Relation between Weeds and Soil

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IluvABbeef

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Going out on a walk out in the hay field and the pasture, I bit of a "weird" question occured to me. Particularly about dandelions, but this could also be with other weeds like lambsquarters, stinging nettle, chickweed, pigweed and stinkweed. So the question goes like this:

What is the significance of dandelions (or other weeds including those listed above) in relation to soil fertility? Do dandelions (or other weeds including those listed above) indicate lack of a particular nutrient in the soil or do they indicate good soil?
 
The weeds in question tend to prefer alkaline soil (pH between 7 and 8.5). Also they are very drought tolerant (and, respond to water very nicely also...lol).

The zillions of seeds they discharge ensure their survival easily. Also, have rather deep tap roots as well as plenty of feeder roots.

Hope this helps...:)
 
The short and not so sweet.

Fertility (available nutrients) is wrong for the crop you are trying to grow and their is a bare spot that mother nature is putting something into that will grow. Not very often she puts something nice in.

What casues bare spots?
drought, overstocking, bad fertility, fire, turning of the soil,.......... round-up :shock:

edit - PH is part of fertiity
 
Around here, ph is the biggest factor controlling the type of weed found in a field. The presense of certain weeds is one of the things I use to determine whether or not to lime. And before somebody jumps on me about not using a soil test - I do.
 
I can relate to the bare spots or big gaping spots where the grass has lost its productivity and dandelions take the place of the decreased-in-production grass. But how do you explain them growing near spruce trees (which is where there is acidic soil), in with the grasses, that sort of thing?
 
IluvABbeef":3g2hzkp8 said:
I can relate to the bare spots or big gaping spots where the grass has lost its productivity and dandelions take the place of the decreased-in-production grass. But how do you explain them growing near spruce trees (which is where there is acidic soil), in with the grasses, that sort of thing?
Is it a difference in ph or to much shade? Maybe both or competition from the trees for nutrients and water.

PS. If we keep going, I'm going to get in over my head. :p

Just wondering, does the ph of your soil change that much from pasture to pasture? Curious cause around here, the ph from the blackland to the sandy loam doesn't change a whole lot. I have never taken a sample out of the woods to know if their is a difference their.
 
1982vett":1s2s8a19 said:
IluvABbeef":1s2s8a19 said:
I can relate to the bare spots or big gaping spots where the grass has lost its productivity and dandelions take the place of the decreased-in-production grass. But how do you explain them growing near spruce trees (which is where there is acidic soil), in with the grasses, that sort of thing?
Is it a difference in ph or to much shade? Maybe both or competition from the trees for nutrients and water.

PS. If we keep going, I'm going to get in over my head. :p

Just wondering, does the ph of your soil change that much from pasture to pasture? Curious cause around here, the ph from the blackland to the sandy loam doesn't change a whole lot. I have never taken a sample out of the woods to know if their is a difference their.

That would be my guess too.
 
Organic farming books have many tips on the conditions that favor certain weeds. For my farm:
I see more dandelions where there is less N.
I see more quack grass where there is low ph.
I see more clover where there is some shade.
 
IluvABbeef":1ef4u1ds said:
I can relate to the bare spots or big gaping spots where the grass has lost its productivity and dandelions take the place of the decreased-in-production grass. But how do you explain them growing near spruce trees (which is where there is acidic soil), in with the grasses, that sort of thing?

You might want to do some reading on the allelopathic properties of dandelions. Alleopathy is a plant's ability to exude a chemical substance from its roots which will impede or retard the growth of its competitors. Dandelions, I think, exude an acid which will tie up iron thus robbing its competitors of a vital ingredient to photosynthesis. This might be what you are noticing.

edit - I don't know much about the spruce forests but I think their are a lot of other species in understory which are also allelopathic in the spruce forest area. Some hurt spruce. Might do a search on this too and might find its a group of plants and not just one causing this.
 
I wouldn't know about the change in pH because I doubt if we've ever taken any soil samples from any of our pastures, just in the fields. The type of soil around here is pretty much uniform, except for wet areas with more loamy soil and then the high spots which are more clayey (as you can already tell, we have more clayey soils up here; more of a clay-loam mix). Now that's out in the open. In with the black spruce or swamp spruce, whichever you want to call it, I have no doubt that the pH would change with a more evergreen terrain. Where I notice the dandelions is outside of the spruce woods, and in the clearings, not in with the spruce. But the thing is is that I just wonder if the pH of the soil is still acidic even beyond the reach of the spruce's branches, like a few feet out from the diameter of the tree? Now that's spruce. For aspen and poplar, I'm certain the soil would be about the same since they're adaptability to the boreal-type soil, at least to the point if the soil ain't too acidic for them. Dandelions also have no trouble growing beside aspens and poplar groves I notice.

