Responses to a 1993 survey showed that drip irrigation was used on 36,400 ha of commercial vegetables in the southeastern and mid-Atlantic United States. Florida led with 44% of total drip-irrigated vegetable area, followed by Georgia, North Carolina, and Pennsylvania, with about 10% each. Drip irrigation was used most commonly on tomato, pepper, and watermelon crops. The most-important benefits of drip irrigation were improved water and fertilizer delivery efficiencies compared to other irrigation systems, such as overhead sprinklers and subirrigation. Challenges with drip irrigation included high installation cost, emitter clogging problems, need for filtration, overirrigation problems, disposal of tubing, and lack of readily available expertise. Most drip irrigation was used with polyethylene mulch and most tubing was thin-wall disposable rather than thick-wall reusable. Eighty-one percent of the drip-irrigated vegetable acreage was fertigated with N and K. Survey responses indicated that drip irrigation use for vegetables is increasing.
Lynn Brandenberger and Bob Wiedenfeld
Using polyethylene mulches has increased earliness, yields, and fruit quality in muskmelon, resulting in their extensive use for melon production with numerous commercial products. However, two problems are associated with polyethylene use: removal and disposal following production. Organic mulches are potential alternatives but, in this study, resulted in significantly lower soil temperatures than all other treatments and generally had lower yields. Soil temperature, yield, fruit size and percent soluble solids were increased by polyethylene mulches compared to bare soil. Crop response differences between polyethylene mulches were not significant for most characteristics measured. There were significant differences in durability and ease of removal of polyethylene mulches. Based our results, durability and ease of removal are the main characteristics on which to base selection. Proper mulch selection can reduce removal costs and enable commercial producers to leave a mulch in place for the production of a second crop.
Certainly trickle (or drip) irrigation is not new to horticulture. In the early 1970s Chapin (1, 2, 3, 4), Gustafson (7, 8), and Hall (9) pioneered its use in horticultural crops in the United States. Kenworthy (10, 11, 12, 13) had introduced the concept of trickle irrigation to fruit growers in western Michigan by 1972. It appeared to be a “natural”; many growers already had deep wells (for hydrocooling cherries) available as excellent water sources. Since then the use of trickle irrigation has spread rapidly throughout the horticultural industry on a worldwide scale. Most draw on deep-well water or on canal, river, or lake water, which may require treatment, filtration or both to render it usable. However, the use of a trickle system for waste disposal was a new application of an existing technology.
A. M. Liptay and H. Tiessen
The effectiveness of polyethylene-coated paper mulches in altering soil environment was investigated. The increase in maximum daily soil temperatures under mulch compared to bare soil was approximately the same for a clear polyethylene laminated on black paper as the clear polyethylene alone. Minimum daily soil temperatures were higher under laminated paper mulch than under black polyethylene. Polyethylene coated paper was as effective as polyethylene in reducing soil moisture evaporation. Studies of bulk density indicated that soils under all mulches were less compacted than the bare soil. Nitrate N levels under mulches were also higher than in the bare soil. The disposal problem encountered with polyethylene mulches at the end of the growing season is eliminated by the use of polyethylene coated paper mulches because the very thin coating of polyethylene disintegrates during the growing season, and the residual paper decomposes in the soil after tilling.
There is world-wide interest in disposal technologies suitable for handling farm wastes. The Northern Ireland mushroom industry generates 200,000 tonnes/year of “spent” mushroom compost waste containing excess salts (P, K, Ca) and heavy metals. Its disposal by landspreading is restricted by EU, U.K. legislation. Farmers in Europe and the United States use this waste as a soil nutrient improver, but such operations are deleterious to the environment owing to microbial loading of soil and the release of human and animal pathogens. An ideal option is to reduce salt levels and pathogen content before granulating the waste into fertilizers. Electroremediation is a novel, in situ environmental technology which utilises low voltage electrical fields to remove salts or metals in contaminated soil sites. We developed electroremediation methods for the removal of excessive salts from `spent' mushroom compost or from soils contaminated with this waste. Electroremediation of excess salts / heavy metals from the horticultural waste was carried out in an anti-corrosive electrolysis tank with a built-in central holding bay for the waste material. A thin layer of charged fluid (rain water, pH 5.5; adjusted with 0.005 n HCl) maintained over the mushroom compost waste achieved the removal of salts when electrical fields ranged from 20 to 200 V were applied across electrodes (spacing 1.5 m apart) in our investigations. Electrode saturation by H+ or OH- and thermal/alkaline front build up were minimised by flushing with cooled (15 °C) fresh rainwater circulated via peristaltic pumps. The above prototype is useful for nutrient tailoring of spent compost waste in bagged compost prior to producing commercially viable granulated fertilizers from wastes.
