in Left Top Pot, no Plant Food; in Left Bottom Pot, Plant Food Scanty; in Both Right Pots, All Elements of Plant Food Present

He should understand also that liquid manure is of more value than solid, because that important plant food, nitrogen, is found almost wholly in the liquid portion. Some of the phosphoric acid and considerable amounts of the potash are also found in the liquid manure. Hence economy requires that none of this escape either by leakage or by fermentation. Sometimes one can detect the smell of ammonia in the stable. This ammonia is formed by the decomposition of the liquid manure, and its loss should be checked by sprinkling some floats, acid phosphate, or muck over the stable floor.

Fonte: Agriculture for Beginners