Acid sulfate soil is the soil which its amount of sulfuric acid is enough to cease plant
         growth and decrease crop yield. 

         How to observe acid sulfate soil area 

         1. Dig the soil about 50 cm. and find yellow sulfuric compound called 'Jarosite'.
             scattered among red and brown compound

         2. Water in the area is clear like begin swung by alum. Its taste is acid or sour.

         Area where acid sulfate soil is found in the Center 

         Acid sulfate soil is found in rather plain or plain area in Thailand.

From the survay conducted by Land Development Department, acid sulfate soil is found in the Center of Thailand covering Nakhon Nayok, Ayutthaya, Pathum Thani, Saraburi, Chachoengsao, Chon Buri, Prachin Buri, Samut Prakan, Nakhon Pathom, Suphan Buri, Nonthaburi, Bangkok and Ratchaburi. Its total area is 6 million rai.

         How to reclaim acid sulfate soil 

         1. Before transplanting, fill water and drain it. Do like this again and in order to leach
             acid and toxic substance from the soil.

         2. Add the lime like slaked lime, marl or ground limestone to decrease acidity in soil.

         3. After adding the lime, leave it 7-10 days. Then, add fertilizer consisted of

             Phosphorus before transplanting.

    

         Adding marl to solve acid sulfate soil problem 

         Marl is Calciumcarbonate which is loamy. It is found in Lop Buri, Saraburi and Nakhon Sawan.

   

         How to add marl 

         Prepare marl in the ratio suitable for soil acidity. Pile it up as a small heap distributed in the area and scatter it throughout the area before soil preparatio. Then, incorporate the soil and leave it 2 weeks for reaction of soil to acidity before planting. Such method is effective and safe because adding marl only one time will solve acidity problem at least 5 years.

         Although adding marl can solve soil acidity problem, there are other factors for plant growth and crop yield. Such fzctors are varieties of plant, fertillzer and pesticide application, maintenance and irrigation. Farmers should select suitable techniques for their area.

         Ratio of adding marl for acid soil reclamation 

         1. Growing rice Add marl 2 ton/rai.

         2. Planting crops or vegetables Add marl 3 ton/rai.

         3. Planting trees Dig the furrow and move the soil surface to the end of the furrow. Then, move below acid soil to the furrow border. Dig the hole 50x50x50 cm. for planting. In the first year, add marl 2 kg./hole and mix it with all of the soil in the hole. Add marl 4 kg.,6 kg., 8 kg. and 10 kg. in the second year, third year, forth year and fifth year respectively. Scatter it around the crown radius increased every year.

         Where marl is available 

         Farmers can buy marl at agricultural equipment store or at Phaputtabaht District,
         Saraburi Province.