PROBLEMS WE'VE HAD IN ZERO-TILLING EDIBLE BEANS

By Jim Pallister

Our rotation has steadily been moving toward no-till. It works like this : wheat - lentils - beans. The reason why we grew beans on our lentil stubble is that we were told "beans love it black" and lentil stubble, even zero-tilled, is relatively black and thus warm.

Unfortunately, what I have to tell you today is that, after four years of trying my darndest to make zero-till work, we cultivated all our lentil ground last fall in preparation for beans.

The edible bean plant is very different from any other plant we grow. Lentils and wheat and lentils will emerge and evenly through any amount of trash. Beans will do nothing until the soil warms to 50 degrees and then their growth is directly proportionate to temperature. Most edible bean growers will also tell you that their bean crops were the ones that came up the fastest and the most even. If it came up in an uneven, feeble fashion it never really recovered, or yielded. The closest parallel I'd use is this: The time frame between seeding and emergence in beans is as critical as anything that happens to the fetus in a mammal. Any damage done will last the rest of it's life.

We have tried a number of things to modify our bean production system towards no-till, even to the point of harrowing up all the lentil straw in rows and burning it. The problem is that as you've observed, there is a mat of straw and chaff on the soil surface that has developed over several years. I made an observation this year that finalized my decision. The areas where the fires had been under the harrow dumps from the previous fall were, of course, quite black. The plants in these strips came in half the time. They achieved twice the vegetative growth and had considerably more pod development. I want that kind of growth across my whole field next year and not just in a few strips.

One method notable difference in the growth habit of beans that impacts on agronomic practices is the fact that the seed itself emerges. Even though a firm seedbed is very beneficial with small crops, dwarf wheat and lentils, I've seen a lot of cases where the bean had trouble emerging or even got puled off and left behind. This plant will not develop. So this becomes another argument for a light tillage.

Two last observations - one pro zero-till and one not. Cutworms were a terrible problem in two different years on our beans. I'm afraid that I can relate this to zero-till although I concede my outrageous rotation of beans following lentils must take some of the blame. One advantage of zero-till is the Roundup opportunity. Since Beans cannot be planted until May 20^th anyway, with no tillage we had a great opportunity to nail some well developed and undisturbed quack before seeding.