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Production of methane via anaerobic digestion of energy crops and organic wastes would benefit society by providing a clean fuel from renewable feedstocks. This could replace fossil fuel-derived energy and reduce its environmental impacts, including global warming and acid rain. Although biomass energy is more costly than fossil fuel-derived energy, trends to limit carbon dioxide and other emissions through regulations, carbon taxes, and subsidies of biomass energy would make it cost competitive. Methane derived from anaerobic digestion is competitive in efficiencies and costs with other biomass energy forms including heat, synthesis gases, and ethanol. The objective of this paper is to review the results and conclusions of research on biomass energy conducted under the sponsorship of the gas industry with periodic co-funding from other agencies. The scope of this program was to determine the technical and economic feasibility of production of substitute natural gas (SNG) from marine and terrestrial biomass and organic wastes using anaerobic digestion as a conversion process. This work began in 1968 and continued until about 1990, ending as a result of low energy prices in the U.S. and reduced emphasis on renewable energy. For each of these feedstock categories, growth or collection (in the case of wastes), harvesting, conversion by anaerobic digestion, and systems and economic analysis were addressed. More recently the potential use of anaerobic digestion for stabilization and recovery of nutrients from solid wastes during space missions was studied with funding from NASA. The application of this process for that function as well as treatment of wastewater and waste gases generated during space missions is addressed.
Abstract
‘Sunfre’ nectarine [Prunus persica (L.) Batsch] has been released to provide a large, productive, high quality, attractive nectarine for areas in Florida which has a minimum of 500 chilling hours below 7°C.
Abstract
Transplanting is an ancient horticultural practice, which is a good thing because our profession is in need of a transplant—an attitude transplant! I was both encouraged and discouraged as I read Dermot P. Coyne's Presidential Address in the Oct. 1985 issue of HortScience 20:805–808. Encouraged, because he raised points that we need to address; discouraged, because he missed the starting point. Allow me to paraphrase an old saying: “Big grad students from little undergrads grow“. Let me lay it out in the open: I was shocked that our President finds no role for undergraduate education in tackling world hunger. I disagree!
Indian mustard (Brassica juncea) has been reported to be a preferred host for diamondhack moth (Plutella xylostellu) and other insect pests when interplanted with cabbage (Brasssica oleracea var. capitata). A cabbage-Indian mustard companion planting study was conducted to determine the seasonal occurrence of cabbage insects and the potential for using a trap-crop system to reduce insecticide applications to cabbage in West Texas. Three-row plots of cabbage 9 m long were transplanted with and without sequentially seeded borders of Indian mustard in three seasons. Harmful and beneficial insects were counted at roughly weekly intervals. Insecticides were applied when insect populations in individual plots reached predetermined thresholds. Indian mustard did not appear to be more attractive than cabbage to lepidopterous pests, but did preferentially attract hemipterans, particularly harlequin bugs (Margantia histrionica). The mustard trap crop eliminated two insecticide` applications in one trial by reducing harlequin bug pressure on the cabbage.
Residues of two fungicides (dodine and fenarimol) and two insecticide/acaricides (amitraz and formetanate) on pear (Pyrus communis L.) leaves were reduced by over-tree sprinkler irrigation applied 24 or 72 hours after pesticide treatment. The difference in residue persistence following over-tree irrigation applied at 24 vs. 72 hours after pesticide treatment was significant only for fenarimol. Residues on leaves from nonirrigated trees at 96 hours post-treatment had declined 24% to 57% from initial levels. Over-tree irrigation further reduced residues by 14% to 47%. For all compounds except dodine, foliar residues measured at 96 hours post-treatment were reduced from initial levels to a greater extent by factors other than over-tree irrigation. Chemical names used: dodecylguanidine monoacetate (dodine); α-(2-chlorophenyl)-α-(4-chlorophenyl)-5-pyrimidinemethanol (fenarimol); N'-(2,4-dimethylphenyl) -N-[[(2,4-dimethylphenyl) imino]methyl] -N-methylmethanimidamide (amitraz); N,N-dimethyl -N'-[3[[(methylamino) carbonyl]oxy]phenyl]methanimidamide (formetanate).
