Browsing by Author "Meera, A V"

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Nutrient economy through seed coating with vermicompost in cowpea
(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 1998) Meera, A V; Prabhakumari, P
An investigation was carried out at the Instructional Farm, attached to the College of Agriculture, Vellayani to evaluate "Nutrient economy through seed coating with vermicompost in cowpea". The experiment was laid out in Completely Randomised Design with nine treatments and three replications. The variety used was Kanakamoni. The treatments include coating of seeds with Rhizobium, vermicompost and a combination of both and also uncoated seeds supplied with either farmyard manure or vermicompost as organic source. Biometric observations like height of plant, number of leaves, seedling girth and number of fruiting branches were not significantly influenced by any of the treatments. However, root characters like root length, root spread and number of effective nodules were found to be significantly influenced by the different treatments. Coating of seeds with vermicompost significantly influenced the grain yield of cowpea and also the number of pods plant-l. Coating seeds with vermicompost combined with the application of full inorganic fertilizers and farmyard manure as organic source recorded the highest grain yield. From the analysis of grain samples, it is inferred that only K and Ca content of grain was significantly influenced by the different treatments. Phosphorus solubilisation capacity of soil was not significantly influenced by any of the treatments. N fixing capacity of soil was significantly influenced by the vermicompost coating of seeds during 30 DAS and 45 DAS. Soil analysis for available nutrients revealed that the different treatments had significant influence on the Ca, Mg, Zn, Cu and Mn content in soil. Use of vermicompost coated seeds produced the maximum uptake of N, P and K at maximum flowering stage and at harvest. Soil application of vermicompost recorded the highest uptake of Ca, Mg, Cu and Mn during maximum flowering stage. Plant analysis for nutrient content indicated that the content of all the nutrients except P was significantly influenced by the different treatments during maximum flowering stage. Yield was positively and significantly correlated with the height of plant, root characters and availability and uptake of nutrients. In the present study, a superiority is shown by vermicompost inoculated plants where farmyard manure was given as the organic source indicating that at times of scarcity of vermicompost, seed treatment could serve the purpose.
Performance potential of organic amendments derived from invasive aquatic weed, Limnocharis flava (L.) Buchenau
(Department of Soil Science and Agricultural Chemistry, College of Agriculture,Vellayani, 2025-01-27) Ambili, S.; Meera, A V
The study entitled “Performance potential of organic amendments derived from invasive aquatic weed, Limnocharis flava (L.) Buchenau” was conducted at College of Agriculture, Vellayani and Integrated Farming System Research Station, Karamana during the period 2022-24. The objectives of the study were production of different organic amendments from the aquatic weed, Limnocharis flava and assessment of their impact on soil health and productivity of okra. Different amendments viz., ordinary compost (OC), vermicompost (VC), microbial compost using solid inoculum (SMC), microbial compost using liquid inoculum (LMC) and biochar (BC) were produced and evaluated. The amendments produced were characterized for physical, electro chemical, chemical and biological properties. The mean residence time for BC production was 1-2 hr. at 300-400 °C and the recovery percentage was 26.16. Recovery % for OC, VC, SMC and LMC were 8.40, 15.10, 11.05 and 12.22, respectively, while composting period was 78, 62, 59 and 50 days. BC recorded the bulk density (0.33 Mg m-3), water holding capacity (261.33 %), pH (9.25), EC (6.42 dS m-1), CEC (13.75 cmol (+) kg-1), AEC (8.72 cmol (-) kg-1), total organic carbon (74.89 %) and C:N ratio (82.39). The highest N (2.14 %) content and lowest C:N ratio (32.32) were obtained for VC. P content (0.73 %) was highest for LMC. K, secondary nutrients (Ca, Mg, S) and micronutrients (Fe, Mn, Zn, Cu and B) were also highest for BC. Heavy metal content was below the detectable level in both source material and the amendments produced. A field experiment was conducted to study the effect of different organic amendments on soil health and crop productivity using okra (variety: Salkeerthi) as the test crop. The treatments included amendments produced @ 25 t ha-1 along with 100 and 75 % of recommended dose of fertilizers (RDF), FYM @ 25 t ha-1 along with 100 % RDF and absolute control. The different amendments had significantly influenced the biometric and yield parameters of okra. Plant height, chlorophyll content, yield and yield attributes and biomass yield were highest for VC along with 100% RDF. Significant improvement in soil physical, chemical and biological