A 2-year field study was conducted on a low- to medium-K testing sandy soil 1) to evaluate the effects of various K management strategies on potato (cv. Russet Burbank) yield and quality and 2) to calibrate a petiole sap test for determining plant K status. Treatments included banded applications of potassium chloride fertilizer at planting with K ranging from 0 to 300 kg·ha–1 in 75 kg·ha–1 increments. Comparisons of preplant broadcast + banded applications and evaluation of in-season applications of potassium nitrate also were made. In both years, tuber yield increased with increasing banded K fertilizer up to 150 kg ha-1 K the first year and 225 kg ha-1 K the second year. In-season applications of potassium nitrate increased tissue K levels, but at equivalent K application rates, timing of K application had no effect on yield. Petiole K concentrations, measured on a dry weight and sap basis, increased with increasing K fertilizer application. Potassium concentrations in nondiluted sap determined with the Cardy K electrode were ≈200 to 2500 ppm lower than those determined by flame emission. The greatest discrepancy occurred at the higher K sap concentrations. Potassium concentrations determined with the Cardy electrode in sap diluted with aluminum sulfate or deionized water were much closer to those determined by flame emission. These results suggest that dilution of the sap is necessary to obtain accurate K concentrations in petiole sap.
, phosphorus (P), and potassium (K) ( Table 1 ). The N content (0.34%) of the pecan wood chips used in 2002 was used to estimate the C:N ratio (143:1) of pecan wood based on an assumed 48.5% carbon content ( Lamlom and Savidge, 2003 ). Five random wood chip
Ixoras (Ixora L.) growing in calcareous sandy soils are highly susceptible to a reddish leaf spot disorder. Symptoms appear on the oldest leaves of a shoot and consist of irregular diffuse brownish-red blotches on slightly chlorotic leaves. Symptoms of K deficiency, P deficiency, and both K and P deficiency were induced in container-grown Ixora `Nora Grant' by withholding the appropriate element from the fertilization regime. Potassium-deficient ixoras showed sharply delimited necrotic spotting on the oldest leaves, were stunted in overall size, and retained fewer leaves per shoot than control plants. Phosphorus-deficient plants showed no spotting, but had uniformly brownish-red older leaves and olive-green younger foliage. Plants deficient in both elements displayed symptoms similar to those observed on landscape plants. Symptomatic experimental and landscape ixoras all had low foliar concentrations of both K and P.
, area, and thickness by ≈20% ( Alireza et al., 2013 ). In addition to changes in growth parameters, many plants show changes in ion accumulation in roots and/or leaves or shoots, with contrasting trends for sodium and potassium accumulation. There is
Fig. 1. Nitrate, phosphate, and potassium leaching from 85:15 sphagnum peat:perlite substrates amended with 0%, 1%, 5%, or 10% biochar. Columns were initially fertilized with 200 mL a 100 mg·L −1 nitrogen fertilizer (20N–4.3P–16.6K) solution. Columns
performance in season 2 than in season 1 ( Fig. 2 ). Table 3. Three-way analysis of variance for main effects and interactions of nitrogen (N), potassium (K), and season (summer and fall) on growth and biomass yield in stinging nettle grown under greenhouse
research has found an increase in nitrogen, phosphorus, and potassium when fertilizer was applied by root formation, our question was whether this uptake was occurring through some combination of basal and foliar uptake. Therefore, we wanted to determine if
treatments from three nutrients at five levels. Nitrogen levels increase from the front to the back of the diagram (right sides of smaller cubes), phosphorus concentrations increase from the left to the right (tops of the smaller cubes), and potassium
`Oso Grande' and `Sweet Charlie' strawberries (Fragaria × ananassa Duch.) in 1991-92 and `Oso Grande' and `Seascape' in 1992-93 were grown in a K fertilization study using polyethylene-mulched and fumigated beds. Potassium was injected weekly into the drip irrigation system at 0.28,0.56,0.84, 1.12, and 1.40 kg K/ha per day. Early, March, and total-season marketable fruit yields were not affected by K rate during either season. The average fruit weight of `Oso Grande' for the early, March, and total-season harvest periods in the 1992-93 season decreased with increased K rate. For the same harvest periods, `Seascape' average fruit weight increased, decreased, and did not change, respectively, with increased K rate. Cull fruit yield during both seasons and fruit firmness during the 1992-93 season were not affected by K rate. Petiole sap, whole leaf, and leaf blade K concentrations increased with increasing K rates on most sampling dates during both seasons. `Oso Grande' and `Sweet Charlie' produced similar total marketable fruit yields the first season, but `Oso Grande' produced higher total yields than `Seascape' during all harvest periods of the second season.
O 5 ), potash (K 2 O), calcium (Ca), magnesium (Mg), sulfur (S), sodium (Na), aluminum (Al), iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn). Although laboratory results reported P 2 O 5 and K 2 O values, actual phosphorus (P) and potassium (K