Pushing residue aside was also often successful. Cover crops appear to have great potential to contribute to the reduction in soil erosion from cropland as evidenced by the biomass and residue covers which could be achieved over winter.

What is less clear from the research, is the link between main or cover crop residues and yield reduction responses. The effects of residues on soil temperature and soil moisture revealed that reduced temperature under residues may delay development but did not necessarily reduce soybean and corn yields. The development of the nitrogen soil test would be a useful tool in the management of soil fertility with cover crops. Similarly, a screening test may be of help in choosing a corn hybrid that may be better able to emerge at cool temperatures.

Tillage Options

"Tillage Options" was identified as one of the research priorities for TED in the Background Paper, prepared by the Centre for Soil and Water Conservation, and by the participants of the initial planning workshop. Eleven tillage-related research contracts were awarded during the TED program. Studies on subsoiling were included in the tillage options category as were development and testing of new planting or fertilizer application equipment for conservation tillage systems.

Several projects provided researchers and fanner cooperators with an opportunity to test promising new planting and tillage equipment under Ontario conditions. Minor modifications to existing technology were also tested such as the cutoff mold board plow which appears to be a viable first step for farmers towards conservation farming. Studies were conducted to assess the benefits of subsoiling on soil properties and subsequent crop yields. Overall, the TED studies did not come out in favour of subsoiling. It does not appear to be cost effective unless a severe compaction problem exists.

A contract resulted in the publication of a booklet by OMAF, entitled "Equipment Modifications and Practical Tips for Use". This publication contained photographs and descriptions of a wide range of modifications to moldboard plows, chisel plows, tandem disks, conservation seed drills, row crop planters and edge-till systems.

Fertility Management

The confirmation that nutrient stratification exists in systems in which tillage does not mix or shallowly mixes fertilizer with the soil was expected. There is no indication that this would be of concern to farm management in terms of application rates and soil testing methods. The TED work indicated that increased phosphorus contribution from these fields is unlikely where conservation tillage achieves a concurrent reduction in sediment detachment.

Further, nitrogen losses from conventional, ridge tillage, and zero tillage corn in runoff and tile drainage were similar and there was no indication that conservation practices would lead to greater pollution of nitrogen in waters. A sod crop dramatically reduced nitrogen losses and nitrogen concentrations in runoff and tile waters relative to any of these corn systems, however, which would suggest that cover crops or intercrops may play a role in reducing nitrate leaching from soils.

The research which examined this possibility found that the cover crops of ryegrass, oilseed radish, and red clover, scavenged nitrogen initially but that soil nitrate levels were often as high or higher under the cover crops during the late fall and winter. The pattern of release of the nitrogen differed widely among the cover crops with some (oilseed radish) releasing too early to be largely available to a corn crop while others immobilized nitrogen to the extent of depressing corn growth early in the season in the absence of supplemental nitrogen. There seems to be considerable opportunity to understand the contribution of cover crops in nutrient cycling.

There was some evidence from this same study that the various cover crops are leached of their nutrients to varying degrees by rainfall. The question of the importance of residues in contributing to soluble P levels was raised.

The manure management studies in TED provided useful agronomic information and tested some interesting and environmentally viable systems for manure applications. The design, timeframe and budget of the manure studies did not allow for full evaluation of the environmental implications of the management. In some cases the manure was not incorporated, such as the applications to established forages and to winter wheat in the spring. These systems have the advantage of providing high ground covers of 50 to 100% which could be expected to minimize runoff and soil erosion.

Other management systems, such as manure applications following winter wheat harvest and soybeans, provide opportunities for manure incorporation. When incorporation is accomplished by tillage which does not involve full soil inversion by moldboard plowing, the main crop residue may provide sufficient cover to reduce soil erosion. Some tillage was shown to be required to maximize corn yields the following year in these studies.

