Use milk. Yep, cow's milk, whether it's whole, skim, 2 %, nonfat--it makes no difference, although raw provides the most benefits. The amino acids, proteins, enzymes and natural sugars benefit the microbes and fungi in the soil.
It also acts as an insecticide on soft-bodied insects because they can't digest the sugars in milk.
"In 2004, Dave Wetzel (a Nebraska farmer) dumped the unpasteurized skim milk on his alfalfa and cool-season grass pastures evenly. Within a few weeks, he noticed greener grasses that his herd flocked towards. Not only were cattle drawn to the milk-fed grass, the area showed higher yields while soil core sampling displayed increased ground porosity."
Here's a link to the article: http://www.minnesotafarmguide.com/news/regional/milk-works-as-fertilizer-says-preliminary-study/article_028652ea-849c-11e0-9dcc-001cc4c03286.html
This is a new one to me!! I use vinegar as a weed spray and a concoction of beer, mouthwash and soda to green up the lawn and those both work well. I may just have to give milk a try, too!
BTW, I can hear the comments now--"But why waste the beer?"