N, P, and K refer to the three main nutrients plants need: NITROGEN for green growth and in compost piles to speed decomposition; PHOSPHORUS for energy, root growth, disease resistance, and production of good fruits, vegetables, flowers and seeds; and POTASH for strong stems, vigorous roots and increased disease resistance. Organic Sources of Calcium Calcium helps break up clay and release nutrients tied up in alkaline soils. It is especially good for cabbage family crops (and can help keep your tomatoes from getting blossom end rot). Organic Soil Modifiers Plants also need HUMUS (with its organic matter and minerals) which is produced by decaying organic matter such as compost, manure, rice hulls and cover crops (compost crops). An alkaline soil can be brought closer to neutral by compost or manure. Compost has a buffering effect on soil, correcting both acid and alkaline conditions. General Fertilizer Program Assuming No Soil Test is Performed (application rates are for 100 sq. ft.) Add all amendments after double-digging. For the first double-dig, compost may be added before double-digging. (1) Beginning with the 6th year, your legumes, compost crops and recycled plant material (in the form of compost) can provide most of your nitrogen, phosphorus and potash. Double-check this periodically with a soil test. (2) Nitrogen Å (% of protein) / 6.25. The 1st & 2nd Yr amounts will provide 0.4 lb pure N / 100 sq ft. (3) For trace minerals: kelp meal is up to 33% trace minerals. Be sure to use cold-water kelp. (4) Save your own. (5) Top priority in typical adobe soil. Breaks up clay, improves drainage, releases nutrients and lowers pH. (6) This amount of compost assumes a compost recipe that results in cured compost which contains 50% soil by volume. Eight cubic feet (12 five-gallon buckets) of cured compost will provide one inch of compost for 100 sq ft. Two cubic feet will provide 1/4 inch of compost for 100 sq ft. You can substitute aged manure for compost the first year if you do not have a ready source of compost; use half the amount recommended above.