Management of nitrogenous fertilizer :
The objective of nitrogenous fertilizer is to reduce losses and increase nitrogen use efficiency (NUE). The methods to reduce nitrogen loss in paddy field are :
- Method of application :
- Soil surface of rice field is classified as oxidized and reduced zones.
- Apply fertilizer according to demands of crop by splitting into 2-3 doses.
- Time of application :
- Apply fertilizer during critical stages of plant (tillering and panicle initiation stage).
- Amount of application :
- Apply fertilizer according to demand of crop by splitting in 2-3 days.
- Selection of suitable fertilizer :
- Ammonical form of fertilizer are better than nitrate form because there is less chances of denitrification and leaching loss .
- Ammonical form of fertilizer are urea , ammonium , sulphate , ammonium phosphate , etc.
- Use of slow release materials or coated urea :
- urea is coated by oil seed cake , neem cake , mud or sulphur and applied on paddy field.
- These coated area release nitrogen slowly and minimizes the loss through denitrification and leaching granular urea also has slow release properly.
- Use of nitrification inhibitor :
- These are the chemicals that slow down the process of nitrification an increase the nitrogen use efficiency.
- Examples are : Thiourea , Potassium azide , etc. used @ 5% of fertilizer.
- Providing ample time for decomposition of organic manure so that nutrients in organic form are readily available in mineral form for plant. Otherwise , there will be immobilization of N due to ammonium fixation.
- Use of manure :
- Reduces loss of N by ammonia volatilization.