Poor crop rotation added to the 2007 soybean woes

If you have ideal growing conditions, as in 2006, you can get away with soy after soy. But not in stress years like 2007

by PAT LYNCH

As I write, the soybean harvest is just starting. Yields are 15 to 20 bushels per acre less than last year and some areas are averaging less than 30 bushels per acre. Lots of fields are producing less than 20 bushels per acre and some yields are single digit. There are areas in Ontario where the yield is zero because they did not get rain until August.

You would like to blame one single factor for these poor yields, but you can’t. Poor soy yields are the result of a number of things, including poor harvest conditions in 2006 causing compacted land. When you harvested in 2006, you did the right thing by getting the crop off. Back then, you knew there would be consequences for harvesting under poor conditions. In some fields, the results were more disastrous than in others.

So what could you have done differently to minimize the effects? Probably the biggest factor is crop rotation. The rotation gurus have been predicting for years the dire consequences of poor rotations. This year, those predictions came true.

If you have ideal growing conditions, as we did in 2006, you can get away with a poor crop rotation. But when we get stress years, as in 2007, the yield consequence is significant. The take-home here is that, even though you do not like growing corn, maybe next year you should grow more of it, since you can make a profit and this will set you up better for good soy yields in 2009.

In 2007, conventional till beans yielded better than no-till. There are some who want to gloss over this fact by pointing out the benefits of no-till. They have to get their head out of the sand and admit that, in a year like 2007, land which is worked will yield better. When you work the land and do not have pounding rains, your beans get off to a better start.

There were numerous fields where emergence was uneven in no-till fields. There was not enough moisture to start the beans that were planted shallow. The shallow planting resulted from setting the drill to plant at the right depth for most of the field, but which proved too shallow for compacted areas. In most years, uneven depth of planting is not a problem since we get enough rain to allow the shallow planted beans to emerge. This did not happen in 2007.

So should you abandon no-till soys and go back to working the ground? Absolutely not. There are too many benefits to no-till.

Another factor that hurt yields in 2007 was a proliferation of insects. We had early infestations of bean leaf beetle, and then we had aphids. After that came the second generation of bean leaf beetles and then spider mites. In many fields, individual insects did not get to threshold levels (as we know them). But areas of fields did get to threshold levels. And we do not have a good read on the combination effect of the different insects. If you can remember this past summer, the aphid numbers did do a lot of bouncing around. Then there was the uncertainty of spraying to kill the aphids and not the predators. In some fields, spraying for aphids gave six to eight bushels per acre. In other fields, it resulted in being able to harvest a crop, even if that yield was below 20 bushels per acre. If we had known then what we know now, some of these fields might not have been sprayed. Even after being sprayed, there was still a crop insurance claim.

Weed control in 2007 also affected yields. Even some Roundup Ready beans had weed flushes from the August rains. In most years, these late flushes would not affect yields because the canopy of the crop would kill late germinators. With the conventional herbicides, in some cases it was too dry to get the best weed control.

Probably the biggest factor in yield reduction was disease. Our seed treatments protect the seed but they do not protect the seedlings or plants. Even though you apply a seed treatment, you will still get disease. The list of diseases that hurt soy yields this year is long. You can get some varietal resistance and some seed treatment help, but the biggest help will be rotation. And some disease can be best controlled by tillage. If you do not want to do this tillage, then the next best way is crop rotation.

Growing soys in 2007 was a challenge. If you grow soys in 2008 the same way as you did in 2007, you are saying you can expect a growing year like that of 2006.