Department of Agricultural and Biosystems Engineering

CONSERVATION TILLAGE NO-TILL SYSTEMS

ISU Extension Pub # AE-3052
Author: Mr. Shawn Shouse, Field Specialist - Agricultural Engineering
Department of Agricultural and Biosystems Engineering, Iowa State University
Date: 12/90
Content reviewed 4/95 by Dr. Mark Hanna

No-till farming, perhaps more accurately described as slot planting, is an increasing prevalent management practice in row- crop farming. Used in conjunction with other measures such as contouring, terracing, or crop rotations, no-till often is chosen to meet soil conservation requirements on highly erodible land.

As the name implies, no-till (or slot planting) involves planting a crop in a narrow slot that is opened by the planter with minimal disturbance of the surface crop residue. No additional tillage is done for seedbed preparation. Additional soil and residue disturbance is limited to fertilizer and pesticide placement and possibly cultivation for weed control, if necessary. This system leads to maximum residue preservation and corresponding reduction in soil erosion by raindrop impact.

Benefits

No-till is beneficial because the soil and its overlying residue are not disturbed. The absence of primary tillage, when accompanied by measures to control soil compaction, helps to build soil structure. After repeated years of no-till, increased soil structure and macropore formation (such as worm holes and root channels) increase water infiltration rates. Undisturbed surface residue greatly reduces soil erosion from raindrop impact and helps prevent surface crusting. Resulting increased water infiltration rates and decreased surface evaporation rates add to plant- available moisture levels.

Economics

Increases in planter fixed costs and possibly herbicide costs generally are offset by reduced fuel, labor, and machinery costs resulting from reduced tillage needs. Potential crop yields depend upon cropping sequence and soil types. Table 1 shows the general trends indicated over many years in various Iowa studies. Individual crops may vary due to weather conditions.

Economic inputs and returns tend to indicate that no-till systems have the most profit potential on soils that would benefit most from increased soil conservation.

Planting

Planters for no-till must be capable of accurately placing the seeds through the overlying residue cover and into the soil with minimum residue disturbance. Generally, this is accomplished with a rolling coulter leading either a disk- or shoe-type seed opener. The leading coulter slices through the residue to allow furrow opening without burying residue. In some conditions, such as evenly spread soybean residue, leading coulters are not necessary on planters with disk openers.

Planter units may or may not follow the previous crop rows. However, soil seedbed conditions generally are more favorable on top of the previous row because of reduced traffic and compaction. When following previous corn rows or planting in heavy residue, double disk row cleaners sometimes are used to move some of the residue away from the seed opener path.

Fertilization

Fertilizer application for no-till systems may consist of broadcast, starter, split applications, or a combination of these. Placement of liquid or dry fertilizer usually is accomplished using disk openers or a rolling coulter followed by a knife applicator. In some cases, split application of nitrogen may be applied during cultivation and covered with soil by the cultivator sweeps to reduce loss. Anhydrous ammonia application may be limited by the desire for minimum residue disturbance (see AE-3054, Conservation Tillage--Fertility Practices and Equipment for no-till and Ridge-till).

Weed Control

Suitable weed control may be the most challenging facet of no-till systems. Because of the lack of tillage for chemical incorporating, herbicide choices are more limited than with conventional tillage. Lack of tillage also permits weed growth to begin before crop growth, sometimes making a chemical burndown treatment necessary. Preemergence and postemergence herbicides are available to control most weeds in corn and soybeans. Special weed control strategies, differing from conventional systems, must be applied.

Summary

No-till (slot planting) systems use special equipment to place seed and fertilizer with minimum disturbance of surface residue. Major benefits are increased soil conservation and potential for reduced input costs. Yield potential depends greatly upon soil conditions and strict attention to appropriate management practices. In appropriate soil conditions, no-till can be an excellent choice for soil conservation in a row crop system.

For more information on conservation tillage systems, see the following publications:

AE-3049 Conservation Tillage--Planning
AE-3050 Conservation Tillage--Effects on Soil Erosion
AE-3051 Conservation Tillage--Effects on Water Quality
AE-3052 Conservation Tillage--No-till Systems
AE-3053 Conservation Tillage--Ridge-till Systems
AE-3054 Conservation Tillage--Fertility Practices and Equipment for No-till and Ridge-till
AE-3055 Conservation Tillage--Cultivators for No-till and Ridge-till
AE-3056 Conservation Tillage--Planters for No-till
AE-3057 Conservation Tillage--Planters for Ridge-till

Table l. Yield potential for no-till relative conventional tillage in Iowa.

Author: Shawn Shouse, extension soil and water engineering specialistDept. of Agricultural and Biosystems Engineering, Iowa State Univ.

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