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The effects of a mulch material on nutrient availability remain questionable. As organic materials decompose, the increased activity of microorganisms immobilizes nutrients (particularly nitrogen) to preform this process. The decomposition of mulch material and the activity of microorganisms may then compete for nutrients applied to ornamental species in the landscape. To examine this question, four widely available mulch materials (pine bark, cypress pulp, pine straw, and cottonseed hulls) and three fertilizer application methods (granule, liquid, and time release), which were applied either above or below the mulch, were established. Beds with and without mulch cover and no fertilization were established as controls. Marigolds, Tagetes erecta `Hybrid Gold', were planted within the beds. Growth response was found to be greatest in beds with cottonseed hulls. Cottonseed hulls are reported to have a high nitrogen content of their own that may influence less immobilization of nitrogen for decomposition. Beds using pinebark showed significant reduction in plant growth. Fertilization application method also demonstrated significant differences in plant response. The use of a granule fertilizer produced the greatest growth response although initial plant loss was observed in beds using this method. The fast release nature of granule fertilizer and potential toxicity were the suspected reason for this observation. Growth data indicated plant performance was unaffected by fertilizer placement.
The objective of this study was to examine the influence of mulch material and fertilizer application method on nutrient availability in a landscape situation. Beds containing four mulch materials (pine bark, cypress pulp, pine straw, and cottonseed hulls) and three fertilizer application methods (granule, liquid, and time release) were established. Fertilizer placement included application either above or below the mulch horizon. Beds with and without mulch cover and no fertilization were established as controls. Marigolds, Tagetes erecta `Hybrid Gold', were planted within the beds. Plants in unmulched or fertilized control beds had greater dry weights than plants in beds with mulch alone. Only plants grown in the cottonseed hull control demonstrated a slight improvement and cottonseed hulls demonstrated the best plant performance overall. The greater nitrogen content of cottonseed hulls may influence less immobilization of nitrogen in the soil solution during decomposition and reduce competition for nutrients between microorganisms and plants. Fertilization improved plant growth in all treatments except pine bark. Beds using pine bark showed significant reduction in plant dry matter accumulation. Potential toxicity or changes in soil chemistry by pine bark may have influenced these results and will be examined in further experiments. Fertilizer placement had no effect on plant growth.
Abstract
Four-hour dark period interruptions of incandescent, red and far-red radiation each night during natural cooling hastened flowering by 22, 15 and 8 days, respectively, over natural daylengths. No additional acceleration occurred when night breaks were applied during natural cooling and forcing as compared to lighting during natural cooling only. The accelerating effect of night breaks was found to be the response to light alone and not total radiant energy or temperature. Bloom date acceleration by night breaks of incandescent light was due to a proportionate acceleration in flower bud initiation. For every week of acceleration there was an average decrease of 2 flower buds and 7 leaves per stem. Bulb potting depth also influenced bloom date. The depth effects on flowering time were independent of lighting treatments. A 4-day acceleration was obtained by setting the bulb nose at the soil line as compared to a 2 inch planting depth.
Plant height was independently influenced by photoperiod-light quality and by potting depth. Height was only slightly affected by supplemental lighting during natural cooling. After forcing temperatures were reached, red and incandescent lighting caused slight height increases while far-red caused pronounced stem stretching. Exposure of the bulb above the soil at potting reduced plant height at maturity.
Abstract
Intact stem apices of Lilium longiflorum Thunb. cv. ‘Ace’ were prepared for scanning electron microscopy to determine floral initiation and differentiation by viewing topographical changes. The apices, after removal of leaves under running water, were frozen in liquid N2, freeze-dried on carbon discs and coated with carbon prior to viewing. Electron photomicrographs were taken of vegetative, transitional and reproductive apices. This method of tissue preparation permitted microscopic evidence of flower bud initiation and differentiation to be obtained in less than 9 hr after removal of the apex from the plant. The apices retained their in vivo configuration, but as dry, permanent, 3-dimensional mounts. Cell net studies of the apical meristem are possible with this technique. This method of preparation is also adaptable to light microscopy.
