Tolerance to low pH and low available phosphorus of various field and forage crops

Six field crops and 7 forage crops were compared in the response to lime and/or superphosphate applications in a field with a soil low in pH and available phosphorus, and the following results were obtained. 1. Barley, sugar-beet and alfalfa are very susceptible, and orchard grass, field bean and oat are tolerant to low pH (most probably Al toxicity). 2. Red-top, alfalfa and red clover are susceptible, and soybean is tolerant to low P. 3. Tolerance to low pH and that to low P are not associated with each other. When low pH and low P conditions are combined, the adverse effects of these conditions are magnified. 4. The adverse effects of these conditions decline with time elapsed after sowing. Thus, in forage crops, except for species which are very susceptible to these adverse conditions, the positive effect of applications of lime and/or superphosphate declines after establishment