The
Value of Rotation Crops
by Diana Roberts
“The value of rotation crops”. This statement may sound like an oxymoron, especially when peas are selling for $ , canola gets $ , and mustard $ . What is the value of a crop other than wheat (whether or not the price of wheat exceeds its production costs)?
Cereals (especially wheat and barley) have been the backbone of PNW cropping systems, and they have benefited from a hundred years of local breeding and research. When considering alternative crops, we are usually trying varieties that are not specifically adapted to our environment so we seldom see them perform optimally. The temptation is to look at the dollar value of the alternative crop alone, rather than considering how it contributes to the value of the whole crop rotation. The latter approach is more complex because it requires looking at a number of factors, several of which are tough to assign a dollar value. However, Palouse farmers have long grown peas and lentils for the yield boost they get with the following winter wheat crop, so whole rotation value is not a new concept. Likewise, spring barley that yields less than one ton/A is often little more than a contributor to exercise in cheatgrass control for the winter wheat crop.
When comparing rotations it is important to average all the inputs and returns over the total years of the rotation, e.g. two years for a wheat-fallow rotation and three years for a wheat-barley-canola rotation.
Any cropping system, whether no-till or conventional, has strengths and weaknesses, but they are not the same strengths and weaknesses. Management strategies should maximize the positive aspects of any rotation and minimize the negative ones. In this article I will focus on direct seed cropping systems.
Alternative crops in direct seeding systems have the potential to
· Spread market risk
· Increase weed control options
· Improve soil water holding capacity
· Improve residue management
· Spread the seeding and harvest workload
· Increase beneficial soil organism populations
· Break disease and insect cycles
In going to direct seeding it is important to adopt the system as a whole in order to maximize on its potential benefits – not to do so has been likened to putting diesel in a gasoline vehicle and expecting it to run. A crop rotation that has worked under conventional tillage will not necessarily work with direct seeding. In choosing crops for the rotation, consider all the factors they will contribute and estimate the inputs and benefits as best you can.
Marketability
Crop marketability is of prime importance to the farming business. Too often it is placed last in the list of considerations, rather like putting prayer at the end of the options to think about in a crisis. Yet the bottom line (or the top line) is that if the crop has no market it’s worthless. That’s what my economist colleagues say and it grieves my agronomist heart to think that a plant that contributes all sorts of wonderful things to a biological system could be worthless! Consider those systems that include cover crops grown purely for their contribution to weed control and soil organic matter… However, until we can place an economic value on soil organism relationships and organic matter levels we can only measure these factors indirectly through the long term financial return over the whole rotational cycle.
An additional consideration in alternative crop selection from a risk management perspective is whether it is eligible for federal farm payments i.e. PFC and LDP, and if the crop is covered by federal crop insurance in your county.
I do believe that for crops that have excellent agronomic benefits it should be worth pursuing marketing options that increase their value. Crops that have more than one market (e.g. hay or grain) are also advantageous.
Weed Management
Weed management is one of the greatest challenges in transitioning to direct seeding. Dwayne Beck of SDSU at Dakota Lakes Research Farm, SD, writes that systems (whether conventional or no-till) consisting of predominantly one type of crop will favor weeds having similar biology and growth patterns (seeding and harvest dates). Local examples are problems with cheatgrass and jointed goatgrass in winter wheat-fallow rotations and wild oats with spring cereals. In both these crops, the grassy weed control available when rotating to canola could be very beneficial. However, if you have a morning glory problem, for instance, a broadleaf rotation could seriously increase your problems. [1] The wag that reads this will think, “So if I diversify my crop rotation I’ll end up with more weed types to deal with….”
