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Bert T. Swanson, James B. Calkins, Daniel G. Krueger and Theresa L. Stockdale

Media fertility is a critical factor in the successful production of container grown plants. Fertility treatments including fertigation and slow-release fertilizers (topdressed and incorporated) were compared. Fertility treatments were studied over a two-year period on a variety of deciduous and evergreen plant materials. Plant growth was quantified based on height, volume, branching, and quality. Soil fertility levels based on leachates were followed during the study. Nutrient release for incorporated fertilizers tested was variable although less so than when the same fertilizers were topdressed. Fertility treatment effects were species-dependent. Several incorporated, slow-release fertilizers, especially those high in nitrogen (Sierra 17-6-10, Sierra High N 24-4-6, Woodace Briquettes 23-2-0, Woodace 21-4-10), show promise for use in two-year container production systems.

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Sam Aslan, Sam Cobb, Jose L. Aguiar and Aref A. Abdul-Baki

Approximately 90% of total date production in the U.S. is localized in the Coachella Valley, southwest California. The remainder is in the bordering Imperial Valley, Calif., and Yuma, Ariz. The date trees (Phoenix dactylifera L.) occupy 2282 ha, have an annual yield of 24,000 tons, and a product value of $62 million. Major varieties include `Deglet Noor', `Khadrawl', `Zahide', and `Majhool'. Although climatic requirements for date production prevail in the Valley, major problems related to soil and water have adverse effects on yield and fruit quality. These include water and soil salinity, high water table, high soil compaction and stratification, and low fertility. Slip plowing has been a recommended practice for decompacting the soil. However, soils get recompacted by machinery used in cultural operations. We recently introduced planting cover crops in a no-till system to improve soil fertility, reduce compaction, and improve drainage.

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Joseph R. Heckman

Yield responses of `Blue Vantage' cabbage (Brassica oleracea L.) to P fertilizer and two commercially available biostimulants—ROOTS and ESSENTIAL-were evaluated on soils very high in P fertility. Head yield was not increased with P fertilizer when cabbage was transplanted into soil with Mehlich-3 soil test P indexes ≥ 112 ppm (112 mg·kg-1). Neither of the biostimlants applied as a root drench at transplanting influenced head yield or plant tissue nutrient analysis.

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Lori Hoagland, Lynne Carpenter-Boggs, David Granatstein, Frank Peryea, Jeff Smith and John Reganold

Organic orchards represent a significant and growing component of Washington state agriculture. Comparison studies have shown that organic apple systems can be equally profitable yet more environmentally sustainable than their conventional counterparts. Despite this success, sustainable methods of weed control, fertility, and soil quality stabilization and improvement have remained a challenge. Intensive cultivation is commonly used to control weeds in organic orchards. This can lead to reduced or degraded soil organic matter, structure, water infiltration, aerated pore space, and other soil productivity parameters. In addition, tillage accelerates nutrient cycling and can result in the loss of valuable nutrients from the system. To address the need for sustainable organic methods of weed management, an integrated study of alternative understory management options was established in a newly planted orchard in 2005. Weed control measures included efficient tillage using a Wonder weeder, organically approved herbicide, wood chip mulch, and living cover mulches. Three rates of nitrogen (low, medium, and high) were applied across the Wonder weeder, wood chip, and living cover mulch plots in order to determine ideal N fertility rate. Analyses of total C and N and N-15 in organic fertilizers, soil pools, living cover biomass, and tree leaves are being used to track N and C cycling and partitioning, N-use efficiency, soil quality, and to determine optimal fertility guidelines. Preliminary results indicate intense competition between living mulch understory and orchard trees, and a trade-off may exist between maximizing soil quality and orchard productivity.

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Aref A. Abdul-Baki, S. Aslan, S. Cobb, E. Beardsley and T. Burke

A 3-year experiment was conducted to identify problems in Coachella Valley date palm (Phoenix dactylifera) orchards that limit vegetative growth, yield, and fruit quality. Major problems that were identified included soil compaction and stratification that restrict water permeation into the root zone, and low fertility as reflected by the low organic -matter content of the sandy soils. To eliminate the impact of these stresses on plant growth, yield, and fruit quality, a no-tillage alternative management system was introduced to replace the conventional practice of tillage that compacts the soil. No-till was coupled with the use of cover crops to enrich the soil with organic matter, fix N, recycle nutrients, and improve water holding capacity of the sandy soil. In already established orchards, an additional treatment—slip plowing—was also implemented to loosen the soil at lower depths to facilitate water permeation. The positive effects of the alternative system on the soil, tree growth, yield, and fruit quality will be presented.

