Rola M. Atiyeh

The influence of humic acids derived from earthworm-processed organic wastes on plant growth

Some effects of humic acids, formed during the breakdown of organic wastes by earthworms (vermicomposting), on plant growth were evaluated. In the first experiment, humic acids were extracted from pig manure vermicompost using the classic alkali/acid fractionation procedure and mixed with a soilless container medium (Metro-Mix 360), to provide a range of 0, 50, 100, 150, 200, 250, 500, 1,000, 2,000, and 4,000 mg of humate per kg of dry weight of container medium, and tomato seedlings were grown in the mixtures. In the second experiment, humates extracted from pig manure and food wastes vermicomposts were mixed with vermiculite to provide a range of 0, 50, 125, 250, 500, 1,000, and 4,000 mg of humate per kg of dry weight of the container medium, and cucumber seedlings were grown in the mixtures. Both tomato and cucumber seedlings were watered daily with a solution containing all nutrients required to ensure that any differences in growth responses were not nutrient-mediated. The incorporation of both types of vermicompost-derived humic acids, into either type of soilless plant growth media, increased the growth of tomato and cucumber plants significantly, in terms of plant heights, leaf areas, shoot and root dry weights. Plant growth increased with increasing concentrations of humic acids incorporated into the medium up to a certain proportion, but this differed according to the plant species, the source of the vermicompost, and the nature of the container medium. Plant growth tended to be increased by treatments of the plants with 50-500 mg/kg humic acids, but often decreased significantly when the concentrations of humic acids derived in the container medium exceeded 500-1,000 mg/kg. These growth responses were most probably due to hormone-like activity of humic acids from the vermicomposts or could have been due to plant growth hormones adsorbed onto the humates.

Pig manure vermicompost as a component of a horticultural bedding plant medium: effects on physicochemical properties and plant growth

This experiment was designed to characterize the physical, chemical and microbial properties of a standard commercial horticultural, greenhouse container, bedding plant medium (Metro-Mix 360), that had been substituted with a range of increasing concentrations (0%, 5%, 10%, 25%, 50% and 100% by volume) of pig manure vermicompost and to relate these properties to plant growth responses. The growth trials used tomatoes (Lycopersicon esculentum Mill.), grown in the substituted media for 31 days under glasshouse conditions, with seedling growth recorded in 20 pots for each treatment. Half of the tomato seedlings (10 pots per treatment) were watered daily with liquid inorganic fertilizer while the other half received water only. The percentage total porosity, percentage air space, pH and ammonium concentrations of the container medium all decreased significantly, after substitution of Metro-Mix 360 with equivalent amounts of pig manure vermicompost; whereas bulk density, container capacity, electrical conductivity, overall microbial activity and nitrate concentrations, all increased with increasing substitutions of vermicompost. The growth of tomato seedlings in the potting mixtures containing 100% pig manure vermicompost was reduced, possibly as a result of high soluble salt concentrations in the vermicompost and poorer porosity and aeration. The growth of tomato seedlings was greatest after substitution of Metro-Mix 360 with between 25% and 50% pig manure vermicompost, with more growth occurring in combinations of pig manure vermicompost treated regularly with a liquid fertilizer solution than in those with no fertilizer applied. Some of the growth enhancement in these mixtures seemed to be related to the combined effects of improved porosity, aeration and water retention in the medium and the high nitrate content of the substrate, which produced an increased uptake of nitrogen by the plant tissues, resulting in increased plant growth. When the tomato seedlings were watered daily with liquid inorganic fertilizer, substitution of Metro-Mix 360 with a very small amount (5%) of pig manure vermicompost resulted in a significant increase in the growth of tomato seedlings. Such effects could not be attributed solely to the nutritional or physical properties of the pig manure vermicompost. Therefore, it seems likely that the pig manure vermicompost provided other biological inputs, such as plant growth regulators into the container medium, that still need to be identified fully.

