Media Amendments Research Articles

Utilization of Sewage Sludge Compost in Horticulture

Sewage sludge is being converted to compost by many municipalities. Its use in the production, establishment, and/or maintenance of horticultural crops is dependent on soluble salt concentration, particle size, stability, dewatering procedures, storage conditions, and crop needs. Soluble salt concentration has the greatest effect on the amount of compost that can be used as a soil or potting media amendment. Because composted sewage sludge is rich in plant nutrients, it can supply many of the nutrient needs of plants, depending on the amount used and if the plants are growing in the ground or in containers. However, improper storage of composted sewage sludge can render the product useless due to the accumulation of acetic acid and alcohol that occur under anaerobic conditions.

Hydrogel as a Field Medium Amendment for Blueberry Plants

Three field experiments were conducted to determine short- and long-term effects of hydrogel mixed with peatmoss, milled pine bark, or soil on growth and yield of blueberry. Rabbiteye blueberry cultivars (Vaccinium ashei Reade) Delite, Tifblue, and Climax, and southern highbush cultivar (V. corymbosum L.) Georgiagem were used as test plants. Hydrogel mixed with soil was detrimental to plant survival. Hydrogel with or without peatmoss or pine bark did not influence yield or berry weight of 3- to 4-year-old `Delite' and 2- to 3-year-old `Tifblue' plants. The southern highbush, `Georgiagem', grown in peatmoss + hydrogel, produced plants of larger volume than those grown in peatmoss alone. Yield or berry weight was not affected significantly by soil amendments. Genetic differences between cultivars affected growth, yield, and berry weight, but the cultivar x soil treatment interaction was not significant.

Imbibition of Water by Rockwool-Peat Container Media Amended with Hydrophilic Gel or Wetting Agent

Water retention at effective water-holding capacity (EWHC) and container capacity (CCAP) were measured in four rockwool-peat potting media amended with a wetting agent and/or a hydrophilic gel in pots 12 cm tall containing 445 cm3 medium, and irrigated by capillary mat, flood-and-drain, trickle emitter, or overhead sprinkler. Water retention was measured by weighing. Irrigation was continued until EWHC (i.e., net water retention when no weight increase could be obtained by further irrigation) was reached. CCAP (i.e., net water retention following saturation and free drainage) was measured at the end of each experiment. Irrigation method and medium amendments significantly affected EWHC. Rank order of irrigation treatments was sprinkler ≥ trickle > flood and drain ≥ mat. Hydrophilic gel increased both EWHC and CCAP, while the wetting agent increased EWHC but decreased or had no effect on CCAP. Significant interactions of gel and wetting agent were observed in some media. EWHC was less than CCAP, and EWHC was better correlated with CCAP with trickle emitter and overhead sprinkler irrigation than with capillary mat and flood-and-drain irrigation.

PLANT GROWTH IN COAL GASIFICATION SLAG-AMENDED MEDIA

Coal gasification slag is an ash byproduct remaining after the volatization process. This material is currently under utilized. A series of experiments were conducted to determine the suitability of coal gasification slag as a growing medium or growing medium amendment. Chrysanthemums, lettuce, poinsettias and some bedding plants were grown in slag or slag amended media in an ebb and flow fertigation system. Slag alone has a high pH and initial slag samples had some very small particle sizes. Plant growth in slag alone was poor because of high pH and low aeration. When slag was amended with moss peat, the pH was lowered to an acceptable range and the aeration was better. Plant growth in peat-slag media was equal to plant growth in a peat-perlite mix. Media composed of peat-slag and bark were also successful in producing crop growth equal to peat-perlite. There were no nutritional problems growing in slag amended media except that boron uptake by chrysanthemum was greater than in other media. Eliminating the small particle sizes by washing the slag makes the slag easier to handle, but does not produce crop growth equal to slag amended media.

Landscape rose response to low moisture levels and a hydrophilic gel

Containerized plants of five low-maintenance rose ( Rosa hybrida L.) cultivars were irrigated at intervals which limited moisture availability for plant growth and development. The cultivars were grown both in a medium amended with a hydrophilic gel and in a control medium. Of the five cultivars, ‘Pink Meidiland’ had the highest leaf water potential ( ψ L) and lowest transpiration ( E), while ‘Ferdy’ maintained the highest E. The smaller leaf surface area of ‘Pink Meidiland’ and larger root to shoot ( R S ) ratio and lower leaf area ratio ( LAR) of ‘Ferdy’ contributed to a more favorable water status despite limited moisture availability. When hydrophilic gel was utilized as a medium amendment, ψ L was generally higher. Gel had little effect on plant biomass and tended to decrease tissue nutrient content.

