Realising the problem of acid soil, which makes land unsuitable for planting, His Majesty initiated a project called Klaeng Din (Trick the Soil) to revive useless land. With the development of his own theory to improve acid-soil conditions for use in agriculture, the project is the world's first innovation for acid-soil improvement.

To celebrate the 60th anniversary of His Majesty's accession to the throne, the National Innovation Agency under the Science and Technology Ministry has honoured HM the King as the Father of Thai Innovation for the Klaeng Din project.

As acid soil contains iron and sulphur in the form of pyrite, when it reacts with oxygen in the air, it releases sulphuric acid and this makes the soil unsuitable for cultivation.

The approach starts with aggravating the soil to make it strongly acidic by leaving the soil dry and then making it wet so as to accelerate its chemical acidification. The process is repeated several times a year until the soil is highly acidic.

Then there are studies to find ways to improve the soil so that it is possible to grow economic crops. Methods used to improve the soil depend on several factors, such as soil characteristics and cultivation type.

According to the royal initiative, there are several ways to minimise or improve highly acidic soil. The first is to control the underground water level above layers of mud and sediment, which helps prevent the pyrite from reacting with oxygen, thereby limiting the creation of sulphuric acid.

The second way is to improve the soil for perennial crops by using water to directly leach the acid and poisonous substances from the soil; mixing marl or lime dust with the acidic soil; or using lime together with water, leaching the acid and controlling underground water.

The third way is to create raised beds in order to cultivate fruit or perennial trees and dig ditches on the sides. This method uses the soil from the ditch to cover the top edge of the raised bed to create a thicker soil surface, and then uses water to leach acid down and mix lime with the soil.

After the process of improvement, the soil will be productive for cultivating rice, perennial crops, fruits, and for fisheries.

After experimenting with the theory for years, the Klaeng Din project has proven a success by improving acid-soil lands in Narathiwat province, and creating new agricultural areas. Agriculturists in the area have utilised the land to plant rice and can now generate yields of 750 kilograms per rai.