Pest Control

Research carried out since 1987 under TED provided substantial evidence to reject the notion that reduced tillage systems lead to greater weed problems and higher herbicide dosages. At the beginning of the TED program a very strong concern was expressed by the most experienced conservation farmers that weed management and the availability of appropriate products was, or could become, a serious problem. By the end of the TED study it seems safe to conclude that their concern is significantly reduced. A number of new mixes and rates of application using currently registered materials and usages have proven to be extremely effective in controlling weeds at reasonable cost. An innovative farmer was able to demonstrate a 60% reduction in herbicide use through the integrated use of a herbicide banding and interrow cultivation. This reduction offers significant environmental and economic benefits, while at the same time appearing to have no adverse effect on weed pressures. The system was developed to the point where the inter-row cultivation was performed at the same time as nitrogen fertilization which meant no additional passes across the field. In effect, the secondary cultivation allowed the farmer to save 60% on his herbicide bill without substantially increasing the costs of his field operations.

No significant problems with either slugs or armyworms were reported, despite the fact that in many of the research plots, residue cover was in excess of 75%. However, the lack of slug problems may be attributed to the drier than normal conditions which generally prevailed during the three field seasons. No evidence that fusarium infections can be linked to the adoption of soil conservation practices was found.

Water Management

Attempts under TED to monitor the water quality impacts of water control structures were unsuccessful due to weather problems. Some empirical data are required to calibrate available models. Once these data are available modelling should prove to be a more reliable and cost effective method of monitoring these structures.

Some tillage and farm management practices, such as cultivation, mulch tillage, residue management and cover crops, have the potential to increase the rates of infiltration and percolation into cropped land. A portable device, the Guelph Pressure Infiltrometer (GPI), was developed and used to compare the infiltration rates from soils under conventional and conservation tillage systems. The GPI provided rapid measurements of a number of soil hydraulic properties and is a promising research tool for further work.

Rainfall simulations were conducted in a separate contract on a large number of TED research sites. Although differences in surface hydraulic properties were not specifically examined, the response of different treatments to the simulated rainfall did show relative differences in surface infiltration rates. The results from the simulations were highly variable, but generally in agreement with those from the GPI study.

At a monitored upland site, surface and tile flow from a fall moldboard plow tillage system and a no-till system were monitored and compared. Very little surface runoff occurred during the first 12 months of the monitoring period. It was concluded that the sandy loam soils at the site were not susceptible to surface runoff and erosion under either the no-till or fall plow systems. When rainfall simulations were conducted on a part of the field that had clay loam soils, both runoff volumes and soluble orthophosphate losses were greater from the no-till soils.

The results from a monitored lowland site indicate that conservation tillage is not sufficient to reduce phosphorus losses from cropland located on flat clay soils. Other measures may be necessary, such as optimizing phosphorus fertilizer use, or controlling the flow and reusing the tile drainage water (subsurface irrigation, creating wetlands, etc.), to keep the nutrients in the fields. The technology and options for accomplishing this were not investigated further.

Problem Understanding

Rated as a high priority was the examination of the nature, extent, and possible remedies to allelopathic and phytotoxic effects related to conservation farming and specific crop rotations. The specific compounds studied were volatile fatty acids (VFA's) which are by products of biological fermentation, and phenolic acids which are organic compounds initially leached from crop residues. Corn did not consistently exhibit a yield reduction response to the presence of crop residues on the soil surface and hence the observation of farmers related to phytotoxicity could not be reproduced in research trials in the field.

Studies were conducted to determine the extent of soil compaction on lowland clay soils in southern Ontario. Results indicated that around 50 to 70% of clay to clay loam soils in Lambton, Middlesex, Kent, Essex, and Elgin Counties have some degree of subsoil compaction. Twenty-five percent of these are considered to be severely compacted. Subsoiling of these lands was generally not beneficial to crop yields, and may be of use only on severely compacted soils.

As a progression from studies carried out in TED and Tillage 2000 examining variability of fields and effects of landscape positions on soil loss, research focused on shoulder slope erosion and the extent to which tillage operations move soil up and down slopes. This research is continuing beyond the TED term.

Summary

The report concludes with a discussion of the TED process and the Results of the research. Recommendations for the planning and management of future research programs are made. In addition specific topics for future research are suggested in the area of soil and water quality, farm management systems, soil fertility and nutrient management, crop residue management and tillage practices.

 

 

 

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Created: 05-28-1996
Last Revised: Thursday, May 19, 2011 05:45:32 PM