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    ThesisItemOpen Access
    Carbon pools in Lateritic soil amended with coirpith-vermicompost and its effect on Tomato (Solanum lycopersicum L.)
    (Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 2019) Aiswarya, R; KAU; Jayasree Sankar, S
    Soil organic carbon (SOC) is considered as the key indicator of soil quality and agricultural sustainability. Among the different management practices that are being followed, application of chemical fertilizers and manures has been recognized as the most systematic and effective means to either enhance soil organic carbon accumulation or reduce the rate of SOC loss. Hence, for studying the effect of coirpith based vermicompost on dynamics of carbon in a lateritic soil, a field experiment was laid out during October 2018 – February 2019, in RBD with 12 treatments replicated thrice, with tomato, variety Manulakshmi, as the test crop. The plot size was 3 x 3 m and plant spacing was 60 x 60 cm. The treatments consisted of an absolute control (T1), coirpith compost at 10 t ha-1 (T2), coirpith based vermicompost at 10 t ha-1 (T3), Coirpith based vermicompost at 10 t ha-1 + soil test based KAU POP (T4), , FYM at 20 t ha-1 + soil test based KAU POP(T5), T3 + 25 % of soil test based KAU POP (T6), T3 + 50 % of soil test based KAU POP (T7), T3 + 75 % of soil test based KAU POP (T8), FYM at 20 t ha1 + 25 % of soil test based KAU POP (T9), FYM at 20 t ha-1 + 50 % of soil test based KAU POP (T10), FYM at 20 t ha-1 + 75 % of soil test based KAU POP (T11), Adhoc KAU organic POP (T12). Raw coirpith was converted into compost using vermitechnology employing the compost worm Eisenia foetida .The composting process got completed within 64 days time span. Coirpith in the raw stage and after composting was characterized for physical, electro-chemical and chemical properties. Advantages of vermicomposting coirpith included a reduction in the content of lignin (32 to 16.7 %), cellulose (25.2 to 10.2 %), C: N ratio (113:1 to 20.5:1) and EC (0.98 to 0.51 dS m-1) and an increase in pH and total nutrients. Soil analysis after the experiment revealed the significance of treatments on electro-chemical and chemical properties as against the control. Significantly higher available K (281.0 kg ha-1) and Mn (75.33 mg kg-1) was obtained in coirpith based vermicompost at 10 t ha-1 + soil test based KAU POP (T4). In case of N, P, Ca and Fe the effect of the treatments T4, T5 (FYM + soil test based POP) and T8 (Coirpith vermicompost + 75 % soil test based POP) were comparable. The labile C fractions viz. water soluble carbon (WSC), hot water soluble carbon (HWSC), permanganate oxidizable carbon (POXC) and microbial biomass carbon (MBC) were also significantly influenced by the treatments and it followed the order POXC > HWSC > MBC = WSC. Further analysis revealed that the treatments T4, T5, T6 (Coirpith vermicompost + 25 % soil test based POP), T8 and T11 (FYM + 75 % soil test based POP) were comparable in influencing WSC, whereas T4 and T5 were similar in deciding HWSC and T4 and T8 in case of MBC. Significantly higher total C was registered by coirpith vermicompost + 75 per cent soil test based KAU POP. Dehydrogenase activity which is considered as an index of microbial activity in soil was significantly higher (146.3 µg TPF g-1soil 24hr-1) in coirpith based vermicompost at 10 t ha-1 + soil test based KAU POP. Integration of chemical fertilizers at different levels with organics, either coir pith vermicompost or FYM, increased microbial population which followed the order bacteria > fungi > actinomycetes. However, the impact of treatments was more pronounced in enhancing bacterial population due to the shift in pH towards neutral value. On considering biometric observations, it was seen that the plant height (104.7 cm), number of fruits per plant and fruit yield (1.84 kg/plant) were significantly higher for the treatment coirpith based vermicompost at 10 t ha-1 + soil test based KAU POP. The effect of coirpith based vermicompost and FYM along with fertilizers at different levels were comparable in determining fruit quality parameters like total soluble solids, ascorbic acid, lycopene and titrable acidity. Applying coirpith based vermicompost at 10 t ha-1 + soil test based KAU POP registered a higher B: C ratio of 2.43 in contrast to 1.57 recorded in the absolute control.