Getting a feel for the soil
Sep. 15th, 2020 13:52![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
torquillI was looking up decomposed volcanic ash (andisol), as that's what we have on the higher parts of the property; the lower parts are dominated by alluvial deposits, partly from andisols, partly from ultisols (old forest soils). The lower areas, thanks to the silt from a couple of centuries of stream activity and rampant plant growth, are pretty fertile, though verging on acidic bog land... I have a decent idea what they're like (probably a bit low in minerals, high in organic matter and sequestered nitrogen and potassium, fertile if you can get it drained and bring the pH up). But the volcanic ash is new to me.
It's supposedly rather dark, though on this property it's more of a medium-brown, mixed with soft brown sandstone rocks. (The bedrock is dark grey basalt, seem easily at the bottoms of the streams around here.) From what I can gather, as the ash decomposes, it becomes increasingly acidic. This may be related to its ability to lock up any available phosphorus, though apparently its calcium levels are all right... its other notable feature is that it holds water like a sponge, thanks to a fluffy, rather open soil structure. It's why there are little springs that run most of the summer, and the pastures remain green even without rain. The sponge uphill is constantly providing a trickle of water all the way down the slope.
So it's easy to dig, and it holds water well while still providing very good drainage. Those are both excellent qualities which are hard to instill in soils that don't have them. It tends toward acidity as it ages, which might fill in the missing piece of the puzzle; I had figured that rampant weed growth and ready moisture had turned the place acidic, but I couldn't credit the speed with which it had happened. Normally it takes more than twenty years or so to go from neutral to 5.0, unless you're in a bog. But if the soil itself is aging to the point where it really tends acidic, that may answer that question.
So it will need regular lime. It may also need regular phosphorus. One article mentioned that grass doesn't require much P, as its roots are limited and it doesn't bear fruit (especially when mowed or grazed), so I probably don't need to waste phosphorus on the pastures or the lawn; having them somewhat P-poor may discourage weeds and weed trees. So that leaves the cottage garden, the orchard, and the slope below the Annex (the vegetable garden is in the alluvial basin). That feels like a manageable area to supplement with bone meal and manures. I should pick up an NPK test at some point, to complement the pH testing, though I have a sneaking suspicion that un-amended soil may show a correlation between acidity and lack of phosphorus.
Apparently it can accommodate and maintain a high level of organic material, which promises good nitrogen and potassium retention if amended. Organic material tends acidic again, though, so adding lime needs to go along with that. Lime should provide calcium and magnesium that may be a bit low, though that may be more of a concern in the garden where the silt could be kind of mineral-poor.
I never was much good at soils, but at least I have enough of a foundation to figure out soil tilth profiles. It's something to start with, anyway.
It's supposedly rather dark, though on this property it's more of a medium-brown, mixed with soft brown sandstone rocks. (The bedrock is dark grey basalt, seem easily at the bottoms of the streams around here.) From what I can gather, as the ash decomposes, it becomes increasingly acidic. This may be related to its ability to lock up any available phosphorus, though apparently its calcium levels are all right... its other notable feature is that it holds water like a sponge, thanks to a fluffy, rather open soil structure. It's why there are little springs that run most of the summer, and the pastures remain green even without rain. The sponge uphill is constantly providing a trickle of water all the way down the slope.
So it's easy to dig, and it holds water well while still providing very good drainage. Those are both excellent qualities which are hard to instill in soils that don't have them. It tends toward acidity as it ages, which might fill in the missing piece of the puzzle; I had figured that rampant weed growth and ready moisture had turned the place acidic, but I couldn't credit the speed with which it had happened. Normally it takes more than twenty years or so to go from neutral to 5.0, unless you're in a bog. But if the soil itself is aging to the point where it really tends acidic, that may answer that question.
So it will need regular lime. It may also need regular phosphorus. One article mentioned that grass doesn't require much P, as its roots are limited and it doesn't bear fruit (especially when mowed or grazed), so I probably don't need to waste phosphorus on the pastures or the lawn; having them somewhat P-poor may discourage weeds and weed trees. So that leaves the cottage garden, the orchard, and the slope below the Annex (the vegetable garden is in the alluvial basin). That feels like a manageable area to supplement with bone meal and manures. I should pick up an NPK test at some point, to complement the pH testing, though I have a sneaking suspicion that un-amended soil may show a correlation between acidity and lack of phosphorus.
Apparently it can accommodate and maintain a high level of organic material, which promises good nitrogen and potassium retention if amended. Organic material tends acidic again, though, so adding lime needs to go along with that. Lime should provide calcium and magnesium that may be a bit low, though that may be more of a concern in the garden where the silt could be kind of mineral-poor.
I never was much good at soils, but at least I have enough of a foundation to figure out soil tilth profiles. It's something to start with, anyway.