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UmmmmHoeing a field by hand or using oxen is not easy.Likewise, work in the rice patties must be hard work.And pedalling a rickshaw full of produce to market?ANSWER TO CliffordK, Sir, does not the proposition illustrate that a man might need only 250sqm of arable land to grow all the nutrients that are needed for a family of five for a year and he is so efficient that he needs spend only three weeks in a year labouring: the sun does most of the work. When you see pictures of a small-holder digging, sowing, fertilising, watering, weeding and harvesting those are rare moments. Automation, while maybe not fuel efficient, has allowed the "mega-farming" practices.if mega -farming practices are desireableIf you are considering fuel/energy... Don't forget to consider the food consumed by the Chinese farmer, his family, and his beasts of burden.see above
Why does the Chinese farmer work so hard? Bored chemist please see my reply to Clifford KHe could slack off and only work half as hard yet remain able to feed his family and still make a large surplus.That sort of thing makes me suspicious. Are you suspicious that the earth might be more fecund than you thought? Also, there's another factor. A relatively small fraction of the American population are farmers but (I think) a rather large fraction of the Chinese population are (or would have been in 1976).The small number of American farmers produce enough food for the population, but require capital equipment and petrols but it seems to take a rather larger number of these "more efficient" Chinese farmers.That seems odd to me.why odd? the bigger the tractor the higherthe output-but at what price?
Looking at Fuel Ethanol production, it is pretty close to 1:1 fuel in, energy out, although part of the extra cost is in fermentation and distillation of the end product.A global food distribution network can distribute a wide variety of foods everywhere, without respect to seasons. Local food distribution networks certainly are much more seasonal, but require much less transportation cost. But what about the energy that is needed to produce the tractor and ploughs divide by their economic life?
"Sir, does not the proposition illustrate that a man might need only 250sqm of arable land to grow all the nutrients that are needed for a family of five for a year "No, it says nothing about that at all.There was no mention of any area of land. It was implied because if the earth was not so fecund one would need a larger area"Bored chemist please see my reply to Clifford K"I did, it's wrong (as above) and it fails to address pest control (other than weeding) which is always a major part of farming. Eat the bug(ger)s" you suspicious that the earth might be more fecund than you thought? "No I suspect the original post is deeply flawed. Without explaining why in the language of physics."Why odd? the bigger the tractor the higher the output-but at what price?"Because the question was about efficiency, without defining how that would be calculated. Not so it is in KWHThe American farmer provides more crops than the Chinese one.At one level that's proof that he is more efficient. No he has more capital equipment which is inefficient. Prove Mr Paturi wrong please "But what about the energy that is needed to produce the tractor and ploughs divide by their economic life? "Very few US, or Chinese farmers are in the business of growing crops for fuel, so this is not relevant to the original post.
250 sq meters16x16 = 256 m2Should I ask what is your proposed disposal of human waste? turn it into compost! [xx(]
You know, thinking about this.American Farmers often go with the assumption that if it can't be mass produced, it is not worth doing.Fly across America, and you will see circular fields laid out on a square grid. Why? Because center pivot irrigation is very efficient in terms of labor, but somewhat inefficient in terms of land.Many crops are bred to be harvested all at once with mechanical pickers, potentially loosing a long growing season worth of harvesting. Again, it saves a lot in labor, but is potentially less efficient as far as overall yield.
Peter Meakin asked the Naked Scientists: Dear Chris, I have tried to put this question to you via Redi at 567 Cape Talk but I don't think you have received it. However the assertion is so brazen that, if true it will change the planet!! Or something. Here it is: "If we convert the energy gained from harvested plants into kilowatt hours and compare it with the energy expended for that harvest, the result is startling: for fifty harvested energy units the American farmer invests 250 fuel energy units, the Chinese farmer only a single of human energy. This means simply that the primitive countryman of the east works at an efficiency rate of 5000 per cent and the USA farmer equipped with the most advanced technical aids, at an efficiency rate of only 20 per cent" Felix Paturi NATURE, MOTHER OF INVENTION Themes and Hudson, 1976Peter MeakinWhat do you think?