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SWEEP Report #40

Management of Mulch Tillage Systems
on Clay Soils

Researchers: 
G.A. Stewart and T.J. Vyn, Dept. of Crop Science, University of Guelph, Guelph, Ont.

Executive Summary

Evaluation Summary (Tech. Transfer Report Summaries)

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Associated SWEEP/LSP Research

 

 

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Completed: March, 1992

Key Words:

clay loam, silt loam, mulch tillage, corn, soybeans, yield, crop rotation, soil properties, residue cover, chisel plow, moldboard plow, offset disc, yield

Executive Summary

Field experiments were conducted at Lucan (silt loam soil) and at Comber (clay loam soil) in 1991 to evaluate mulch tillage system effects on soil properties and corn growth and yield. At each location two experimental sites were established; one following a previous crop of grain corn and one following soybeans.

The aim of this study was to provide specific recommendations for various mulch tillage systems in regards to the effect of soil moisture content at the time of fall tillage and on the timing of spring secondary tillage within a mulch system. In addition, various tillage equipment was assessed for its impact on soil properties and corn growth following previous crops of corn and soybeans.

Measurements were taken on soil roughness, residue cover, soil moisture, aggregate size distribution, penetrometer resistance and corn growth and yield.

Soil physical properties and crop response were not affected by soil moisture contents at the time of fall tillage when the range between "wet" and "dry" conditions was 2-5% (gravimetric soil moisture). No particular mulch implement appeared to be less suited than others to working in wetter soil conditions.

Harrowing or levelling operations in the fall following chisel plowing and performing secondary tillage earlier in the spring may effectively reduce soil drying rates. However, those practices will probably have a noticeable impact on seedbed conditions only in springs where there are significant and prolonged early spring drying trends.

In general, mulch tillage systems were more suited to corn production in terms of soil conditions and corn yield when soybeans rather than corn was the previous crop. However, following soybeans, nearly all mulch tillage systems reduced residue cover to levels where significant protection from soil erosion will not be provided.

Our recommendations based on this study would be to perform no fall tillage operations following soybeans and to limit tillage in the spring to a minimum.

Following corn, most mulch tillage operations provided adequate soil residue cover but, produce soil physical conditions (coarser seedbeds, greater soil strengths) inferior to those obtained by moldboard plowing. Generally this did not result in lower corn yields on the silt loam soil but on the clay loam soil mulch systems tended to result in corn yields lower than those obtained by moldboard tillage.

This study was conducted over a single season which included some extreme weather conditions and therefore caution should be exercised in drawing conclusions from this data.

Evaluation Summary

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

The aim of this study was to provide specific recommendations in regards to: 1) the effect of soil moisture content at the time of fall primary mulch tillage, 2) the timing of spring secondary tillage within a mulch system and 3) the interaction of the two previously mentioned factors with various tillage implements and depths of operation.

The study was conducted on silt loam and clay loam soils. The fall tillage treatments included no tillage, moldboard plow, offset disc, chisel plow (equipped with sweeps or twisted shovels). All tillage treatments were done under wet and dry conditions (relatively speaking). The twisted shovels were operated at 12 and 15 cm. depths and with or without a levelling harrow. Spring secondary tillage was done with a cultivator.

The tillage implements performed equally well in the wetter conditions. Harrowing or levelling operations in the fall following chisel plowing and performing secondary tillage earlier in the spring may reduce soil drying rates. However, this may only make a difference to the seedbed conditions during an early dry spring.

The mulch tillage systems tested performed better when corn was planted into soybean rather than corn residue. However, the amount of residue left after mulch tilling soybean residue was not sufficient to provide adequate erosion protection. The authors recommend that no fall tillage operations be performed following soybeans and to limit tillage in the spring to a minimum.

Following corn, most mulch tillage operations provided adequate soil residue cover but, produced coarser seedbeds than did moldboard plowing. Generally this did not result in lower corn yields on the silt loam soil, but on the clay loam soil, mulch systems tended to result in corn yields lower than those obtained when moldboard tillage was used.

Comments:

This study set out to answer many of the questions farmers have been asking about mulch tillage. The information gathered after one season seems to suggest that mulch tillage on a clay loam soil may produce lower corn yields. The same system on silt loam soils may not reduce corn yields. Unfortunately this study was only conducted for one growing season making it impossible to draw definite conclusions. Three years of information would have provided more answers to the questions. It does provide some support for the idea that soybean residue requires little tillage to prepare a seedbed. The results bring forth the questions: Is it wise to break the soil to increase the rate of drying and/or to save soil moisture? Does a smooth soil surface dry more uniformly than a rough surface?

Associated SWEEP/LSP Research:

  • LSP 7002 - Management of Fine Textured Poorly Drained Soils for Intensive Agriculture
  • LSP 7006/7007 - Management of Fine Textured Poorly Drained Soils for Intensive Agriculture: Characterization of a Forage Factor - Parts I and II
  • LSP 7012 - Improving the Degraded Structure of Fine Textured Soils with Deep Tillage and Grass and Legume Crops
  • LSP 7013 - Improving the Degraded Structure of a Clay Loam Soil with Deep Tillage and Grass and Legume Crops
  • LSP 7015 - Crop Production With a No-Traffic Tillage System
  • LSP 7019 - Impact of Soil Compaction in the Production of Processing Vegetable and Other Cash Crops

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

(A) Further research is needed in this area in order to overcome some of the reluctance to switching from fall plowing.

 

 

 

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Created: 05-28-1996
Last Revised: Thursday, May 19, 2011 03:07:56 PM