Changes in biochemical properties of cow manure during processing by earthworms (Eisenia andrei, Bouché) and the effects on seedling growth

Summary The biochemical changes in fresh cow manure caused by the earthworm Eisenia andrei (Bouche) were measured over a period of four months, under controlled laboratory conditions. Earthworms were introduced into each of four plastic containers (0.4 × 0.27 × 0.15 m) containing fresh cow manure (2500 g), and four containers containing manure but without earthworms served as controls. Earthworms reduced the pH and decreased the moisture content in the manure. The C:N ratio of the manure with or without earthworms decreased progressively from 36 to 21. The ash and total nitrogen contents increased greatly for a few weeks after the introduction of earthworms, reflecting a rapid breakdown of carbon compounds and mineralization of nitrogen by the earthworms. CO2 evolution decreased rapidly (44%) one week after the introduction of earthworms, and continued at a lower rate throughout the 17 weeks (51% reduction as compared to 22% without earthworms), indicating increasing stability of the organic matter. Earthworms reduced microbial biomass early in the process, but enhanced nitrogen mineralization and increased the rates of conversion of ammonium-nitrogen into nitrate. The major general effect of earthworms on the organic wastes was to accelerate the maturation of the organic wastes as demonstrated by enhanced growth of lettuce and tomato seedlings.

Influence of earthworm-processed pig manure on the growth and yield of greenhouse tomatoes

The eAects of earthworm-processed pig manure (vermicompost) on germination, growth, and yields of tomato (Lycopersicon esculentum Mill.) plants were evaluated under glasshouse conditions. Tomatoes were germinated and grown in a standard commercial greenhouse container medium (Metro-Mix 360), substituted with 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100% (by volume) pig manure vermicompost. The control consisted of Metro-Mix 360 alone without vermicompost. Plants were grown for 158 days and were frequently supplied with a complete mineral nutrient solution. The germination rates of tomato seeds increased significantly upon substitution of Metro-Mix 360 with 20%, 30%, and 40% vermicompost. Seedlings grown in 100% pig manure vermicompost were significantly shorter, had fewer leaves, and weighed less than those in Metro-Mix 360 controls. Incorporation of 10% or 50% vermicompost into Metro-Mix 360 increased the dry weights of tomato seedlings significantly compared to those grown in the Metro-Mix 360 controls. The largest marketable yield was in the substitution of Metro-Mix 360 with 20% vermicompost (5.1 kg/plant). The average weight of a tomato fruit in substitution of Metro-Mix 360 with 20% vermicompost was 12.4% greater than that in the Metro-Mix 360 control. Substitution of Metro-Mix 360 with 10%, 20%, and 40% vermicompost reduced the proportions of fruits that were non-marketable, and produced more large size (diameter > 6:4 cm) than small size (diameter < 5:8 cm) tomato fruits. There was no significant diAerence in overall tomato yields between Metro-Mix 360 and 100% pig manure vermicompost. Some of the growth and yield enhancement resulting from substitution of Metro-Mix 360 with pig manure vermicompost could be attributed to the high mineral N concentration of the pig manure vermicompost. However, other factors might have also been involved since all plants were frequently supplied with all required nutrients. These factors need to be investigated in future studies. ” 2000 Elsevier Science Ltd. All rights reserved.

THE INFLUENCE OF EARTHWORM-PROCESSED PIG MANURE ON THE GROWTH AND PRODUCTIVITY OF MARIGOLDS

The effects of additions of earthworm-processed pig manure (vermicompost) on the growth and productivity of French marigold (Tagetes patula) plants were evaluated under glasshouse conditions. Marigolds were germinated and grown in a standard commercial greenhouse container medium (Metro-Mix 360), substituted with 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100% (by volume) pig manure vermicompost. The control consisted of Metro-Mix 360 alone without vermicompost. Plants were supplied regularly with a complete mineral nutrient solution for 121 days. The greatest vegetative growth resulted from substitution of Metro-Mix 360 with 30% and 40% pig manure vermicompost, and the lowest growth was in the potting mixtures containing 90% and 100% vermicompost. Most flower buds occurred in the potting mixtures containing 40% pig manure vermicompost (19.4 buds), and fewest in the potting mixtures containing 100% vermicompost. Marigolds grown in Metro-Mix 360 substituted with 90% and 100% pig manure vermicompost had the fewest and smallest flowers. After substitution of Metro-Mix 360 with 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90% vermicompost, the marigold roots were larger than those of plants grown in the Metro-Mix 360 controls. Substitution of Metro-Mix 360 with any concentration of pig manure vermicompost, with all needed nutrients provided, increased the overall nitrate-nitrogen concentrations of the marigold leaf tissues at flowering stage. Some of the marigold growth and productivity enhancement, resulting from substitution of Metro-Mix 360 with pig manure vermicompost, may be explained by nutritional factors; However, other, factors, such as plant-growth regulators and humates, might have also been involved since all plants were supplied regularly with all required nutrients.

