Soy Bean Management for 2011  10/26/11 9:06:58 AM

There are many management practices that go into growing a good soybean crop.  I get a lot of questions about micronutrients, foliar fertilizer products, fungicides, and others.  There is a place for most of these after we have taken care of the basic managements practices.  Basic management practices like soil fertility, seed selection, seed treatment, weed control, insect and disease control, make-up most of the yield.  After these have been taken care of is the time to look at “high end” practices.  It is important to control what is controllable in order to take advantage of, or reduce the impact of things that aren’t controllable like the weather.  If you plan for a good crop by taking care of the basics you have a better chance to reap the rewards of a good growing season.  If you don’t take care of the basics, you are planning to have a bad crop, no matter what the growing conditions are.

Soil Fertility—Did you see yellow leaves on your soybeans last year?  That is a sign of potash deficiency.  I saw more potash deficiency signs last year in eastern Kansas than I have ever seen before.  Phosphorus deficiency is a little harder to detect by just looking at the plants, but in most cases if you are seeing potash deficiency there is a pretty good chance that phosphorus is also low.  Typically we depend on carryover phosphate and potash from the previous corn or wheat crop to take care of the fertility needs of soybeans.  Because of higher input costs or changes in rotations, that carryover isn’t there anymore.  We have also had relativity good yields from most of our crops and those higher yields have taken more nutrients form the soil.  Just as a point of reference, a 150 bushel corn crop removes 59 pounds of phosphate and 40 pounds of potash; a 40 bushel wheat crop removes 22 pounds of phosphate and 13 pounds of potash.  These removals are just in the grain.  If you are taking the straw or stalks off, these numbers are as much as 5 times higher for potash.  A 40 bushel soybean crop will need 33 pounds of phosphate and 59 pounds of potash.

Do you have enough phosphate and potash in your soil to grow a good soybean crop this year?  The only sure way to know is to have a good soil test; but if you saw deficiency symptoms last year there is a pretty good chance you need to up your rates on phosphate and potash this year.  If you do get a soil test, check out what the pH level is.  If it is below 6, liming will improve the uptake efficiency of phosphate and potash.

Weed Control—Most University research on yield will show a direct benefit to early season weed control in soybeans.  That means that weeds and grasses that come up with the crop are robbing yield.  The easy fix is to use a pre-emergence herbicide to stop weeds before they come up.  There are several economical products on the market that will do the job.  Selecting the right product to fit the weed spectrum for your field is important.   Another benefit to pre-emergence herbicides on soybeans is resistance management.  Year after year of using glyphosate products has led to resistance of some weed species.  I’m sure you have noticed that some weeds are not as easy to kill with glyphosate as they used to be.  Changing to a chemical with a different mode of action will help get those hard to kill weeds; and using pre-emergence products is the best way to do this.

The major chemical companies such as Syngenta, Dow and Monsanto have marketing programs that will help pay for the second in-crop spraying of their glyphosate product if you use their pre-emergence product followed by their “branded” glyphosate product.  Branded glyphosate products are a little more expensive than the generics, but the difference is cheap insurance.

Seed Treatment—University research has shown a consistent 2 to 4 bushel yield advantage to treated soybean seed. This one is a no brainer.  A $3.00 to $4.00 treatment of ApronMax will return a minimum of $15.00 to $20.00.  There is also a yield advantage to an insecticide based seed treatment such as CruiserMax, but the results are less consistent and the return is not as great as the fungicide treatment.  The insecticide seed treatments will control early attacking insect such as bean leaf beetles, but don’t expect control on larger soybeans because the insecticide gets more diluted as the plant grows.

In Crop Insecticides and Foliar Fungicides—The decision about whether or not to use these products is a little easier.  You have the benefit of being able to evaluate the condition of the crop and estimate the yield potential.  Just scout your fields during the growing season and make an “as needed” decision.

At Beachner Grain, we recommend soil testing to determine your fertility needs, but at the very least you should apply at least the amount of phosphate and potash to cover crop removal.  Pay particular attention to potash.  Even though not that much is removed with the grain, like all legumes, soybeans require a large amount of potash to produce the crop.  

As for weed control we think the best option is to use a pre-emergence product followed by an in-crop application of a glyphosate product. 

Seed treatment should be an automatic decision.  The yield benefits are too great to ignore. 

In-crop spraying of insecticides and fungicides should be done on as needed basis based on insect or disease pressure and potential for return on investment.

Remember, the quickest way to recover cost of production and get a return on investment is to increase yield.  This statement is true regardless of in-put costs or grain prices.  The management practices discussed here, are all geared toward increasing yield.  There are other practices that sometimes have an impact on yield, but are not always consistent and should only be considered after the basics have been taken care of.

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