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#1
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Why are cereals annual crops?
I am wondering why cereals such as oats and wheat need to be planted
every year, at expense (labour and machinery). The grass on my lawn seems to keep growing from year to year, even after cutting. Does wheat die after ripening and forming seed? Even if the plants lasted two years before ploughing and e.g. growing beans then that would save a lot of fuel. Is this what zero tillage is about? Is ploughing needed to cut down on weeds? Can you buy perennial cereals, or are there people working on breeding (or genetically engineering) them? Dave. |
#2
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Hi,
Technically cereals are "semelparous plants" These are monocarpic plants with a single reproductive event. So when the plant flowers it then dies. Of course these include the annual plants, but also some quite long-lived plants (remember some of the bamboos will grow vegetatively for years, flower once and then die). The survivorship curves of such plants all show a dramatic increase in mortality following flowering. In semelparous plants all of the meristems of the plant die following flowering, and thus the whole plant dies. The mechanism of senescence in such plants is not known, but it seems to be related to the mobilization of plant resources to produce developing seeds. My suspicion is that if you tried to genetically engineer cereals to become annuals then you would radically reduce grain yields. "You can't get something for nothing". Best Wishes, Martin Hodson wrote: I am wondering why cereals such as oats and wheat need to be planted every year, at expense (labour and machinery). The grass on my lawn seems to keep growing from year to year, even after cutting. Does wheat die after ripening and forming seed? Even if the plants lasted two years before ploughing and e.g. growing beans then that would save a lot of fuel. Is this what zero tillage is about? Is ploughing needed to cut down on weeds? Can you buy perennial cereals, or are there people working on breeding (or genetically engineering) them? Dave. |
#3
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Surely annual crops have many advantages: quick results, ease of working
(allowing the field to be cleared and fertilized every year), etc. Some plants that are actually perennials are grown as annuals. PvR schreef I am wondering why cereals such as oats and wheat need to be planted every year, at expense (labour and machinery). The grass on my lawn seems to keep growing from year to year, even after cutting. Does wheat die after ripening and forming seed? Even if the plants lasted two years before ploughing and e.g. growing beans then that would save a lot of fuel. Is this what zero tillage is about? Is ploughing needed to cut down on weeds? Can you buy perennial cereals, or are there people working on breeding (or genetically engineering) them? Dave. |
#4
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Thanks for the information which I can follow up.
I stayed at an arable farm's B&B for 2 1/2 years, and am interested in the result of the kind of calculations done to maximise net profit per acre, since the high cost of fuel may change the kind of crops grown. (The money yield is more important that the tonnage.) |
#5
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In article .com,
wrote: Thanks for the information which I can follow up. I stayed at an arable farm's B&B for 2 1/2 years, and am interested in the result of the kind of calculations done to maximise net profit per acre, since the high cost of fuel may change the kind of crops grown. (The money yield is more important that the tonnage.) Read up on "permaculture", a system of farming that depends mainly on perennial plants. You asked earlier about "no-tillage" systems. In these the crop residue is knocked down and perhaps disked in, and herbicides are used heavily to control weeds and volunteers. There are a lot of trade-offs in expenses here, not the least that weeds rapidly develop resistance to each new herbicide, and new herbicides that are still under patent are sold for whatever the market will bear. Some herbicides are persistent, and limit your choice of crop in subsequent years. E.g. if you use a broadleaf herbicide like atrazine, you can't follow your maize crop with soybeans or alfalfa. If you plant Roundup-resistant canola, you can't use Roundup to control the innumerable canola volunteers that appear the next spring. IIRC, there are efforts in progress to develop perennial forms of maize and some small grains, but none have been successful yet. Another approach would be to domesticate a perennial grass into a grain crop. It could take millennia by standard methods, but it might be possible to speed it up by gene transfer methods. Overall, it's remarkable how very few food plants have been domesticated out of the enormous number of edible species. One problem with perennial crops is the length of time it takes to get a reasonable profit per acre. This is one of the motivations for developing dwarfing rootstocks for fruit trees -- they make the trees bear sooner. Note that starchy nuts like acorns and chestnuts are fairly similar to grains in nutritional value, but the trees are slow to bear, and the farmer still has to pay the mortgage while waiting for the trees to mature. (People used to be able to plan far into the future, but it's not usually economically possible now. Pepys recorded in the 1660's that the French were planting large acreages of oak trees, so that 300 years later, in the 1960's, France would have a domestic supply of oak masts for sailing vessels, to better compete with the British navy.) |
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