Abstract
In the present study rice straw (R, control) was mixed with Cowdung (C), Azolla (A) and cellulolytic fungus Aspergillus terreus (F) in different combinations viz. RC, RA, RF, RCF, RCA, RFA and RCFA and subjected to aerobic composting (Acom) and vermicomposting (Vcom - with Eisenia fetida). It was found that addition of azolla and cattledung to two parts straw(RCA-666: 314:20 g) caused fastest degradation (105 days), gave maximum population buildup of E. fetida (cocoons, hatchlings and worm biomass), highest decline in pH, EC, TOC and C/N ratio and maximum increase over control in N(17.72%), P(44.64%), K(43.17%), H (7.93%), S (14.85%), Ca(10.16%), Na(145.97%), Fe(68.56%), Zn(12.10%) and Cu(32.24%). Rice straw (R) took longest time for degradation i.e. 120 and 140 days and had lowest content of nutrients in Vcom as well as Acom group. RCFA was also converted into Vcom at the same time but other parameters were less than RCA except for highest content of B (19.87%), Mg(21.27%) and Mn (5.58%). Bioconversion of three parts straw (RCA-735:245:20 g) was also faster (110 days) with vermicomposting than all the mixtures of Acom group (130–140 days) but nutrient content was slightly less than RCA with 2 parts straw. The results show that azolla reduces dependence on cattledung for recycling the carbon rich rice straw and enhances its agronomic value.
Highlights
Burning of straw affects fertility of soil and accounts for air and surface water pollution
Minimum time was required for bioconversion of both RCFA and rice straw + cattledung + Azolla (RCA) in the Vcom and aerobic composting (Acom) groups respectively
This study clearly indicates that the rice straw, a menace to farmers for storage and usage can be efficiently converted into a nutrient rich plant growth promoting vermicompost with addition of A. terreus, azolla and cattledung
Summary
Burning of straw affects fertility of soil and accounts for air and surface water pollution It leads to emission of large amounts of suspended particulate matter and silica besides gases like CH4, CO, volatile organic compounds (VOC), nitrogen oxides and halogen compounds[10,11]. The weed biomass rich in fibres, proteins, lipids, carbohydrates, minerals and vitamins can be efficiently used for vermicomposting nitrogen deficient organic wastes[18,19]. It is found abundantly in waste water ponds in the villages. This study is first of its kind to use combination of fungus, azolla and cattledung for enhancing the bioconversion of rice straw into a nutrient rich plant growth medium
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