example proposal

Activity proposal: Soil and plant assessment post-tsunami
IGM. Subiksa dan Achmad Rachman
Indonesian Soil Research Institute
Key messages
• Soil, water or plant sampling must be done carefully, because the sample will represent soil condition over several hectares.
• The quality of soil, water and plant sampling will determine:
⎯ the accuracy of test results
⎯ the success of land management.

Introduction
Natural healing of tsunami-affected agricultural land depends on landform, soil texture, soil type and rainfall. Concave landforms need more restoration time than flat or convex landforms because salt accumulates in the dips and depressions. Land with sandy texture and low CEC tends to heal faster than clayey soils with high CEC. Mineral soils will heal more slowly than peat soils. Indeed, seawater may have a good effect on peat chemical properties. Finally, rainfall is the main factor in restoring soils health; the higher the rainfall, the faster the soil is leached of salts.
This training activity aims to:
• collect data on soil, water and plants over time, and evaluate the impact of the tsunami on the landscape
• identify the areas still affected by the tsunami.

Expected outputs are:
• time series information on physical and chemical properties of soil and water after the tsunami
• maps of the areas still affected by the tsunami.

Methodology
Materials and tools
Materials needed for this activity are soil maps, topographic maps, plastic bags, bottles, stationery, label paper, and chemicals for soil analysis. Tools needed are EC meter, PUTS or trough pH, sample auger, and laboratory tools for analysis.
Site sampling selection
Soil sampling will be done in several agro-ecosystems namely sawah, rain fed areas, upland and swampland. Sampling sites will represent soil types or soil texture types and be free of accumulated manure, straw or ash. The sampling site should represent general land condition.The soil and water sampling site in each agro-ecosystem will refer to a toposequence or soil mapping unit (polygon) in the topographic map. The land coordinate (refer to UTM) should be determined to ensure that further sampling is on the same site. Each sampling site will be plotted on the soil map or topographic map.
Methods of soil/water sampling
In each site, two soil samples will be taken at 0-20 cm and 20-40 cm depths. Each sample will be a composite of five sub-samples taken within a 5 m radius using a Belgie auger or tube sampler. For analysis purposes we need about 0.5 kg for each sample in a clearly labelled plastic bag. The label will include the sample number, depth of soil taken, and location. Sample details will also be entered in a notebook with the date of sampling and site coordinates (refer to UTM).
For the analysis of physical soil properties, three core samples will be taken at 0-10 cm, 10-20 cm, 20-30 cm and 0-40 cm depth.
Water samples, 0.5 litres each, will be taken from the same site (ground water or surface water) and from the nearest river or creek. Samples should be free of debris and mud, bottled, and clearly labelled.
Samples will be taken every three months (ie four times a year) at the same site to assess nutrient dynamics and rate of natural land healing.
Soil and water analysis
The soil samples will be analysed in the laboratory for soil texture, organic matter, EC, pH, phosphorus, potassium (HCl 25% extractable), phosphorus (Bray), potassium (Morgan), cations, cation exchange capacity, aluminium, hydrogen and DTPA micronutrients. Soil properties such as pH and EC can be measured in the field. Water samples will be analysed for pH, EC and mineral content.
Soil and water data interpretations
The analysis results will be evaluated immediately and linked with plant growth. The assumption is that the tsunami introduced high salt levels (EC > 40 dS/m) in the soil, so tsunami effects will be observed in EC, pH, ESP and SAR parameters. Soil EC of <2 dS/m is generally not harmful for growth of most plants. Soil pH > 6,0 indicates that base cations are dominating the exchange complex. The value of ESP (exchangeable sodium percentage) of about 10% is considered as the presence of sodium hazard (sodicity). The SAR (sodium absorption ratio) value for soil and irrigation water must not exceed 10 for soil with low salinity. The SAR critical value is lower in more saline soil.
Nutrient dynamics will be observed in graphs of the time series data which will show nutrient dynamics over the year. This information will help us evaluate nutrient balances and recommend strategies for amelioration and fertilising, which can then be extended to similarly affected land elsewhere.
Plant growth evaluation
Crop performance could provide indications of physical and chemical soil conditions. For instance, in rice crops, stunted growth or burnt leaf tips indicate strong salinity. Plant growth in tsunami and non-tsunami areas will be compared to learn to recognise tsunami effects on plants so that we can take appropriate actions to restore soil health.