In a study on Michigan organic soils of the effects of Na, applied as common salt and in the form of mine-run potash containing NaCl, on yields of different crops and the amt. of salt required, the following conclusions were drawn: The amt. of response to Na that will be shown by a Na-responsive crop is dependent on 4 factors: composition of the fertilizer (content of Na), composition and drainage of the soil, var. of the crop, and seasonal climate. Mine-run Carlsbad potash (containing 56% NaCl) gave yield increases comparable to those obtained with Michigan common salt Vars. of celery, sugar beets, and canning peas showed considerable variation in yield increases and in amt. of Na absorbed from given applications of salt. Organic soil shows some variation in natural content of Na, although it generally is very low. Drainage probably removes some Na. Crops generally are able to respond to heavier applications of salt with good drainage than with poor. Response to a salt is likely to be greater in a wet season than in a dry one if the drainage is good. Crops may be divided into 4 groups on the basis of their response to Na, as follows: (1) little or no response even with insufficient potash supply; (2) slight to medium response with insufficient potash supply; (3) slight to medium response with ample potash supply; (4) large response with ample potash supply.