Question

Which of the following is not a nitrogenous fertilizer?
[A] Ammonium sulphate
[B] Urea
[C] Ammonium nitrate
[D] Superphosphate

Answer 1

HINT: Fertilizers which do not contain nitrogen are non-nitrogenous fertilizers. Here the correct answer is a calcium based fertilizer. It contains calcium and phosphorus and is also known as monocalcium phosphate.

COMPLETE STEP BY STEP SOLUTION: We know that a fertiliser is synthetic or a natural material mixed with the soil to give the plants growing in that soil the nutrients that it needs while growing.
These fertilisers are of various kinds depending upon their base of origin i.e. natural or synthetic and the compounds used for making it. The most common fertilizers are nitrogenous bases but there are others like phosphates and potassium based.
Now let us discuss the fertilizers given to us and find out if they are nitrogenous or not.
Firstly, we have Ammonium sulphate. It is an inorganic salt with the formula ${{\left( N{{H}_{4}} \right)}_{2}}S{{O}_{4}}$. It has various commercial uses but most commonly it is used as a soil fertilizer. It consists of 21% nitrogen and 24% sulphur.
As we can see it contains nitrogen, therefore it is not the correct answer here.
Then we have Urea. We also know it by the name carbamide and it is an organic compound with the formula $CO{{\left( N{{H}_{2}} \right)}_{2}}$. It is the most commonly used nitrogenous fertilizer due to its high nitrogen content. It contains around 46% nitrogen.
Urea is also a nitrogenous fertilizer therefore this is not the correct answer either.
Next we have Ammonium nitrate. It is a chemical compound with formula $N{{H}_{4}}N{{O}_{3}}$. It is also a nitrogenous fertilizer but it is not as strong in nitrogen content as urea. It contains around 34% nitrogen.
And lastly, we have Superphosphate. It is monocalcium phosphate which is an inorganic compound with chemical formula $Ca{{\left( {{H}_{2}}P{{O}_{4}} \right)}_{2}}$. It is commonly found in the monohydrate form.
We can see from the above discussion that monocalcium phosphate does not contain nitrogen.

Therefore, the correct answer is option [D] superphosphate.

NOTE: Nitrogen based fertilizers are very commonly used but only a fraction of these fertilizers is converted into plant matter. The remaining is accumulated in the soil. There are many adverse effects of nitrogen and phosphorus based fertilizers on the environment. Due to heavy rainfall, these fertilizers are washed away into waterways and cause eutrophication of freshwater bodies. These run-offs are the primary cause of depletion of oxygen in parts of the ocean.