$62.$ The process of converting atmospheric nitrogen to a form that plants can absorb is known as biological nitrogen fixation. Which of the following does NOT contribute to this process?

$-$ A$)$ Rhizobium bacteria in legume roots

$-$ B$)$ The Haber$-$Bosch process

$-$ C$)$ Cyanobacteria in water ecosystems

$-$ D$)$ Mycorrhizal associations in some non$-$leguminous plants

$63.$ Potassium chloride $($KCl$)$ is often used as a fertilizer in agriculture. What is a potential drawback of using KCl in chloride$-$sensitive crops?

$-$ A$)$ It can lead to nitrogen deficiency.

$-$ B$)$ It may cause chloride toxicity in sensitive crops.

$-$ C$)$ It decreases the soil pH drastically.

$-$ D$)$ It binds with phosphorus, making it unavailable to plants.

$64.$ The production of nitric acid via the Ostwald process involves several steps, including the catalytic oxidation of ammonia. What is a significant byproduct of this process that has environmental implications?

$-$ A$)$ Oxygen

$-$ B$)$ Nitrous oxide

$-$ C$)$ Methane

$-$ D$)$ Sulfur dioxide

$65.$ In an effort to reduce environmental pollution from fertilizer runoff, what strategy might a farmer employ to enhance nutrient use efficiency?

$-$ A$)$ Increase the rate of fertilizer application

$-$ B$)$ Apply fertilizers only during heavy rainfalls

$-$ C$)$ Use controlled$-$release fertilizers

$-$ D$)$ Focus exclusively on organic fertilizers