properties were observed on applying the organic amendments. The highest yield of 23.70 t ha-1 was obtained for T3 (VC @ 25 t ha-1 + 100% N: P2O5:K2O), which was 88 % higher over absolute control and 58 % higher over Package of Practices Recommendations. BC along with 100 % RDF recorded 91.05 and 57.05 % yield improvement over control and PoP. Total N, P, K, Ca, S, Mn, Zn, Cu, and B uptake by plants were also highest for VC along with 100% RDF (T3). The highest Fe uptake was observed in VC along with 75 % RDF (T4). Mg uptake was highest for LMC along with 100% RDF. The different amendments had resulted in decrease in bulk density and increase in water holding capacity, pH, EC, CEC and AEC of postharvest soil. T3 (VC + 100% N: P2O5:K2O) recorded the highest value for available N (393.05 kg ha-1) and dehydrogenase (199.74 μg TPF g-1 soil 24 h-1) activity. Available P2O5 (91.34 kg ha-1) and Fe (246 mg kg-1) were highest for LMC + 100% N: P2O5:K2O (T7). BC + 100% N: P2O5:K2O (T9) recorded the highest values for K (224.82 kg ha-1), Ca (391.67 mg kg-1), Mg (62.00 mg kg-1) and S (20.10 mg kg-1) while Mn (55.74 mg kg-1), Zn (190.50 mg kg-1), Cu (5.33 mg kg-1) and B (0.69 mg kg-1) were highest for BC along with 75% N: P2O5:K2O (T10). Yield parameters viz., total fruit yield, fruit yield per plant and fruit length were on par for the treatments applied with vermicompost along with 100 (T3) and 75 % RDF (T4). B: C ratio was also found to be 2.01 for both the treatments. Application of biochar produced from the weed resulted in very good improvement in the physical and electrochemical properties and secondary and micro nutrient contents of the soil. The nutrient composition of amendments varied with the method of conversion. Hence, it could be concluded that application of L. flava vermicompost @ 25 t ha-1 along with 75 % RDF could be recommended for cultivating okra and could be considered as the economically viable option for utilization of this aquatic weed. Incorporation of L. flava biochar helped in improving the soil physical and chemical attributes. L. flava using different composting strategies using vermicompost, biochar, etc. along with inorganic nutrients can be utilized as effective strategies for disposal of weed and to improve soil health and crop productivity.
Phytoremediation of inorganic contaminants in vellayani wetland ecosystem
(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2017) Meera, A V; Manorama Thampatti, K C
An investigation entitled ―Phytoremediation of inorganic contaminants in Vellayani wetland ecosystem‖ was carried out at the Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, during 2013-16. The objective of the study was to track the potential sources of contaminants threatening the Vellayani wetland ecosystem and suggest a viable phytoremediation technology. The experiment comprised of four parts. The first part involved a peripatetic survey in the catchment of Vellayani lake along the rivulets that contribute water to Palappoor, Pallichalthodu, Reservoir bund, Arattukadavu RB, Valiyavilagam, Mannamvarambu and Manamukku sites. Three rivulets per site were identified, and geocoded water and sediment samples were drawn from five sampling points under each rivulet during pre and post monsoon seasons of 2014-15. Among the physical properties of water colour, turbidity and suspended solids were above the maximum permissible limit (MPL). Chemical properties viz., pH, EC, NO3-N, NH4-N, P, Fe, Al, Pb, Cd and BOD of water showed significant difference among the sites during both the seasons but COD was significant only for post monsoon. P content and BOD exceeded the MPL and Al the desirable limit. Coliforms were detected at all sites during both seasons and were above the MPL. Texture of the sediment varied from sandy clay to sandy clay loam. EC, OC, NO3-N, NH4-N and P contents of sediment showed a decreasing trend during the post monsoon season. Arattukadavu RB was the most contaminated site followed by Palppoor and Manamukku the least contaminated site preceeded by Mannamvarambu and Valiyavilagam with respect to water and sediment quality. No pesticide residue was detected in water and sediment. The highest plant density was noticed for Cynadon dactylon L. In the second part, potential sources of contaminants were identified as automobile workshops/servicing centres, domestic wastes from hotels/houses and sewage. Out of the 29 species of dominant macrophytes, highest biomass was recorded by Limnocharis flava L. (Buch.). In shoot, the highest concentration for Fe was recorded by M. vaginalis, Panicum repens L. for Aland S. trilobata for Pb and Cd. In root, the highestconcentration for Fe, Al, Pb and Cd was showed by Eichhornea crassipes Mart., Monochoria vaginalis (Burm.f.), Colacasia esculenta L. and Sphagneticola trilobata L. respectively. Sediment from Arattukadavu recorded the highest contents for Fe, Al, Pb and Cd and count for bacteria, fungi and actinomycetes. It was observed from the study that concentration of Fe, Al, Pb and Cd decreased with the distance from the source of