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Urban myth
OPINION LETTERS Urban myth From Chris Smaje The notion that the city is greener than the countryside is rapidly becoming a modern myth. But Shanta Barley misses the fact that what happens in cities and the countryside are inextricably linked (6 November, p 32). If you assume that deforestation and industrial agriculture are afflictions of rural life that have nothing to do with urban resource demands then cities can look pretty green. The same is true if you assume that the essentially urban lifestyle of modern country dwellers, with their energy-hungry cars and houses, is the only rural life possible. Yet many rural peoples have historically provided for themselves without long-term
resource degradation. We could learn from these models. The main reason for the rural flight to the city is that country dwellers are peculiarly vulnerable to exploitation by urban – and rural – elites. Sensible proposals for rural land reform would deliver more ecological benefit than another romantic paean to the dynamism of the urban slum. Frome, Somerset, UK From Marc Mills If the exodus to the city should “lift the strain of intensive agriculture from the land”, as Shanta Barley states, where will those urban immigrants get their food? Will it be grown in their living rooms? People do not stop eating when they move to a city. Barley quotes David Lee on biogas: “You need to hit a certain
Enigma Number 1624
French magic numbers
integer in the one on the right: “twenty—five” has 10 letters, “eight” has five letters, and so on. I wondered whether I could Richard England create a new magic square on the left such that every integer in it 25 258 812 12 10 105 56 6 when written as a word in French contains the number of letters 2 215 15 28 28 3 37 711 11indicated by the corresponding 18 18 22 225 5 8 89 94 4 integer in the square that we already have on the right. It isn’t possible to do this, but I have In a magic square the sums of each created a new square in which row, column and major diagonal seven of the integers fulfil this are equal. There is a remarkable requirement and the other two relationship between the two are each just one letter short of magic squares shown here. Each the number of letters required. integer in the one on the left when As in the English example, all written as a word in English the integers in my new square contains the number of letters are considerably less than 100. indicated by the corresponding Please submit my new square. WIN £15 will be awarded to the sender of the first correct answer opened on Wednesday 12 January 2011. The Editor’s decision is final. Please send entries to Enigma 1624, New Scientist, Lacon House, 84 Theobald’s Road, London WC1X 8NS, or to [email protected] (please include your postal address). Answer to 1618 No common factors: the three-digit number is 129 The winner Bernard Cammack of Raumati South, New Zealand
28 | NewScientist | 4 December 2010
scale of waste generation for that sort of methane capture to be efficient and economical”. This flatly contradicts Sujata Gupta’s article from the same issue, in which it is stated that a backyard 1000-litre biogas digester can produce enough methane to run a fridge for 16 to 20 hours (6 November, p 14). Installing one of these in every house would be cheaper than a sewerage system, and would also cut the amount of waste that goes into landfill. Torquay, Queensland, Australia
Carbon farming From Lynn Erselius One thing missing from your list of 50 ideas that will change science (16 October, p 32) is the idea of farmland as a dynamic carbon sink. Permanent pastures store large amounts of carbon, and organic matter can accumulate in systems such as permaculture in which ploughing is avoided. We also know that a young or newly coppiced stand of trees accumulates carbon, whereas the carbon balance of established forest is closer to neutral. This knowledge can be combined to create novel farming systems which could be instrumental in mitigating climate change. Recent research shows that systems associating trees with arable crops lead to increased production per unit area. In Agronomy: crops and cropping systems published by Agropolis International, a scientific community for agriculturalists,
Christian Dupraz of the French National Institute for Agricultural Research wrote that yields of both poplars and winter cereals are greater when they are grown in association rather than in single culture. He suggests this may be due to modified rooting patterns in the mixture, with the trees rooting more deeply, so avoiding drought stress in the summer. If nut trees formed part of such a system it could further boost food yields, providing a healthy alternative for meat. This is important if we in the west are to reduce our consumption of animal produce. Sylvo-arable systems might be in their infancy, but with so much land devoted to farming, and demand for food increasing, they deserve our attention. Changing the focus from single crops to the system as a whole and the soil as a carbon sink would revolutionise farming. As a bonus it would be good news for biodiversity. Brussels, Belgium
Network overload From Tom Phillips, GSM Association At the GSM Association, which represents the interests of the mobile communications industry worldwide, we have a slightly different take on the problem of smartphones overloading networks from that in your article (30 October, p 44). We agree there is a wireless capacity issue, but think developments in mobile technology will help.
