Department of Agricultural and Biosystems Engineering

CONSERVATION TILLAGE PLANTERS FOR NO-TILL

ISU Extension Pub # AE-3056
Author: Dr. Mark Hanna and Mr. Jeff Lorimor, Department of
Agricultural and Biosystems Engineering, Iowa State University
Date: 11/90
Content reviewed 4/95 by Dr. Mark Hanna

No-till is an excellent cultural system for erosion control. No- till often is called slot till because a narrow slot is opened during planting. All planters actually do at least some tillage during planting.

Equipment

Most newer, heavy frame conventional planters with double disk openers can plant into untilled soybean stubble without additional equipment. Some type of rolling seed covering mechanism (disks, press wheels) other than knives should be used.

Coulters

Planting into cornstalks or a forage crop usually requires a coulter mounted ahead of the seed opener. Mounting the coulter on the planter unit is preferred for a close linkage with depth of the individual seed openers. A second option is to mount the coulter on the planter frame.

Various types of coulters are used. Straight coulters cut residue with minimum tillage. Used with a depth band, they control depth of a slot opener shoe on one manufacturer's model. Smooth coulters often are salvages and used for on-farm modifications.

Ripple coulters have a small wave in them, about 1 inch. When the ripple is just inside the circumference of a smooth edge, they often are called bubble coulters. This style is popular since little tillage is needed when the coulter is mounted just ahead of double disk openers.

Fluted coulters have a wide wave on the edge, about 2.5 inches. They often are used if the coulter must be mounted 2 to 3 feet ahead of the opener so that the opener may follow in tilled soil. An aggressive tiller, the fluted coulter can throw soil out of the seed furrow at speed greater than about 5 mph or if soil is too moist. Be prepared to slow down, or experiment without the coulter. Iowa State University tests have shown little difference between the action of different diameter coulters.

One exception to using leading coulters is using a planter with staggered double disk openers to cut out corn stubs. Avoid moving soil with these row cleaners when not tilling, so planting will not be done in a furrow.

Weights

Heavier frame planters made in recent years have down-pressure springs to transfer enough weight for coulters and seed openers to cut residue and penetrate the soil. Down-pressure kits for older planters often are available from suppliers. Additional weight (if needed) may be added by filling fertilizer and pesticide boxes or by using cast iron weights.

Additional weight often is added to markers, but is not necessary if foam is used or when using old rows as a guide. Even if additional weights are used, marks are difficult to see in standing sod.

Management

Use a combine chopper or straw spreader during harvest. Avoid stopping in the middle of the field if possible to limit troublesome residue piles during planting the following spring. Avoid planting before the soil is ready. It is important to stay off the soil when it is too wet.

Untilled soil is hard to penetrate. Soil will try to float each disk or coulter out of the ground. As more points try to enter the soil at greater depth (such as fertilizer openers), additional downward force is required to maintain depth. Weight requirements increase for both depth and number of coulters. Research at Iowa State University has shown that 400 pounds per coulter or more may be required. If planter fertilizer application is desired, consider using forward swept knifes behind leading coulters to help counter upward flotation.

Coulter depth should be set at seed depth to « inch below seed depth. Although a coulter is necessary for most cornstalk and sod situations, be flexible. If soil is being thrown and residue can be handled without it, experiment without a coulter.

Coulters may throw early preplant herbicides out of the row causing weed breakthroughs in the row. The second pass of a split application with the herbicide banded over the row can catch many of these breakthroughs.

For planters used conventionally on some acres and no-till on others, don't expect to just add coulters and plant. Recheck depth and other settings. Depth wheels may roll over residue or harder soil causing shallow planting. Untilled soil does not compact or behave as does tilled soil.

Wide or long planter frames are hazardous during transport. Red reflectors are suggested for extreme left and right rear corners as well as an amber reflector on the extreme left front corner. A SMV sign should be clearly visible. Beware of overhead power lines with folding wing equipment.

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

Authors: Mark Hanna and Jeff Lorimor
Dept. of Agricultural and Biosystems Engineering, Iowa State

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