Browsing by Author "Mayadevi, M R"

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    Efficiency of vermiconversion and decomposition of farm residues on soil health, yield and quality of banana (Musa spp.)
    (Department of Science and Agricultural Chemistry, College of Horticulture,Vellanikkara, 2016) Mayadevi, M R; Sushama
    An investigation entitled “Efficiency of vermiconversion and decomposition of farm residues on soil health, yield and quality of banana (Musa spp.)” was undertaken at College of Horticulture and Banana Research Station, Kannara during 2013-2015. The objectives of the study were to compare the efficiency of native and exotic earthworms on vermiconversion of farm residues and the effects of different modes of vermicomposting on soil health, yield and quality of banana and to evaluate the in situ decomposition of banana crop residues An experiment with seven treatments and three replications was laid out in randomized block design to assess the composting efficiency of native and exotic earthworms. Seven treatments included absolute control as soil (S), ex-situ compost in silpaulin vermibed without earthworms (Ex-C), ex-situ vermicompost in silpaulin vermibed using Perionyx excavatus (Ex-P), ex-situ vermicompost in silpaulin vermibed using Eisenia foetida (Ex-E), in-situ vermicompost in banana planting pits using Perionyx excavatus (In-P), in-situ vermicompost in banana planting pits using Eisenia foetida (In-E), in-situ compost in banana planting pits without earthworms (In-C). In the next study, the prepared composts were tested along with recommended doses of fertilizers and FYM to assess their effects on growth, yield and crop quality of banana var. Nendran in RBD with seven treatments replicated thrice. The treatments were absolute control (S), 300:115:450g N:P2O5:K2O plant-1 + FYM at the rate of 20 kg plant-1 (POP) , exsitu vermicompost in silpaulin vermibeds with Perionyx excavatus at the rate of 20 kg plant -1 (Ex–P), ex-situ vermicompost in silpaulin vermibeds with Eisenia foetida at the rate of 20 kg plant -1 (Ex–E) , in-situ vermicompost in crop pits with Perionyx excavatus at the rate of 20 kg plant -1 (In-P), in-situ vermicompost in crop pits with Eisenia foetida at the rate of 20 kg plant -1 (In-E), in -situ compost at the rate of 20 kg plant -1 (In-C). After the harvest of the crop, the entire residues from each plant was incorporated in the respective crop pits and the insitu degradation of the banana residues was monitored. The salient findings are summarized as follows In the first trial, the composting efficiency of native and exotic earthworms under different modes of composting was compared. Chemical properties of compost like pH, electrical conductivity, and content of primary nutrients were significantly affected by modes of composting. Exotic earthworms like Eisenia foetida produced higher auxin content in the compost whereas Perionyx excavatus registered higher dehydrogenase activity under ex-situ mode of composting. The total microbial load was recorded in the compost prepared without earthworms under both modes of composting. Compost yield was more in ex-situ composting methods and Eisenia foetida was more efficient in composting as compared to Perionyx excavatus. Humic acid characterization by Fourier Transform Infra-Red spectroscopy revealed a similar spectra from different treatments and were found to be characterized by aromatic rings and triple bonded skeleton. Presence of relatively higher quantity of polysaccharide like substances was observed in insitu mode of composting. The spectra of humic acids for ex-situ composts prepared using Perionyx excavatus revealed a nitrate band of characteristic shape appearing prominently. Perionyx excavatus produced humic acids with high aromaticity both under ex-situ and in-situ mode of composting. Scanning electron microscopy revealed neo-formed CaCO3 nodules embedded in humic acids in the ex-situ vermicompost produced by Eisenia foetida. Transmission Electron Microscopy of humic acids indicated a globular structure for vermicompost prepared by Perionyx excavatus and a lamellar structure with voids for vermicompost prepared using Eisenia foetida. On field experimentation with different treatments using Nendran banana as the test crop, the highest yield was obtained for combined application of fertilizers and farm yard manure as per POP. Number of fingers per hand and number of functional leaves were found to influence the yield, irrespective of treatments. The number of days to bunching and harvest was significantly reduced for banana under in-situ composting. Higher content of total, reducing and non-reducing sugars were observed for in-situ composting treatments. On the contrary, higher titratable acidity was recorded for the control treatment. Both vitamin C content and sensory parameters were complimentary for POP treatment. Increased absorption and translocation of nutrients such as N, P, K and Mg in fruits were observed under organic nutrition using Perionyx excavatus. For the next study, the residues of banana were added to the respective pits for monitoring the carbon and nitrogen mineralization. The carbon mineralization with respect to time was fitted to single pool exponential model to derive the rate of mineralization and half-life. It revealed crop residues pre-treated with vermicompost using exotic earthworms had a higher rate of C cumulative mineralization. Nitrogen addition by both exotic and native species of earthworms were almost similar under in-situ conditions. The banana residue decomposition by Eisenia foetida was about 3.5 times higher than that of Perionyx excavatus. Calcium content of Perionyx excavatus pre-treated residues added the maximum calcium to the soil.
