Browsing by Author "Aparna, B"

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Assessment of soil quality in the post flood scenario of AEU 4 in Alappuzha district of Kerala and generation of GIS maps
(Department of soil science and agricultural chemistry, College of Agriculture, Vellayani, 2020) Arya, V S; Aparna, B
The present study was carried out during 2018-20 in the Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani. The study was envisaged to assess the soil quality of post flood soils of AEU 4 in Alappuzha district and to work out soil quality index (SQI). A preliminary survey was conducted using a pre-designed questionnaire to assess the effect of flood and cropping history of the locality. Rice is the major crop cultivated in the study area and majority of the farmers follow conventional method of farming practices in the paddy fields. On the basis of survey conducted in the post flood areas, 75 geo referenced surface soil samples were collected from 17 flood affected panchayats of AEU 4 in Alappuzha district. The soil samples were analysed for physical (bulk density, particle density, porosity, moisture content, water holding capacity, aggregate stability), chemical (pH, EC, organic carbon, available N, P, K, Ca, Mg, S and B) and biological (acid phosphatase) attributes. From the study, it was observed that bulk density of 78.67 per cent of samples were lower than 1.20 Mg m-³ while that of particle density of 81.34 per cent of samples were less than 2.2 Mg m-³. The lowest value for particle density was observed in Kavalam (1.67 Mg m-³). Neelamperoor recorded the highest value for porosity (64.7 per cent), clay content (42.3 per cent) and water holding capacity (57.1 per cent) and the lowest value for sand per centage (22.7 per cent) and bulk density (0.66 Mg m-3). The predominant textural class observed in the soil samples of the study area belonged to sandy clay loam category. From the perusal of the data, it was observed that 78.67 per cent soils were extremely acidic and 98.67 per cent of samples had EC less than 1 dS m-1. 94.67 per cent of soils were high in organic carbon content and the highest value was recorded from Neelamperoor (5.39 per cent). With regard to major nutrients, available nitrogen content was medium (69.34 per cent), available phosphorus content was low (48 per cent) and Available potassium was high (76 per cent) for most of the samples. Highest and lowest values for available Ca and Mg were recorded from Kainakary and Pandanad respectively. In the case of boron, 93.33 per cent of samples were deficient in boron. Acid phosphatase activity was found to be the highest in Veliyanad and while the lowest value was noticed in Ambalappuzha South panchayat. Soil quality evaluation was done by scoring of indicators in minimum data set and integration of the indicator scores into SQI. Statistical tool, principal component analysis (PCA) was used for the selection of MDS and the indicators selected include porosity, WSA, sand content, pH, EC, organic carbon, available K, Ca, Mg and B and acid phosphatase. The highest SQI was reported in Veliyanad while the lowest value was recorded from Puliyur. Land Quality Index (LQI) and Nutrient index (NI) were computed for the study area and LQI was the highest for Purakkad (8.39) followed by Veliyanad (6.47). Kavalam reported highest value for nutrient index of nitrogen whereas Kainakary reported the highest nutrient index value for phosphorus. Correlation study of the analysed parameters was carried out and thematic soil maps were generated for the analysed parameters using ArcGIS software. Comparative evaluation of pre flood data from State Planning Board (2013) with that of the post flood data generated in the present study revealed that soil acidity has increased after flood. The flood has a positive impact on organic carbon content, available K, Ca and Mg by increasing the status while the status of available P and B got decreased.
