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D.H. Taylor, C.F. Williams and S.D. Nelson

Where coarse-textured materials, such as gravel, underlie the root-zone layer of sports turf soil profiles, water retention in the root-zone layer is increased. The objective of this research was to determine the water retention characteristics in sand and sand: peat mixtures placed over coarse-textured layers and to determine how sand particle size and type of peat in the mixtures influenced water distribution after drainage. Soil profiles consisted of 30 cm of sand or sand: peat mixtures over 5 cm of predominantly coarse and very coarse sand, which in turn was over 10 cm of gravel. Excess water was added to the profile and allowed to drain for 24 or 48 h, following which water content and air-filled porosity (AFP) in the mixtures were evaluated. Regardless of the root-zone mixture, the coarse-textured sublayers resulted in a wet zone in the lower portion of the root-zone mixture. An unamended, predominantly medium and coarse sand, when used in the 30- cm root-zone layer, maintained ≈10% AFP in the lower 6 cm after drainage. Sand: peat mixtures using this sand generally maintained 3% to 8% AFP in the lower 12 cm of the root-zone layer. An unamended, predominantly fine and medium sand root-zone layer had ≈6% AFP in the lower 9 cm and sand: peat mixtures using this sand had <5% AFP in the lower 12 to 18 cm of the root-zone layer, with significant portions remaining at or near saturation after 24 or 48 h of drainage.

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Jennifer L. Boatright, J.M. Zajicek and W.A. Mackay

Two experiments were conducted in which a polyacrylamide gel (Hydrosource, Western Polyacrylamide) was incorporated into 56 × 38-cm, raised, concrete beds, 20 cm deep, with a drain pipe in the center of each bed. In Expt. 1, treatments included (in grams of i.a. N) 0, 186, 372, or 558 plus 0 or 366 g hydrogel/m2, for a total of eight treatments. Each treatment was replicated three times. Petunia plants were transplanted into each plot for a total of 30 plants per treatment. Plants were kept well watered. Polymer incorporation had no effect on soil water retention, soil NO3 or NH4 retention, or plant growth. Expt. 2 included treatments of 0 or 186 g of ai N and 0 or 366 g hydrogel/m2. Each treatment was replicated six times with 10 plants per replication, resulting in a total of 60 plants per treatment. Minimal irrigation was imposed on treatments. This study demonstrated that under suboptimal conditions of minimal irrigation and fertilization, polymer incorporation significantly increased soil moisture (17%), NH4 retention (83%), and NO3 retention where additional N was added (64%) compared to soils without polymer.

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Joyce A. Swenson, S. Alan Walters, Michael E. Schmidt and She-Kong Chong

Water management is often the key to successful vegetable culture. Various mulching/tillage systems are often utilized in tomato production, depending upon the available resources of a particular grower, to achieve better water use efficiency. A study was conducted to compare six different mulching/tillage systems to observe the influence of these systems on soil water retention as well as on `Fabulous' tomato (Lycopersicon esculentum Mill.) production. Winter ryegrass and wheat were the cover crops utilized and were mowed with the following six treatments then applied: 1) Conventional tillage (CT), 2) black plastic over conventional tillage (BP), 3) no-till with cover crop sprayed with Glyphosate prior to transplanting (NT-GLY), 4) strip-till with cover crop sprayed with Glyphosate prior to transplanting (ST-GLY), 5) no-till in which cover crop was mowed periodically during the growing season (NT), and 6) strip-till with cover crop mowed periodically during the growing season (ST). This test was conducted under severe drought conditions (45.4 mm of rain from 1 July to 30 Sept. 1999) with plants receiving no supplemental water via irrigation at any time throughout the study. Soil moisture was measured periodically throughout the growing season at a depth of 20 cm; soil and mulch surface temperatures were taken at similar timings as soil moisture. Soil moisture levels during the growing season indicated different patterns of water depletion when comparing the six treatments. There was no significant difference between the winter rye and wheat with respect to water depletion or tomato yields. Lower early tomato yields under NT, ST, NT-GLY, and ST-GLY indicate that cooler soil conditions, while aiding in the retention of soil moisture, delay early tomato production when compared to the warmer soil conditions found under CT and BP. Results also indicate that late season harvests under NT and ST systems produce predominantly cull fruits with a high incidence of blossom-end rot. The NT-GLY and ST-GLY systems tended to produce comparatively lower levels of cull fruit and blossom-end rot in late season harvests than any of the other six treatments.

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Paraskevi A. Londra, Maria Psychoyou and John D. Valiantzas

over a period of 20 years, sterile, and has a high water retention capacity (57% v/v) ( Werminghausen, 1972 ). Furthermore, UFRF has been found to increase air-filled porosity and water infiltration of fine texture soils and water retention of coarse

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W.G. Harris, M. Chrysostome, T.A. Obreza and V.D. Nair

scale ( Bouma et al., 1982a ) and the properties of soils that affect water retention ( Bouma et al., 1982b , 1982c ). Both of these dimensions are accounted for in soil drainage classes, which are interpretations about how well suited soil drainage is

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Guifang Qi, Jean-Charles Michel, Pascal Boivin and Sylvain Charpentier

Soil physics studies usually include two complementary aspects: 1) soil solid phase organization; and 2) transport processes. The water retention, Ψ(θ), and hydraulic conductivity curves, K (Ψ) or K (θ), are usually measured to characterize the

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Philip J. Brown, Lambert B. McCarty, Virgil L. Quisenberry, L. Ray Hubbard Jr. and M. Brad Addy

, which causes problems with rooting depths, organic material accumulation, fertility, and water retention ( McCarty et al., 2016 ). To improve this, turf facilities often combine sand with native soil containing some clay to take advantage of sand’s rapid

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Gregory E. Welbaum, Zhen-Xing Shen, Jonathan I. Watkinson, Chun-Li Wang and Jerzy Nowak

water contents were measured by drying samples at 98 °C for 24 to 48 h and results are expressed as a percentage of the soil dry weight (fresh weight – dry weight/dry weight × 100). Effects of priming with 50 m m sucrose solution on the water-retention

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Panayiotis A. Nektarios, Serafim Kastritsis, Nikolaos Ntoulas and Panayiota Tsiotsiopoulou

at a depth of 35 cm (as indicated by the tension that the water content decreased from the saturated water content of 38.2%). The non-amended soil had the least moisture retention at saturation as a result of the smaller size and space of the pores

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Salvatore S. Mangiafico, Julie Newman, Donald J. Merhaut, Jay Gan, Ben Faber and Laosheng Wu

compacted soil, weed cloth, or gravel. Given these considerations, soil water samples extracted with suction lysimeters from below the root zone may serve as indicators of solute concentrations in leachate, but should be interpreted cautiously, especially