I take it salt in soil is a sign of poor drainage and/or insufficient rainfall. When Rome finally took out Carthage they plowed salt into the soil. Carthage never came back from that and the place is still desert today, but the soil is no longer salty. Even in a desert there's been enough rain and drainage to leach it all away centuries ago.
One of the long term problems with pumping well water and other irrigation for crops is it tends to build minerals in the soil faster than natural drainage. The soil moves towards desert over a period of centuries. There are vast deserts in the world that were once lush agricultural lands. The desert of Iraq was one of the birthplaces of agriculture and there was a History Channel show this week on a Sahara site that was once a grain farming community.
In some places the salt is of geological origin: former seabeds. The groundwater in some parts of the world is so heavily laden with salts
*from within the ground* that it is not drinkable and very few species of plants can survive either. It takes a *lot* of rainfall to remove so much salt.
One cause of desertification is centuries of extraction of organic matter, and soil nitrogen, by humans. Intense agriculture does that, where biomass is produced in one place and consumed somewhere else.
Not necessarily, it is a complex issue with more than one cause, see:
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Rome finally took out Carthage they plowed salt into
Yes rainfall will tend to remove salt just as it leaches all soluble salts over time. It isn't clear to me if the proverbial application of salt by Rome resulted in the desert, I suspect there is more to it than that.
That can happen but it is not the only way that soil damage can be caused. Irrigation water can raise the water table so that salty water that was safely buried comes up to interfere with plant growth
The soil moves towards desert over a period of
I wouldn't assume that all that was all due to salinity, over grazing and other mismanagement contributed. It is much easier to damage soil and allow deserts to encroach than the reverse.
See:
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I seem to recall that there have been some climate change effects in the fertile crescent too (over millenia not the last century) but I cannot find the reference to it.
I thought that the forests of north Africa met the same fate as the forests of Britain (cut to make ships), however I don't seem to find a supporting cite for that opinion.
I think you'll find that the raising of the salt level in the land between the Tigris and the Euphrates rivers via irrigation is the accepted mechanism for the collapse of agriculture there.
Both clay and sand need organic matter, but sand needs far more organic matter than clay because it naturally has less nutrients.
I'd say that and for the following reason: Clay soil is made of extremely fine particles and it is the lack of big particles that makes clay so hard to work but those fine particles hold nutrients well. Sand is made of big particles and it is the lack of fine particles that makes sand so freedraining and so nutrient free.
The opposite of clay soil is sand. Add sand to clay and you improve the clay, add clay to sand and you improve the clay.
Yes. Try it. A friend and I both fell on this idea when my friend was at the local rural/landscaping supplier and bemoaning the fact that her soil was so clayey. On and on she moaned and our extremely laconic business owner just finally drawled 'have you ever thought of adding sand' and walked off. It makes sense if you think about it for a second.
Our tractor doesn't have a front end loader - it has pallet prongs. And I'm too old and feeble to turn it by hand. I've decided not to sweat the small stuff. My piles eventutally rot and forms a decent looking humus so I use what i do get.
I was told that much wood was cut to make charcoal. The charcoal was then used in smelting iron. When I was about five I once saw a pile of wood smoldering just north of Philadelphia. It was 50 yards high by about 300 round.
when it dries too much yea, that's about what happens if there is no organic matter to keep it lightened up or if it is left bare between crops. it's does a number on the hands trying to weed or plant.
the reconditioned area i did this past summer had nothing added to the clay besides it being killed off (to get rid of the sow thistle that was taking over). then i tilled it a few inches deep to give seedlings a chance to get roots down in and to soak up the rain (instead of it running off the compacted soil). oh and i took the advantage of it being all dug up and leveled it more to keep the water from running off too quickly into the east ditch.
i seeded it with two legumes, alfalfa and birdsfoot trefoil (in a spiral pattern). it took a while to get going, the alfalfa has very deep roots after several years and will help break through that clay hardpan layer that often develops. both were chosen for color, and because they fix nitrogen. if they are mowed they both come back low growing and with some color, but so far we haven't had to mow there.
