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Craig A. Storlie, Philip E. Neary, and James W. Paterson

The effects of fertilizer rates and application frequency on drip-irrigated bell peppers (Capsicum annuum L.) were evaluated at two sites in 1992 and one site in 1993 in southern New Jersey. Yield and fruit quality were greatest with 158N-69P-131K lb/acre at the site with a sandy loam soil. Yield and fruit quality responded to additional fertilizer at sites with loamy sand soils. Average marketable fruit weight increased with increasing fertilization rate at one of the two loamy sand sites. The incidence of sun scald decreased with increasing fertilization rate. Increasing the frequency of drip-applied fertilizer from 11 to 22 days did not affect yield or fruit quality in either year when the same amount of fertilizer was applied. These results show that maximizing the yield of bell peppers grown on loamy sand soils in New Jersey may require higher fertilization rates than previously recommended.

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James E. Altland, James S. Owen Jr., Brian E. Jackson, and Jeb S. Fields

component for container nursery production. Although pine bark processing and storage practices can ultimately affect its physical properties and performance in containers, pine bark age, source, and type of sand for utilization as an amendment are among the

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Michael T. Deaton and David W. Williams

Sand-based athletic fields hold several distinct advantages over native soil root zones. The consistent particle size, high porosity and infiltration rates, and resistance to compaction make sand-based systems one of the best growing mediums for

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Brian E. Jackson, Robert D. Wright, and Michael C. Barnes

supply enough fines to give desired CC of the substrate. Another approach to increasing CC by adding fine particles would be to amend large-particle PTS with peatmoss, aged PB, sand, or other organic or inorganic materials that characteristically have a

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E.E. Albregts, C.M. Howard, and C.K. Chandler

Strawberry (Fragaria × ananassa Duch.) was grown for two seasons on a fine sand soil to study the plant and fruiting response of three cultivars to K rates of O, 56, 112, 168, and 224 kg·ha-1. `Dover' total fruit yields increased linearly with rate both seasons while the maximum March yield the first season was with 170 kg K/ha. April yields increased linearly with K rate the first season. `Tufts' and `Chandler' responses to K rates were not consistent for monthly or total fruit yield. The average fruit weight of `Dover' and `Tufts' decreased linearly with increasing K rate for March and for the season in 1984, while `Dover' gave a positive linear average fruit weight response to K rate during Apr. 1986. `Dover' leaf K decreased from December to February, and K deficiency symptoms were expressed by February in treatments receiving lower rates of K. Leaf K concentrations of `Dover' correlated well with K rate.

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Alex X. Niemiera, Ted E. Bilderback, and Carol E. Leda

Pine bark (PB), either unamended or amended with sand (S) at 9 PB: 1 S or 5 PB:1 S (v/v), was fertilized with solutions of 100,200, or 300 mg N/liter solution and tested for N concentration using the pour-through method (PT). PB, 9 PB: 1 S, and 5 PB: 1 S had porosities of 84%, 75%, and 66%, respectively. PT NO3-N concentrations, obtained via PT, of the 5 PB:1 S substrate were 43%,28%, and 15% higher than PB NO3-N values for the 100,200, and 300 mg·liter-1 treatments, respectively. Differences in N concentration obtained with PT can be attributed to substrate physical characteristics. Based on the results, data for PT should be interpreted with regard to substrate porosity.

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Mark A. Nash and Franklin A. Pokorny

Component and particle-size effects on shrinkage of two-component potting media were determined. Milled pine bark-sand mixtures were used to determine particle-size effects on shrinkage. Shrinkage curves formed an inverted V with maximum shrinkage at the 1:1 (v/v) ratio. No shrinkage occurred when bark was mixed with bark or sand with sand. Shrinkage increased linearly in the range of 0% to 50% bark and decreased linearly in the range of 50% to 100% bark. Each half of the shrinkage curve was a mirror image of the other half. Shrinkage curves for peat-sand and peat-perlite were similar in form to that of bark-sand media.

