Fertilizers

What are the "big three" nutrients in fertilizers?

Nitrogen (N), phosphorus (P), and potassium (K)

Why is phosphorus-free fertilizer used in some places?

To prevent algae blooms caused by phosphorus runoff.

What environmental issue is caused by fertilizer runoff into the Gulf of Mexico?

The creation of a "dead zone" with depleted oxygen levels.

What are common synthetic nitrogen fertilizers?

Ammonium nitrate (NH₄NO₃) and anhydrous ammonia (NH₃).

How does soil pH affect nutrient availability?

It determines how easily plants can absorb nutrients.

What are two organic sources of nitrogen?

Chicken manure and dried blood. (bone meal)

What historical material was traded globally for fertilizer in the 19th century?

Guano from seabirds.

What nutrient is mined from rock deposits and used in organic farming?

Rock phosphate.

How does industrial nitrogen fixation impact the environment?

It consumes large amounts of energy and relies on natural gas.

Why are feathers used in fertilizers?

They contain nitrogen-rich proteins.

What role do legumes play in nitrogen fixation?

They fix nitrogen for their own use but add little to soil nitrogen when harvested.

What is greensand, and why is it used?

A potassium-rich rock used as an organic fertilizer.

How can phosphorus be recovered sustainably?

Through research into phosphorus recovery from waste.

What is the environmental impact of potassium mining?

It depletes buried rock deposits and has significant ecological costs.

How do organic fertilizers compare to synthetic ones in cost?

Organic fertilizers are more expensive.

What was a key development in agricultural chemistry during the 19th century?

Liebig's theory of mineral nutrients (N, P, K)

What is kelp meal, and how is it used in fertilizers?

A natural source of potassium, though it contains only 2% potassium.

Why is feather waste explored for use beyond fertilizers?

It can be repurposed into bioplastics.