this was left to grow (i only walked on a certain pathway to avoid compacting the soil again). this fall i had to move a rhubarb plant and there was a spot along the edge of this whole patch where i wanted to put the rhubarb... that gave me a chance to check out the depth of the roots from the alfalfa and trefoil and to see how the soil was doing. we hadn't had much rain late in the summer, but this fall the rains have been enough to keep it moist and the worms have been going nuts as compared to how it used to look. there were not very many worm signs before. when i was digging there were plenty of worms so i'm taking that as a good sign. and the times when i've walked across it it has been soft and squishy instead of like walking on pavement. so from that i'd say that tilling and staying off it while replanting can be a good approach as long as you don't need to run a mower over it or walk on it when the seedlings are starting.
the alfalfa will take several years to get the deep roots established. we'd tried an alfalfa patch before for the purple flowers but it was not left long enough to get established before it was changed to another garden. so this time we'll leave it for a longer time period and see how this all works out.
i may intercrop it next year with beans to take advantage of the space and get some return on the weeding.
i'm hoping this winter the deer will bed down back there and eat that area up instead of messing around in the other garden they've been using that is much closer to the house (about 20ft from where i'm typing this from -- i'd like to sleep instead of hearing them clomping around at 4am).
i always offer to trade people who have too much sand for clay, but so far nobody has taken up the offer. :) bring buckets... adding organic matter does help, but i'd add some clay too because it helps the worms (night crawlers like it for their burrows) and holds nutrients and moisture.
On my clay soil, i tend just put grass seed on it. Then I go with raised beds. However, I am always experimenting, I will try clay and sand with compost and see how things work out. I am forever line trimming.
Better IMHO is mulching instead of tilling. Mulching reduces run-off, and a mulch like alfalfa (lucern) will feed the soil with both "C" and "N", and no tilling will preserve the earthworms habitate (as opposed to rototilling which turns them in to worm emulsion).
Venison would be healthier than most of what you can buy in a store.
Talking about garden problems and approaches to fixing them are good for the newsgroup, thanks.
we don't have the many cubic yards of mulch it would have taken to recondition that entire area. instead i took the approach i did because there weren't that many worms to begin with in that part of the soil (the top few inches of dry hard-pan clay) and it really needed to be softened up so that seedling roots could get established (before the frosts came). for smaller areas mulching is much easier i would agree. oh, and i did need to level it, tilling helped move a few cubic yards eastwards.
the hunters have been booming all around us, but we still see many running during the day now (groups of six or more).
I am slowly restoring the badly damaged soil on two small parcels of land. Both are on slopes and I am also gradually terracing them. Terracing is not a natural condition, but most people would consider it an improvement on the original.
Couple of things I've observed. Purslane loves nitrogen and sucks ths soil dry. Cheatgrasses do not like too much nitrogen. Some of the major weeds of disturbed soils do the soil rather a lot of good. Two examples are Kochia and redroot pigweed. Both are annuals that grow deep taproots.
Starting out, there was zero organic matter hence absolutely no worms. Compaction was significant, and rain water mostly ran off. The soil is still far from heathy but the patches where I began are far better now. They grow grass, all kinds of grass. I pull up clumps of grass and transplant the clumps into other spots where I have previously mulched heavily with horse manure. A few years ago I started pulling all mustard weeds, just so that none managed to set seed. Then there were no mustards so I started pulling pigweed ditto. This year there was nearly no pigweed so I started pulling kochia. What is left? An increasingly varied abundance of native perennial wildflowers (mallows and asters, mostly) and grasses. I have started digging wildflowers and distributing them to gardening friends, leaving the grasses to fill in the holes. Next summer I expect I will be pulling kochia again, and purslane, and then I'll be done with weeding that parcel! I won't worry about the cheatgrasses; they won't be able to compete with the perennial grasses that are coming in now.
"Google" a photo to be sure, but around here red root pigweed is wild amaranth. The leaves are edible like spinach and in the fall the grain is very healthy. I always leave one or two in the garden. Steve
Yes, it is edible, even fairly tasty when young and tender. However, like rhubarb leaves pigweed has oxalate crystals and I don't want much oxalate in my diet. Also, this pigweed accumulates nitrates, which I also don't want to eat much of, and in light of the fact I am adding so much manure to the soil the available nitrates are likely to be high.
Purslane is edible too, and tastier than pigweed. So are the mustards.
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