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SWEEP Report #13

The Effect of Moldboard Shape on the Residue Management
Potential of the Moldboard Plow

J. Sadler Richards, Conservation Management Systems, Ecologistics Limited, Waterloo, Ontario

Executive Summary

Evaluation Summary (Tech. Transfer Report Summaries)

Associated SWEEP/LSP Research

View / Download Final Report  [2512 KB pdf]



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Completed: July, 1990

Key Words:

moldboard plow, conservation tillage, modified moldboard plow, residue management

Executive Summary

The erosion of agricultural land and the associated pollution of Lake Erie with sediment and phosphorus have been identified as major agronomic and environmental problems in Ontario. Of the several methods available to control soil erosion and phosphorus movement, conservation tillage systems are rated among the best. A need exists for a conservation tillage system that will maintain crop yield and provide adequate residue cover.

Fall weather conditions in Ontario often prolong harvest and fall primary tillage is done in excessively wet soil. Under these conditions the moldboard plough has been and will likely continue to be the implement of choice for many farmers. The main problem in using the moldboard plough is that the implement tends to bury almost all residue from the previous crop. As a result the potential for controlling soil erosion is considered poor. Little work has been done to improve this performance.

In order to understand and determine the potential for using the moldboard plough as a conservation tillage tool, two approaches were examined. The first included documenting the relative amounts of residue cover obtained after ploughing cereal and grain corn stubble with three commercially available shapes and makes of moldboards. The second approach, incorporated into the same research trial, involved studying the residue management capabilities of different configurations of the modified moldboard plough as first used by Vyn, Daynard and Ketcheson.

The modified moldboard trial was located on three different sites in Essex county. Site 1 was located on cereal stubble on a clay soil located near Comber, Ontario. Sites 2 and 3 were located on grain corn stubble on clay loam soils near Harrow, Ontario.

The trial was set up as a split-plot design consisting of four replications. The main plot treatments included three of the most popular commercially available shapes and makes of moldboards and moldboard ploughs. The three plough makes selected were Overum, White and John Deere. The subplot treatments consisted of three modifications (cuts) to the moldboard shape and one control (full size moldboard).

Soil surface residue cover data were collected at four different times within the project time frame. They included: before ploughing (Fall '88); after ploughing (Fall '88); after spring run-off (early Spring '89); and after planting (Spring and Summer '89). Prior to treatment implementation it was found that, in general, Site 2 had 13 percent less residue cover than Sites 1 and 3. All sites had an average residue cover above 80 percent.

In general, the third cut on all three types of ploughs left the greatest amount of residue in fall after the ploughing treatments were implemented in spring, after run-off, at all sites.

As a result of abnormal weather in Essex county in the spring and summer of 1989 the seedbed was prepared twice at Sites 2 and 3. This probably caused some residue to be destroyed, buried or moved out of the plot area, thus influencing the amount of residue left after planting. The amount of soil surface residue left after planting for all sites was well below the Ontario benchmark of 20 percent cover needed for erosion control.

When after-planting soil residue cover was measured it was found that on Site 1 the third cut on the moldboards for all three plough makes and the second cut on the White plough left significantly more residue cover. At Site 2 the White first cut treatment and at Site 3 the John Deere second cut treatment left significantly more residue than other treatments.

Moldboard draft was measured using a unit designed and built by the Ontario Centre for Farm Machinery and Food Processing Technology (OCFMFPT) that was mounted between the tractor hitch and the plough. Two load cells measured the pull in the left and right lower links of the tractor's 3-point hitch. It should be noted that for each plough make one side of the linkage to the tractor (right hand link for the Overum, left hand link for the White and John Deere) pulled with greater pounds force than the other side of the linkage regardless of the moldboard shape. The magnitude of the difference in pull varied somewhat between moldboard cuts and was not always greater as more cuts were made relative to the pull recorded for full size moldboards.

Volumetric soil moisture content was measured using a device called IRAMS and a Campbell Pacific Nuclea Portaprobe. The moisture content was measured on the day of ploughing (all sites) and the day of planting (Sites 2 and 3). The volumetric soil moisture content on the day of ploughing and the day of planting were quite similar among treatment plots within each site. As a result the potential effect of soil moisture content on other parameters measured was considered equal across all treatments.

The soil surface conditions after ploughing were visually assessed after all ploughing treatments were implemented. The conditions tended to be relatively even and smooth for all moldboard treatments except the third cut treatment across all three sites.

Soybean plant emergence and vegetative growth stage data were collected at the cereal stubble site (Site 1) but heavy rains and crusting experienced in Essex county may have influenced these site-specific results.

After one year of study the following conclusions were made:

  1. Soil residue cover left after ploughing and spring run-off tended to increase as a greater portion of the moldboards was removed .

  2. Soil surface smoothness after ploughing tended to decline as a greater portion of the moldboards was removed.

  3. At a furrow width of 16 inches, maintenance of a 6 inch ploughing depth became more difficult as a greater portion of the moldboards was removed.

  4. Although the magnitude of the increase in residue cover left on the soil surface after ploughing with modified moldboards was substantial at two of the three sites, the actual amount of residue cover remaining after ploughing and spring run-off tended to be slightly less or within 20 to 30 percent.

  5. For the Overum and John Deere ploughs, the specific draft tended to decline as a greater portion of the moldboards was removed. Specific draft of the White plough tended to increase at the two of three sites.

Evaluation Summary

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

A one year modified moldboard plow trial was conducted comparing three makes of plows. Since standard plows were designed to bury all surface residue, each plow was modified by removing a portion of the moldboard bottom to retain surface residue. The objective of the trial was to document the potential for a modified moldboard plow to attain a minimum of 20% of the soil surface covered with residue after planting.

The reasons for using the moldboard plow in this study are as follows: (i) it is a low cost modification; (ii) it is easily integrated with most operations; and (iii) no significant loss in yield is anticipated.

Three makes of plows were evaluated in the study with three cuts to each plow. Numerous measurements were taken in each plot - after primary tillage, secondary tillage and after planting. The trials were conducted on clay loam and clay soils in three locations and two different crops.

Although after primary tillage 20-30% residue levels were attained, none of the plows were able to meet the minimum 20% after-planting guidelines necessary to qualify them as conservation tillage systems.



  • the smaller the moldboard the more residue left after plowing


  • modified moldboard plow fails to achieve the minimum 20% residue cover after planting

  • the smaller the moldboard the rougher the soil surface after plowing

  • study reveals some of the changes in draft which may be encountered when modifying the moldboard plow

Associated SWEEP/LSP Research:

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

None required.




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Created: 05-28-1996
Last Revised: Thursday, May 19, 2011 01:46:34 PM