pnut pnut Peanut Science 0095-3679 0095-3679 American Peanut Research and Education Society 10.3146/i0095-3679-1-2-8 Articles Effect of Calcium Source, Rate, and Time of Application on Soil Calcium Level and Yield of Peanuts (Arachis hypogaea L.)1 J. A. Daughtry and F. R. Cox 2 Former Graduate Student and Associate Professor, Soil Science Department, North Carolina State University, Raleigh, N. C. 27607

1Paper No. 4382 of the Journal Series of the North Carolina Agricultural Experiment Station, North Carolina State University, Raleigh, N. C. The use of trade names in this publication does not imply endorsement by the North Carolina Agricultural Experiment Station of the products named, nor criticism of similar ones not mentioned.

 7 1974 7 1974 1 2 68 72 American Peanut Research and Education Society 1974 American Peanut Research and Education Society Abstract

Studies were conducted both in the laboratory and in the field to determine the relative availability of calcium from several calcium sulfate materials, and their effect on the yield and grade of peanuts. The initial rate of Ca leaching in the laboratory study was greatest for Phosphogypsum, medium for the regular finely-ground anhydrite landplaster and least for the granular anhydrite landplaster. With continued leaching the Ca level extracted after applying the three sources became similar. Some differences were noted in the rate of leaching that were associated with soil properties, primarily cation exchange capacity.

In the field, the materials were applied early in the season and at flowering. No consistent difference existed among the sources in soil test Ca or SO4-S levels during the growing period. These levels were lower, however, late in the season if the materials had been applied early rather than at flowering. Similar conclusions were reached when evaluating the temporary pH drop caused by applying the Ca sources.

Yield and grade of peanuts were affected by applying the Ca sources in one field study. The positive response was similar from the three materials which, in this particular study, were applied only at flowering.