March
1999
By Dr. Jochum Wiersma, U of M Small Grains Specialist
Library
Prairie Grains is the official
publication of
the Minnesota
Association of
Wheat Growers,
North Dakota Grain Growers Association,
South Dakota Wheat, Inc., and the Minnesota Barley
Growers Association.
The absolute yield is what’s possible with no limiting factors except the genetic potential of the crop. It is the theoretical maximum yield of wheat.
The attainable yield is the yield possible in any given environment, year, and area. It is limited by the climate, weather, depth of soil, and other factors that we cannot manage.
The affordable yield of wheat is limited by available water, growing degree days, temperature extremes, the intensity of sunshine, and day length.
The actual yield is what’s harvested in any given field. It is the outcome of the ability of the crop to respond or take advantage of the growing conditions counter-balanced by weeds, insects, diseases, soil compaction, frost, or other production hazards. The actual yield may also be called the allowed yield. As in, yield allowed by production competitors and other but manageable problems or limitations in the field, offset by the price paid to achieve that yield.
I encourage you to consider allowed yield before scaling back crop inputs too much for the coming growing season.
When evaluating the need for inputs, it
makes the most sense to have the actual yield approach
the allowable yield, such that each additional amount of
the input will at least pay for itself. The allowable
yield is the yield level at which we control those
factors we can exercise control over. Since each input
comes with its own cost, you have to evaluate the return
of the input before trying to achieve the allowable
yield.
If the additional yield as a result of the input pays for
the input itself, it is worth the additional input. But
how do you decide? First, although we are working in a
biological system, assume each decision as an independent
factor.
For several of the factors, we have
very good to reasonably well-defined decision guides:
Soil testing and setting a reasonable yield goal (a.k.a.
the allowable yield) will allow you to calculate your
fertilizer needs to within the pound. For wild oats (and
soon for foxtail), we have thresholds available which
will allow you to determine whether that input will have
a return. We have a foliar fungicide decision guide for
leaf diseases including Septoria, tanspot, powdery mildew
and rusts. There are degree-day based thresholds for
aphids and orange wheat blossom midge that help track
population peaks. Even for Fusarium Head Blight or scab,
we have some very good environmental indicators that will
help us in the decision-making process.
One underlying theme should resonate through very clearly
– if you want to control input costs, you will have
to scout the crop. Only then can you make sound, economic
decisions.
But why, you may ask, do I still strive to reach the
allowable yield? Very simple: you have your fixed and
variable costs per acre, and each additional bushel
produced will reduce the fixed portion of your cost per
bushel (you divide the total cost per acre over the total
number of bushels produced) and thus lowering your cost
per bushel produced. Subsequently, that allows you to be
the more competitive in the marketplace.
With the current prices for wheat, everyone including your banker, screams to reduce your input cost. Why? In lean times like these everyone gets cautious and wants to minimize financial exposure. But are you really reducing your risks by cutting out inputs that pay for themselves? Actually, you are in a sense increasing your risks, because you forfeit your opportunity to control a biological risk that will move your actual yield away from the allowable yield, and increase your cost per bushel produced.
We are by human nature averse to risk. Farmers are no different. Indeed, it takes a strong stomach to invest in input expenditures in lean times like these to ultimately reduce your risk. Skimp if you must, but don’t drop back so much that your crop yield and quality will suffer because of it.
After this rather theoretical discussion about allowable yields, costs, and risks, following are some ways to reduce your input cost (without affecting your allowable yield).
1. Re-negotiate rent.
2. Use bin-run seed if you must, but clean it and check
for germination and vigor.
3. If we have an early spring, wait an additional 2-3
days and kill the first flush of wild oats with your
seedbed preparation (soil temperatures have to get above
40°F).
4. If we have an early spring, consider harrowing your
wheat rather than using a grass herbicide.
5. Eliminate a seed treatment when you have a good
seedbed, soil temperatures have warmed up sufficiently
and weather forecasts indicate that a rapid germination
can be expected.
From the Wheat Research File
Agronomic Response of Spring Wheat with ACA Seed Application
Wheat seed vigor, plant performance, and economic return can be improved with seed applications of Agricultural Crop Additive (ACA), an ammonia zinc acetate product originally developed by Amoco Oil Co., Chicago, to be used as an additive to anhydrous ammonia that currently is a product of United Agri Products.
LeRoy Spilde, associate plant sciences professor at North Dakota State University, evaluated the effect of ACA in 1994-96 on seed germination, plant emergence, plant growth rate, grain yield and grain test weight under laboratory and field conditions when applied to seed.
Germination percentage and seedling growth rate increased significantly in the lab tests. Field trial results indicated that spring ACA seed treatments were all higher than the untreated check for grain yield and test weight. Net return with 1.7 and 3.4 fl oz/bu rates was significantly higher than the check. Similarly, data indicated that the economic return would favor a 1.7 fl oz/bu rate — about one-half the recommended rate for soil application.
Spilde says more research is needed to study minimum rates for optimum response, the effect on additional crops, different environmental conditions, and the potential for tank-mixing ACA with other products.
See the complete research report on the web: www.ag.ndsu.nodak. edu/ndagres/fall98/ar21198a.htm
Grains Magazine
March 1999