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- Author or Editor: Allen V. Barker x
Activators are suggested as adjuvants to accelerate rates of composting of plant residues. Three activators, two microbial preparations and one enzyme-based material, were assessed. The feedstock for composting was a 1:1 volumetric ratio of vegetative food wastes and autumn leaves from broadleaf trees. Composting was conducted in 0.35-m3, covered, plastic bins. In one experiment, the bins were filled to capacity twice, once at treatment initiation and at 1 week later. Treatments included no activator, an addition of each microbial preparation individually, addition of the enzyme-based activator individually, and additions of one of the microbial preparations and the enzyme-based activator in combination. The individual applications were at full-strength according to recommendations on the labels, and the combinations were at full-strength or at half-strength according to the recommendations. Piles in the bins were turned weekly, and activators were added weekly or only once according to the manufacturers' recommendations. Composting proceeded for 60 days. In a second experiment, the same protocols were followed with the modification that feedstock was added to each bin weekly for 60 days, followed by a 30-day curing period. Temperatures of the compost were recorded weekly. Piles were moistened weekly after turning. None of the activators accelerated the rate of composting relative to the rate with no activators. Rate of composting was evaluated by comparison of the weekly temperatures of the piles, the volume of compost produced, and the texture of the compost. Tomato (Lycopersicon esculentum Mill.) plants grew equally well in composts from each of the treatments. The conclusion was that compost activators did not modify the process or quality of compost produced from food and tree-leaf residues.
Abstract
Nitrogen is used in large amounts by plants, for it is assimilated into many compounds that are essential and principal plant constituents. Proteins, including enzymes, cofactors of enzymatically catalyzed reactions, genetic material, and chlorophyll, are a few of the N-containing components of plants. Because of the major role of N in plant nutrition, it has been suggested that significant improvements in plant genetic resources could be made by increasing the efficiency of N use in crops (Vose, 1963). Increased efficiency in N use may allow for increased crop productivity or quality and permit plants to survive under conditions of limited supplies of N. Manufacture of N fertilizers accounts for about one-third of the energy consumption in agricultural production, or ≈ 1% of the total energy consumption in the United States (Davis and Blouin, 1977). The fraction of total energy consumption represented by manufacture of N fertilizers is small, but some consider this usage to be a significant portion of the total. Costs of N fertilizers, nevertheless, vary with costs of energy. Consideration of conservation and costs have stimulated interests further for developing cultivars that are efficient in N use.
Abstract
Until the development of modern chemical fertilizers began in about 1840, natural and organic materials supplied virtually all the plant nutrients to the soil. The use of chemical fertilizers increased gradually until about 1940. Since then the total consumption of chemical fertilizers in the United States has increased nearly fivefold to about 40,000,000 tons annually (28). The development and use of modern chemical fertilizers has decreased the relative importance of organic fertilizers. Today, organic materials account for less than 1% of the N fertilizers sold in this country (27). Phosphate rock materials account for about 20% of the present P fertilizer consumption in the United States, and over 85% of these materials are consumed in Illinois and Missouri (4). Natural potassic fertilizers, such as seaweed, greensand, and granite dust, apparently account for an insignificant fraction of the K fertilizer materials sold in this country, since muriate of potash alone accounts for nearly 90% of the commercial K fertilizers consumed here (4).
Major compostable materials in municipal solid wastes (MSW) are sewage sludge, paper, garbage, and autumn leaves. Five composts made from these wastes separately or in mixtures and one compost made from agricultural wastes (chicken manure and cranberry pomace) were evaluated for production of grass sods. Perennial ryegrass (Lolium perenne L. 'Pennfine') was seeded in 3.5-cm-deep layers of compost in plastic trays and grown in a greenhouse. Seed germination was inhibited in immature sludge-based and mixed MSW composts relative to germination in the other composts. High ammonium levels in the immature sludge-based and mixed MSW composts appeared to limit germination, as these composts had ammonium-N levels ranging from 1,000 to 2,000 mg/kg. Ammonium-N in the agricultural compost was 200 mg/kg, whereas that in the leaf-based composts was 10 mg/kg. In general, germination in all media was sufficient to establish a stand. Thereafter, growth of sods in the sewage-based, mixed MSW, and agricultural composts benefitted from the rich supply of N and exceeded that in the leaf-based composts. Mixing of composts with soil gave no advantage other than slightly increased seed germination but diluted total N supply and increased weediness of the sods.
Studies were made of ethylene evolution by `Heinz 1350' tomato fruits from plants that had received nitrogen nutrition from ammonium or nitrate salts in soil-based media. Fruits of plants receiving ammonium nutrition had higher ammonium concentrations, higher occurrences of blossom-end rot, and higher rates of ethylene evolution than fruits from nitrate-grown plants. Fruits showing blossom-end rot had higher ammonium concentrations and higher rates of ethylene evolution than normal fruits only if the plants received ammonium nutrition. Ethylene evolution increased as fruits from nitrate-grown plants ripened but without a concurrent increase in ammonium concentrations in the fruits. Ammonium accumulation in fruits apparently induces blossom-end rot and enhances ethylene evolution, but ammonium accumulation does not appear to be a naturally occurring phenomenon in ripening fruits or in fruits that have blossom-end rot arising from other casual factors.