Keeping a worm farm is an easy project
Worm castings -- AKA poop -- add valuable nutrients to the soil and is easy to make. The hardest part is making the bin and that's not difficult.
This collection of links and publications are compiled information about managing nutrient levels in your pasture. This includes soil testing and assessment, application of fertilizers and minerals, and nutrient cycling in a forage pasture.
Phosphorus is an important plant nutrient for growing dairy forages. Unfortunately, many dairies have more phosphorus excreted and stored in manure than they can use during a crop year. Soils have the ability to store moderate over-applications of phosphorus for future crop production, but continued over-application can lead to losses of phosphorus to surface water.