Huge drop in land used for agriculture although water plentiful
Since 1988 the amount of land on Rarotonga used for growing, has dropped by 73 percent and it has nothing to do with the water supply

Visitors to the Farmers Market at the Punanga Nui next Wednesday will marvel at the variety of crops on display but may not comprehend the huge drop in land under cultivation on Rarotonga.
According to the Ministry for Agriculture, the 2011 census shows that land used for growing has dropped by 73 percent since 1988.
This big drop in land under cultivation on Rarotonga has little to do with the water supply although the availability of water still presents some problems.
With weather patterns changing due to climate change and other factors, some consideration needs to be given to sustaining a sufficient supply of water in the wider context of food security.
Water supply has been treated as a single policy issue without regard to the separate requirements of the domestic /commercial sectors and the agricultural sector. There are no separate reticulation systems where water is concerned. One pipe or system is used for both domestic/commercial usage and agricultural use. For example, in one part of Upper Tupapa, the first water outlet on a pipe to 9 homes is used by a grower to water his taro patches. Farms and homes share the same pipelines and the use by both during times of water shortages affects pressure.
For domestic/commercial use policy you have the benefit of fixed outlets-homes and commercial buildings. It is easier to come up with policies governing use of water when a building is involved. There is certainty where to lay pipes and place water tanks. Rain can be collected by utilizing the building’s roof. Metering is easier however this also raises issues to do with user pays and water quality.
Where agriculture is concerned, with no structures, wide open spaces the demands in each year vary according to crop, crop rotation, area under cultivation and seasonal growth. Permanent arrangements for collection points, pipes and tanks are more difficult. Consideration could be given to inflatable or transportable water storage facilities. However these would all add to production costs, drive up prices to consumers and put our exports at a disadvantage.
While it is relatively easy to measure the use of water in terms of quantity by fixed buildings the demands of the agriculture sector are more difficult to measure and quantify season to season.
Without the benefit of metering, estimates regarding agricultural use need to be made.
According to Associate Minister for Agriculture, Kiriau Turepu himself a major planter in Matavera, water is an issue on Rarotonga. He told the Times last week, we should see some improvements if the water project funded by the Chinese proceeds. He also said there was an ample supply of underground water.
Turepu said less water will be required if less produce is grown.
Indeed, the Ministry’s records show that the amount of land in use for agriculture has decreased dramatically since 1988. This is probably due to more land being used for housing.
There is close to 5,000 acres of arable land on Rarotonga according to William Wigmore of the Ministry.
The agriculture census in 1988 showed that about 50 percent, or 2,097 acres were in use for agriculture. However, by the time of the census in 2000, 1,153 acres were in use and the latest census in 2011 showed just 558 acres were in use for agriculture. That, according to the Ministry’s William Wigmore, means since 1988 to 2011 there has been a 73 percent reduction in the amount of land in use for agriculture.
Does that translate into a similar drop in the amount of water used? Without metering, that is not known.
Wigmore says many farms are using the “drip” irrigation system. The application of continuous running water can cause rot and disease if the soil is too wet. The use of mulch and dry coconut fronds around plants will help reduce reliance on water. The placing of cut grass around fruit trees also helps and will encourage the growth of micro-organisms.
There are no plans by government to tap into and utilize the underground water system in times of severe drought although two previous studies in 1992 (French Consultants) and 1998 (SOPAC) have estimated there is more than enough water underground to meet the daily needs of growers and domestic/commercial users.
In the 1992 study, it was estimated that by the year 2000 the total water demand would be 32,000 cubic metres per day (farms-23,500 cubic metres allowing for drought and waste, domestic/tourist/industrial-8880 cubic metres allowing for some leakage).
In 1992, the Consultants calculated that for the 32 kilometers of coastline, some 47,000 cubic metres of fresh water per day was flowing underground to the sea. For every 100 metres of beach, 5,400 litres of fresh water is flowing out into the lagoon each hour. This is more than enough to cater for both farm and domestic/commercial use especially since 1988 there has been a dramatic drop in the amount of land in use for agriculture.
A private study in 2008 estimated there was some 130,000 litres per day flowing underground in the Titikaveka area between the CICC church and Titikaveka College.
The 1998 study showed coastal water wells were feasible if protected against contamination say from piggeries but recommended more tests and the development of a policy for times of drought.
As more arable land on Rarotonga is taken up by housing, other possibilities besides reducing production, for reducing pressure on the water system by growers, is to turn to more drought resistant crops. Some steps are already taking place for instance with Moringa which thrives in poor, dry soils.
In next week’s Herald we look into the reduction in land under cultivation and whether some arable land should be protected to ensure future security of the food supply. -Charles Pitt

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