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    Spatial variability and dynamics of arsenic in selected coastal rice ecosystems of Kerala
    (Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellanikkara, 2025-02-12) Rashbi Jahan, V; Mayadevi, M R
    Arsenic (As) is a naturally occurring toxic metalloid, that can cause detrimental effects on plants as well as humans. Though the elevated level of As is not reported from the paddy soils of Kerala, the tropical climate and high amorphous Fe minerals in the soil may cause an excessive dissolution of arsenic in the soils of Kerala. Hence, a study entitled “Spatial variability and dynamics of As in selected coastal rice ecosystems of Kerala” was designed to understand the spatial distribution of As in paddy soils of coastal agroecological units (AEU), namely, Northern coastal plain (AEU 2) and Kaipad lands (AEU 7) and to study the effects of agricultural amendments such as lime and organic manure on As content in these soils. Thirty-eight and eight georeferenced, grid-based (5 x5 km2) irrigation water and soil samples each were collected from paddy fields of panchayats under the Northern coastal plain (AEU 2) and Kaipad lands (AEU 7), respectively, at a sampling intensity of one panchayat from one grid forming a total of ninety-two samples. The pH of irrigation water from AEU 2 varied between 5.94 and 8.58, and that of Kaipad lands (AEU 7) from 7.46 to 8.6. The electrical conductivity (EC) of AEU 2 varied from 0.03 to 4.59 dS m-1 and between 0.02 and 17.02 dS m-1 from AEU 7. The content of As in irrigation water ranged from 0.02 µg L-1 (Feroke, Kozhikode) to 1.56 µg L-1 (Matool, Kannur) in AEU 2. In AEU 7, the lowest and highest As reported were 0.08 µg L-1 (Cheruvathur, Kasaragode) and 4.67 µg L-1 (Ezhome, Kannur), respectively The pH of the soils of the Northern coastal plain (AEU 2) varied from 3.08 to 7.42, and EC from 0.05 dS m-1 to 4.46 dS m-1. The organic carbon varied from 0.19 per cent to 5.33 per cent. The pH of soil from Kaipad lands (AEU 7) varied from 4.2 to 7.23; EC from 0.05 dS m-1 to 12.12 dS m-1. The organic carbon varied between 0.31 per cent and 3.94 per cent. The available As in soils of AEU 2 varied from 0.65 µg kg1 (Chorodu, Kozhikode) to 832.87 µg kg-1(Vallikkunnu, Malappuram) and showed a significant negative correlation with available Iron (Fe) (r = -0.369*), Phosphorus (P) (r = - 0.351*), and a significant positive correlation with available Calcium (r = 0.384*), Magnesium (r = 0.432**). The available As in soils of Kaipad lands varied from 0.35 µg kg-1 at Pilicode to 1255.2 µg kg 1 at Pallikkara, Kasaragod. However, none of the samples reported As content more than the prescribed critical limit of 100µg L-1 set by the Food and Agricultural Organization for irrigation water and 5800 µg kg-1 set by the Geological Survey of India for agricultural soils. The total As in soils of AEU 2 varied from 1.5 mg kg-1 (Chemnad, Kasargode) to 37 mg kg-1(Vallikkunnu, Malappuram), and that of AEU 7 from 6.5 mg kg-1(Pilicode, Kasargode) to 36.5 mg kg-1(Pallikkara, Kasaragode) and was positively correlated (r = 0.639***) with available As. Results revealed that 58 % (N=38) of soil samples from AEU 2 and 25% (N=8) from AEU 7 recorded more than the critical limit of 20 mg kg-1 of total As recommended by The European Union and Agency for Toxic Substances and Disease Registry (ASTDR) for agricultural Soils. A batch incubation study was conducted to study the effects of lime (fine lime powder) and organic manure (cow dung) on available arsenic content for 30 days, and chemical analyses were done at 1,3,5,10,15 and 30th day of incubation. The composite soil samples from AEU 2 and 7 were spiked individually with As at 400 mg kg-1 of soil and were used for the study. The As spiked soils were incubated with lime at 600 kg ha-1 (T2) and 1200 kg ha-1 (T3), organic manure at 5t ha1 (T4), 10t ha-1 (T5) and a combination of lime at 600kg ha-1 and fresh cow dung at 5t ha-1 (T6) against As spiked soil as control (T1). The combined application of lime at 600 kg ha-1 and organic manure at 5t ha-1 (T6) significantly increased the soil pH of the AEU 2 from the 15th to 30th day of incubation, whereas in AEU 7, lime at 1200 kg ha-1 (T3) significantly (p=0.05) increased the pH up to 30th day of incubation. Irrespective of the AEUs, the highest reduction in available Fe was recorded in lime-amended soils at 600 kg ha-1 from the 10th to the 30th day of incubation and available As exhibited a significant negative correlation with available Fe in soils of Northern coastal plains under organic manure amendment. Irrespective of the AEUs, the organic manure at 10t ha-1 significantly increased the available P content up to 15th day of incubation. Irrespective of AEUs, the highest available As was recorded by control soil (T1) up to the 30th day of incubation. A significant reduction in available As was reported from T5 (organic manure at 10 t ha-1) up to the 10th day of incubation in AEU 2. However, irrespective of AEUs, the combined application lime and organic manure (T6) significantly reduced the available As up to 30th day of incubation. Hence, incubation study of arsenic dynamics under liming and organic manure regimes revealed that the application of soil amendments like lime and organic manure effectively reduced available As in soils of the Northern coastal plain and Kaipad lands. Also the sources and dynamics of geogenic and anthropogenic As and its contributing factors in agricultural systems need to be studied extensively.