Water Absorption of Hydrophylic Polymers (Hydrogels) Reduced by Media Amendments

Abstract Water absorbency of 4 commercially available hydrophylic polymers (hydrogels) (Agrosoke, Liqua-gel, Mizuace and Terra-sorb HB) in response to 4 media amendments (Micromax, Osmocote 18N-2.6P-10.0K (18-6-12), gypsum and dolomitic limestone) and the combination of 4 amendments was determined. Water absorbency of 4 hydrogels was reduced by all amendments except Osmocote added to Liqua-gel. Generally, hydrogel absorbency was reduced most by Micromax and the combination of media amendments, followed by gypsum, Osmocote, and dolomitic limestone. None of the hydrogels functioned as advertised.

WATER RETENTION IN SOILLESS POTTING MEDIA

Water retention was measured in soilless potting media irrigated by capillary mat, flood and drain, drip or overhead sprinkler. Media were amended with wetting agent or hydrophilic polymeric gel. Pots 12 cm high with a volume of 465 cm3 were loose-filled to the top with media. Potted media were wetted overhead with 120 ml water, then pots were randomly assigned to irrigation treatments. Capillary mat irrigation was continuous; other irrigation treatments were applied daily. Water retention was measured by weighing. Irrigation was continued until no further retention was measured. Water retention was significantly affected by irrigation method and medium amendments. Irrigation method followed the order overhead >= drip > flood and drain >= mat. Hydrophilic gel increased water retention, but in contrast to previous results, wetting agent did not, nor was any interaction of gel and wetting agent observed. Retention of water at container capacity, measured in situ at the end of each experiment, was significantly larger than actual retention.

WATER RETENTION IN SOILLESS POTTING MEDIA

Water retention was measured in soilless potting media irrigated by capillary mat, flood and drain, drip or overhead sprinkler. Media were amended with wetting agent or hydrophilic polymeric gel. Pots 12 cm high with a volume of 465 cm3 were loose-filled to the top with media. Potted media were wetted overhead with 120 ml water, then pots were randomly assigned to irrigation treatments. Capillary mat irrigation was continuous; other irrigation treatments were applied daily. Water retention was measured by weighing. Irrigation was continued until no further retention was measured. Water retention was significantly affected by irrigation method and medium amendments. Irrigation method followed the order overhead >= drip > flood and drain >= mat. Hydrophilic gel increased water retention, but in contrast to previous results, wetting agent did not, nor was any interaction of gel and wetting agent observed. Retention of water at container capacity, measured in situ at the end of each experiment, was significantly larger than actual retention.

Aggregated fly ash as a medium amendment for the production of container grown nursery stock

Abstract Royal beauty cotoneaster (Cotoneaster dammeri C. K. Schneid, ‘Royal Beauty') and Hicksii taxus (Taxus x media Rehd. ‘Hicksii') were grown in media amended with several levels of aggregated fly ash. In general, no differences in root or shoot growth was noted in either species as a result of the media in which they were produced. Higher than normal B levels were observed in the leaf tissue of taxus as the level of the aggregated fly ash in the media increased, while no differences in B levels were noted in the leaf tissue of the cotoneaster. Both Cu and B concentrations in the root tissue of taxus increased with increasing levels of aggregated fly ash in the media, while the level of P in the root tissue decreased under the same conditions.

Municipal Compost as a Medium Amendment for Chrysanthemum Culture1

Abstract Foliar analysis data (N, P, K, Ca, Mg, Na, Zn, Mn, Fe, Cu, and B) and growth parameters (flower diameter and dry weight and flowering stem weight and length) indicated that municipal compost could be used as a soil amendment for chrysanthemum culture. Compost amendment produced plants high in foliar K, Cu, B, and Zn. A marginal leaf injury was observed in compost-grown plants. While K, Cu, and Zn toxicities were disproven, B toxicity still remained a possible explanation for the symptoms. Plants grown in perlite media were high in K, Ca, Cu, Al, B, and Zn, and perlite amendment may have accented the leaf injury observed in compost media. Negative correlations of growth parameters occurred with foliar K, Cu, Al, B, Na, and Zn concentrations.

Experiments in biological and chemical control of Fusarium wilt (F. oxysporum f. melonis (Leach and Currence) Snyd. and Hans.) of muskmelon.

Selected antagonistic biota used in the planting medium reduced Fusarium wilt of muskmelon significantly. In combined treatments they augmented control given by fungicidal amendments to infested soil and (or) seed. Combined treatments that consisted of amendments to two or more of the three treatment components, soil, seed, planting medium, frequently were more effective than treatments of one component. Retaining the jiffy pot when transplanting enhanced control given by biological and fungicidal amendments. Under conditions highly favorable for wilt, protection given by antagonistic biota in the planting medium and fungicidal amendments frequently diminished after 35 days. Although reductions in population of the pathogen to low levels did not preclude high plant losses, evidence supports the view that the minimum requirements for satisfactory control include (1) reduction of populations of the pathogen to low levels, (2) continuous protection of the host through interaction of antagonistic biota and residual biota of treated soils, and (3) resistance imparted to the host by systemic action of fungicides. Results encourage the use of the jiffy pot and the planting medium when planting in the field for protecting the plant from injury and to provide a medium in which biological and fungicidal amendments may be applied at any desired time in advance of seeding and transplanting.