Better soil, fewer weeds

Herbicide resistance linked to soil health

IT IS a double dish this week – speculating on soil heath and herbicide resistance.

What is the connection there between these two major implications for our farming system?

Many years ago this same question came up in our southern and West Australian areas with respect to acid type soils.

Not that we have many highly acidic soils in the northern region, however the considered process should be applied to your own circumstances.

The basic premise is that crops growing in unhealthy soil cannot compete very well with weeds.

Big statement, and I am not too big on bold statements like this, as somewhere or someone will prove you wrong, however in this case I believe that is a fairly safe assumption.

Admittedly, for much of our information on these weed resistance issues, we are learning from our West Australian cousins, who went through this dilemma with rye grass and radish in a barley crop trial in low pH soils.

So for your knowledge, the trial was applying lime to their acidic soils to promote good barley growth.

We do know that lime applied at up to two tonne per hectare and mouldboards ploughed into the soil actually doubled the barley crop grain yield.

A good return on investment would be my judgment.

Wild radish plants per square metre on the other hand in this trial were reduced by more than 50%.

A good result for increased grain yield and less radish

plants.

So the trial summary read that the crop competition from the barley growing in a healthier soil environment certainly impacted and reduced the radish numbers per square metre.

We can make the assumption that while weeds do suffer from poor health in acid soils, our barley crop suffered more.

So if your nutritional practices are not as good as they can be for your crop and I

include nematodes in this thought as well, then your crop competition will not be as good.

That will lead to probable increased weed numbers and improved weed fitness, which will be to the detriment of your

crop and a bigger weed seed bank.

While we are still on this herbicide background to solve our problems, we also need to improve our complete farming system for better crop growing and less weeds.

❝The basic premise is that crops growing in unhealthy soil cannot compete very well with weeds. — Paul McIntosh

PHOTO: GREG MILLER COMPLETE FARMING: Better soil meant increased barley yields and fewer weeds in a West Australian trial.