D25 - Use of water for irrigation
Source: MAFF, Irrigation
Agriculture accounts nationally for less than 3% of all surface water and groundwater abstractions, although there are major regional differences (the east coast, central Midlands, East Anglia and southeast England are consistently drier than the west and north). Irrigation accounts for the most significant use of water in agriculture and the overall volume of water used for this purpose has been increasing steadily since the start of the 1980s. The increase is the result of a shift towards more water-dependent crops such as potatoes, vegetables and sugar beet. Spray irrigation is practised in the summer periods when rainfall is lowest. Other uses also place severe stress on water sources at a critical period for the environment.
Most produce is now grown under contract. Contracts generally stipulate that adequate irrigation water must be available to ensure quality and continuity of supply. This, combined with higher business risk resulting from growing higher value crops, has led to an increase in the number of irrigation reservoirs and in the amount of water stored.
The volume stored (as a percentage of the 164 million m 3 used in 1995 the fourth driest year in the past 40 years) has risen substantially from 13% in 1982 to 39% in 1995.
Various forecasts have been made of future irrigation water demand and, although these are subject to considerable uncertainty due to climate change, CAP reform and market conditions, the consensus is that the level will reach 250 million m 3 by 2021, an increase of 52% on 1995. In 1995, over three-quarters of crops were not supported under CAP, thus requiring UK farmers to compete with farmers in other countries at world market prices. The move towards irrigating only higher value output crops such as potatoes and vegetables makes better economic sense, as the use of irrigation water provides a higher return on investment than in the past. However, these higher value crops require greater inputs of nutrients and pesticides and this may create increased risks of pollution. On the other hand, these risks are likely to be minimised by the high level of management skills needed to grow the crops.
Farmers and growers are encouraged through such devices as MAFF Irrigation Scheduling and the MAFF Irrigation Water Assessment and Management Plan to use water more efficiently, thereby reducing water demand in areas short of supplies, particularly during periods of low rainfall.
Targets have not been established in this area, but might in future relate to the capacity of water storage on farms or to an ideal ratio between the amount of water abstracted for irrigation and water storage capacity. Any targets should probably relate only to eastern England, the main region in which crops are irrigated.
Adoption of alternative farm management systems
Nitrate and phosphorus losses from agriculture
Pesticides in rivers
Agriculture obtains water either from mains supply, from licensed abstraction, from surface to groundwater sources or from rainfall. There are no nationally reported statistics on the quantity of mains water used in agriculture, although some figures are available through water company customer information databases. The Environment Agency, through the abstractions licensing system, collates information on water taken from surface and ground water sources. There is a wide range of uses of water on the farm from stock-watering, washing down yards, cleaning equipment, dilution of chemical sprays as well as irrigation of crops.
Most abstractions from inland and tidal waters in England and Wales must be licensed. Abstractions from surface waters of less than 20 m 3 for domestic and agricultural purposes (excluding spray irrigation) are, however, exempt from regulation. DETR collects data from the Environment Agency and water companies that are published annually in its Digest of Environmental Statistics. However, the reliability of the data from the early years (pre-1991) is open to question. Spray irrigation is the only type of irrigation currently regulated and, for licensing purposes, is not classed as agricultural use but is collated separately. Data on spray irrigation going back to 1970 are presented.
The OECD has calculated that in the UK annual freshwater availability is 76 billion m 3 of which 12 billion m 3 are used for all purposes. Agricultures share is very small.
MAFF has carried out 16 irrigation surveys since 1955 and these provide a good quality data set with information on the volume of water used, the types of crops it is used on and other items such as equipment, reservoirs and sources of water. These data also include water used for trickle irrigation, which has gained popularity in recent years and is not recorded by the Environment Agency licensing system. The surveys also show the total capacity of reservoirs, lined and unlined, and of other forms of storage such as tanks from 1974 onwards (with the exception of 1977 when the data set was considered flawed and not published).
It is, however, acknowledged that this does not show the effect of irrigation on different crops, or regional variations. An additional indicator might be included on irrigation practice. This could show adoption of good practice in respect of the equipment used and timing of applications. It could later be split into the different types of irrigation. It might also reflect regional differences in irrigation. The indicator could be flanked by an indicator on total water use in the agriculture sector or even, in the long term, an indicator on water efficiency in agriculture. MAFF surveys provide information on the type of equipment used on farms but this is related neither to volume of water, nor area on which water is used and cannot therefore provide an overview.