Agronomy Library > Winter Annuals/Other

Residue Management Strategies are an Important Part of the Farm Business Strategy
Author: Murray Green
Date Created: June 20, 2003
Last Reviewed: February 23, 2007

Direct seeding, or as some farmers call it, No Till farming, is a major step toward sustainable crop production. But direct seeding requires some planning to help to make the best net return from farm inputs. Is a plan in place on your farm to deal with the affect that the residue left on the land after harvest will have on the planting conditions for 2004? 

Residue management should be part of the planning of your annual cropping system. It is the part of the system that ensures the field surface in the spring will be in good condition for subsequent equipment operations and for growth of the next crop. A farm management strategy for handling crop residue has three goals:
-Uniform and consistent soil conditions and residue cover across the field.
-The planter must be able to clear through the residue present on the field.
-Placement of the seed through crop residue into the best possible seed bed conditions.
 
Uniform and consistent soil conditions across the field.
Why is a uniform distribution of old crop residue important?
 
• A significant difference in the seed bed moisture will occur where there is a large variation in residue cover.
• Large variations in seed bed temperature will exist between the covered and not covered areas. This may affect both germination and early seedling development.
• The ground opener may not be able to keep heavy residue from falling back and covering the seed row. This may result in gaps in the seed row.
• Piles of straw or uneven residue could cause plugging between the shanks. The machine must pull around and start again causing a reduction in field efficiency. 

Residue clearance through the planter
How well the planter handles residue depends on the type of crop, the amount of residue, how it is spread, and the design of the planter. In order to clear residue through the planter, it is sometimes recommended that the stubble height be no more than the width of the planter's shank spacing. Taller stubble will always be flattened for some reason in some areas of the field, and will be a problem in the spring. Stubble too tall to pass through the planter can be mowed if necessary in the spring, but at a cost of 5 to 7 dollars per acre. Compared to combining which costs about 2 dollars per acre more to cut 200 mm (8 inch) stubble instead of 350 mm * (14 inch), it makes sense to plan your residue management with the harvest system. 

Stubble height and its condition is of little concern for some types of planters. Coulter equipped planters and disc type openers will handle most residue situations, even after stripper headers. Another device being tested is called a residue manager. At this time, residue managers show some promise, but test results to prove if they improve plant emergence are not conclusive. 

Generally, residue problems are not consistent across a field. Problems frequently occur in just a small area of the field such as lodged crop areas or where the combine header was not low enough to cut all the pea vines, or, maybe in an "alien crop circle". If this causes the planter operator to have to pull around and unplug the machine more than a few times in a field, something needs to be done about it. One could harrow lodged crop areas to try to break up the residue, but not in pea stubble! If the problem exists on only 2 or 3 acres in 80, then a tandem disc on those few acres would be the quick solution, assuming a disc still exists on the farm. Having experienced this problem once, most direct seeders take the time with the combine to make sure those problem areas are picked up during harvest. 

Part of the crop residue in heavy residue areas could be removed. If there is a demand for livestock feed and bedding then an opportunity exists to both generate revenue and to solve the residue problem.
 
Seed placement through crop residue
Placing seed at the proper location in the seed bed is likely the most important task any piece of farm machinery has is to do. So it is logical that this task should receive the greatest attention by an operator. In some ways planting is made easier in a direct seeding program. Residue and stubble cover help to preserve soil moisture close to the surface. In other ways, all too well known to direct seeders, the task can be a monumental if the straw and chaff hasn't been spread properly. 

The surface residue has considerable influence on whether or not the ground opener can do its job. An even spread of residue, particularly the chaff from the combine shoe, is important to keep the depth to soil moisture consistent over the field. The openers can then be set to place the seed at least a half an inch into the seed bed moisture. If the variation of depth to moisture is too great, then if the openers are adjusted deep enough in the drier places, they are too deep in the areas where there is residue cover that has maintained shallow soil moisture; where the soil is possibly quite cold as well.
A thinner layer of residue on the surface will help to prevent straw and chaff from collecting in front of the opener and then rolling around the shank or opener and falling back onto the seed row. A reasonable balance between the stubble heights, 200 to 250 mm (8 to 10 inches) left by the cutter-bar, and the amount of straw which is chopped and evenly spread from the combine, will provide the best seeding conditions. If this situation doesn't exist on a field after harvesting is complete, the first alternative is to harrow the residue to improve its distribution. Harrowing is best done later in the day when the residue is dry. It will help to break up piles and matted material and spread the residue more evenly. 

The forward speed of the planter may affect the manner in which the surface residue and the standing crowns of stubble spread and flow around the opener. A few situations have been encountered when increasing forward speed reduced the residue build up in front of the opener. There was also less residue falling back on top of the seed row. Several different speeds may be tried to see if the flow of residue and the field finish improves. But increased speed removes more soil from the seed row furrow, so the soil cover depth over the seed must be rechecked, particularly the seed depth of the front rows. 

Disc type openers, coulters preceding hoe openers, and stubble managers are intended to penetrate through, or clear a path through the residue. They will improve seed placement under many conditions, but close attention to the residue conditions and seed placement is still required. 

The simple but effective ground opener, that is, the "perfect one", has not yet appeared. One should not expect it any time soon either! There are just too many different farming conditions on the prairies for one size fits all. But with residue management becoming regular part of farm management, many openers will handle the many seed placement requirements that farmers want. Simplicity is a key feature predictable for predictable ground opener performance.
 
Tips for fall or spring residue management
• If poor residue conditions cause plugging and prevent getting the necessary acres done, or if the seed placement is compromised by the residue on the surface, do something! A harrow pass is the first option.
• Conduct some diagnostic field trips. Look at the residue condition in the fields well before planting. One may observe that a residue problem needs to be corrected long before the planter gets there. Have a look at last year's stubble. Are there gaps in the seed row that were the result of previous residue interference?
• Harrowing in the spring, particularly on wet or clay soils must be done with a tractor with a very light foot print. That is, not more than 10 psi in any tire and virtually no wheel slippage.
• Cut crops short enough so straw and stubble will pass between openers and under the planter's frame. Stubble height should be no greater than the shank spacing distance of the planter. Sometimes some minor modifications to the planter will improve the flow of residue.
• Aim for a balance between the stubble heights with the amount of chopped residue spread on the surface. A critical eye from the combine seat will make a difference in spring planting.
• If your combine has sufficient capacity, use the combine to cut the crop to the proper height. Using the combine to cut stubble to the proper height costs roughly $2 per acre1*. Spring stubble mowing costs about $5 to $7 per acre.
• Install pick-up guards on the combine or windrower so areas of lodged crop and crop vines can be picked up and chopped by the combine. It is less frustrating to do this with the combine than to continually having to unplug the planter.
• Watch for areas where tall stubble will be flattened, such as pre-harvest sprayer tracks, lodged crop, banked snow, trampled by livestock, field borders, or that strip of crop up the middle that wasn't enough to go back for (at 2 am).
• Ensure that the combine's chopping and spreading equipment does its job well enough for the planter to clear the residues. Again a critical eye from the combine will perceive a problem developing.
• Harrow stubble fields to press the loose straw into the soil surface. This improves the flow of crop residue through the planter. Harrow soon after combining for the best opportunity to germinate shattered grain (volunteer) and weed seeds.