SOIL AND PLANT CALIBRATION FOR CUCUMBERS GROWN IN THE MID-ATLANTIC COASTAL-PLAIN

Few soil test and plant tissue calibration data exist for cucumbers (Cucumis sativus L.). Two years of a singly-replicated cucumber fertility study were conducted to develop soil and plant data for calibration purposes employing the Boundary Line Ap-proach. Fertility treatments consisting of 4 K levels (as KCl), 3 Mg levels (as MgCl2), 3 pH levels (as Calcitic limestone), and 4 N rates (as urea ammonium nitrate) were factorially arranged and completely randomized to give 108 treatments in both 1987 and 1988. Analyses were performed upon leaf samples for N, P, K, Ca and Mg at early bloom and soil samples for Mehlich (M) 1- and 3- P, K, Ca and Mg, and pH. Cucumber yields were determined on early (two fruit pickings) and total (four fruit pickings) sampling periods. High-yielding cucumbers were attained at soil K (Ml = 64 mg/kg) and Mg (Ml = 29 mg/kg) levels lower than currently recommended. No significant differences in correlation coefficients between either Mehlich (Ml, M3) extractant and cucumber leaf P, K, Ca and Mg concentrations were found. Co-2 efficients of determination (R) values for the relationships (in 1987, 1988) between Ml- and M3-extractable P (0.53, 0.40), K (0.77, 0.64), Ca (0.81, 0.71) and Mg (0.89, 0.74) were all highly significant (P ≤ 0.01). No significant differences were noted between early and total h1gh-y1eld1ng cucumber leaf concentrations and ratios developed for use as preliminary sufficiency ranges and DRIS norms, respectively. A reevaluation of cucumber coastal plain soil test calibrations, especially with regard to K, appears necessary. This study provides further support for the conversion of Ml to M3 soil extraction methodology. © 1990, Taylor & Francis Group, LLC. All rights reserved.