Department of Agricultural and Biosystems Engineering

RIDGE-TILL SYSTEMS

ISU Extension Pub # AE-3053
Author: Mr. Shawn Shouse, Field Specialist- Ag Engineering,
and Dr. Stewart Melvin, Department of Agricultural and Biosystems
Engineering, Iowa State University
Date: 12/90
Content reviewed 4/95 by Dr. Mark Hanna

Ridge-till is a management practice steadily gaining acceptance in Iowa. Its popularity is due largely to its soil and water conserving residue management plus yield potentials generally equal to or exceeding those of no-till (slot planting).

Ridge-till, a variation of till planting, uses a modified cultivator to build large row ridges at layby. These ridges, along with their overlying residue, are left undisturbed until planting time. The planter removes the top of the ridge, exposing a band of clean, moist soil for the new seedbed. No tillage is performed for seedbed preparation. Additional residue disturbance is limited to fertilizer and pesticide placement, and cultivation for inter-row weed control and ridge building.

Benefits

The primary benefits of ridge-till result from minimum disturbance of surface residue. Seedbed tillage is limited to removing ridge tops to expose a 7- to 14-inch strip of soil for planting. High surface residue levels reduce soil erosion from rain drop impact and help prevent surface crusting, resulting in increased moisture infiltration. Residue cover conserves soil moisture and provide a more favorable seedbed condition when ridge tops are removed.

The absence of primary tillage, when accompanied by measures to control soil compaction, helps to build soil structure. After repeated years of ridge tillage, increased soil structure and macropore formation (such as worm holes and root channels) increase water infiltration rates. Large row ridges on contours provide some additional surface storage for rainfall, also increasing infiltration.

On wet soils, high ridges promote seedbed drainage and exposed ridge tops increase soil warming. Clearing residue from the ridge top allows quicker warming of the soil by the sun and may reduce allelopathic (growth inhibiting) effects of heavy residue on early plant growth. Removing a thin layer of soil from the seedbed also may remove many weed seeds from the seedbed strip. While ridges are beneficial in terms of soil erosion control and increased infiltration, they make turning very difficult on end rows and point rows. Nonridged or seeded turn strips and headlands are highly recommended for ridge tilled fields.

Economics

Increases in planter and cultivator fixed cots generally are offset by decreases in fuel, labor, and tillage machinery costs, particularly if existing equipment can be modified. Potential crop yields depend upon cropping sequence and soil type. Studies indicate ridge-till yield potential generally are comparable to conventional tillage systems and equal to or better than no-till (slot planting) under similar conditions, particularly for poorly drained soils. Individual crop yields may vary due to weather conditions.

Planting

In addition to accurately placing the seed, ridge-till planters must remove the ridge tops an guide the planter units on the ridges. These additional functions can be accomplished with specially designed planters or add-on modifications to conventional planters.

Removing the ridge top usually is performed by a disk or sweep-type row cleaner, sometimes preceded by a leading coulter to cut the residue. The row cleaner is set to remove residue and a thin layer of dry soil to expose a clean, level ridge top approximately 7 to 14 inches wide. Disk-type row cleaners may utilize double disks in a "snowplow" configuration or a single horizontal disk operating like a round-nosed sweep.

Guidance must be provided for the planter to keep the row cleaners and planter units operating on top of the existing ridges. Inclined wheels or rollers that follow the ridges generally supply this guidance. They may be attached to each end of the planter frame or to each individual planting unit (see AE-3057, Conservation Tillage -- Planters for Ridge-till).

Fertilization

Fertilizer application for ridge-till systems may consist of broadcast, starter, split applications, or a combination of these. Placement of liquid or dry fertilizer generally is accomplished by 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 nitrogen 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

Weed control in ridge-till systems generally involves a combination of herbicides and mechanical cultivation. Because of the lack of tillage for chemical incorporation, herbicide selection is limited to preemergence and postemergence products. Weed growth in the row is removed at planting. If weed growth in the row middles is heavy, or first cultivation will be delayed, a chemical burndown treatment of the row middles may be beneficial.

Cultivators for ridge-till must be designed with sufficient clearance and weight to operate in heavy residue and have provisions for ridge building during the last cultivation (see AE-3055, Conservation Tillage--Cultivators for No-till and Ridge-till).

Ridge Building

Success of the ridge-till system depends upon construction of large row ridges on which to plant the following crop. Cultivators for ridge-till are equipped with disk hillers or ridging wings that throw soil from the row middle into a ridge along the crop row. Ridging attachments are removed or adjusted for early cultivation to avoid burying young plants.

Summary

Ridge-till systems use special cultivation and planting equipment to plant the crop in a narrow, clean strip on top of the previous crop ridges. Major benefits are associated with increased soil conservation due to residue preservation and potential for reduced input costs. Ridges can make turning very difficult on end rows and points rows. Yield potentials depend upon soil conditions and appropriate management practices, and generally are equal to or greater than no-till. In appropriate conditions, ridge-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-305l Conservation Tillage--Effects of 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

Prepared by Shawn Shouse, extension soil and water engineering specialist, Southwest Area
Author: Shawn Shouse, Extension soil and water engineering spec.
Dept. of Agricultural and Biosystems Engineering, Iowa State Univ.

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