Green sand is great for soil building but what you add this season doesn’t do anything until the following season and it’s difficult to find these days. I always add dry kelp, oyster shells, worm castings, trace minerals, precipitated bone meal, and a handful of other dry ingredients about 8 weeks prior to any planting. Nematodes are a must to water in several times a season and off season too. We have compost areas that are constantly turning into great soil additions after it breaks down to mix in your garden areas. We add worms 2 times a year. We grow them and the earth worm castings are another favorite. My special sauce is in the compost teas that I brew. We sprout our own mycelium to add to the tea just before watering in. The secret to good compost teas besides the right ingredients in the tea bags is the proper aeration and bloom times in the barrels. We use multiple 50 gallon olive barrels.