The allelopathic ability of dandelions really makes sense, because of the areas found around home here that have just a patch of dandelions with barely a blade of grass. Not in the lawn of course, thank goodness, but mostly here and there occaisonally in the pasture and hayfields. I haven't done much research on the spruce tree effects of different plants, so I couldn't give you an answer to that.

Now here's something that raised my eyebrows from another forum: the poster said that dandelions are an indicator of poor calcium in the soil. I found it interesting, but I'm skeptical if it's true or not. Steve, I really can see about the lack in nitrogen though; dandelion's won't grow where there's an abundance of alfalfa. A little different for the bunch of clover we have on one pasture though... :?

Dandelions are just so weird.
 
IluvABbeef":2vkikulr said:
even beyond the reach of the spruce's branches, like a few feet out from the diameter of the tree?

I would think this is correct as the needles can be carried some distance with the wind.
 
IluvABbeef":2eysbj30 said:
What is the significance of dandelions (or other weeds including those listed above) in relation to soil fertility? Do dandelions (or other weeds including those listed above) indicate lack of a particular nutrient in the soil or do they indicate good soil?

The significance could be nothing, or it could be everything. No, I don't think that dandelions or most any other type of weed indicates a lack of any particular nutrient because weeds grow in good and bad soil. I think most weeds indicate some type of disturbance that killed out/set back the grass/crop and allowed them to get a foothold from which they multiplied. Weeds tend to have a shorter germination time, as well as a faster growth rate than grass or crops.
 
msscamp":3ce5yhym said:
IluvABbeef":3ce5yhym said:
What is the significance of dandelions (or other weeds including those listed above) in relation to soil fertility? Do dandelions (or other weeds including those listed above) indicate lack of a particular nutrient in the soil or do they indicate good soil?

The significance could be nothing, or it could be everything. No, I don't think that dandelions or most any other type of weed indicates a lack of any particular nutrient because weeds grow in good and bad soil. I think most weeds indicate some type of disturbance that killed out/set back the grass/crop and allowed them to get a foothold from which they multiplied. Weeds tend to have a shorter germination time, as well as a faster growth rate than grass or crops.

Actually, the presence of Dandelions, in mass, usually indicates an alkaline soil in that spot. Many grasses prefer a slightly acidic soil. If the Dandelions were a real problem then sulpher could be added to move more towards 6.5 or thereabouts.
 
Jogeephus":2n1jwa1h said:
IluvABbeef":2n1jwa1h said:
I can relate to the bare spots or big gaping spots where the grass has lost its productivity and dandelions take the place of the decreased-in-production grass. But how do you explain them growing near spruce trees (which is where there is acidic soil), in with the grasses, that sort of thing?

You might want to do some reading on the allelopathic properties of dandelions. Alleopathy is a plant's ability to exude a chemical substance from its roots which will impede or retard the growth of its competitors. Dandelions, I think, exude an acid which will tie up iron thus robbing its competitors of a vital ingredient to photosynthesis. This might be what you are noticing.

edit - I don't know much about the spruce forests but I think their are a lot of other species in understory which are also allelopathic in the spruce forest area. Some hurt spruce. Might do a search on this too and might find its a group of plants and not just one causing this.

Here is two you probable did not think of: They are Bahia grass and also Black Walnut Trees.
The lambs quarter plants will not last long when you start grazing. The cows go for them first.
 
One thing I've noticed with dandelions vs the other mentioned weeds. Dandelions don't need an open space, they do very well in thick lush grass. Most other weeds, give them little moisture some soil stirring warm temps and they show up. Rich soil, sand, wherever. You could have the most balanced soil and and have the best crop of weeds.
Up here the dandelions are about the first forage, cattle love them, eat them down. Then the grass grows and I hardly notice the dandelions till the next spring. Don't seem to take anything from the grass. This Spring we had pastures that were yellow. Now the grass and clovers are doing very good. Of coarse we've has some rain this year.
 

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