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SWEEP Report #6

A Survey of Crop Residue in Southwestern Ontario 1987

Researchers:
Peter Roberts, Soil and Water Management Branch, Ontario Ministry of Agriculture and Food, Guelph Agriculture Centre, Guelph, Ont., and Dell Coleman, Inland Waters/Lands Directorate, Environment Canada, Centre for Inland Water, Burlington, Ont.

Executive Summary

Evaluation Summary (Tech. Transfer Report Summaries)

View / Download Final Report  [753 KB pdf]

Associated SWEEP/LSP Research

 

 

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Completed: March, 1988

Key Words:

residue, windshield survey, tillage systems, crop rotations, reduced tillage, no-till, ridge tillage

Executive Summary

This report represents the results of a study of crop residue conducted by a combined windshield/on-site survey of over 10,000 fields in southwestern Ontario in the spring of 1987. The purpose of the survey was to provide a detailed data base for the Soil and Water Environmental Enhancement Program (SWEEP). SWEEP is a 5-year program aimed at reducing phosphorus loadings from cropland run-off and to improve or maintain the productivity of agriculture in the Lake Erie Basin. The survey gathered baseline data for percent residue cover of the soil surface for various combinations of crops and tillage systems.

Conservation tillage practices increase residue cover and enhance erosion control. This data, along with that collected in the "Cropping, Tillage and Land Management Practices" report of March, 1987 will allow estimation of relative soil loss from fields. It will also serve as a benchmark against which the effect of implementing soil and water management practices can be evaluated at the conclusion of the SWEEP Agreement.

The survey was conducted by driving predetermined random routes twice through the counties of the SWEEP study area, with stops approximately every 0.8 km to record cropland information. At each site information was gathered on present crop, residue levels of the previous crop, and tillage type.

An attempt was made to include a representative subsample of interview survey sites visited in the "Cropping, Tillage and Land Management Practices" study (Coleman & Roberts, March 1987), in order to allow comparison of crop residue data with detailed cropping and tillage information.

An analysis of the data reveals that 16% of fields in southwestern Ontario have 20% or more residue cover, while just 10% of the fields surveyed had 30% residue cover.

Residue levels were compiled on a county and regional municipality basis, by tillage type, previous crops, and cropping sequence.

Study results showed that conventional tillage occurred most commonly (72.8%), while 18.6% of fields were not tilled, 8.0% were reduced tilled and 0.5% were ridge tilled. Over 95% of conventionally tilled fields occurred in the 0-15% residue category, while 3% of conventionally tilled fields occurred in the 75-100% category. For reduced tillage, most fields were in the 15-30% residue category at 40.6%, with a similar response (40.0%) in the 30-45% residue category.

The higher residue categories are dominated by fields in the not-tilled category. Most of this category was made up of forage and hay residue. These are densely growing crops which tend to provide a high degree of surface cover.

County results showing the distribution of crops planted indicate that corn (26.3%) was predominant. Hay or forage constituted 20.9%, while spring and fall grain made up 11.9% and 12.5% respectively.

To assess the representativeness of the results, the information was compared to the distribution of crops by county found in the report by Coleman and Roberts, 1987. A good deal of similarity was seen among percentage occurrence of the various crops between the two surveys.

Reliability of the crop residue estimate was judged by a cross-tabulation of actual measured residue cover in percent with estimated residue cover. For all residue cover categories, it was found that one can be over 96% confident that when a residue cover class was estimated, the value was in its proper class.

Residue levels of previous crops that were not identifiable (fallow), occurred 3.8% of the time in the Before Secondary Tillage (BST) phase, but their occurrence increased to 12% in the After Secondary Tillage (AST) phase of the study. Results showed that during the AST phase, higher proportions of fields occurred in the 0-15% residue cover category, while most decreases occurred in the 45-75% and 75-100% residue categories.

With the exception of small grains, the proportion of fields in the 0-15% residue category increased markedly during the AST phase, for most crops.

For example, the proportion of fields in corn having just 0-15% residue cover increased from 70.4% during the BST phase to 83.3% during the AST phase. By comparison, the number of corn fields having residue in the higher residue categories fell by approximately 13 percentage points.

