Background: The distribution of earthworms is usually diverse and their population fluctuates in relation to the different physico-chemical properties and land use patterns of the soil of southern parts of India. This particular study examined distribution and relative abundance of earthworms under different land use patterns and their influence on the physico-chemical properties of the soil. We measured the species composition of earthworm communities across the three different land use ecosystems and effect of abiotic factors on them from various ecological regions of southern India (southern Odisha). Methods: The linear relationship between different physico-chemical parameters of soil across three land use types and earthworm density is obtained by Pearson correlation analysis in the months of June to September. The association of physico-chemical parameters of different habitats with earthworm populations is analyzed using two-way ANOVA. Principal component analysis is (PCA) used to characterize the effect of different soil properties on the distribution of earthworm populations across three different habitats. Results: A total of ten species of earthworms belonging to five families were identified. Four species of earthworms are identified, i.e., Pontodrilus bermudensis, Parionyx excavates, Pheretima alexandri, Lampito mauritii, most abundantly in forest lands, while the other six species are mostly found in agriculture and grass land. The earthworm density is significantly correlated (P < 0.01) with the availability of organic OC, total nitrogen, phosphorus, and water holding capacity across the three habitats, the forest land in particular. Both ANOVA and PCA results revealed a significant impact of habitat conditions on the soil physico-chemical properties as well as earthworm density. Conclusions: This particular study has provided new information regarding the influence of different earthworm population on abiotic factors of soil across three land use patterns. It is also noticed that the distribution of earthworm was higher in forest lands and followed by grasslands having high organic manure rather than agricultural land.

The study aimed to assess the genuine impact of phosphogypsum on the growth, feeding, respiration and regeneration of earthworm Eisenia fetida. In laboratory condition the earthworms were cultured under 0% (control), 4%, 8% and 10% concentration of phosphogypsum for 30 days. After completion of every 10 day changes in the above parameters were observed to track the impact of phosphogypsum. With increasing exposure duration and concentration of phosphogypsum lower growth rate, declined feeding habit, maximum respiration rate and deprived regeneration power were noticed. The highest and lowest growths were 1.39 gm at 0% and 0.05 gm at 10%, respectively. Maximum feeding rate was 32.65 with a minimum rate 16.20 g g -1 live tissue. Respiration rate was highest at 10% i.e. 0.0578 g -1 live worm tissue hr -1 kg -1 soil, as most of the energy used to respire to sustain in such diverse condition and 0.575 g -1 live worm tissue hr -1 kg -1 soil recorded as lowest in 0%. The rate of regeneration was deeply hampered and there was no viable worms left at 8% and 10% concentration to assess. Regeneration was only observed at 0% and 4%.

Copper such as copper oxychloride has wide use as a fungicide/bactericide which prevents infection in plants. The recommended dose of copper oxychloride for rice fields is 3 g/l which contains   50% copper i.e 1.5 g copper/l or 1500 ppm. The earthworms that play a major role in soil physical, chemical and biological improvement of soil are exposed to the copper fungicide. During the suspension culture the epi-anecic earthworm, Lampito mauritii (Kinberg) could not survive beyond 30 ppm. So, the earthworms were exposed to lethal levels of copper i.e., 0, 10, 20 and 30 ppm of copper and the effect on growth, feeding, respiration, excretion and regeneration was found to be significantly deleterious. On exposure to a sublethal dose of copper oxychloride the respiration increased but there was a marked reduction in growth, feeding, excretion and regeneration. The positive contribution of the earthworm was hampered but it continued to utilize energy from the system and this was the major finding of this work.

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