Agronomy Library > Soil Conservation

20 Years of Conservation Tillage - What Have We Learned?
Author: Wayne Lindwall, Agriculture and Agri-Food Canada
Date Created: January 20, 1998
Last Reviewed: March 25, 2003

Source: Alberta Conservation Tillage Society 1998 AgriFuture Proceedings.

Water Use Efficiency and Crop Yield
Stubble height is not only important for trapping snow and increasing overwinter moisture conservation but tall stubble improves water use efficiency and crop development during the growing season as well.

Long-term NT effects on crop nitrogen use efficiency are more important than long-term NT effects on crop water use efficiency. These effects vary with soil texture and length of time under NT. Yields under NT can increase, decrease or stay the same with time.

Tillage is not necessarily bad. For many producers in the Brown soil zone a reduced tillage system with timely herbicide application may be the most practical and economical.

Importance of Crop Sequence or Rotation
Diversified extended rotations work well with NT and NT works well with diversified extended rotations. Establishment and early growth of most crops are not adversely affected by NT.

Weed and Disease Control
Most published research to date would indicate that crop rotation and weather have a greater impact on pest problems (weed, disease and insects) than tillage systems. Crop rotation or the inclusion of oilseed and pulse crops with cereals will help-minimize the risk of pest problems with conservation tillage or direct seeding systems and rotation of herbicide use will reduce risk of herbicide resistance as well.

Equipment Development
The best seeding system or row spacing will likely continue to depend on soil zone and predominant moisture conditions.

Closing the crop canopy as quickly as possible and thoroughly exploiting nutrients and water in the inter-row area are key to maximizing the efficiency of crop water use.

The combine is still the best machine for distributing crop residue uniformly and with the variety of straw spreaders that are now available this should not be a major issue or limitation in most situations. However, the debate will likely continue regarding the optimum height of stubble and how much straw or chaff needs to be returned to the land in the interest of organic matter sustainability and erosion protection.

Soil Fertility (Soil Quality) Considerations
No-till does slow N mineralization and that optimum fertilization is more critical with no-till than with conventional tillage systems. However, more importantly no-till can increase soil C and support a potentially higher level of productivity than conventional tillage systems. But, crop rotation or cropping intensity will have a greater impact on soil quality and soil C content than the tillage system used.

Soils under minimal disturbance (direct seeding) receiving adequate annual inputs of C and N can increase soil organic matter and function, therefore, as net sinks of atmospheric CO2.

Economic and Energy Inputs
Total herbicide and fuel cost is much less for zero and minimum tillage than for conventional tillage.

Fertilizer inputs (particularly nitrogen) are the most significant economic and energy inputs in most intensive farming systems on the prairies. Adequate fertilizer inputs are probably the most important and cost effective farm inputs in terms of sustainability and productivity. However, producers can reduce their inorganic fertilizer inputs by including N-fixing legumes in their crop rotations and by applying livestock manures when the opportunity arises.

Other Environmental and Soil Biological Issues
Zero till and direct seeded fields are more biologically active than conventionally till fields.

2,4-D residues disappeared much more rapidly on no-till plots compared to conventionally tilled plots, presumably because of increased biological activity with no-till.

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