With fall plantings well underway in much of the country, I thought some might like some information on weed identification. Even when you have performed soil tests, the weed growth in a field can be extremely indicitave of soil Ph and condition. I spend alot of time trying to identify the different weeds on the land, and research their preferred Ph and nutritional requirements.

Here is a good, but not totally complete link for weed ID. http://www.weedalert.com/index.shtml This one might even be a bit better: http://www.ppws.vt.edu/weedindex.htm

The first step is to identify a weed - then use a search engine like google.com to look up information on Ph for that plant. Some plants grow well in a wide range of soil conditions, what you are looking for are "indicator plants" that grow in a narrow range of Ph. Remember, a soil test is usually an average of sample taken across a whole field. Some sections are sure to be more basic and others more acidic, its helpful to know how to use weed growth as an indicator.

When acessing a field, I look for concentrations of weeds, in areas of the field. Pockets of weeds, OF THE SAME TYPE, indicate that something is different in that section of soil. By knowing what soil conditions different weeds preffer, you can monitor the success of a lime application across a field, or make educated guesses regarding Ph on small plots that you might not have soil sampled.

For example, I was very pleased to see lambsquarter weeds growing in my corn this year. Its an indication that the soil Ph is better than it was, since it generally preffers a neutral Ph.

Other indicator plants I use are:

Acidic conditions: Daisy, Queen annes Lace, fern, moss, plantain

Near Neutral conditions (6.5-7.0): Milkweed, Wild mustard, dandelion, chickweed

Hope this is of some value to some. If I've left out indicator plants that others are aware of - please add them to this post.