There’s definitely truth to that statement, as broadleaf weeds will tend to proliferate in a broadleaf crop. However, long-term no-tillers in South Dakota and other regions report decreased weed populations and herbicide use. Crop diversity has the potential to enable use of a wider array of post emergent herbicides, which is important in preventing multiplication of herbicide-resistant weeds. When choosing an alternative crop, always check beforehand that there are chemicals labeled for in-crop use and that these herbicides will not damage following crops. Table 1 shows herbicide availability for several crops.
|
Crop Type |
Seeding
|
Harvest |
Water Use
|
Broad- |
Grass
|
|
Winter |
Grass
|
Sept- |
July- |
Low-Mod
|
Many
|
Adequate
|
|
Spring |
Grass
|
Mar- |
Aug
|
Low
|
Many
|
Adequate
|
|
Sunflower
|
Broadleaf
|
May
|
Oct- |
High
|
V.
limited
|
Limited
|
|
Millet
|
Grass
|
May- |
Oct
|
Low
|
Limited
|
None
|
|
Flax
|
Broadleaf
|
April
|
Aug
|
Low
|
Adequate
|
Many
|
|
Safflower
|
Broadleaf
|
April- |
Sept
|
Low- |
None
|
None
|
|
Canola
Mustard
|
Broadleaf
Broadleaf
|
April
April
|
Aug
Aug
|
Low-Mod
Low
|
One
[2]
None
|
Adequate
None
|
|
Barley
|
Grass
|
Mar- |
Aug- |
Low
|
Many
|
Adequate
|
|
Oats
|
Grass
|
Mar- |
Aug
|
Low
|
Adequate
|
None
|
|
Peas/lentils
|
Broadleaf
|
Mar- |
Aug
|
Low
|
Adequate
|
Adequate
|
|
|
|
|
|
|
|
|
Plant competition is important in weed management. A crop that canopies early is less likely to need a post-emergent herbicide than one, such as safflower, that forms a dense stand as it matures but grows slowly initially. Since preplanting incorporation of herbicide is more difficult under direct seeding systems, crop canopy response becomes an important factor.
Growing warm season crops that are seeded later than normal can provide a longer window to manage early germinating, cool season weeds. The challenge with warm season crops in our climate is not to run out of moisture and heat before maturity. On the Wilke Farm we have been using millet as a warm season grass as it uses less water and matures more quickly than corn. In 1998 we obtained excellent wild oat control with RoundupÒ prior to seeding. The last two years have been relatively cool summers, allowing the wild oats to continue to germinating and the millet varieties currently available are not vigorous early enough to compete well with the weeds.
Soil water holding capacity
Soil type, environment, and tillage system each affect the water holding capacity of a field. Crops with deep taproots (e.g. canola and safflower) leave behind macropore channels into the soil as their roots decompose. These channels, if left undisturbed by tillage, can increase water infiltration into the soil.
Different crops have varying water requirements, and this should be considered in crop choice in any season. In the PNW we have a good idea prior to spring planting how much water will be available for the growing season, and can choose crops accordingly (Table 1).
Residue management
When selecting a crop and a variety, it is important to consider how its residue will affect the following crop. Broadleaf crops generally have dark residue and less of it than do the cereals. This enables the soil to warm up more quickly in the spring; so broadleaf’s can be beneficial preceding early seeded spring cereals.
Variety choice can also be important. Most direct seed drills can cope well with upright residue, but weak stemmed varieties that leave the residue lying down can cause problems for the following seeding operation.
Workload efficiency
When choosing a crop consider its season length and time of seeding and harvest in order to avoid a crunch in farming operations, especially if dry fall conditions have reduced winter wheat acreages. Table 1 shows relative season lengths for several crops.
Soil organism relationships
Not every crop or crop rotation has the same capability for enhancing soil organism populations. Wheat is fairly neutral for earthworms, but two years of wheat in a four-year rotation will decrease levels of VAM fungi (mycorrhizae that increase nutrient availability to the crop). Earthworms generally prefer legume and oilseed crops. Brassicas (canola and mustard) increase earthworm populations and will temporarily reduce VAM fungi levels. Corn, oats, sorghum, and perennial grasses all enhance VAM fungi activity. Both earthworms and VAM fungi populations increase in flax crops. These fungi like soils with lots of organic matter and can have a negative impact on a crop that does not provide enough OM. For example, if wheat follows after alfalfa, the mycorrhizae will attack puny wheat seedling roots that are seeking phosphorus. Barley seedlings have larger roots so they are less affected.
