Effect of vermicompost on soil fertility and crop productivity - beans (Phaseolus vulgaris).

Field experiments were conducted at Sivapuri, Chidambaram, Tamil Nadu to evaluate the efficacy of vermicompost, in comparison to inorganic fertilizers–NPK, on the physio-chemical and biological characteristics of the soils – clay loam soil (CLS) and sandy loam soil (SLS) and on the growth, yield and nutrient content of beans – Phaseolus vulgaris. Results showed that the application of vermicompost @ 5 tonnes ha-1 had enhanced significantly the pore space (1.09 and 1.02 times), water holding capacity (1.1 and 1.3 times), cation exchange capacity (1.2 and 1.2 times). It reduced particles (1.2 and 1.2 times), and bulk density (1.2 and 1.2 times), pH (1 and 1.02 times) and electrical conductivity (1.4 and 1.2 times) and increased organic carbon (37 and 47 times), micro (Ca 3.07 and 1.9 times, Mg 1.6 and 1.6 times, Na 2.4 and 3.8 times, Fe 7 and 7.6 times, Mn 8.2 and 10.6 times, Zn 50 and 52 times and Cu 14 and 22 times) and macro (N 1.6 and 1.7 times, P 1.5 and 1.7 times, K 1.5 and 1.4 times) nutrients and microbial activity (1.4 and 1.5 times) in both soil types, particularly more in CLS. The growth, yield (1.6 times) and quality (protein (1.05 times) and sugar (1.01 times) content in seed) of bean were enhanced in CLS than SLS. On the other hand, the application of inorganic fertilizers @ 20:80:40 kg ha-1 has resulted in reduced porosity (1.03 and 1.01 times), organic carbon (1.04 and 9.5 times) and microbial activity (1.02 and 1.03 times) in both soil types.

Life cycle of Lampito mauritii (Kinberg) in comparison with Eudrilus eugeniae (Kinberg) cultured on different substrates.

Growth (length, biomass and mean growth rate) and reproduction (total duration, clitellum appearance, clitellum completion, cocoon commencement, rate of cocoon production, incubation period, hatching success and mean number of hatching per cocoon) of indigenous Lampito mauritii (Kinberg) in comparison with exotic Eudrilus eugeniae (Kinberg) cultured on three feed substrates-clay loam soil, cowdung and pressmud (filter cake) have been studied over a period of 360 days under laboratory conditions (30 +/- 2 degrees C, 60-65% moisture). There is a positive relationship between length and biomass of both worms cultured on three feed substrates throughout the period of study The decrease of worm length and biomass observed slightly on 63-70th days in Lampito mauritii and 42-49th days in Eudrilus eugeniae cultured on three fed substrates are the results of the onset of cocoon production. After 270 days both worms in all these fed substrates show decreasing trends of length and biomass which are due to continued reproduction and aging. Among the three fed substrates, pressmud supports significantly maximum worm length and biomass (between 90-130 days in Eudrilus eugeniae and 110-170 days in Lampito mauritii), earlier attainment of sexual maturity (between 51-76 days in Limpito mauritii and 27-37 days in Eudrilus eugeniae), earlier commencement of cocoon production (37.7 +/- 0.0 days in Eudrilus eugeniae and 76.4 +/- 0.10 days in Limpitomauritii), shorter incubation periods (16.3 +/- 0.28 days in Eudrilus eugeniae and 26.7 +/- 0.81 days in Limpito mauritii), more hatching success (98% in Limpito mauritii and 86% in Eudrilus eugeniae), more mean number of hatchling percocoon (3.2 + 0.03 in Limpito mauritii and 2.6 +/- 0.06 in Eudrilus eugeniae) and shorter duration of life cycle (108.8 +/- 0.07 days in Limpito mauritii and 60.2 +/- 0.09 days in Eudrilus eugeniae) than cowdung and clay loam soil.

Diversity of microflora in the gut and casts of tropical composting earthworms reared on different substrates.

The diversity of fungi, bacteria, yeast, actinomycetes and protozoa were analysed in the gut and casts of Eudrilus eugeniae, Lampito mauritii, Eisenia fetida and Perionyx excavatus, both qualitatively and quantitatively as influenced by different feed substrates like clay loam soil, cowdung and pressmud. While actinomycetes (Streptomyces albus, S. somaliensis, Nocardia asteroides, N. caviae and Saccharomonosporia) were not digested by any of these species of worms, protozoa (Amoeba proteus, A. terricola, Paramecium trichium, Euglena viridis, E. orientalis, Vorticella picta and Trichomonas hominis) and yeast (Candida tropicalis, C. krusei C. albicans and Cryptococcus neoformans) were totally digested. Certain species of fungi (Saksenae vasiformis, Mucor plumbeus, Cladosporium carrionii, C. herbacium, Alternaria sp., Cunninghamella echinulata, Mycetia sterila, Syncephalostrum racemosum, Curvalaria lunata, C. geniculata and Geotrichum candidum) and bacteria (Pseudomonas aeruginosa, Bacterium antitratum, Mima polymorpha, Enterobacter aerogenes, E. cloacae, Proteus vulgaris, P. mirabilis, P. rettgeri, Escherichia coli, Staphylococus citreus, Bacillus subtilis, B. cereus, Enterococci and Micrococci) were completely digested. Certain other species were not digested fungi like Aspergillus fumigatus, A. flavus, A. ochraceous, Trichoderma koningii (except by Eeugeniae), Fusarium moniliforme (except by E. eugeniae) and Rhizopus sp., and bacteria like Klebsiella pneumoniae and Morganella morganii) and these were multiplied during the transit of the organic residues through the gut of worms. The microbial proliferation was more in the casts, due to the environment prevailing--rich in nutrient supply and large surface area available for growth and reproduction of the microbes that lead to enhanced microbial activity and humic acid contents in the casts.