Development of environment-friendly agricultural production technology in islands


The project will suggest a sustainable agricultural production system, and develop techniques to use local recyclable fertilizers and a technology to manage the efficient use of the limited water resources. And then, we will develop a decision-making system for the government officials to use.
Specifically, measures to safeguard water resources are urgently needed because many small island countries dotting the Pacific Ocean, etc. are very susceptible to a rise in sea level and extreme reduction of rainfall due to climatic changes. For islands where the bedrock is made of coral limestone, as a ‘high island model’ made of raised limestone plateaus of coral reefs, we will focus on a coral lime plateau over which a deep underground stream is flowing over in Negros, Philippines. Focus shall also be on a freshwater environmental phenomenon called the “freshwater lens", which floats because of the density differential at the top part of the aquifer which includes the underground seawater in Laura, Marshal Islands which serves as a low atoll island model.
JIRCAS is endeavoring to develop a small-scale desalination device that can supply freshwater from seawater at low cost in response to the serious need to secure water for drinking, irrigation, and other purposes during drought.
As for the groundwater in high islands, nitrogen contamination is quantitatively evaluated by the ratio method etc. and the contribution rate of each source is estimated. The origin of the nitrogen is also estimated and available evaluation method for groundwater nitrate contamination will be developed. As for the low-lying islands, a technology to monitor the dynamics of the freshwater lens is being developed and the change of the groundwater storage volume is analyzed by simulating the dynamics of the freshwater lens, so that a sustainable intake method and water quality conservation measures can be suggested.
To promote an agricultural production system which has minimal loading on the groundwater, a local recyclable fertilizer source is being looked into and a fertilizer application technology, which makes effective use of the advantageous properties, is being developed to contribute toward mitigating the contamination. An irrigation system, which makes effective use of the fertilizer source, shall likewise be developed in the highly elevated lands of mountainous atoll islands where the soil is shallow and the fertility is poor. A decision making system will be finally developed by summarizing the outcomes which can be used for local development by the administrative officers.

Fig.1 Wells in Negros which are threatened by nitrogen contamination.

Fig.2 Laura district in Marshall Islands with an underground freshwater lens


Laura Lens Conservation and Management Manual

Manual, Appendx