Fertilizer Sources and Application Flashcards

Which fertilizer source has the highest nitrogen content by weight at approximately 82%?

Answer: Anhydrous ammonia

Anhydrous ammonia (NH3) contains approximately 82% nitrogen by weight, making it the most concentrated dry or liquid nitrogen fertilizer source.

What is the primary advantage of polymer-coated urea over conventional urea?

Answer: Reduced volatilization and controlled release over time

Polymer-coated urea releases nitrogen slowly over weeks to months, reducing volatilization losses and synchronizing N supply with crop demand.

Diammonium phosphate (DAP) has an approximate analysis of:

Answer: 18-46-0

DAP (diammonium phosphate) has a standard analysis of 18-46-0, meaning 18% N and 46% P2O5.

When applying potassium chloride (muriate of potash) to a chloride-sensitive crop, what is the best alternative potassium source?

Answer: Potassium sulfate

Potassium sulfate (K2SO4) provides potassium without chloride and is preferred for chloride-sensitive crops like tobacco and some fruits.

Which application method best reduces ammonia volatilization loss when surface-applying urea?

Answer: Incorporating urea into the soil or injecting it

Incorporating urea into the soil through tillage or injection dramatically reduces ammonia volatilization by keeping urea in contact with soil moisture and cation exchange sites.

What is the primary reason sulfur-coated urea releases nitrogen more slowly than uncoated urea?

Answer: The sulfur coating must degrade or crack before water can dissolve the urea

The sulfur coating acts as a physical barrier; as it weathers and cracks, water enters and dissolves the urea, releasing nitrogen gradually.

A producer wants to apply 120 lbs N/acre using urea (46-0-0). How many lbs of urea per acre are required?

Answer: 261 lbs/acre

Divide the desired N rate by the N fraction: 120 ÷ 0.46 = 261 lbs urea/acre.