Tillage in 2001: Consider the options

Implementing a new tillage strategy in 2001 takes planning, and now is the perfect time to start. How you manage residue and tillage during and immediately after this year's harvest can influence the effectiveness of next year's tillage operations a great deal, especially if you plan to move to a conservation tillage system such as ridge-till, strip-till, or no-till. Conservation tillage practices not only help keep soil in place and improve water quality but also help conserve moisture.

Each tillage practice has distinct advantages and disadvantages, requires specific equipment investments, and requires that you learn how to successfully implement the practice in your operation. In this article, we discuss the merits of one of these tillage practices that has been widely used--ridge-tillage--and present some of the facts you need to consider as a producer to implement this tillage practice.

Ridge-tillage is a conservation tillage option for farmers with almost any operation. Crop residue from the previous year's harvest remains on the soil's surface after harvest until planting (unless nutrients are injected). The crop residue protects and stubble limits the impact of wind and water erosion over the fall, winter, and early spring. In some areas, where conservation of moisture is an issue, ridge-tillage is an excellent system for enhancing soil moisture storage and harvesting water from snow during the winter.

In the spring, crops are planted on ridges that stand 4 to 6 inches above the surface of the surrounding field. The ridges are exposed and the dark soil helps them warm more quickly than the surrounding soil. Warmer soils accelerate germination and crop growth, improving yields and providing other benefits such as a quickly established crop canopy.

Time line planning for ridge-tillage

Ridges are normally formed during second cultivation in the preceding crop year. If ridge-tillage will be done in 2001, but ridges have not been built, consider using a row crop cultivator after fall harvest so that ridges will have a chance to settle and weather over winter.

Ridge-tillage activities include leaving the crop stubble and residue on the field's surface at harvest to overwinter. The next operation is ridge top removal and planting with a sweep or row cleaner, and planting the seed on top of the ridge.

After the crop emerges, nitrogen is applied as a side-dress. Two cultivation passes are required to manage weed populations. The cultivator should be run fairly deep on the first pass to control weeds and loosen the soil. The final cultivator pass should be a secondary weed control pass and build the soil into a rounded or flat-topped ridge.

Advantages of ridge-tillage

The soil warms faster with ridge-tilling than with no-till, helping seeds germinate faster, and hastening plant growth. Ridge-tillage allows for increased water infiltration and reduced runoff, as well as less evaporation. A "dry zone" is created by the ridges--water drains off the ridge and leaf canopy to fall between the rows, where the soil is protected by crop residues. Nutrients can be applied in the dry zone (the shoulder of the ridge), and pesticides can be banded on the ridge. With dry zone nutrient application, nutrients are less likely to run off the field and enter streams and other water bodies. Therefore, a major advantage of ridge-tillage is that it helps to overcome the concern of cool, wet soils at planting.

Banding pesticides on the ridge helps reduce pesticide loading on the field, and limits runoff of pesticide-loaded water. Ridge-tillage also leaves sufficient potential residue cover after planting, with at least 30 percent of the soil surface remaining covered by residue after planting, and only about one-third of the soil's surface disturbed at planting. When the crop is planted, the residue is moved to the furrows, but is moved back to the ridge crest during the ridging operation.

Disadvantages of ridge-tillage

Ridge-tillage requires specially designed equipment, such as a ridge cultivator or ridge planter, and precise wheel spacing. Because it requires two cultivation passes, it also requires more time and is more labor-intensive, and the size of some producers' operations may limit their ability to implement the practice.

Managing fertility is a challenge in ridge-tillage systems, especially with immobile nutrients and lime. Nutrient application is also a challenge, And if broadcast applied, phosphorus and potassium have a tendency to become stratified in the first 12 inches of soil. To address these problems, it is recommended that you take soil samples from both the ridge shoulder and the row to a depth of 6 to 8 inches. Weed management also depends on timely cultivation and the effectiveness of banded herbicides.

Ridge-tillage requires a specialized set of equipment to build, work with, and maintain the ridge. Often, the equipment and the producer performs more than one operation in a pass through the field. The equipment and tool bar must be properly equipped and adjusted to avoid disrupting the ridge. Planters in ridge-tillage must be able to cut residue, penetrate the soil to the desired depth, and provide proper seed-to-soil contact. Most planters are outfitted with a ridge-cleaning device that clears crop residue, while leaving soil on top of the ridge. Some examples of ridge-cleaning devices used include disk furrowers, steel spider wheels, wide sweeps, or horizontal disks. Cultivators are used to control weeds and rebuild or shape the ridges.

Summary

Ridge-tillage is a conservation option that many Iowa producers could incorporate into their operations to control inputs, improve water quality, conserve moisture, and reduce soil erosion, while not sacrificing yield. It has limitations, but if it is the right fit, it can provide many benefits.

This article originally appeared on pages 150-152 of the IC-484(20) -- August 7, 2000 issue.