ACIAR project work in Aceh has had an unexpected benefit to agriculture in coastal Java. An instrument that measures soil salinity, called an EM38, was introduced to ACIAR project members in 2005. The EM38 allowed rapid assessment of soil salinity levels in tsunami-affected soils ¹. Following its use in Aceh, two EM38s were transferred to national institutes for soils and rice. In Java, the Indonesian Soils Research Institute has used the EM38 to survey over 100,000 hectares of farm land subject to tidal inundation and seawater intrusion during the dry season.

Indonesian Soils Research Institute has produced salinity maps based on the 2009 survey of Indramuri district rice fields.

Rice fields in Indramayu, North Java, occupy 55% of the district. Survey results indicate that 32% of these fields currently have high and very high levels of salinity that can affect rice production. The impacts of salinity levels are particularly exacerbated in the dry season rice crop. Less irrigation water is available and farmers are using saline ground or river water. The potential for future sea level rises to affect coastal farmland could exacerbate this situation.

The crop is at most risk when irrigated with saline water during transplanting of seedlings into rice fields. The addition of fresh water reduces plant stress from water loss caused by salt, and dilutes and flushes salt from water bodies and the top soil.

The EM38 is a portable tool permitting rapid assessment of soil salinity.

Research and extension staff from Aceh and other parts of Indonesia were trained in the use of the EM38.

The results of this survey will help local authorities to manage salinity levels in Indramayu rice fields, requiring greater use of salinity-tolerant rice varieties, adding gypsum to the soil and improving the drainage and irrigation networks to allow fresh water to flush salt from the worst affected fields. This approach is similar to the post-tsunami rehabilitation efforts of salt-affected fields in Aceh.

Authorities can direct their limited resources to more affected areas and plan for potential increases in this problem in the future if predicted sea level rises eventuate.

More information: deddyerfandi@yahoo.co.id

¹ www.dpi.nsw.gov.au/agriculture/resources/soils/salinity/general/assess-indonesia