Effect of applications of fine limestone. III. The yield and nitrogen content of inoculated and non-inoculated alfalfa grown on Shelby loam

An investigation was made on Shelby loam to study the effects of fine limestone applications in the row and beside the row on the yield and nitrogen content of inoculated and non-inoculated alfalfa plants. The plants were harvested at the stage of inflorescence, oven-dried, and analyzed for total nitrogen by the Kjeldahl method. The data obtained were analyzed statistically according to the method of analysis of variance and the results are summarized as follows: A mercury dust used to control the "damping-off" organism probably prevented a thorough inoculation of the alfalfa grown in the inoculated series on Shelby loam. In the inoculated series a concentration of nodules was observed in the limed zone where the fine limestone was applied in the row. The total dry weight and total nitrogen content of the plants grown on fully limed soils were highly significantly greater than in the case of the plants grown on soils receiving limestone in the row or beside the row. The total dry weight and total nitrogen content of alfalfa grown on the untreated soils was highly significantly less than those secured on the soils receiving limestone. The nitrogen content of alfalfa grown on the variously limed soils varied similarly, irrespective of the degree of inoculation. The total dry weight and total nitrogen content of alfalfa grown in the inoculated series on Shelby loam was highly significantly greater than those plants grown in the non-inoculated series. The yield of alfalfa grown on the soil receiving 500 pounds of fine limestone in the row appeared to be nearly as great as that secured from the fully limed soil; however, the total nitrogen content of the plants was much less. Apparently the partial liming of Shelby loam is quite favorable for the growth of alfalfa but only as the full lime requirement of a soil is reached will maximum nitrogen fixation be obtained.