Comments by "Xyz Same" (@xyzsame4081) on "Real Engineering"
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@michaelcrockis7679 you only think of the layered system above ground, but in natural systems (except in the desert there it is reduced) there is a huge system underground - if it is a natural forest or prairie for instance, or any man made system imitating a natural eco system, be it a garden, a food forest and forest with timber, fields, parkland, rotational grazing, ....
Of course monocultures of soy, corn, wheat etc. do not have the rich soil life (they can if the farmers use regenerative methods and mostly stay away from spaying things). Conventional fields also do not have good, dark water absorbant soil with alot of organisms.
The difference in the ability to absorb water can differ by factor 10 (same slope, soil, adjacent fields, after harvest, one conventional and one managed with no till and always with mulch cover).
Water can become a VERY expensive resource when it is lacking, and it can cost even more when downpours (often following draughts) carry away topsoil. Even if the topsoil is degraded - it still is substrate / mass and can be improved at lot within 2 - 3 years. But not when it is gone. Soil can be rebuilt from scratch but that takes more time than improving what is there.
And as the degradation of soil progresses conventional farmers have to add more and more nitrogen fertilizer, use herbicides and pesticides (good soil feeds plants well so they are in general more robust).
Artificial fertilzer and the other spraying are bad for soil life. The large machines also compact the soil, and the bare soil is also detrimental to soil life, never mind eriosion and compaction.
So it is a downwards spiral.
Smart farmers meanwhile integrate cover crops (some of them fix nitrogen from the air, for instance clover, those are quite poplar) see Dave Brandt who became an expert in using green manure / cover crops.
U.S. farmers sow deep rooting daikon radishes, sometimes by plane to loosen the soil and bring up nutrients from the deeper ground.
Problem is they usually terminate with machines (having animals eat the crop is not an option with big ag, and even a homestead might get into proglems when there are rows of not yet ready cash crops and the other rows are grazed by livestock (cattle, goats, chickens, geese, sheep). Of all of them sheep might be the most realistic option.
But still they have to be fenced off (electric fence), there better not be a street nearby just in case something spooks them. And of course they should not eat the cash crop or wander off and trample it down.
Cotswold Seeds has sheep of neighbours on their test farms to help them terminate cover crops (the animals poop and pee so the fertilize the ground anyway. But for huge operations using animals is tricky. and making fodder is more work - and it is not going to be "green manure" then, only protective cover crop.
and that can mean using glyphosate, (cutting a covercrop does not mind it will not regrow and outpace the newly planted seeds of cashcrops).
And mainly use of 1 variety or at the max a mix of 2. It becomes harder to get the crop down at th right time and than use it as mulch and somehow sowing a new cash crop onto the "green manure".
Those farming practices try to avoid ploughing and tilling (it is also bad for soil life) it also destroys the valuable fungal networks.
So terminating a cover crop or working in green manure and sowing out the cash crops onto / into it so that it will germinate is quite a craft and science.
It can increase yields, and above all it reduces need for water, prevents erosion, builds soil, binds carbon from the air (that is when soil gets darker, with associate very dark soil with being fertile and good - it is, these are the humin aggregates that contain a lot of carbon).
Having mulch or green mulch can save a harvest if there is a very dry summer.
It also reduces the need to buy fertilizer and pesticides and especially herbicides (the soil is covered year round), so weeds have no chance where would they grow.
So the yields are good or normal but a much reduced costs. = higher profits.
Plus the fields cope better with heavy downpours and draughts.
But on the other hand they use glyphosate to terminate cover crops. Brandt may have found way to avoid that at most times, but I guess many farmers are not quite as curious and intent on upping their game and cracking the code.
The more diverse the cover crops / green manure are the better the results. But big ag with monoculture crops and use of machines usually has a hard time to deal with that. Sure they could harvest the cover crop and then use it as fodder. Always assuming that they can sow on that. They could even make compost and applying that later (no need to terminate that and they are flexible WHEN and how thick they apply it).
One of the main problems seems to be how to plant the next crop and get good germination.
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