contamination. Higher quantities of Fe was extracted by E.crassipes and M.vaginalis; Al by M. vaginalis and L. flava and Pb and Cd by L.flava and E.crassipes from the wetland ecosystem. In the third part, four pot culture experiments were carried out with graded doses of Fe (1000, 2000 and 3000 mg kg-1), Al (750, 1000 and 1250 mg kg-1)and Pb and Cd (50, 75 and 100 mg kg-1) to determine the hyperaccumulation ability of selected macrophytes based on a screening trial. The macrophytes were grown in sediment and water collected from the Vellayani wetland ecosystem for a period of 45 days. From the study it was observed that E. crassipes was the best hyperaccumulator for Fe, M. vaginalis for Al and L. flava for both Pb and Cd and can be identified as the best phytoextractors for the same. Root was the major retention site for all the metals. Among the rhizosphere microbes, fungi maintained a positive relation with levels of of Fe, Al, Pb and Cd and a negative relation by bacteria and actinomycetes. In the fourth part, the macrophytes showing highest hyperaccumulation ability for each metal (based on part III) were raised in pots containing the respective metals (2000 mg Fe kg-1, 1000 mg Al kg-1 and 75 mg Pb /Cd kg-1) for 60 days. The plants were harvested and the biomass was put to different disposal methods viz., composting, vermicomposting, ashing and production of biochar and was used for the pot culture experiments with amaranthus. The treatment effects were significant for biomass production and metal extraction. Among the four disposal methods, vermicomposting had resulted the highest biomass production for all except Pb. Regarding the metal extraction by amaranthus, application of ash (T4) showed the highest removal and the least by the biochar (T5). The metal retention in soil was highest for biochar and least for ash. Loss of metals from the processed materials was also lowest for biochar. Thus the best disposal technique of phytoextractors /hyperaccumulators is conversion to biochar. The viable phytoremediation technology is to raise suitable phytoextractors / hyperaccumulators in the contaminated area and dispose them through biochar production.
Soil carbon dynamics in a rice based cropping system
(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2019) Chethankumar, P; Meera, A V
Utilization of biochar from different bioresources for soil health and crop production
(Vellayani Department of Soil Science and Agricultural Chemistry, College of Agriculture,Vellayani, 2024-01-20) Diya Rajendran; Meera, A V
The study entitled “Utilization of biochar from different bioresources for soil health and crop production” was carried out during 2021-2023 in the Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani and Integrated Farming System Research Station, Karamana. The objectives of the study were characterization of biochar produced by pyrolytic conversion of bioresources generated in farming systems and assessing their influence on soil health and crop production. The study comprised of four parts viz., production and characterization of biochar from different bioresources, bioassay study for selection of best four biochar, incubation experiment to study the nutrient release pattern and field evaluation of the effect of biochar on crop performance and soil health. Biochar was produced from seven different organic residues viz., teak leaf, coconut leaf, banana pseudostem, crop residue of vegetables, Eichhornia crassipes, Limnocharis flava and Colocasia esculenta, by the process of pyrolysis and the synthesized biochar were analysed for physical and chemical properties using standard procedures. Temperature of pyrolysis and residence time for various organic residues ranged between 250-5000C and 30-120 minutes, respectively. Highest recovery percentage of 46.53 % was recorded for coconut leaf biochar and lowest, 24.93 % for E. crassipes. Teak leaf biochar recorded the highest bulk density (0.48 Mg m-3) and EC (4.70 dS m-1), while banana pseudostem biochar had a higher water holding capacity (327.74 %). The produced biochar has an alkaline characteristic, with pH values ranging from 8.19 (C. esculenta biochar) to 10.40 (Banana pseudostem biochar). CEC (14.10 cmol kg-1), total carbon (67.52 %), N (1.34 %), K (2.24 %), S (0.33 %) and Zn (69.37 mg kg-1) content were highest for banana pseudostem biochar while P (0.77 %), Mn (173.76 mg kg-1), Cu (37.12 mg kg-1) and B (47.40 mg kg-1) were highest for L. flava biochar. Calcium (0.57 %) and magnesium (0.43 %) content were highest for crop residues of vegetable biochar while iron (2314.15 mg kg-1) content was highest in biochar produced from C. esculenta. C: N ratio was highest in C. esculenta biochar (128.35) and lowest in banana pseudostem biochar (50.38). 