One respect that is often disregarded in animal husbandry is the disposal of liquid manure. Even small farm animals produce manure. But the 65 billion livestock animals worldwide produce far more of it. How to dispose of it?
The negative effects of methane emission have already been dealt with under 51% of all greenhouses gases are caused by raising farm animals".
Everybody knows that the smell can be an extreme nuisance, and we often criticize farmers for it. But we should come to understand that we bear a part of the responsibility when we consume milk and meat every day. In Germany alone, about 200 billion tons of liquid manure are spread on the fields year by year.
Other than the disgusting smell, the consequences for soil and ground water are less directly noticeable. Liquid manure contains some nutrients that are to be given back to soil in order to make it more fertile. Yet, this method of fertilizing is very ineffective (see below) and a part of the liquid manure directly affects ground water deteriorating it with nitrates and phosphates and has a very bad influence to nature and humans' health.
This problem goes along with meat and milk production. It is still believed by many that liquid manure makes fields more fertile. On the contrary: it deteriorates soils and their fertility in the long run. It would be far more effective to use compost as a fertilizer.
To spread liquid manure on the fields is in the first place a means of disposing of the vast amounts of excrements and it solely serves this purpose.
Even if liquid manure was a suitable fertilizer, the soils could impossibly absorb the vast masses of it.
In the USA far more peculiar methods are used to deal with the problem of waste disposal, as Mark Devries reveals in his documentary "Speciesism: The Movie."
The enormous pig fattening stations of "Smithfield Foods", the world's largest producer of pork, e.g. use immense liquid manure pits. They mix the liquid manure with water and spray it in the air thus dispersing it in the atmosphere as a kind of thin haze. People living near such stations suffer from a range of illnesses.
What Mark Devries has found out using a drone can be seen in this Youtube video which has been clicked on millions of times.