Soil Improvement in DPRK

Soil improvement work is mainly targeted at neutralizing acid soil.

Acid soil contains much hydrogen or aluminum ions.

These ions obstruct normal growth of plants by fixing the roots of plants and solidifying plants' albumin. They also give a negative effect on the functions of bacteria necessary for plants.

To resolve these effects, acid soil is neutralized with alkalis such as lime. However, appropriate acidity differs according to plants. For example, slightly acid soil is favorable for rice, while barley prefers alkali soil.

Soil can be acidulated in following cases;

1. Areas which have a great amount of annual precipitation,

2. Cold and humid areas where organic acid is formed due to the irresolution of an organisms,

3. Soil in which chemical fertilizers were applied for a long time,

4. Areas where there was no reasonable control of water,

5. When chemical wastes from factories such as highly acidified water, iron sulphide, sulphurous acid gas and acid streamed into arable lands,

6. When the acid substances of low quality contained in the waters of sea, lakes and swamps gave effects upon soil,

7. When strongly acid water flowed into lands from rivers.

North Korea's measures for soil improvement are as follows;

1. To give top priority to land control. A typical example is deep plowing which prevents evaporation of moisture in land caused by a pneumatic system and capillary phenomenon,

2. To apply much organic and phosphate fertilizer to land to increase humus soil,

3. To increase amounts of calcium fertilizer applied to acid soil, and improve the physical and chemical properties of soil grains at the same time,

4. To promote proper inter-row cropping,

5. To supply deficient microelements such as boron and molybdenum,

6. To properly apply lime and nitrolime fertilizer,

7: To spread silt over the fields according to the conditions of areas;

8: To burn soil in wide areas of farms and fields,

North Korea has also taken measures to prevent soil erosion. They are;

1. Contour-line cultivation based on building ridges between rice fields according to contour lines to prevent farmland from being washed away;

2. Strip cropping -- to create pastures in farmland between fields divided by contour lines,

Underground Water and Hot Springs

Underground water is classified into free, cave and crack water according to its natural form, and into cold, average and hot springs according to its temperature. It is also classified into mineral springs according to its quality.

There are various kinds of underground waters of good quality in north Korea, as water can percolate downward into the ground due to a high annual precipitation and many rivers and lakes in north Korea.

Complex geological features of north Korea is also related to its rich underground water resources.

Cracks formed by heavy crustal movements in the Mesozoic era facilitated water to percolate underground, causing the formation of a numbers of springs.

Widespread layers of sand, many limestone areas and mountains also contributed to the formation of underground water.

North Korea is blessed with underground water and is also rich in hot springs.

Hot springs, in a scientific term, is natural spring water which has higher temperature than the annual temperature of a certain area.

North Korea defines hot springs as natural water springs which have temperature higher than 25℃ and contains more than one kind of metallic ions such as carbon and chlorine ions.

The temperatures at which water springs are defined as hot springs differ according to countries -- 25℃ in Japan, 20℃ in Europe and 21.1℃ in the U.S. -- but a water temperature higher than 20℃ may be a common term for hot spring in the world.

The main components of hot spring water in north Korea are sodium bicarbonate and sodium chlorate, and also many hot springs contain gases such as radon and hydrogen sulphide gases.

Ongjin hot springs have the highest temperature of 60℃-120℃ in the north, where more than 1,200 tons of water gush out in a day. Pugok hot springs (50℃-74℃) are the hottest springs in the south.