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Saturday, May 12, 2007
Indicator Weeds - What's your soil up to?
Seems weeds can tell you alot about your soil: what's there and what's lacking. If the soil's lacking what most plants need, these indicator weeds will come in, take root and muscle out the other plants. So what to do? Fortunately there's a lot of information out there. From Ontario, we get some hints: "...3) Some weeds or plant species are signs of poor fertility. For example, Orange Hawk Weed (Devil's Paint Brush) are signs of low phosphorus. Poor establishment and survival of legumes indicate a possible low pH problem. The appearance of moss can mean low nitrogen levels and/or poor soil drainage. Taking a soil test is the first step to determine how to correct these problems. ..." omafra.gov.on.ca
Greenmanradio.com has a very good list that cross-references many different soil conditions: "...White clover (Trifolium repens) loves wet but infertile conditions. I'll bet there's some red sorrel (Rumex acetosella) around too, since it loves the wet, acidic Oregon soil. Check the table below for several kinds of indicator weeds and the soil conditions they thrive in. ..." greenmanradio.com
Mother Earth News, in 1987 - had an especially good article on weeds, including what many of them indicate: "...Acid soil: Ox-eye daisy (Chrysanthemum leucanthemum), curly dock (Rumex crispus), sheep sorrel (Rumex acetosella), sow thistle (Sonchus species), prostrate knotweed (Poly-gonum aviculare), lady's-thumb (Polygonum persicaria), wild strawberries (Fragaria species), plantain (Plantago major), rough cinquefoil (Potentilla monspeliensis), silvery cinquefoil (Potentilla argentea), hawkweeds (Hieracium aurantiacum and pratense), knapweeds (Centaurea species).
"Alkaline soil: Field peppergrass (Lepidium virginicum), goosefoot (Chenopodium species), gromwell (Lithospermum officinale), true chamomile (Anthemis nobilis), bladder campion (Silene latifolia). ..." the list goes on and on! motherearthnews.com
For turf management: http://www.turf.uiuc.edu/weed_web/indicator_weeds.htm