Iranian Journal of Environmental Health Science & Engineering 01/2008;
Source: DOAJ

ABSTRACT Field experiments were conducted during 2002-2003 on clay loam, sandy loam and red loam soil at Sivapuri, Chidambaram, Tamil Nadu, to evaluate the efficacy of vermicompost on the physico-chemical and biological characteristics of the soils and on the yield and nutrient content of blackgram - Vigna mungo, in comparison to inorganic fertilizers nitrogen, phosphorous, potassium. Vermicompost had increased the pore space, reduced particle and bulk density, increased water holding capacity, cation exchange capacity, reduced pH and electrical conductivity, increased organic carbon content, available nitrogen, phosphorous, potassium and microbial population and activity in all the soil types, particularly clay loam. The yield and quality (protein and sugar content in seed) of blackgram was enhanced in soils, particularly clay loam soil. On the contrary, the application of inorganic fertilizers has resulted in reduced porosity, compaction of soil, reduced carbon and reduced microbial activity.

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    ABSTRACT: The reduction of 2,3,5-triphenyltetrazolium chloride to triphenylformazan has been used to estimate the dehydrogenase activity of the soil microflora in situ. Preliminary investigations suggest that the formation of the formazan may be used as an index of endogenous respiration in soil since a significant correlation has been obtained between dehydrogenase activity and the oxygen uptake of a number of different untreated soils. A direct relationship also was observed between formazan formation and the respiration of a soil sampled at intervals after the application of fresh plant material. In a survey of a number of field soils no relationship was found between dehydrogenase activity and bacterial numbers; however, the two parameters were parallel during the decomposition of flax residues added to one of the soils.
    Canadian Journal of Microbiology 05/1959; 5(2):229-35. · 1.18 Impact Factor
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    ABSTRACT: Vermicomposting differs from conventional composting because the organic material is processed by the digestive systems of worms. The egested casts can be used to improve the fertility and physical characteristics of soil and potting media. In this study, the effects of earthworm casts (EW), conventional compost (CP) and NPK inorganic fertilizer (FT) amendments on N mineralization rates, microbial respiration, and microbial biomass were investigated in a laboratory incubation study. A bioassay with wheat (Triticum aestivium L.) was also conducted to assess the amendment effects on plant growth and nutrient uptake and to validate the nutrient release results from the incubation study. Both microbial respiration and biomass were significantly greater in the CP treatment compared to EW treatment for the initial 35 days of incubation followed by similar respiration rates and biomass to the end of the study at 70 days of incubation. Soil NO3− increased rapidly in the EW and CP treatments in the initial 30 days of incubation, attaining 290 and 400 mg N kg−1 soil, respectively. Nitrate in the EW treatment then declined to 120 mg N kg−1 soil by day 70, while nitrate in the CP treatment remained high. While ammonium levels decreased in the CP treatment as nitrate level increased with increasing incubation time, a low level of ammonium was maintained in the EW treatment throughout the incubation. The wheat bioassay study included two additional cast treatments (EW-N and EW2) to have treatments with higher levels of N input. Plants grown with CP or FT treatment had a lower shoot biomass and higher shoot N content than in EW-N and EW-2 treatments, and also showed symptoms of salinity stress. Ionic strength and other salinity indicators in the earthworm cast treatments were much lower than in the CP treatment, indicating a lower risk of salinity stress in casts than in compost. All cast and compost amendments significantly increased wheat P and K uptake compared to either the non-amended control or the mineral fertilizer treatment. The results show that casts are an efficient source of plant nutrients and that they are less likely to produce salinity stress in container as compared to compost and synthetic fertilizers.
    Soil Biology and Biochemistry 02/2003; · 4.41 Impact Factor
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    ABSTRACT: Tillage intensity affects soil structure and the loss of soil organic C and N. We hypothesized that no-tillage (NT) and conventional tillage (CT) differentially affect three physically defined particulate organic matter (POM) fractions. A grassland-derived Haplustoll was separated into aggregates by wet sieving. Free light fraction (LF) and intra-aggregate POM (iPOM) were isolated. Natural abundance 13C was measured for whole soil C, free LF C, and iPOM C. The mean residence time of soil C under CT (44 yr) was 1.7 times less than in NT (73 yr). The amount of free LF C was 174, 196, and 474 g C m-2 for CT, NT, and NS, respectively. Total iPOM C amounts in CT, NT, and NS were 193, 337, and 503 g C m-2, respectively. The level of fine iPOM C (53-250 micrometer) level in macroaggregates (250-2000 micrometers) obtained after slaking was five times greater in NT vs. CT and accounted for 47.3% of the difference in total POM C between NT and CT. The amount of coarse iPOM C (250-2000 micrometers) was only 2.4 times greater and accounted for only 21% of the difference in total POM C. Sequestration of iPOM was observed in NT vs. CT, but free LF was not influenced by differential tillage. We conclude that differences in aggregate turnover largely control the difference in fine iPOM in CT vs. NT and consequently SOM loss is affected by both the amount of aggregation and aggregate turnover.
    Soil Science Society of America Journal 01/1998; · 2.00 Impact Factor

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