nGlobal irrigation in early 1990’s: F16% of total cropland F36% of total harvest nIrrigation’s contribution to increased production n(seeds, water, fertilisers, agrochemicals) nUses about 65% of total available freshwater, and expected to decline to 60%in Y2K. Irrigation, productivity and the future

nContributed more than 1/2 of productivity gains since 1970 nAsia:2/3 of food supply from <1/2 of cultivated area. n40% of all agricultural production from 20% of arable land in developing countries (Seregeldin 1996) n46% grain, 57% total value of wheat and rice in developing countries produced under irrigation in nSee overhead of production and arable area Irrigation, productivity and the future (contd)

The future of irrigation? n : buoyant investment in irrigation projects n(high yielding varieties, and good grain prices) nbetween 1961 and £500 bn (‘95 prices) nHowever, there has been a decline in investment due to: Ffall in grain prices Freal costs of irrigation increased Fthus low rates of return Flow efficiencies of projects Fgrowing competition for freshwater (65%) Fenvironmental concerns nHowever, the need for irrigation projects remains

The future of irrigation? nThe future of large-scale funding seems to be giving priority funding the improvement of existing irrigation systems nHowever, the future of irrigation and water provision both seem to be intricately linked to the ability of agriculture to feed the human population nSee overhead of human population and noverhead of water provision scenarios

Choice of irrigation systems: (Is it worthwhile irrigating?) nclimate and soils ntopography nwater supply ncrop types nlabour nlegal aspects nOther issues: Ffarmer training available, pests, machinery: spares and mechanics?,

Choice of irrigation systems: nclimate and soils ntopography Fwill affect choice of irrigation method, height of fields compared to water supply, use of pumps, levelling costs, nwater supply Felevation, distance, quality, cost, quantity of water required is frequently underestimated, need to consider seasonal availability and maximum demand ncrops Fmay have to introduce new crops- will they sell? FIs the price of crop > irrigation costs?

Choice of irrigation systems: nlabour Fmore intensive than rain-fed cultivation, small farms- little added labour, more tied to land nlegal aspects Fmany countries have legislation governing the use of limited water resources, common rights, upstream uses nOther issues: Ffarmer training available, pests, machinery: spares and mechanics?,

Soil and Water Conservation n“Runoff agriculture provides moisture by collecting surface/subsurface runoff where other sources are likely to too costly, unsustainable or damaging.“ n“Concentration of surface runoff for cultivation” nEffectively uses moisture that would otherwise go to waste (unavailable to agriculture) nCharacteristics and advantages of runoff farming: Fcheap to establish Fuses local materials (remote areas) Fa sustainable practice Fimproved harvest security Fimproved yields, more crops per year Fimprove quantity and quality of streamwater and groundwater recharge

Soil and Water Conservation nAgronomic techniques FMulching Fplastic sheets underground Fsoil amendments FFallowing FConservation tillage nMechanical techniques (devices that act as cross-slope barriers Ftrash lines Fstone lines Fwattling/staking Fcontour bunds, hillside ditches, soil pits, terraces

Soil and Water Conservation nVegetative techniques Fplant cover Fagroforestry nFog and mist harvesting F litres per day from 48m 2 mesh trap FFurther reading: FBarrow 1987 FHillel 1997 FStern 1979