"I think of my gun as a tool for converting worthless human garbage into valuable fertilizer."

Poultry droppings are harmful to plants when fresh but after a period of composting are valuable fertilizers.

Outside every field you find a home-made latrine, waiting for passing cyclists to contribute valuable fertilizer.

A smelly nuisance in a stable is valuable fertilizer if you move it to the south forty.

Sewage sludge could be a valuable fertilizer for use in British forests, according to the Forests Authority.

It can be further neutralized with ammonia to form ammonium sulfate, a valuable fertilizer.

In this position it competes with the cultivated rice and uses valuable fertilizer and space.

Colonial breeders produce guano which is a valuable fertilizer.

He had it mined for bat guano, a valuable natural fertilizer.

For them, manure isn't valuable fertilizer but a vexing disposal problem.