THE RELATION OF THE CONCENTRATION OF CALCIUM ION REQUIRED BY ALFALFA TO THE AMOUNT PRESENT IN SOIL SOLUTION

Abstract

Alfalfa grown in water culture solutions containing varying amounts of Ca as CaSO4 required 16 parts per million for continuous growth, while 32 p.p.m. produced the most economical growth. Ca present in excess was non-toxic. Application of limestone and S increased the water soluble content of potted soils more than did manure and super-phosphate. The water soluble Ca content in field soils was below the continuous growth requirement during the early part of the season. The beneficial effects obtained from limestone applications on some soils seem to be due to increase in the soluble Ca content as well as to correction of acidity.