A. Fortuna, P.E. Rieke, L.W. Jacobs, B. Leinauer, and D.E. Karcher
Rapid aquatic plant growth in Michigan's smaller lakes has reduced their navigability and recreational use. Harvested aquatic weeds have posed a new waste disposal issue for municipalities. Application of lake weeds as a soil amendment on area farms was viewed as a possible waste management option that might benefit local sod producers. The objectives of this study were to 1) estimate the amount of plant-available N (PAN) released from lake weed material, 2) determine the chemical composition of aquatic plant tissues and their effect on plant-available moisture, and 3) study turfgrass response to lake weed applications using the criteria of turfgrass quality, growth, and N uptake. Rates of lake weed refuse applied to field plots were 96, 161, and 206 Mg·ha-1. Two 47-day laboratory incubations were conducted with the same rates of refuse. Relative to biosolids, the metal content of the lake weeds was low and the nutrient content high. One megagram of lake weeds contained 0.37 kg of P and 2.5 kg of K. The decay constant for the C fraction in lake weeds was 8 to 10 days and 16 days for the N fraction. Estimates of the N supplied by lake weeds (570, 960, and 1200 kg PAN/ha) were based on data from C and N incubations. Application of lake weeds significantly increased plant-available soil moisture and significantly enhanced sod establishment and turf density, resulting in decreased weed pressure. However, excess N was present at higher application rates. Management concerns during the application of lake weeds should focus on nutrient loading and the timing of plant-available N release. Depending on methods of weed harvesting, we observed that large amounts of unwanted trash present in the plant biomass could discourage use by growers. Land application of lake weed refuse could ease waste disposal problems, reduce fertilizer inputs for sod growers, and improve the moisture status of sands. Further, this information can be of value to environmental regulatory agencies in determining safe and proper use of such waste materials.
B.E. Branham and D.W. Lickfeldt
With increasing pressure to reduce disposal of yard waste in landfills, many homeowners are seeking alternative methods for grass clipping disposal. When turf is treated with pesticides, the collected grass clippings become a potential source of injury to susceptible plants that come in contact with the clippings. In this study, grass clippings were collected at 2, 7, and 14 days after pesticide treatment from a turf treated with chlorpyrifos, clopyralid, 2,4-D, flurprimidol, isoxaben, or triclopyr. The clippings were used as a mulch around Lycopersicon esculentum Mill. (tomato), Phaseolus vulgaris L. (bush bean), Petunia ×hybrida Hort. Vilm.-Andr. (petunia), and Impatiens wallerana Hook. f. (impatiens). Beans were planted 4 weeks prior to mulching, whereas the other plants were grown in the greenhouse for 6 weeks and transplanted into the field 2 weeks prior to mulching. Clippings containing residues of clopyralid, 2,4-D, or triclopyr killed tomato, bean, and petunia plants when used 2 days after pesticide treatment (DAPT) and severely injured these same species when mulched 7 and 14 DAPT. Flurprimidol injured tomato, impatiens, and bean plants when present on mulch collected 2, 7, and 14 DAPT, but was not lethal. Flurprimidol slowed plant growth, caused darker green leaf color, and reduced flowering when mulched at 2 DAPT. Isoxaben injured tomato and bean plants when present on mulch used 2, 7, and 14 DAPT but was not lethal. Injury was not as severe in the second year of the study, indicating different environmental stresses and climatic conditions make predicting pesticide injury for all growing seasons difficult; however, grass clippings from a turf treated with herbicides or plant growth regulators should not be used for mulch around sensitive plants for at least 14 DAPT. Chemical names used: 0,0-diethyl O-(3,5,6-trichloro-2-pyridinyl) phosphorothioate (chlorpyrifos); 3,6-dichloro-2-pyridinecarboxylic acid, triethylamine salt (clopyralid); 2,4-dichlorophenoxyacetic acid, dimethylamine salt (2,4-D); α-(1-methylethyl)-α-[4-(trifluromethoxy)phenyl]-5-pyrimidinemethanol (flurprimidol); N-[3-(1-ethyl-1-methylpropyl)-5-isoxazolyl]-2,6-dimethoxybenzamide and isomers (isoxaben); 3,5,6-trichloro-2-pyridinyloxy acetic acid, triethylamine salt (triclopyr).
