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John M. Smagula and David Yarborough

Experimental plots in a commercial lowbush blueberry (Vaccinium angustifolium Ait.) field deficient in N and P received preemergent 33.6 and 67.2 kg/ha rates of N (urea), P (23 % phosphoric acid), N+P (DAP), N+P+K (S-10-5) or N+P+K (fish hydrolysate, 2-4-2). A RCB design with eight replications of 12 treatments was used. Fertilizer containing N alone was as effective in raising N leaf concentrations, as those containing N and P. However, leaf phosphorus concentrations were raised more by fertilizer providing N and P than only P. Fish hydrolysate fertilizer was as effective as 5-10-5 in raising leaf N, P and K concentrations in prune and crop year leaf samples.

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Ben Ami Bravdo

Drip fertigation enables control of the root environment in regard to the volume of irrigated soil, the soil matric potential in the immediate vicinity of the roots and the concentration and composition of the minerals. Application of daily NPK fertilization to citrus was found to promote root production with a large surface area and maintenance of controlled NPK concentrations at various stages of growth and development resulted in high productivity due mainly to increased number of fruits produced. Continuous maintenance of appropriate NPK concentrations at the immediate vicinity of the roots during three successive years improved fruit size without apparent reduction in quality. This was attributed mainly to a well balanced crop load and mineral status as expressed in leaf mineral analyses.

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Robert J. Dufault, S. Hopkins and P. Sandifer

Our objectives were to determine 1) if shrimp sludge has any value as a soil amendment in broccoli production and 2) an appropriate rate of sludge for head production. Four levels of N–P–K per 15-L pot (in grams; 2.0 N–0.07 P–1.4 K; 4.0 N–0.14 P–2.8 K; or 6.0 N–0.21 P–4.2 K; and 0.0 N–P–K) were factorially combined and replicated 10 times with four volumes of shrimp sludge (0%, 10%, 20%, and 40% v/w in 15-L pots blended with 100%, 90%, 80%, and 60% Metro Mix 300, respectively). Four-week-old `Emerald City' broccoli transplants were planted into sludge + media–fertilizer mixtures on 12–14–95 and were grown to harvest maturity in a greenhouse. As sludge volume increased, the days to harvest, plant height, and root fresh weight: head fresh weight ratio decreased, but leaf number, fresh weight and area, head fresh weight, stem diameter, and shoot: root fresh weight ratio increased. As N–P–K rate increased, leaf number, area, and fresh weight, stem diameter, head fresh weight, and shoot: root fresh weight ratio increased, but root: head fresh weight ratio and plant height decreased. Using head fresh weight as the determinant, heaviest heads were optimized with 20% sludge and 4.0g N–0.14g P–2.8g K per 15-L pot. Sludge alone or N–P–K alone did not produce the heaviest broccoli heads as using combinations of sludge and N–P–K in a fertility program.

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Ronald Garton and Irvin E. Widders

Processing tomato seedlings cultured in 288 cell plug trays were fertilized with solutions containing either 75-32-62 or 150-64-124 ppm N-P-K until the 4 to 5 true leaf stage (12 cm tall). At this developmental. stage, the seedlings were nutrient conditioned with 0-0-0, 75-32-62, 150-64-124, 300-128-248 or 450-194-374 ppm N-P-K for up to 12 days. Within 3 days of initiation of pretransplant fertilization treatments, both the contents and mean concentrations in shoot tissue of total N, P, K and soluble NO3 - were significantly altered. The maximum effects on tissue concentrations were observed within 5 days. Shoot growth rate of seedlings was affected within 5 to 8 days by a modification of elemental concentration within fertilizer solutions. The benefits of nutrient conditioning on tomato seedlings will be discussed.

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Gail S. Lee and Tina G. Teague

In soils that can range in pH from the low 4's to 7, depending on the location and liming history, deficiency of Zn, B, and Mo coupled with the soil acidity complex of Mn toxicity had been previously identified as severe limiting factors in producing quality Brassica crops. Fertility studies on fall and spring planted Brassicas focused on the effect of including/not including micronutrients during various phases of growth when NPK preplant fertilizer was reduced. Differential responses to reduction in preplant NPK and applications of micronutrients was found to be dependent on planting time (fall or spring), species of Brassica planted and cultivar. Nutrient uptake in leaf blades and petioles was followed. In broccoli timing of micronutrient applications significantly affected the harvest period length. Broccoli final yields of the B, Zn and Mg treatments were found to contribute ≈75% to 80% of the final yield of a full range micronutrient solution.

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DESMOND MORTLEY, V. KHAN, C. BONSI and E. RHODEN

Fertilizer placement under plastic was studied on 2 tomato cultivars (`TI-130' and `Floradade') during 1989. Treatments were 1, 2 or 3 increments of fertilizer broadcast, banded, broadcast/banded of banded with 1 or 2 sidedressings and a check. Fertilizer applied was NPK at 135-90-84 kg·ha-1 as a ammonium nitrate, triple superphosphate and muriate of potash, 10cm to each side of the plants and 10cm deep. Vine, total, marketable and early yields for lower rates either Br or Ba were as good as those of the full rate Br or Ba with 2 sidedressings (Ba/SD2). Leaf N, P, K, Ca and Mg for `TI-130' were not affected by placement. The Ba/SD2 placement Increased leaf N for `Floradade' but leaf Ca was reduced in all treatments vs the check. Leaf Mn was increased markedly by placements involving broadcasting at all rates.

