Secondary Nutrients
       Introduction
          Calcium, magnesium and sulphur are considered as 
              secondary nutrients for plants; however, they play   
              no secondary role in plant nutrition. 
                They are just as essential for plant nutrition as 
               any of the other 14 essential plant nutrients.
         Although,  secondary  nutrients  are  needed  in 
       lesser amounts than that of primary nutrients but 
       they are important for plants. 
              They have been called the “synthesizers” because  
                   of their functions in living organisms.
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                 Secondary Nutrients
       Introduction
               Many factors can affect the availability    
                   of these three nutrients to plants. 
        The best estimates of their availability can be 
        determined by soil analysis or a combination 
        of soil and plant analyses.
              However,  field  observations  and  deficiency 
              symptoms are also important diagnostic tools.
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                 Secondary Nutrients
           Sulphur (S)
       Sulphur is becoming more of a limiting nutrient in crop 
       production than in the past, for several reasons
             Higher crop yields require more S
                  Increased  use  of  high  analysis  fertilizers 
                containing little of no S
         Reduced  amounts  of  atmospheric  S 
         fallout from the sky
               Reduced  soil  S  reserves  from  organic  matter 
               losses due to mineralization and erosion. 
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                 Secondary Nutrients
           Sulphur (S)
       Most S in the soil is tied up in organic matter and cannot 
       be used by the plant until it is converted to the sulphate 
       (SO4) form by soil bacteria. That process is known as 
       mineralization. 
          Sulphur can be applied as broadcast or banded 
          fertilizer  material  or  applied  through  irrigation 
          systems (furrow and sprinkler).
               Sulphur  is  also  an  important  nutrient  for  proper 
               nutrition of forage crops that will be consumed by 
               livestock.
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                 Secondary Nutrients
      Sulphur (S): Role in Plants
       Sulphur (S) is an essential part of amino acids cysteine, 
       cystine and methionine. Hence, it is essential for protein 
       production.
           S is involved in the formation of chlorophyll and 
           in the activation of enzymes. It is a part of the 
           vitamins biotin and thiamine (B1).
            In most plants it makes up 0.2 to 0.3 per cent of dry 
            matter.  Thus,  it  is  as  important  in  plant  growth  as 
            phosphorus  and  magnesium;  but  its  role  is  often 
            underestimated. 
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