Were your corn and soybean yields not quite what you'd hoped for last year?

Maybe it was the weather. On the other hand, there might be some things you can do to bump those yields up to where you want them.

First, you need to identify the yield-limiting factors. Get out in fields and scout, advise Craig Lamoureux, an Asgrow Seed Co. agronomist in northwestern Iowa, and Brian Meese, Asgrow Concept Farm coordinator.

"It's hard to know what's going on out there if either you or someone who works for you is not out there looking," says Meese. "A second way to know that there might be a problem is to actually check yields. If you don't know what your yield is, you can't be sure there's a problem at all."

Here's a checklist of yield-limiting factors to look for:

1) Management practices, such as prevention of soil compaction, row width, soil fertility, seeding rate and variety selection.

Variety selection is particularly important, Meese believes.

"Look for the right variety or hybrid for the field, the management practice, the prevalent disease, the herbicide program you are planning or used last year, and nutrient tolerances, such as high-calcitic or low-iron soils," he says.

"Remember, there's a wealth of information available from the extension service and from private sources such as herbicide and seed companies."

2) Drainage. For many growers, this should be the first area to investigate. If land needs drainage and you haven't addressed that problem, you have a lid on your yields even if you do a lot of other things right.

3) Insects such as bean leaf beetle, green clover worm, European corn borer, corn rootworm, cutworm, etc.

4) Diseases on roots, stems, leaves, pods, etc.

"Learn to recognize the symptoms of gray leaf spot in corn and white mold and brown stem rot in soybeans," Meese suggests. "Other problems that relate to root and seedling rots and blights are caused by fusarium, pythium and rhizoctonia. Learn how to recognize these, too."

5) Sudden-death syndrome. This is a bean disease that warrants a separate classification. It's new to many growers and is spreading. If plants are dying, look for foliar symptoms similar to those of brown stem rot.

6) Soybean cyst nematode.

"It's a big problem in soybean production over a wide area, and a lot of people who have problems don't recognize the symptoms," Meese states.

7) Herbicide injury. It can be just cosmetic, or a yield robber.

There are two types to watch for. First is drift from adjacent fields. The solution here is to be more careful in herbicide application. The second type is carryover from herbicides applied the previous year or setbacks due to herbicides used in the current year.

Meese suggests using STS soybeans if you plant beans after using an ALS inhibitor in corn - even if you don't intend to use the companion herbicide. And if you use imidazolinone herbicides on your beans and follow with corn, while carryover isn't certain, planting IR or IT hybrids might help you sleep better.

He notes that Asgrow personnel see a consistent 2-bu/acre advantage with the STS soybean-herbicide system. They're also seeing about the same benefit from Roundup Ready beans where Roundup is the only herbicide used.

8) Inadequate nodulation. Soybeans need nitrogen, but you do not have to apply it if you make sure there's a good strain of rhizobia in the soil.

"If you've been out of beans for several years, you may need an inoculant," Meese says.

9) Subpar weed control. Yield monitors have shown some shocking yield cuts from weed patches. To avoid that yield basher, sharpen your weed identification skills. Then match the highest-rated herbicides to your particular weed problems.

To do a good job of correcting yield-limiting factors, Meese and Lamoureux recommend using drainage maps, soil and soil-test maps, and, if practical, developing yield maps to know each field.

"Then know what to look for in the field or get help in scouting," says Meese.