>>2385826start a compost. most have be written here about it allready and it will still take you a year roughly to be ready.
what you can do anytime
get some limestone/dolomit-chalk sprinkle it on the soil.
get horn meal and mix into garden soil
get cow/horse/chicken manure pellets and mix into soil
<<== get this, mix a small teaspoon in water and apply to soil. (humus/powerhumus)