Brian A. Krug, Brian E. Whipker, and Ingram McCall
Eight experiments were conducted to develop height control protocols for greenhouse-forced hyacinth (Hyacinthus orientalis) bulbs. `Pink Pearl' hyacinth bulbs were treated with flurprimidol preplant bulb soaks to determine optimal timing of treatment, soak duration, quantity of bulbs that could be treated before the solution lost efficacy, bulb location of solution uptake, and if higher concentrations of flurprimidol can be used to overcome stretch that occurs with extended cold treatment. No difference in height control occurred when bulbs were soaked in flurprimidol the day of, 1 day before, or 7 days before potting; therefore, growers can treat bulbs up to 1 week before potting with no difference in height control. All preplant bulb soak durations of 1, 5, 10, 20, or 40 min controlled plant height. Any soak durations ≥1.3 min resulted in similar height control, which would provide growers with a flexible time frame of 2 to 40 min in which to soak the bulbs. When 1 L of 20 mg·L-1 flurprimidol solution was used repeatedly over 20 batches of five bulbs, solution efficacy was similar from the first batch to the last batch, indicating the soak solution of flurprimidol can be used repeatedly without loss of efficacy. Soak solution temperature was also tested to determine its effect on flurprimidol and paclobutrazol uptake. Temperature of the soak solution (8, 16, or 24 °C) had no effect on flurprimidol and only at a temperature of 8 °C was the efficacy of paclobutrazol lower. Postharvest heights of `Pink Pearl' hyacinths were similar whether only the top, bottom, or the entire bulb was soaked. Control provided by flurprimidol, paclobutrazol, or uniconazole preplant bulb soaks varied among the three hyacinth cultivars Delft Blue, Jan Bos, and Pink Pearl, so growers will have to conduct their own trials to determine optimal cultivar response to preplant bulb soaks. Also, `Pacino' sunflowers (Helianthus annuus) were treated with residual soak solution of flurprimidol to determine if substrate drenches could be used as a disposal method. Fresh and residual solutions of flurprimidol (1.18, 2.37, or 4.73 mg/pot a.i.) applied to `Pacino' sunflowers were similar in their efficacy of controlling height, which would enable growers to avoid disposal problems of residual soak solutions.
Mouna Benmbarek, Y. Desiardins, and R.R. Simard
Landfiling and incineration constitute the most commonly used methods of biosolid disposal. To minimize the environmental risk, their chemical and biological characteristics have been the subject of several investigations.
The present research was undertaken to evaluate the agronomic value of municipal solid wastes (MSW) and composted de-inked sludge (CDS) in a field experiment for sod production. Four variables in a split factorial design, were investigated at two sod farms: compost (MSW and CDS), soil (sandy loam and clay loam), application method (surface applied 6cm and incorporated 20cm), and the application rate (50-100 and 150t/ha). Controls consisted of unfertilized and unamended but fertilized plots. Both experimental sites were seeded with kentucky bluegrass.
Preliminary data indicate that the two biosolids promoted the sod growth at the rates applied. However, a better plot cover was observed if composts were rototilled at a depth of 6cm as compared to the conventional treated plots. Measurements of root and foliar weights revealed that the turf growth was enhanced with increasing rates, which is probably caused by additional soil macronutrients showed by the analysis. Seed germination and seedling emergence were not delayed as indicated by the observed increase in the water retention capacity of the soil especially at higher compost rates.
Carol Shennan, Stephen R. Grattan, Don May, and Carol J. Hillhouse
Reuse of saline drainage water for crop irrigation has been proposed as one strategy to reduce the drainage volume requiring disposal in California. A 6 y study to assess the feasibility of cyclic saline drainage reuse in a processing tomato/ cotton /cotton rotation was conducted. Treatments were: 1. fresh water applied throughout, 2. saline water applied after 1st flower to tomatoes, 3. saline water applied to tomato and the next cotton crop. Saline water generally improved tomato fruit quality, but did not reduce yields during the first 4 years. In year 6, yields were reduced 17% (n.s.) and 30% (p<0.05) in treatments 2 and 3 respectively, relative to the control. Monitoring of the root zone showed that boron has accumulated over time in saline treatments and may be limiting crop production more than soil salinity. Selenium was readily leached by periodic fresh water use and did not accumulate to levels of concern in tomato tissues. Other work has shown that salinity can enhance tomato susceptibility to root rot which may limit this practice in some areas. However, the data show that high value crops like tomato can be incorporated into saline reuse schemes if managed appropriately.