GOVERNMENT OF TAMILNADU
DEPARTMENT OF SERICULTURE

Soils and Reclamation  

            Soil analysis is done in order to find out the quantity of essential nutrients available to plants and other relevant physical and chemical characteristics such as water retention, salinity, alkalinity, acidity, etc.’ which influence plant growth. For soil testing, only a very small quantity of the huge and vast soil mass in the field is actually used for soil testing.

Fertility rating of soil with respect to mulberry

pH

Electrical conductivity (dS/m)

Organic Carbon (%)

Available Nutrients (Kg/acre)

N

P2O5

K2O

Low <6.3

Normal <1.0

Low <0.5

Low<108

Low <9

Low <50

Normal 6.3-7.2

Critical

1.0-2.0

Medium

0.5-1.0

Medium

109-212

Medium

10-22

Medium

51-120

Moderately High

7.3-8.3

Injurious

>2.0

High

>1.0

High

>213

High

>22

High

>120

High

>8.3

-

-

-

-

-

 

Reclamation of Acidic Soils

            Soil of very acidic nature is not suitable for mulberry cultivation. Soil becomes acidic because of its origin from material acidic in nature or due to excessive leaching of lime and other bases or continuous use of acid forming fertilisers like ammonium sulphate and urea. Acidic soils occur in the high rainfall areas.

            Acidic condition of soil can be corrected by adding liming materials like dolomite, calcitic lime stones, burnt lime, Hydrated lime, lime sludge and slags, depending upon the availability. Ground limestone (Calcium carbonate) application is common.

            The quantity of lime stone required varies according to the texture of soil and degree of acidity. For further requirement, we may contact soil-testing laboratories.

Reclamation of Alkaline soils

            Alkalinity soil is due to the presence of salt (carbonates of calcium, magnesium and sodium) comparatively in high degree. They may be saline or saline-alkali or alkali depending upon the exchangeable sodium percentage. These soils usually occur in semi-arid and arid regions and the conditions are not ideal for mulberry growth. Generally they are deficient in nitrogen content, as the organic matter content is extremely low and the high pH and exchangeable sodium percentage cause reduction in the availability of plant nutrients.

            Gypsum application is one of the common amendments used in reclamation of alkaline soils. Quantity of gypsum to be applied depends upon the extent of soil alkalinity, soil texture and the crop to be grown. Before gypsum application, it should be in powder form. Gypsum passed through 2 mm sieve has been found to be satisfactory. Application of gypsum broadcasting at 9 MT/ha followed by irrigation reduces the pH of red loamy soil from 8.55 to 7.45.

            Instead of Gypsum, Plenty of good quality water has to be used for flooding and leaching the dissolved salt. Green manuring or straw as surface mulch is also recommended.

 Reclamation of Saline soils

            Saline soils are those which contain high quantity of soluble salts and show electrical conductivity above 4dS/m, pH below 8.5 and exchangeable sodium percentage of <15. High water table with high salt content, low rainfall and high evaporation rate, irrigation with saline water, poor drainage, use of salt producing fertilisers, etc., are some of the reasons leading to saline soil condition.

            Reclamation of saline soil is aimed at bringing down the salt concentration step by step. This is achieved by a process whereby solutions of high salt concentration in the soil is displaced by less concentrated solution. Any practice that will reduce the upward movement of water and salt by reducing evaporation or by increasing infiltration will also enhance salt leaching and soil reclamation. Therefore, plenty of good quality water for flooding and leaching and use of surface mulches are recommended.