A researcher who is doing an experiment on fertilizer rate wants to apply nitrogen (N) at 50 kg per hectare and phosphorus (P) at 50 kg per hectare. Assume Urea and Di-ammonium Phosphate (DAP) fertilizers are the only nitrogen and phosphorus fertilizers available in store. The experimental plot size of the researcher is 2000 m2. Calculate the amount of urea and DAP fertilizers that the researcher has to apply to 2000 m2 experimental plot size. Assume N is 46% in urea and 18% in DAP and P2O5 is 46% in DAP fertilizer. The atomic weight of P is 31 and O is 16.
The amount of Urea and DAP will be 21.7 and 50 kg for 2000 m2 land. However, 9 kg urea will come from the applied 50 kg DAP as 18% N have in DAP. So, finally 21.7-9 kg = 12.7 kg need to be applied.
I ha=10000 Square meter.
50 Kg P for hectare = 10 kg P for 2000 m2 because 10000/ 2000 =5 for this reason 50/5 = 10 kg P for 2000 m2 .
Amount of Nitrogen also =50/5 =10 kg N for 2000 m2
P * 2.29 = P2O5 10 *2.29 =22.9 Kg DAP for 2000 m2 ,and this amount contains nitrogen also(18%)nitrogen
29.9 *(18/100) = 5.382 kg nitrogen as a result of adding DAP.The remain quantity of nitrogen (10-5.382=4.618 kg nitrogen must be add fro urea which equal to (4.818 *(100/46) =10.473 kg urea for completing the amount of nitrogen to 10 kg per 2000 m2.
See this study Article Nitrogen use efficiency and critical leaf N concentration of...
First calculate the dose of DAP fertilizers (which contains 46 % P2O5 and 18 % N) to provide P2O5 in 2000 meter square area (0.2 hectare) @50 kg P2O5/ ha...
(50 kg/ha×0.2 ha)×100/46= 21.74 kg DAP is required...
Now see, how much nitrogen will be provided by 21.74 kg DAP as DAP contain nitrogen also that is 18 %
100 kg DAP will provide 18 kg N
then 21.74 kg DAP will provide 18×21.74/100= 3.91 kg N...
Requirement of nitrogen is 50 kg/ha...
Then remaining amount of nitrogen that is 50-3.91= approximately 46.09 kg N will be supplied by using urea (contain 46 % N)....
Amount of urea required to supply 46.09 kg N
(46.09 kg/ha × 0.2 ha)×100/46%= 20 kg urea...
Calculate the amount of nitrogen 250kg/hac Urea and 125/hac DAP for 4 square meter research plots?
The molecular weight of DAP (NH4)2HPO4 =132 which contains 21% N. First we must calculate amount of DAP for 4 square meter:
125 kg DAP for ha or for 10000 square meter , it means fore 4 SQM = 125 *(4/10000) = 0.05 Kg =50 gram DAP per exp.unit.
or 125kg DAP/ha conatins 125 *21% =26.25 Kg N was added from DAP.It means we must add (250-26.25 =223.75 kg N /ha from urea which contains 46%N which equivalent to 223.75* (100/46)=486.41 kg urea /ha = 486.41 (4/10000)=0.19456kg per 4 square meter or 194.56 gram urea per 4 square meter .
Note:The calculation was done on the base of N% in DAP not on the base of NH4.
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