You can make your own fertilizer as shown on this web page (and many other web pages).
How can I test my home-made fertilizer to determine the nutrients that are available in it? Traditionally, commercially-available fertilizers are labeled with the percentage (by weight? I'm not sure) of nitrogen, potassium, and phosphorous (the "N, P, K" labeling). I'd like to be able to analyze my own home-made fertilizer (and my compost, and even the soil) for these and other nutrients. (Quantitative analysis, I guess.)
Thank you for any ideas.