159 Bioassay study was carried out for 28 days using okra seedlings to select best four biochar for field study. The biochar produced from seven different bioresources were mixed with 2 kg soil @ 0.5 and 1 % w/w basis and FYM @ 1 % w/w basis and 10 okra seeds were placed in each pot. Coconut leaf, banana pseudostem and L. flava biochar recorded the highest germination percentage (96.67 %) and it was on par with biochar derived from crop residues. Banana pseudostem biochar recorded the highest values for shoot length (33.04 cm) and shoot biomass (2.23 g plant-1) and it was on par with L. flava biochar and FYM treated soil. Root length (23.97 cm), root biomass (0.60 g plant-1) and root volume (4.90 cm3) of the okra seedlings were highest in L. flava biochar treated soil and it was found to be on par with crop residue of vegetables biochar and FYM supplied treatments. Teak leaf biochar applied @ 1 % recorded the lowest values for germination percentage, shoot length, shoot biomass, root length, root biomass and root volume. Based on the results obtained from bioassay study, four biochar viz., coconut leaf, banana pseudostem, crop residue of vegetables and L. flava were selected for the incubation and field experiments. The nutrient release pattern from the selected four biochar was monitored after incorporation to soil based on a 90 day incubation study. Biochar and FYM were added @10 g kg-1 of soil. Periodic sampling and analysis of samples were done at 0, 30, 60 and 90 days of incubation. The incubation study revealed a slow and sustained release of nutrients from biochar. Biochar treated soils showed significantly higher value for pH and EC compared to FYM treated soil till the end of the incubation period. The pH was significantly higher for banana pseudostem biochar treated soil while EC was higher in soil applied with crop residue of vegetables biochar. During initial period of incubation, the mean values for available N, K, S and Zn content were highest for FYM treated soil but as incubation period progressed, banana pseudostem biochar treated soil recorded the highest values. The mean value for P, Fe, Cu and B were significantly higher for FYM treated soil during initial period and later stages, it was for L. flava biochar applied soil. Similarly, exchangeable Ca and Mg content were highest in FYM treated soil during initial period and as incubation period progressed, the crop residue of vegetables biochar treated soil recorded the highest values. A field experiment was conducted during 2023 to compare the effect of biochar from different bioresidues and FYM application on soil health and crop production using okra as the test crop. The treatments consisted application of selected four biochar viz., coconut leaf, banana pseudostem, crop residue of vegetables and L. flava biochar @ 25 t ha-1 along with 100 and 75 % of recommended dose of fertilizers (RDF) and FYM @ 25 t ha-1 along with 100 % RDF and soil with 100 % RDF only. The physical, chemical and biological properties of soil were markedly improved by the application of biochar. Reduction in bulk density, increase in water holding capacity, pH, EC, CEC, organic carbon and nutrient availability were observed with biochar application compared to FYM incorporation. Banana pseudostem biochar application recorded the highest values for organic carbon (1.92 %), available N (334.56 kg ha-1), K (258.45 kg ha-1), S (23.27 mg kg-1), Zn (3.73 mg kg-1) and dehydrogenase (192.78 µg of TPF g-1 soil 24 h-1) and microbial biomass carbon (81.97 mg kg-1) content of post harvest soil. Available P (91.78 kg ha-1), Fe (132.08 mg kg-1), Mn (34.89 mg kg-1) Cu (2.77 mg kg-1) and B (0.667 mg kg-1) content were higher in soil applied with L. flava biochar. Biochar application had significantly influenced the biometric and yield parameters of okra. Plant height, biomass yield and fruit yield were highest in treatments supplied with banana pseudostem biochar and it was on par with the treatments received L. flava biochar. Nutrient content of index leaf at harvest also indicated the beneficial effect of biochar in comparison to FYM and conventional fertilizers. Plant biometric attributes, fruit yield and soil health parameters for biochar application @ 25 t ha-1 and RDF at 100 and 75 % were on par. The highest B: C ratio (1.70) was recorded in treatment supplied with banana pseudostem biochar @25 t ha-1 along with 75 % RDF, which indicated that 25 % reduction in fertilizer application is possible through biochar application. There was 21 % increase in yield by banana pseudostem biochar application compared to FYM. It may be inferred that physico-chemical properties of biochar varies with the source material and their assessment for phytotoxicity is essential for ensuring the safety for agricultural use. Coconut leaf biochar, banana pseudostem biochar, crop residues of vegetable biochar and L. flava biochar had ideal physical and chemical 161 properties that qualify them to be used as good soil amendments which improve the soil physical, chemical and biological properties. FYM and biochar application had a positive effect on soil properties during incubation and field study. However biochar application exhibited sustainable effects than FYM. From the study, it can be concluded that banana pseudostem biochar @ 25 t ha-1 along with 75 % RDF is the economically viable and best treatment.