Cut your bought or home grown spring onions about 3cm (1in) above the root. Use the leaves in cooking and add the stem/roots to a glass with clean water to rehydrate roots. Change water daily & keep in a well lit position such as a windowsill or kitchen bench. Watch green leaves regrow.
Basically, a hard thwack to the balls would do the trick.   Also, a man could stop producing sperm because â¦of a hormone imbalance, especially age related.     Men never stop making spermatazoa after the onset of puberty, as long as their testicles remain intact.
https://news.nationalgeographic.com/news/2010/03/100318-men-sperm-1500-stem-cells-second-male-birth-control.html How a Man Produces 1,500 Sperm a Second A man's constant supply of sperm is created in a much more complex way than previously thought, says new research that could someday lead to male birth control. View Images The sperm in this file photo were likely created in a fraction of a second.