Earthworm-processed organic wastes as components of horticultural potting media for growing marigold and vegetable seedlings.

We germinated and grew tomato, pepper, lettuce, and marigold seedlings in a standard commercial soilless plant growth medium (Metro-Mix 360), and in coir/perlite and peat/perlite-based container media substituted with 10% or 20%, by volume, of vermicompost derived from pig manure or food wastes. Half of the treatments were watered with liquid inorganic fertilizer while the other half received only water. Germination rates of tomato, pepper, lettuce, and marigold seeds in the coir/perlite mixture did not differ significantly from that in Metro-Mix 360. However, the germination rate of tomato, pepper and lettuce seedlings was very low in the peat/perlite mixture. Substituting some of the peat/perlite mixtures with equal amounts of vermicomposts, particularly pig manure vermicompost, enhanced germination rates greatly, making it comparable to that in the commercial medium (Metro-Mix 360). Pepper, lettuce, and marigold seedlings grown in Metro-Mix 360, which already contains a starter nutrient fertilizer in its formulation, had greater root and shoot dry weights than those grown in the control media (coir/perlite mix and peat/perlite mix). Substituting coir/perlite and peat/perlite mixtures with 10% or 20% of either vermicompost enhanced the growth of seedlings significantly, resulting in an overall plant growth as good as and sometimes better than that in Metro-Mix 360. When the plants were provided daily with a complete fertilizer solution, marigold seedlings in peat-based substrate with 20% pig waste vermicompost, and lettuce seedlings in both coir and peat-based substrates, mixed with 20% food wastes vermicompost, produced greater shoot dry weights than those grown in the commercial potting medium. The growth enhancements tended to be greater in peat/perlite-based mixes than in coir/perlite-based mixes, more so with the addition of pig manure vermicompost than with food waste vermicompost. Earthworm-processed pig manure and food wastes would be suitable materials for inclusion into the formulation of soilless potting media, since substitution of these media with relatively low concentrations of vermicomposts can promote plant growth.

Effects of humic acids derived from cattle, food and paper-waste vermicomposts on growth of greenhouse plants

Humic acids were extracted from cattle, food and paper-waste vermicomposts using an alkali/acid fractionation procedure which produced 1 g dry wt humates from 400 g vermicompost. They were applied to a soilless growth medium, Metro-Mix 360 (MM360), at rates of 0, 250 or 500 mg humates kg - 1 dry wt of container medium, to young marigold, pepper, and strawberry plants grown in pots in the greenhouse. A range of 0, 20, 100, 150, 200, 250, 500, 1000, 2000, 4000 mg of humates kg - 1 of container medium was used for tomatoes. Effects of the humic acids on the plant heights, leaf areas, shoot dry weights, root dry weights of peppers, tomatoes and marigolds and numbers of fruits of strawberries were assessed. Substitution of humates ranging from 250-1000 mg kg - 1 MM360 increased root growth of marigolds and peppers, and increased root growth and numbers of fruits of strawberries significantly (P ≤ 0.05). Leaf areas, plant heights and above-ground dry matter weights increased considerably in plants grown in pots containing humic acids but they were not significantly different from those grown in MM360 only (P ≤ 0.05).

Vermicompost stimulates mycorrhizal colonization of roots of Sorghum bicolor at the expense of plant growth

Summary Two greenhouse experiments were conducted on the biological and nutritional effects of vermicompost on Sorghum bicolor growth and root infection by arbuscular mycorrhizal fungi (AMF). Two rates of sterile and non-sterile vermicompost (5% and 20%) were added to two media (peat and mineral). In experiment 1, all treatments received AMF inoculant but in experiment 2 uninoculated treatments were included. The addition of vermicompost to substrates increased N, P and K levels. Vermicompost stimulated mycorrhizal colonization of roots in both experiments, particularly in the peat medium. Shoot and root dry weights were increased by vermicompost in the absence of AMF. Inoculation with AMF reduced dry weights particularly at the higher rate (20%) of vermicompost. Steam sterilization of vermicompost had no consistent effect on mycorrhizal colonization but generally enhanced dry weights relative to the non-sterile treatment.