A procedure was developed for the rapid quantitative determination of K, P, Ca, Mg, Mn, Fe, Cu, B, and Zn content in plant tissue by direct reading emission spectrometry using spark excitation and the rotating disc electrode technique. Aliquots of standard reference material, ground to pass a 40 mesh screen, are weighed into high form porcelain crucibles and ashed at 450°C for 6 h. Five milliliters of an internal standard-buffer solution (0.2% cobalt and 0.5% lithium in 1 N HCl) are added to the remaining ash. The resulting solution is subjected to a 30-sec burn on the spectrometer, and the intensity ratios for each element are recorded. Known concentrations ( X) and intensity ratio units ( Y) are entered into a stepwise regression computer program, and the linear, quadratic, and cubic regressions of Y on X are determined. Sample values are entered as Y into the appropriate regression equation which is then solved for X. If quadratic or cubic regression equations are used, the program will select the appropriate root. Relative standard deviations for samples determined over a several-day period generally were less than 10%.

Potassium sulfate was applied to established, non-irrigated, K deficient trees on fine textured soil by banding, placing in augered holes and injecting into the soil. Additional trees received a heavy compost mulch in early fall. Trenches were dug in the fall beside trees to break roots and then were backfilled with K 2 SO 4 , dolomite lime or a combination of the two. One percent K solutions of KNO 3 or K 2 SO 4 were sprayed on trees four times during the growth season.Sweet cherry trees only responded to compost mulch applications within two years. August midshoot leaf K, leaf N and fruit size were Oregon Agricultural Experiment Station

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The Diagnosis and Recommendation Integrated System (DRIS), which uses nutrient element concentration ratios as indicators of nutrient deficiency, was used to evaluate current sufficiency ranges for hazelnut trees. Reference values that were derived from published and unpublished field data were used to calculate DRIS indices for N, P, K, Ca, Mg, Mn, Fe, Cu, B, and Zn. A nutritional imbalance index (NII) was computed as the sum of DRIS indices irrespective of sign, and a threshold NII value (mean NII + 1 SD), above which severe imbalances are expected, was established. DRIS diagnoses were then compared with the sufficiency range approach to determine if relative deficiencies or excesses associated with severely imbalanced trees would have been routinely detected in 624 mineral analyses of hazelnut leaves. A previously published field trial was also reevaluated. DRIS diagnosis generally agreed with the diagnoses made by the sufficiency range method, especially if sufficiency ranges for some elements were made more narrow. However, some nutrients were never identified by DRIS as a major relative deficiency or excess in any of the trees judged severely imbalanced, based on the sum of DRIS indices. Nitrogen and Mg deficiencies were not detected unless lower NII thresholds were used. Unfortunately, lowering NII thresholds enough to detect N and Mg deficiencies identified some high-yielding trees as severely imbalanced. DRIS will not detect all deficiencies or excesses. Therefore, DRIS is best viewed as a supplement to sufficiency range diagnoses that provides additional information when severe imbalances are detected.

Nitrogen, as urea, was applied to filbert (Corylus avellena L.) trees at the rates of 0, .68, 1.36, and 2.72 kg N/tree/year from 1971-1977. Nitrogen applications significantly increased leaf N, yield, and tree size. Leaf P levels were reduced by N applications in all years. Soil pH, measured after 7 years of N application, significantly declined as N application rate increased. Leaf Mn levels were increased by N applications in all years, probably due to the decrease in soil pH. Yields were expressed as a quadratic function of N and the standard ranges for leaf N in filbert were categorized as follows: deficiency (visible symptoms present) < 2.0% dry weight; below normal 2.0 − 2.2%; normal 2.2 − 2.4%; above normal > 2.4%.