Two photos of spinach plants in organic growing media. The compost mix (from the bag) tested high soluble salts (3.4 mS/cm) and ammonium (64). Spinach plants on showing symptoms of high soluble salts are stunted, yellowed and have burned leaf tips. Plants were also bottom watered with additional organic fertilizer. Notice the soluble salt build-up on the media surface. The spinach plants in the second photo are the same plants after a week of watering with clear water from the top and letting water drain through, leaching out the soluble salts. Plants are growing out of the injury, however they are uneven in the flats which will cause uneven watering problems. Compost can vary from batch to batch. Always test new batches of compost before use.