Rating chart for soil test values

No.                Nutrient                     Low           medium          High
 
1.         Organic Carbon %              < 0.5         0.5 - 0.75         0.75 >
              (for Nitrogen )    

2.        Available P2O5  (kg/ha)     < 10          10-25                25>

3.       Available  K2O (kg/ha)        < 120           120-260         260>

4.      Available Nitrogen (kg/ha)  < 280            280-560         560>

                           

                                pH value

Extremely acid                <4.5
Very strangly acid          4.5-5.0
Strangly acid                  5.1-5.5
Medium acid                    5.6-6.0
Slightly acid                     6.1-6.5
Nutral                                6.6-7.3

Mildly alkaline                 7.4 - 7.8
Moderately alkaline        7.9 - 8.4
Strangly alkaline            8.5 - 9.0
Very straghly alkaline      > 9.1

P% x 2.29 = P2O5
K% x 1.20 = K2O

Conversion factor from Oxide to Element.
  
    Oxide % X factor             =          Element

1.  CaO % X 0.71                 =          Ca %
2.  MgO % X 0.60                =          Mg %
3.  Na2O % X 0.74               =          Na %
4. K2O % X 0.82                  =          K %
5. P2O5 % X 0.43                =          P %

Conversion factor from Element to Oxide.

     Oxide % X factor              =        Element

1. Ca % X 0.71                      =      CaO %
2.  Mg % X 0.60                    =       MgO %
3.  Na % X 0.74                     =       Na2O %
4.  K  %  X 0.82                     =       K2O %
5.  P % X 0.43                       =       P2O5 %

Text Book Soil Science
T.D. Biswas & S.K. Mukherjee (1992)

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