Extension Communications
Extension 4-H Youth Building
Ames, Iowa 50011-3630
(515) 294-9915
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Extension Communications |
4/14/04
Contacts:
Mahdi Al-Kaisi, Agronomy, (515) 294-1923, malkaisi@iastate.edu
Mark Hanna, Ag and Biosystems Engineering, (515) 294-0468, hmhanna@iastate.edu
Jean McGuire, Continuing Education and Communication Services, (515) 294-7033,
jmcguire@iastate.edu
Tillage Implement Design and Its Effect on Soil
AMES, Iowa - The weather is improving, and some Iowa producers have already started fieldwork. However, there is still time to finalize preparation of tillage implements for spring fieldwork. Consider checking and evaluating the design of soil-engaging components of your tillage implements, assessing the potential for soil erosion and thinking about what should be done to produce a successful crop.
No matter what the goal for spring tillage -- spreading residue evenly, preparing the seed bed, incorporating herbicides, or preparing for the next crop in rotation -- a properly adjusted and used tillage implement will result in fewer trips to the field, better management of the quality and performance of the crop, and, hopefully, lower potential erosion.
Straight, narrow teeth, or shanks (2 inches wide), on a chisel plow allow for deep penetration into the soil, with the least turning of soil and burying of residue of any primary tillage implement. Changing to twisted shanks increases soil mixing, buries more residues and leaves the soil exposed to erosion.
Recently, deep rippers have been the source of much discussion and research. If deep ripping is used for treating real soil compaction, it should be used in dry soil. Therefore, this operation may be best suited as a fall practice rather than a spring practice. Very narrow blades or shanks fracture the soil in planes running from the tip diagonally to the soil surface, breaking the compacted soil layer and allowing heavily rooted plants to gain greater access to subsoil moisture and nutrients.
Primary tillage is focused on soil fracturing so it will destroy soil structure and bury a great deal of crop residue -- particularly those fragile ones such as soybean residue -- leaving the soil exposed to erosion. Primary tillage operations should be the last choice when improving soil productivity.
When it comes to secondary tillage -- preparing the soil seedbed for planting -- most farmers use a field cultivator. Field cultivators come equipped with a variety of soil-engaging points, from narrow tines to wider shovels and sweeps.
Tines, shovels and sweeps come in many shapes and sizes. The shape determines what the soil-engaging points do in the soil. Narrow tines tend to fracture the soil, and wider sweeps tend to lift and mix surface soil and residue and are commonly used for chemical incorporation. Setting a blade at a sharper angle (or pitch) usually means more soil will be disturbed. Implement weight is supported by the underlying soil. Therefore, wet and nearly saturated soil can be compacted underneath the secondary tillage.
Shank spacing on the implement, as well as operating speed and operational depth, all influence how much residue will be buried by any tillage implement. Increased depth and, to some extent, faster speeds translate into more soil being thrown over the crop residue.
Consistency in maintaining the soil-engaging points on tillage equipment is also important. Proper adjustment of only half of the blades on any implement means the implement will be only 50 percent effective in each tillage pass. Therefore, proper maintenance and adjustment are keys to achieving the desired results. It is well worth the time it takes to properly set up, test and adjust the equipment, and check it daily, rather than just rolling hard and fast through the season, trusting to luck.
Knowing your tillage implements and their settings can go a long way in establishing a good seedbed, sufficient seed-to-soil contact and hardier and more profitable crops. These techniques require fewer trips through the field, more efficiently use fertilizers and leave the soil better prepared to withstand erosion.
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Funding support provided by USDA Natural Resource Conservation Service through Cooperative Agreement No. 74-6114-10-03.
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