The proportion of fields in beans having 0-15% residue increased from 61.4% during the BST phase to 95.6% during the AST phase. For beans, the higher residue categories lost a total of approximately 34 percentage points. With the exception of forages, corresponding losses in residue occurred for the remaining crops.

During the BST phase, 54% of forage fields occurred in the 0 - 15% residue category. These were fields which had been plowed down in preparation for planting another crop. Hay which remained during the AST portion of the study was being kept an additional year. As a consequence, 83.5% of the entries in the 75-100% residue category are a result of forages being maintained from year to year.

Cropping sequences were one of the more interesting pieces of information available from the survey. For example, where the present crop was corn, 63.4% of those fields had previously been corn, 16.6% of present corn crops had previously been small grains while 11.1% of fields had previously been seeded to beans. Four percent of present corn fields had insufficient residue to determine what the previous crop had been.

An analysis of crop residue for a previous crop-present crop combination can show the probability of having a certain level of residue through many types of cropping sequences. As an illustration, the mean value of residue cover resulting from a corn-corn-grain-hay-hay rotation is provided. In the first year when corn follows a previous crop of hay, a 10% level of residue was found on average. In the second year when corn follows corn, one would expect to find 12% residue cover. In the third year of the rotation, when spring grain follows corn, an average residue cover of 9% would likely be found. When hay follows spring grain in the fourth year, a crop residue cover of 33% would be anticipated. In the final year of the rotation when hay follows hay an average residue cover of 73% would result. Over this rotation, the average value of crop residue was 27%.

Average residue cover levels for any other crop sequence can be derived with the data found in this report. Results showed that incorporating a forage/hay into a rotation increased crop residue cover substantially.

The survey was designed to collect information about crop residues before secondary tillage (after-wintering) and after secondary tillage (after-planting). The before secondary tillage information proved to be useful only in a limited fashion. The only crops in the before secondary tillage category during the spring are untilled crop stubble and primary tilled fields. Forage/hay and fall planted grains are crops which have already received secondary tillage. The main value of the before secondary tillage portion of the survey is to allow estimation of the over-winter protection afforded by stubble, forage or fall grain.

This data will enable additional analysis and comparisons to be made and will be used to evaluate the effects of conservation practices in the SWEEP program.

 

Evaluation Summary

(From Technology Transfer Report Summaries - A. Hayes, L. Cruickshank, Co-Chairs)

In 1987 a windshield survey was conducted to provide a detailed data base of the percent residue cover for various cropping and tillage systems. The information will serve as a benchmark against which the effect of implementing soil and water management practices can be evaluated. The survey was conducted by driving a predetermined random route twice through the SWEEP watershed counties with stops every 0.8 km to record cropland information. Information recorded at each site included: present crop, residue levels before and after secondary tillage, and tillage type. An attempt was made to include a representative subsample from the survey conducted in 1986 - "Cropping, Tillage and Land Management Practices" to allow comparisons between the data.

The results indicated that 16% of the fields have 20% or more residue cover and 10% of the fields have over 30%. Conventional tillage occurred most often (72.8%) while 18.6% of fields were not tilled and 8% were reduced tilled and 0.5% were ridge tilled. Almost all the conventional tilled fields were in the 0-15% residue cover category while the reduced tilled fields fell into the 15-30% and 30-45% categories. The predominant crop was corn (26.3%) followed by hay or forage (20.9%), fall grain (12.5%) and spring grain (11.99%).

Comments:

As with any survey this one has limitations in the accuracy of the reporting as most observations were made from the car (surveyors went into 1 in 10 fields) and this distorts the residue cover amounts.

Associated SWEEP/LSP Research:

  • SWEEP Report #0 - Cropping, Tillage and Land Management Practices in Southwestern Ontario 1986

Future Research: ( ) indicates the reviewers suggestion for priority, A - high, C - low.

(A) A similar survey should be conducted in the final year of SWEEP to see if the objectives of SWEEP have been met for Ontario.

 

 

 

 

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Created: 05-28-1996
Last Revised: Thursday, May 19, 2011 01:01:11 PM