resource degradation. We could learn from these models. The main reason for the rural flight to the city is that country dwellers are peculiarly vulnerable to exploitation by urban – and rural – elites. Sensible proposals for rural land reform would deliver more ecological benefit than another romantic paean to the dynamism of the urban slum. Frome, Somerset, UK From Marc Mills If the exodus to the city should “lift the strain of intensive agriculture from the land”, as Shanta Barley states, where will those urban immigrants get their food? Will it be grown in their living rooms? People do not stop eating when they move to a city. Barley quotes David Lee on biogas: “You need to hit a certain
Enigma Number 1624
French magic numbers
integer in the one on the right: “twenty—five” has 10 letters, “eight” has five letters, and so on. I wondered whether I could Richard England create a new magic square on the left such that every integer in it 25 258 812 12 10 105 56 6 when written as a word in French contains the number of letters 2 215 15 28 28 3 37 711 11indicated by the corresponding 18 18 22 225 5 8 89 94 4 integer in the square that we already have on the right. It isn’t possible to do this, but I have In a magic square the sums of each created a new square in which row, column and major diagonal seven of the integers fulfil this are equal. There is a remarkable requirement and the other two relationship between the two are each just one letter short of magic squares shown here. Each the number of letters required. integer in the one on the left when As in the English example, all written as a word in English the integers in my new square contains the number of letters are considerably less than 100. indicated by the corresponding Please submit my new square. WIN £15 will be awarded to the sender of the first correct answer opened on Wednesday 12 January 2011. The Editor’s decision is final. Please send entries to Enigma 1624, New Scientist, Lacon House, 84 Theobald’s Road, London WC1X 8NS, or to [email protected] (please include your postal address). Answer to 1618 No common factors: the three-digit number is 129 The winner Bernard Cammack of Raumati South, New Zealand
28 | NewScientist | 4 December 2010
scale of waste generation for that sort of methane capture to be efficient and economical”. This flatly contradicts Sujata Gupta’s article from the same issue, in which it is stated that a backyard 1000-litre biogas digester can produce enough methane to run a fridge for 16 to 20 hours (6 November, p 14). Installing one of these in every house would be cheaper than a sewerage system, and would also cut the amount of waste that goes into landfill. Torquay, Queensland, Australia
Carbon farming From Lynn Erselius One thing missing from your list of 50 ideas that will change science (16 October, p 32) is the idea of farmland as a dynamic carbon sink. Permanent pastures store large amounts of carbon, and organic matter can accumulate in systems such as permaculture in which ploughing is avoided. We also know that a young or newly coppiced stand of trees accumulates carbon, whereas the carbon balance of established forest is closer to neutral. This knowledge can be combined to create novel farming systems which could be instrumental in mitigating climate change. Recent research shows that systems associating trees with arable crops lead to increased production per unit area. In Agronomy: crops and cropping systems published by Agropolis International, a scientific community for agriculturalists,
Christian Dupraz of the French National Institute for Agricultural Research wrote that yields of both poplars and winter cereals are greater when they are grown in association rather than in single culture. He suggests this may be due to modified rooting patterns in the mixture, with the trees rooting more deeply, so avoiding drought stress in the summer. If nut trees formed part of such a system it could further boost food yields, providing a healthy alternative for meat. This is important if we in the west are to reduce our consumption of animal produce. Sylvo-arable systems might be in their infancy, but with so much land devoted to farming, and demand for food increasing, they deserve our attention. Changing the focus from single crops to the system as a whole and the soil as a carbon sink would revolutionise farming. As a bonus it would be good news for biodiversity. Brussels, Belgium
Network overload From Tom Phillips, GSM Association At the GSM Association, which represents the interests of the mobile communications industry worldwide, we have a slightly different take on the problem of smartphones overloading networks from that in your article (30 October, p 44). We agree there is a wireless capacity issue, but think developments in mobile technology will help.