Manure Media Research Articles

Moisture requirements in the life cycle of Perionyx excavatus (Oligochaeta)

The moisture content of the substrate is generally considered to be the major abiotic factor that influences the growth and reproduction of earthworms. The moisture requirements of P. excavatus were studied in cattle manure (particle size 500–1000 μm) at 25°C by exposing the worms to different, but constant moisture levels. The results showed that the worms grew and reproduced best between moisture levels of 75.2 and 83.2%. The moisture preferences of both juvenile and clitellate specimens were determined at 25°C in undivided moisture towers filled with a cattle manure medium in which a moisture gradient had developed. It was clear from the results that juvenile and clitellate worms preferred a moisture content of ca 81%, although cocoon deposition by clitellate worms was highest at a somewhat lower moisture level of 78.5%. It can be concluded that moisture influences the growth and reproducton of P. excavatus and that the most favourable moisture content for both is ca 80%.

Short-term measurements of uptake of nitrogen fixed in the rhizospheres of sorghum (Sorghum bicolor) and millet (Pennisetum americanum)

In a series of short-term experiments root systems of young sorghum and millet plants inoculated with N2-fixing bacteria were exposed to 15N2-enriched atmospheres for 72 h. The plants were grown in a normal atmosphere for up to 22 days after the end of the exposure to allow them to take up the fixed N2. Environmental conditions and genotypes of sorghum and millet were selected to maximise N2-fixation in the rhizosphere. Detectable amounts of fixed N (> 16 μg/plant) were rapidly incorporated into sorghum plants grown in a sand/farmyard manure medium, but measurable fixation was found on only one occasion in plants grown in soil. N2 fixation was detectable in some experiments with soil-grown millet plants but the amounts were small (2–4 μg/plant) and represented less than 1 % of plant N accumulated over the same period. In many cases there was no detectable 15N2 incorporation despite measurable increases in ethylene concentration found during an acetylene reduction assay.

Culture of marine microalgae with natural biodigested resources

The growth response of Pavlova (Monochrysis) lutheri (Droop) Green was assayed in a culture medium enriched with organic extracts aerobically biodigested from cow and chicken manures and from the macroalgae Macrocystis pyrifera (L.) C. Agard. The results indicate that, with a traditional inorganic medium and elutriated, aerobically digested manures, it is possible to attain similar maximum algal densities and equivalent algal growth rates for similar time-periods despite large differences in inorganic nitrogen and phosphorus content. The cause for this is speculated to be the conversion of organic nitrogen and phosphorus in the manure medium to inorganic forms and the presence of growth stimulatory substances in the elutriate.

THE DEMONSTRATION OF GROWTH STIMULATING SUBSTANCES FOR HISTOPLASMA CAPSULATUM AND BLASTOMYCES DERMATITIDIS IN INFUSIONS OF STARLING (STURNIS VULGARIS) MANURE.

Comparisons of growth and viability ofH. capsulatum on Sabouraud's medium with agar medium plus infusions of soil with and without starling (S. vulgaris) manure indicate that: 1. The largest number of viable conidia and smallest number of hyphal elements were developed on agar plus infusion of loam soil enriched with starling manure (Medium No. 3). 2. The largest volume of growth occurred on the Sabouraud's medium which was chiefly vegetative mycelium showing the lowest viability of any of the media tested. 3. Preliminary results indicate thatH. capsulatum will grow as well and produce as many viable conidia on dilute starling manure medium alone as when this medium is mixed or diluted with soil infusion. 4. Repeated passage ofH. capsulatum on infusion of naturally infected soil medium (No. 1) increased the number of total particles, the percentage of microconidia and the total viability. Similar comparisons with soil or starling manure media were made on the growth ofB. dermatitidis except that Sabouraud's medium was not included. These comparisons indicate that: 1. The largest number of viable conidia with a small number of hyphal elements was developed on starling manure infusion (medium No. 4). 2. Repeated passage ofB. dermatitidis on starling manure infusion (medium No. 4) resulted in an increase in the number of total particles, the percentage of microconidia, and the total viability.

Concerning soils, germs and worms

Dendrobaena veneta, an earthworm species from Europe, has been reported to have the potential to combat organic waste problems and to be a producer of protein. This study was concerned with the effect of moisture on growth, maturation and cocoon production of this species. Moisture preferences of clitellate worms were studied with the aid of cylindrical moisture towers filled with cattle manure, ground to a particle size of 500 ⩽ 1000 μm and moistened. A moisture gradient was allowed to develop in the towers and after the worms were added they were kept at a temperature of 15°C and a relative humidity of 47.7%. Juvenile worms were exposed to different moisture contents in glass flasks filled with cattle manure medium and kept at 15°C. The highest frequency for clitellate worms was between 77.9 and 78.7% while their moisture preference ranged between 67.4 and 84.3%. For cocoon production the highest frequency was between 73.1 and 79.9%. The optimum moisture content for growth and maturation of juvenile worms was 75%. From the results it appears that this earthworm species could be utilized in organic waste with a relatively high moisture content. However, comparing the reproductive capacity and maturation time with that of other vermicomposting species, D. veneta seems to be a less successful earthworm species for vermicomposting.