ECOLOGICALLY-SOUND PEST, WATER AND SOIL MANAGEMENT STRATEGIES FOR NORTHERN GREAT PLAINS CROPPING SYSTEMS
Location: Agricultural Systems Research Unit
Title: Where does Strip Tillage Fit in Montana and Wyoming Sugarbeet Production
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: January 7, 2009
Publication Date: January 12, 2009
Citation: Stevens, W.B., Evans, R.G., Iversen, W.M. 2009. Where does Strip Tillage Fit in Montana and Wyoming Sugarbeet Production [Abstract]. 36-40.
Sugarbeet in Montana and Wyoming is often grown in a two year rotation alternating with spring grains. Normally, a sugarbeet grower will make five or more passes across a field for fertilizer application, disking, plowing or ripping, leveling, mulching and hilling. The high price of diesel fuel is making the conventional land preparation system unsustainable in the Lower Yellowstone Valley region where 2008 production costs are estimated to be about $900/ac for sugarbeet, mostly due to high fertilizer, chemical and fuel costs.
Because of the high cost of intensive tillage along with frequent stand loss due to blowing soil, interest in some type of strip till for sugarbeet has been strong for many years. However, relatively little work has been done on strip tillage of sugarbeet over the last 20 to 25 years for both practical and technical reasons even though its potential has been widely recognized. Although there has been no single great breakthrough, several advances in herbicides, irrigation technologies, tillage and planting equipment, and the success of strip tillage for large seeded crops have given rise to the idea that many of the difficulties faced by earlier attempts with sugarbeet could be overcome, and the potential benefits made it worth another look.
There is an increasing amount of sugarbeet production under self-propelled center pivot irrigation due to reduced labor availability and other considerations. We recently completed a study on the interaction between irrigation method and tillage on two-year, overhead sprinkler irrigated sugarbeet-malt barley crop rotations at the Montana State University Eastern Agricultural Research Center farm (10 ac) near Sidney, MT. We expected that strip tillage techniques would work well under sprinkler irrigation with flat planting sugarbeet, and it was included in this study because it reduces the number of equipment passes compared to the raised bed systems, which are not needed under sprinklers. This research showed that flat planting with standing stubble combined with the tilled strips can provide the same or increased benefits of wind erosion control and improved soil water levels at the surface as the commonly used bedding system.
Five years of results have shown that strip tillage will produce yields comparable to conventionally tilled sugarbeet in the Lower Yellowstone River Valley. In addition, the presence of standing small grain residue before each sugarbeet crop potentially makes strip tillage a viable way to reduce the risk of crop damage due to soil erosion by wind in the spring. This is an attribute that should make irrigated sugarbeet rotations eligible for USDA conservation programs such as CSP, as well as an acceptable practice for required NRCS farm conservation plans. It should also be noted that the strip tillage treatment doesn’t require any more tillage than the conventional tillage following sugarbeet harvest before the succeeding barley crop.
One of the central tenets of this research is that strip tillage is not just a minimum tillage technique. It affects the tractor, planting, cultivation and harvesting equipment. Fertilization amounts, timing and placement may have to be altered. Use of strip tillers in sugarbeet rotations after small grains will also require some changes to planting and cultivation equipment and practices to handle the high residue levels. Herbicide and other pest control programs may also have to be modified to be effective in high residue conditions. Beet harvesters may require some adjustments in very heavy soils if residue and mud build up on rollers. Therefore, strip tillage must be considered as an integral part of an entire cultural system that minimizes equipment passes through the field.
High level guidance of the strip tiller and subsequent operations is especially critical if each operation is done separately. Mechanical or hydraulically assisted RTK-GPS guidance is highly recommended for both the tiller and the planter to ensure accurate placement of both fertilizer and seed within the strip. However, if strip till, fertilizing and planting are being done in one operation in the spring, the high level guidance systems are probably not necessary.
Maintaining standing stubble is desired for wind erosion control and to trap snow in the winter. Standing stubble probably should be at least 15 cm (6 inches) or higher and needs to be sustained until the beets are sufficiently large to withstand spring wind storms. Due to non-uniform residue deposition by the combine and wind, row cleaners or “trash whippers” are recommended for the strip tiller to remove lose residue and avoid plugging. If planting is done as a separate operation, row cleaners are also recommended for the planter as well because some residue will have been moved back onto the tilled strips by wind. A straw and chaff spreader on the combine is highly recommended to ensure uniform residue cover and avoid wet spots in the spring as well as to avoid plugging of tillage and planting equipment by piles of residue.
Strip tillage is not a method that enhances weed control. Prior to Roundup Ready® sugarbeet, weed control programs couldn’t rely solely on herbicides to keep the fields clean. Control of weeds impacted by wheel traffic seems to be especially difficult for herbicides. Growers need to cultivate under strip till should use equipment designed for high residue conditions.
Snow catch across a field also appears to be much more uniformly distributed under fall strip tillage compared to conventional fall tillage. Measured surface soil moisture (top 15 cm) is higher in strip tilled plots and more uniform compared to adjacent conventional till plots. This may save an irrigation to get the beets germinated and avoid crusting problems. Emergence data shows that sugarbeet in a dry spring get a better start with strip till.
Heavy soils must be worked at a medium moisture level in the fall to get a good seedbed under strip till. If it is worked too wet the shank merely cuts a slot, and if it’s too dry the clods don’t break down. Completing the strip till operation in the fall allows the strips to settle and collect moisture for better seed germination. The window of opportunity for tillage in the spring can be very short, but strip till on sandy soils should produced satisfactory conditions.
Strip till also requires a planter designed for high residue conditions and equipped with toothed-wheel row cleaners or “trash-whippers” on the front to lightly clear off loose surface residues that may have blown into the tilled area over the winter to avoid any “hair pinning” of straw that might create undesirable air spaces near the sugarbeet seeds. It was determined that the planter’s seeding depth gauge wheels should be very close to the point of seed drop. Planters that control the seeding depth by use of a packer wheel 20 cm (8 inches) or more behind the point of seed drop may have difficulty in consistently placing the seed at the required shallow depths because of the undulations of the strip tilled seed bed.
We feel that strip tillage fits well in the typical sugarbeet-small grains rotations of Montana and Wyoming, especially where protecting seedlings from wind-blown soil is a major concern. To date, this research has been conducted only on sprinkler irrigated sugarbeet, but we believe that these techniques, or modifications thereof, should also work on furrow irrigated fields. Some growers are already trying this and it should perform well with sufficient slope (e.g., 0.3% or greater) and if the cut straw is removed from the field following small grain harvest while leaving the standing stubble. Other irrigation parameters such as length of run and soil type would also impact the success of furrow irrigation. Furrow forming equipment may have to be a combination of a high trash cultivator and special shovels and forming tools. The retarding effect of the residue on irri