Indian mustard trap crops have successfully reduced pesticide use on commercial cabbage in India. Diamondback moth has been a serious pest of cabbage in Texas and has demonstrated resistance to most classes of insecticides. Use of a trap crop could fit well in an integrated management program for cabbage insects, Three-row plots of spring and fall cabbage were surrounded by successive single-row plantings of Indian mustard in trials at Lubbock, Texas to determine the efficacy of interplanting for reducing insecticide applications. Insects in the cabbage and Indian mustard were counted twice weekly, and insecticides were applied selectively when economic thresholds were reached. Indian mustard was highly attractive to harlequin bugs, and protected intercropped spring cabbage. Cabbage plots without mustard required two insecticide applications to control the infestation. False chinch bugs were also highly attracted to Indian mustard. Lepidopterous larvae, including diamondback moth, did not appear to be attracted to the trap crop. Indian mustard trap crops reduced insecticide applications to spring cabbage but had no positive effect on fail cabbage.
The Virginia Gardener Nutrient Management Education Program addressed non-point, urban-runoff pollution of Virginia's streams, estuaries, and groundwater, and included a calendar aimed at alerting the garden consumer to the connection between overfertilization and water pollution. Over 15,000 calendars were requested.
A survey of calendar recipients was conducted. 1500 persons were chosen at random, a subsequent address check confirmed adequate distribution among the regions of the state. The response rate was 28%. Responses indicated that 91.3% of those surveyed had changed their garden practices in some way because of the calendar. 90% of the respondents indicated that the calendar had shown them a connection between proper gardening techniques and water quality, with 82.2% indicating the calendar had been moderately to greatly successful in showing them this connection.
The 1989 Virginia Gardener Calendar was an effective method of educating garden consumers about the connection between water quality and nutrient runoff, and cultural practices which lessen the need for fertilizer in the home garden.
Micropropagated (MP) raspberries (Rubus idaeus L. var. idaeus) are sensitive to moisture and temperature extremes and to certain preemergent herbicides used at transplanting. We examined fertilizer placement and row covers in conjunction with various weed management strategies to identify beneficial practices for newly planted, MP primocane-fruiting `Heritage' raspberries. Uncontrolled weed growth during plant establishment inhibited raspberry cane growth and production into the second and third growing seasons. Handweeding and herbicide treatments successfully controlled weeds, but soil moisture was apparently insufficient for optimum growth of the MP raspberries when these treatments were imposed, even with normal rainfall in early summer and drip irrigation in late summer. Polyethylene and straw mulches during the establishment year provided both weed control and adequate soil moisture, resulting in more cane growth in the first and 2nd year, and higher yields the 2nd year. Primocane density after the third growing season still was influenced by first-year weed management practices. Raspberry plants responded best to straw mulch without row covers as plant growth was better in both years. Canes were thicker, yields were higher, and a larger portion of the total crop was harvested early. Row covers were beneficial only in bare-soil treatments, and method of fertilizer placement had no effect on any measured variable. Mulching newly transplanted MP raspberries is an alternative to herbicide use that also provides physiological benefits to the plant through microclimate modification.
Abstract
Organic acid components of tissues of grapefruit (Citrus paradisi Macf.) were analyzed by gas-liquid chromatography. At harvest, in autumn, malic acid was the main component of the flavedo (78% of total acid content), with malonic, adipic, citric, succinic and oxalic, ranging in order from 11% to 2%. In the albedo, malic was again the prevalent acid (67%), with malonic, adipic, oxalic and succinic acids ranging in order from 19% to 2%; citric acid was present in traces only. In the juice, citric was the prevalent acid (87%), malic attained 12% while other acids were present only in minute amounts. Malic, malonic, adipic and succinic acids in the flavedo declined when the fruit was left on the tree but increased during off-tree storage. Oxalic acid disappeared from the flavedo during storage. Orange and grapefruit acids are compared.
`Golden Delicious' apple [Malus sylvestris var. domestica (Borkh.)] cortex disks suspended in solutions containing a nitric oxide (•NO) donor [S-nitrosoglutathione (GSNO) or sodium nitroprusside (SNP)], •NO gas, or nitrite (KNO2) were used to identify impacts of •NO on ethylene production and NO2 – on •NO and ethylene production. Treatment with GSNO or SNP reduced ethylene biosynthesis compared with control treatments containing equimolar concentrations of oxidized glutathione (GSSG) or Na4(CN)6 respectively. Apple disk exposure to •NO gas did not impact ethylene production. Treatment with NO2 – resulted in increased •NO production and decreased ethylene biosynthesis. Generation of •NO increased linearly whereas ethylene generation decreased exponentially with increasing NO2 – treatment concentration. •NO was enhanced in autoclaved tissue disks treated with NO2 –, suggesting that its production is produced at least in part by nonenzymatic means. Although this evidence shows •NO is readily generated in apple fruit disks by NO2 – treatment, and ethylene synthesis is reduced by •NO/NO2 – generated in solution, the exact nature of •NO generation from NO2 – and ethylene synthesis modulation in apple fruit disks remains to be elucidated.