Break disease and insect cycles
Diverse crop rotations are important in direct seed systems to break cycles of soilborne diseases such as Cephalosporium stripe and Rhizoctonia. Changing between winter and spring cereals helps with some pathogens, while including a broadleaf crop is necessary for others. Using a broadleaf crop more than once every four years is risky as canola, mustard, sunflower, safflower, peas, and lentils are all susceptible to white mold (Sclerotinia) even though they represent several different botanical families. Rotating out of cereals also reduces the habitat for insect pests such as Hessian fly that overwinter in residue.
Following is an example of the thinking process we used to select sunflower as a broadleaf crop to try in a 4-year rotation on the Wilke Farm in 2000. In 1998 we grew mustard and safflower but both suffered from the cool spring and record high temperatures we had that July, even though mustard is considered relatively heat tolerant. Safflower has no labeled post-emergent herbicides and was not competitive with the wild oat populations we need to manage.
In 1999 we grew canola and mustard, but we had germination problems in the residue and unfavorable cold conditions that spring. Another cold spring was predicted by one source so we wanted to go with larger seeded crops that should have better emergence capability. We chose peas for the 3-year rotation as they had a post emergent herbicide labeled for grassy weed control and they had done fairly well in the area the previous year.
In the four-year rotation we expected a high wild oat population in the broadleaf strips as these weeds had germinated continually in the preceding millet crop during the cool summer of 1999. (The failure of millet to help manage grassy weeds consistently has been a continual disappointment and frustration.) We knew it would be important to choose a crop that had germinated well, had post emergent herbicide options, and would compete with the wild oats. Sunflowers looked promising as their later seeding date would permit more wild oat control prior to seeding and a good stand should shade out weeds. There were several marketing options – confectionery (15 c/lb) or oilseed (12.5 c/lb) and the rejects from either could go for birdseed (8.5 c/lb). The crop is eligible for LDP payments. Harvesting would require a header with sunflower pans, but we had access to one locally. Table 2 shows the cost and yield estimates calculated by Aaron Esser.
Table 2. Input costs and break-even yield for sunflower and peas in 2000.
|
Sunflower
|
|
Peas
|
|
|
|
|
|
|
|
|
Operation
|
Rate
|
Cost/A
|
Operation
|
Rate
|
Cost/A
|
|
|
|
|
|
|
Roundup
|
15 oz
|
$4.20
|
Roundup
|
15 oz
|
$4.20
|
Roundup
|
15 oz
|
$4.20
|
Roundup
|
$0
|
0
|
Seed
|
|
$10.00
|
Seed
|
180 lb
|
$33.30
|
16-20
|
70 lb
|
$9.45
|
16-20
|
0
|
0
|
Deep
band
|
60 lb
|
$14.40
|
Deep
band
|
60 lb
|
|
Poast
|
2.5 pt
|
$23.50
|
Assure
II
|
8
oz
|
$9.36
|
Insecticide
|
?
|
?
|
Insecticide
|
0
|
0
|
|
|
|
|
|
|
Total
cash cost
|
|
$61.55
|
Total
cash |
|
$61.26
|
|
|
|
|
|
|
Estimated
selling |
|
$0.12
|
Estimated
|
|
$0.05
|
|
|
|
|
|
|
Breakeven
yield
|
|
513 lb/A
|
Breakeven |
|
1225 lb/A
|
|
|
|
|
|
|
We seeded the crop with a John Deere 750 (not a precision planter) so didn’t achieve a completely uniform stand. However, where the coverage was good the crop did a good job of shading weeds, though wild oats showed its ability to grow to any height to reach sunlight. We did use a post emergent herbicide and also had to spray for sunflower moth, which we had not budgeted for. The crop is still drying down and waiting for harvest, so I don’t know the final numbers. But they will go into the value of the whole rotation anyway!
References
and recommended reading:
Dwayne L. Beck and Ron Doerr. 1992. No-till guidelines for the arid and semi-arid prairies. Dakota Lakes Research Farm, Pierre, SD. http://www.dakotalakes.com/publications.htm
Aaron Esser. WSU Cooperative Extension, Ritzville, WA. Personal communication.
Chris Laney. Wilke Project Cooperator, Sprague, WA. Personal communication.
[1] In the reference article cited, Dwayne Beck describes a well thought out way of managing morning glory that could be adapted to local rotations
[2] Does not include Roundup Ready™ and IMI™ cropping systems
For more information contact WSU Extension, (509) 477-2048.
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