I installed a raised bed in 2013 using potting soil peat moss composted cow manure and compost. The first year it raised all the vegetables that I planted but since then it has gone down hill. I add compost and composted manure each year along with leftover potting soil from pots in witch I plant my tomatoes. Any suggestions as to what I can do to make it productive again?
I would start with a soil test. Check out your state's Extension Service; some states offer this for free. Problems are showing up in soils with too much organic matter and toxic, high levels of nutrients. Nitrogen moves through the soil quickly but phosphorus, for example, does not. Toxic levels depress yields. If done through the Extension Service, you will be given information on how to correct any problems. Check out this information: https://ag.umass.edu/soil-plant-nutrient-testing-laboratory/fact-sheets/corrective-measures-management-of-over-fertilized