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Laura K. Hunsberger, Carolyn J. DeMoranville, Hilary A. Sandler, and Wesley R. Autio

Uniformity of sand deposition on cranberry (Vaccinium macrocarpon) farms was examined to evaluate the potential use of two sanding methods to suppress swamp dodder (Cuscuta gronovii) seedling emergence by seed burial. During a 2-year study, 24 farms were evaluated with sand applied by either water barge or directly on ice. To measure the depth of sand deposited on the surface, soil cores were taken every 5 m in a grid pattern on a randomly selected portion of a commercial Massachusetts cranberry farm. Both application methods delivered nonuniform depositions of sand with the majority of the samples measuring less than the target depth. Surface diagrams depicting sand depths indicated no particular patterns of error or deposition that could be advantageously adjusted by the grower at the time of application. Mean actual: target depth ratios were 63% and 66% for barge and ice sanding, respectively (100% indicating actual equaled target). In the best scenario (two farms), 47% of the sanded area received less than the target amount; 11 farms had at least 90% of actual sand depths below the target depth. For farmers targeting 25-mm sand depths (depth expected to suppress dodder germination), the mean actual: target depth ratio was 58%, indicating half of the actual sand depths measured less than 15 mm. Compaction of the sand layer due to the elapsed time period (6 weeks or more) between sand application and measurement may have contributed to the large number of samples that were lower than the target depth. Even so, the irregularity of deposition patterns and the large proportion of sand depths that were less than 25 mm indicated adequate suppression of dodder seedling emergence would be unlikely with either sanding method.

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Maria Fisher, David Eissenstat, and Jonathan Lynch

In annual plant species, root death has been assumed to be closely correlated with shoot senescence. However, in a preliminary study with common bean grown in sand culture beyond physiological maturity (114 days), no root death occurred. We investigated whether the incidence of bean root death was higher under field conditions than in sand culture. Root death was defined as root disappearance. The sand culture consisted of silica sand and P-loaded alumina. Plants in this system were fertigated twice daily with complete nutrients supplied in adequate amounts. The field planting was on a Hagerstown silt loam in central Pennsylvania. Roots were observed using minirhizotrons every 1 to 3 weeks after planting. In sand culture, incidence of root death was monitored on a population of 170 roots from three plants between 25 and 88 days (shoot senescence) after planting Root death was 10%. In the field study, 55% of the 53 roots examined died between 32 and 93 days (shoot senescence) after planting. Biological factors present in the field and not present in sand culture appeared to contribute to root death. The persistence of roots in sand culture suggests a lack of programmed root senescence in contrast to shoot senescence. This has interesting implications for resource allocation during reproduction and in face of belowground herbivores and pathogens.

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Kathryn S. Hahne and Ursula K. Schuch

Velvet mesquite [Prosopis velutina Woot., Syn.: P. juliflora (Swartz) DC. var. velutina (Woot.) Sarg.] has become more popular in arid landscapes of the southwestern U.S., but little information on N requirements during the seedling stage is available. In addition to optimize growth of seedlings, minimizing N in runoff during production is an important consideration. Experiments were conducted to determine how biomass production and N leaching were affected first by different ratios of ammonium and nitrate N in sand culture and second by different N concentrations when seedlings were grown in two substrates. Mesquite seedlings produced the greatest biomass after 120 days when fertigated with a solution of 33 NO3 : 67 NH4 +. Loss of N through leachate was 40% greater when NH + 4 comprised two thirds or more compared to one third or none in the fertigation solution. Nitrogen in leachate was highest after 16 weeks of treatment, coinciding with the reduced growth rate of seedlings. The second experiment utilized either sand or commercial growing media and a fertigation solution of 33 NO3 : 67 NH4 +. Fertigation with 200 mg·L–1 N after 60 days in either substrate produced greatest biomass, while rates of 25, 50, or 100 mg·L–1 N produced about half of that biomass. With few exceptions, less N in either form was found in leachate when seedlings were grown in media and were fertigated with the two higher N rates compared to seedlings grown in sand at the two higher N rates. Plant morphology, biomass accumulation, photosynthate allocation, and the fate of N in the growing substrate and in leachate were strongly affected by the choice of growing substrate.