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Martha Elena Pedraza-Santos, David Jaen-Contreras, M. Alejandra Gutièrrez-Espinosa, Teresa Colinas-Leon and Cristina Lopez-Peralta

Effects of inoculation with arbuscular endomycorrhizal fungi (Acaulospora scrobiculata and Glomus mosseae) on acclimatization and growth of chrysanthemum (Dendrathema glandiflora Tzevelev) plants, propagated in vitro, under different conditions of fertilization (0, 20, and 40 mg·L-1 of NPK) were studied. Mycorrhizal colonization did not influence surviving percentage of chrysanthemum plantlets during the acclimatization stage; however, we could colonize the developing roots and reduce the amount of inoculum needed and beneficial effects on plant growth were obtained during early stages of colonizing. Plant growth in greenhouse was regulated by synergism between the effect of endomycorrhizal fungus type and soil fertilization with N, P, and K. Effects of A. scrobiculata were observed as an increasein number of leaves, leaf area, stem diameter, root volume and fresh and dry weight of leaves, stem and root. The G. mosseae fungus improved N, P, Mg, and Zn content in leaves; P, K, Ca, Mg, and Zinc in stem and Ca content in root. On the other hand, A. scrobiculata only increased N content in leaves, stem and roots; P content in leaves and roots, and Ca content in stem. Percentage of mycorrhizal colonization on roots was affected by adding N, P, and K to soil. The highest values were obtained with fertilization doses of 20 mg·L-1. The number of spores of mycorrhizal fungi was increased by adding fertilizer to soil (40 mg·L-1 of NPK).

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K.T. Demchak and C.B. Smith

In a 3-year study with broccoli [Brassica oleracea var. botrytis (L.) Mill. cv. Green Comet], NP or NPK fertilizer at rates of 56N-56P-0K, 56N-56P-56K, and 56N-112P-56K (kg·ha-1) were banded in plots to which three types of lime had been applied—calcitic, calcitic with 3% Mg, or dolomitic. Fertilizer and lime controls were included. Previous liming had raised the soil pH from 5.3 to 7.2-7.4. Effects of lime on yields were greatest when no fertilizer was applied. Dolomitic lime was the most effective, increasing total yield by 49%, terminal weight by 54%, and hastening maturity. Fertilizer effects were most evident when no lime had been applied, with all fertilizer treatments increasing total yield, terminal and plant weight, and hastening maturity. Most changes occurred in the 56N-56P-OK treatment. Effects of lime when fertilizer was applied and effects of fertilizer when lime had been applied were less consistent. Lime alone, especially types containing Mg, increased leaf P, which generally followed the-same trend as total yield. Calcitic lime increased leaf Ca and dolomitic lime increased leaf Mg over other lime treatments. Calcitic lime with 3% Mg increased leaf Ca, but not leaf Mg, compared to the check. All lime treatments decreased leaf Mu, B, and Zn. Fertilizer treatments usually increased leaf N and Mn. Phosphorus uptake was increased by either lime or fertilizer application. Regression analysis strongly suggested that P was the element most responsible for yield increases.

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Gerry Neilsen, Peter Parchomchuk, Michael Meheriuk and Denise Neilsen

Various schedules of 40 g N and 17.5 g P/tree per year were applied with irrigation water (fertigation) to `Summerland McIntosh' apple (Malus ×domestica Borkh.) trees on M.9 rootstock commencing the year of planting. Leaf K concentrations averaged 0.82% dry mass, indicating deficiency, by the third growing season. This coincided with extractable soil K concentrations of 50-60 μg·g-1 soil in a narrow volume of the coarse-textured soil located within 0.3 m of the emitters. The decline in leaf K concentration was reversed and fruit K concentration increased by additions of K at 15-30 g/tree applied either as granular KCl directly beneath the emitters in spring or as KCl applied as a fertigant in the irrigation water. K-fertilization increased fruit red color, size, and titratable acidity only when leaf K concentration was <1%. Fruit Ca concentration and incidence of bitter pit or coreflush were unaffected by K application. NPK-fertigation commencing upon tree establishment is recommended for high-density apple orchards planted on similar coarse-textured soils.

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Donna Ballard, Juanita Popenoe, Bradford Bearce and Jeffrey Skousen

Strawberry (Fragaria × Anaassa cv. Tribute) plants were planted in 15 cm standard pots filled with overburden soils from three West Virginia surface mine sites. Initial pH levels were 6.5, 4.4, and 3.6. Prior to planting pH levels were adjusted with CaCO3 to 6.5-6.7 in each soil. Each soil was amended by mixing in 60.85 g/pot (62.5 dry kg/ha) of sewage sludge, Sudan-sorghum hybrid green manure crop, hardwood residues, or unamended. A dry fertilizer (.10-.045-,089, N-P-K) was also mixed into the soil at a rate of 0.5 g/pot (454 kg/ha). Plants were grown from 3-6 to 10-16, 1992, on which date harvests and measurements were performed. The sludge treatments significantly increased fresh and dry weight accumulation, number of leaves, leaf area, and number of runners per plant above that of the control plants. The hardwood residues amendment delayed first date of ripe fruit and decreased average fruit fresh weight in one of the soils. Hardwood residues also decreased leaf number in another soil. The pH levels were raised to 6.8-7.3 by the sludge in all soils and remained at or near these values during the growing period.