Contradictions in standardization: the case of block irrigation in smallholder schemes in Zimbabwe
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In many smallholder irrigation schemes in Zimbabwe poor water use is cited as one common problem. Water is reportedly lost during conveyance, distribution and application in the field. The causes of this problem are varied. Most of the losses are said to be at or below the field channel gate (Pearce and Armstrong, 1990: 18). Inequitable distribution of water between blocks, between head and tail users along canals and differential water distribution at field level have been documented (Pazvakavambwa, 1984a; Pearce and Armstrong, 1990; Donkor. 1991). Over- irrigating has also been cited as another problem, particularly in gravity schemes (Makadho, 1993). These studies, in various ways, have emphasized the need for solutions to be found to the water-management problem in smallholder irrigation. Agritex, the government department with the mandate to develop smallholder irrigation in the country, alongside its extension service mandate, has taken steps.to address poor water use. One strategy that has been employed is the block system of irrigation. This system is currently used in most ‘new’ schemes constructed after 1985, in those that are under rehabilitation as well as in other ‘old’ schemes that are being re-organized. There are perceived advantages associated with this system. These advantages, gleaned by the author from interviews and discussions with a number of Agritex engineers and extensionists, fall into three categories. The most frequently advanced reason is efficient water use through accurate irrigation scheduling. The second advantage which relates to economic aspects of crop production is that it is easier to market the crop produce. Thirdly, block irrigation is conceived as making crop rotations easier to implement which ultimately results in improved maintenance of soil fertility. A related advantage is the possibility of better past and disease control.