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" 1 necessary to be pumped, wastes energy-intensive fertilizer by leaching, 2 and reduces production by waterlogging and salination cannot be a part 3 of this package. 4 Figure 1 [Hopper (6)] shows a sixfold increase in rice production ~ 5 per unit area as farming intensity in Japan increase~^ More than half 6 of this increase was the consequence of technical innovation and struc- 7 tural reforms in the rural economy. These reforms established the full 8 range of institutions and infrastructures needed to support high pro- 9 ductivity agriculture. Evapotranspiration tends to be rather constant 10 per unit of cropped area, and therefore, these reforms greatly increased 11 crop yield per unit water consumed. Particularly if the high level 12 water management possible with high-frequency irrigation were practiced, 13 it is entirely possible tha~ the highest yields with many crops could 14 be obtained with as little as half the water now being used. Because 15 fertilizer and water are usually the two highest continuous energy 16 inputs, if by efficient water management these could be kept at an ade- 17 quate level with minimum inputs,. the one-time energy inputs represented 18' by ~~ructural reforms that yield such high increases in production have 19 the potential of raising the energy efficiency of high-intensity farming 201 Syst2~~ above that of low-intensity syste~. Of course, without ade- 21 ql!.ote fertilizer, water, and other necessary inputs, little gain from 22 structural reforms can be expected. 23 Thus, relatively high energy input into irrigation may often be 24 justified by its catalytic effect on other inputs. But we should not 25 stop looking for less energy intensive ways to irrigate efficiently. 26 Aside from their energy requirement, sprinkler- and drip-irrigation 27 SYSt2~S are rather conplicated, requiring many different kinds of ?arts I Ou2983