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John R. Clark

Fertility and soil preparation practices for blackberries from numerous states were reviewed to determine common recommendations. Soil pH was uniformly suggested to be 6.0–6.5, with the use of dolomitic lime commonly preferred for pH adjustment. Organic matter additions were often recommended, using cover crops or animal manures the year before planting. Additionally, the incorporation of P and K the fall before planting was commonly suggested, with rates of application dependent on soil test levels. Nitrogen applications were recommended each year, with rates increasing to the maximum suggested in years 2 or 3. Ammonium nitrate was always the preferred N source. Rates ranged from 28 to 56 kg N/ha for the first year to 67 to 90 kg N/ha for mature plantings, with rates largely dependent on soil type, with sandy soils receiving the higher rates. Application of K was usually recommended for every other year, based on soil test levels.

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Kenneth L. Steffen, Michael S. Dann, Jayson K. Harper, Shelby J. Fleischer, Sizwe S. Mkhize, Doyle W. Grenoble', Alan A. MacNab, Ken Fager and Joseph M. Russo

During the initial season of implementation, four tomato production systems differing in soil management, pest control practices, and level of inputs, such as labor, materials, and management intensity were evaluated. These systems were CON, a low input (no mulch, no trellising, overhead irrigation, preplant fertilization, scheduled pest control), conventional agrichemical system; BLD, a high input [straw mulch, trellising, trickle irrigation, compost fertility amendment, integrated pest management (IPM)], ecologically-oriented system that emphasized the building up of soil organic matter levels and used no agrichemicals to supply fertility or for pest control; BLD+, a system similar to BLD, except that agrichemical pesticides were used; and ICM, a high input system (black polyethylene mulch, trellising, trickle irrigation, fertigation, IPM pest control) that used agrichemicals to supply fertility and for pest control. Soil characteristics and fertility levels in the BLD and BLD+ systems were modified with extensive amendments of spent mushroom compost and well-rotted cattle manure. Levels of agrichemical NPK calculated to meet current crop needs were supplied to the CON and ICM systems, with 75% of fertility in the ICM system supplied through the trickle irrigation lines (fertigation). The BLD system had a greater soil water holding capacity and sharply reduced irrigation requirements. During a wet period, fruit cracking and evidence of water-mold root rot were significantly higher in the ICM system than the BLD and CON systems. Defoliation by Alternaria solani was greatest in the BLD system and least in the ICM system. The BLD and ICM systems resulted in a 1 week earlier peak yield compared to the CON system. The yield of No. 1 fruit was 55% to 60% greater in the BLD+ system than the other three systems, which were comparable in yield. Net return was highest in the BLD+ system, although the benefit/cost ratio was greatest in the CON system. This multidisciplinary study has identified important differences in the performance of diverse production systems during the unique transitional season.

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Joseph R. Heckman, Thomas Morris, J. Thomas Sims, Joseph B. Sieczka, Uta Krogmann, Peter Nitzsche and Richard Ashley

1 Extension Specialist in Soil Fertility. To whom reprint requests should be addressed. E-mail address: . 2 Extension Specialist in Soil Fertility. 3 Professor of Soil and Environmental Chemistry. 4 Associate Professor. 5

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James B. Calkins and Bert T. Swanson

Media fertility, nutrient availability, and subsequently plant nutrition are critical factors that can be modified by growers to produce quality container-grown plants. The trend in container fertility has been toward incorporation of slow-release fertilizers; however, fertility release curves are variable and fertilizer longevity for many fertilizers is limited. Seventeen slow-release fertilizers were compared for longevity and plant performance over a 2-year production cycle using deciduous and evergreen plant materials. Plant growth was quantified based on height, volume, branching, dry weight, and quality. Soil fertility levels based on leachates were followed. Nutrient release for the incorporated fertilizers evaluated was variable. Fertility treatment effects were species-dependent. Several incorporated, slow-release fertilizers, especially those high in nitrogen and having extended release curves, including Nutricote 20–7–10, Scotts Experimental 24–6–10 and 26–6–11, Scotts Prokote Plus 20–3–10, Sierra 17–6–10, Sierra High N 24–4–6, Sierra Experimental 24–4–8, Woodace 21–4–10, Woodace 23–7–12, and Woodace Briquettes 23–2–0, show promise for use in 2-year container production systems.

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C. A. Mullins and R. A. Straw

`Blue Ridge' snap beans were planted with no fertilizer or banded rates of 560 kg ha-1 of a 10-4.4-8.3 fertilizer on soils with medium fertility in 1990 and 1991. Foliar applications of water soluble fertilizers containing nitrogen, phosphorus, and potassium were made at early bloom and in split applications at early bloom and repeated 10 days later. No response to fertilizer banded at planting or to foliar nutrient applications was found in snap bean yields or pod quality. Most fertilizer applications at planting increased plant size and lodging in 1990, but not in 1991. With the use of a rotation schedule and winter cover crops, snap beans showed no response to fertilization on soils of medium fertility.