Use of groundcovers in the landscape is often limited due to their slow establishment rate compared to that of turf. Hedera helix L., (English ivy), Euonymus fortunei `Coloratus' (Turcz.) Hand.-Mazz. (purpleleaf wintercreeper euonymus), and Liriope spicata Lour. (creeping lily-turf) were evaluated in a full sun and 50% shade environment to determine the effects of fertilizer applications on their establishment and growth. Fertilizer treatments, of 13N-13P-13K at a rate of.45 kg/93 m2, used were: 1) at planting only; 2) at planting and once during the summer; 3) at planting, in summer, and once in the fall; or 4) at planting, in summer, in fall, and once the following spring. Data collected included fresh and dry weight comparisons of pruned material, percentage canopy cover, plant quality and vigor by visual assessment and photographs, and time required for maintenance of each plot. Results show limited fertilizer effects and interaction according to species during the first several months of growth. Establishment and survivability of Hedera was influenced mainly by light exposure rather than fertilizer applications. There was no difference in establishment rates between Liriope and Euonymus, however, under shade, Euonymus did not develop its characteristic fall color. Hedera was established in one season under 50% shade and can be considered very competitive with turf under the same conditions.
To examine the effects of mulching and fertilization on nutrient availability and plant growth in landscape beds, plots were established using four mulches (cottonseed hulls, cypress wood, pine bark, pine straw) and three fertilizer application methods (granular, liquid, time-release). Fertilizer was applied either below the mulch on the soil surface or over the mulch surface. Marigolds, Tagetes erecta L., were planted during the summer, followed by pansies, Viola×wittrockiana Gams, during the winter. Applied fertilizers, existing soil nutrients, and water-soluble nutrients from the new mulch provided an adequate supply of nutrients for marigold growth. Placement of fertilizer above or below the mulch did not affect marigold growth. Pansy growth was limited by depletion of soil N during the marigold season and by leaching of applied nutrients in the winter while plants were not actively growing. Mulch lowered soil temperatures and slowed pansy recovery in the spring. Pine straw allowed soil temperatures to rise earlier in the spring and improved pansy growth.
Lysimeters have been used extensively in the study of soil water and the movement of compounds in solution. In the management of landscape plantings where the use of various fertilizer application methods is common, loss of NO3-N from the fertilizer source may limit plant growth and be less cost-effective. During a study examining the influence of mulch type (cottonseed hulls, cypress wood, pine bark, and pine straw) and fertilizer application method (granular, liquid, and time-release), a simple lysimeter was constructed to examine NO3-N loss under normal irrigation and cultural practices in annual beds. Losses of large quantities of NO3-N were initially seen in all treatments during the 1st week followed by a gradual decline to the study's end. Liquid and time-release fertilization methods contained NO3-N as a partial source of N and limited plant growth due to early rapid N loss. Granular fertilizer contained no NO3-N source and demonstrated the greatest plant growth at the lowest cost per square meter.
Euonymous fortunei `Coloratus' (Turcz.) Hand.-Mazz. (purpleleaf wintercreeper euonymus) is a groundcover species commonly grown in the landscape and known for its characteristic purplish-red color in the fall. This species is dimorphic, having both juvenile and adult forms present in established plants. Young plants, planted from 5.7-cm containers, were grown under full sun and 60% shade and evaluated for 1 year from May 1998. Four fertilizer treatments, up to four applications, were applied over the year. Data collected included the percent of adult and juvenile plants per plot, percent canopy cover, plant quality, and fresh and dry weights of pruned plant material and whole plants. Results showed that 73% of Euonymus planted in the shade were “adult-like” in form, while only 44% of Euonymus planted in the sun were “adult-like” in form. These results were analyzed with the percentage canopy cover determined for March, April, and May 1999 and showed no interaction of the two variables. By the end of the study, the mean percent of canopy cover was 77% under the shade and 74% under the sun. These values were not significantly different. While it appeared that the maturity of the plant did not effect the percent of groundcover coverage in a plot, the more mature or “adult-like” plants were visually undesirable within a plot of juvenile plants, and vice versa due to morphological differences.