Biodissolution of silicate minerals by silicon solubilizing bacteria (ssb) in wetland rice
(Department Of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2021-11-29) Akhila Ashokan; Aparna, B
ABSTRACT The present study entitled “Biodissolution of silicate minerals by silicon solubilizing bacteria (SSB) in wetland rice” was carried out to evaluate the effect of silicate solubilizers on the solubility and availability of native Si and its impact on crop growth and yield of test crop rice (var. Uma). The study was undertaken in three parts viz; a survey, an invitro study and a field experiment. Geo-referenced soil samples from the wetlands of southern laterites (AEU 8) were collected to identify the silicon deficient locations for further study. The lowest available Si (15.20 mg kg-1) was recorded from Integrated Farming System Research Station (IFSRS), Karamana and hence the wetland at IFSRS, Karamana was selected as the experimental site for further study. A laboratory incubation study was carried out for a period of three months using two sources of silica viz; calcium silicate (S1) and paddy husk ash (S2) at different doses: D1 (100 kg ha-1 of silica), D2 (75 kg ha-1 of silica) and D3 (50 kg ha-1 of silica). The soil was incubated and silicon solubilizing bacteria (SSB) was inoculated at two doses viz; 2 kg ha-1 (I1) and 5 kg ha-1 (I2). From the study it was observed that the availability of P, K and Si nutrients were significantly increased through the application of Si sources and SSB. However the availability of Fe, Mn and Al were reduced when the soil was incubated with SSB and Si sources. Application of 100 kg ha-1 of silica as calcium silicate along with 5 kg ha-1 of SSB (D1S1I2) significantly increased the availability of major nutrients and Si, and while the availability of heavy metals like Fe, Mn and Al were reduced. A field experiment was also carried out at Integrated Farming System Research Station, Karamana to evaluate the effect of silicate solubilizers on the solubility and availability of native Si and its impact on crop growth and yield in rice (var. Uma). The treatments imposed were the various combinations of Si sources (calcium silicate and paddy husk ash) and SSB at the dose of 5 kg ha-1. It was observed from the study, that the grain and straw yield were found to increase with the soil application of SSB at 5 kg ha-1 along with 75 kg ha-1 silica as calcium silicate (T4). In the case of yield attributes, soil application of SSB @ 5 kg ha-1 along with 50 kg ha-1 silica as paddy husk ash (T6) recorded the highest value for number of panicles/m2 and panicle length. Thousand grain weight was found to increase with the soil application of SSB @ 5 kg ha-1 along with 75 kg ha-1 silica as calcium silicate (T4). The application of SSB and Si sources significantly improved the available Si content in the soil. From the present study, it is evident that the application of SSB and Si sources also had a synergistic effect in improving the availability of N, P, K, Ca, Mg, S, Zn and B content in the soil. Soil application of SSB at 5 kg ha-1 along with 75 kg ha-1 silica as calcium silicate (T4) was also effective in reducing metal toxicities by decreasing available Fe, Mn and Al content in the soil. The grain and straw uptake of N was significantly higher in soil application of SSB at 5 kg ha-1 along with 75 kg ha-1 silica as paddy husk ash (T6) than the other treatments. However, soil application of SSB @ 5 kg ha-1 along with 75 kg ha-1 silica as calcium silicate (T5) was found to increase the uptake of P, K and Si in grain and straw With regard to soil enzymes viz; deaminase and dehydrogenase activity, soil application of SSB @ 5 kg ha-1 along with 75 kg ha-1 silica as paddy husk ash was found to be the superior (243.41 nmol mg−1 h−1 and 408.92 μg of TPF hydrolysed g-1 of soil 24 hrs-1 respectively). Root characters like, root volume and root weight were found to the highest with the soil application of silica at 100 kg ha-1 (T2) and soil application of SSB @ 5 kg ha-1 along with 75 kg ha-1 silica as paddy husk ash (T6) respectively. With respect to the economic analysis, soil application of SSB at 5 kg ha-1 along with 75 kg ha-1 silica as calcium silicate (T4) recorded the highest value for net income. However, soil application of SSB at 5 kg ha-1 alone (T7) was found to be the best with respect to B: C ratio (1.63). From the study it is concluded that the application of SSB and Si sources significantly enhanced the availability of nutrients as well as alleviate the metal toxicities of Fe, Mn and Al in lateritic wetland soils. The soil application of SSB at 5 kg ha-1 along with 75 kg ha-1 silica as calcium silicate significantly improved yield and yield attributes and there by the net income while the soil application of SSB at 5 kg ha-1 alone recorded the highest B: C ratio. With respect to soil attributes, the treatment with soil application of SSB at 5 kg ha-1 along with 75 kg ha-1 silica as calcium silicate (T4) was found to be the best.
Characterization, conversion and evaluation of selected lignocellulosic biomass
(Department of Soil science and Agricultural Chemistry, College of Agriculture, Vellayani, 2014) Anushma, S; Aparna, B
The study entitled “Characterization, conversion and evaluation of selected lignocellulosic biomass” was conducted during the period 2013-14 at the Department of Soil Science & Agricultural Chemistry, College of Agriculture, Vellayani. The main objectives of the study were the characterization of the lignocellulosic biomass from selected plant sources, assessment of various microbial and enzymatic sources for degrading the lignocellulosic biomass into compost and evaluation of the resultant compost for assessing its manurial value. The experiment was completed in three stages. Representative samples of water cabbage (L. flava), coir pith, water hyacinth (E. crassipes) , and farm wastes (dried leaves and pseudostem of banana) were collected and analysed for bio-chemical composition. Water cabbage recorded 2.74 per cent N, 0.30 per cent P, 0.33 per cent K, 16.98 C:N ratio, and no detectable levels of heavy metals except Ni (0.55 ppm) and inferred as the best substrate in terms of nutrient content followed by water hyacinth, farm wastes and coir pith respectively. The substrates were converted to composts using various inoculants viz. T. reesei, P. sajor-caju, Composting Inoculum and commercial enzyme cocktail (cellulase/pectinase and lactase) and physico- chemical and biological characteristics were analyzed. A mixture of water cabbage and Composting Inoculum) was concluded as the best in terms of nitrogen content , cellulase activity, maturity period, C:N ratio and no detectable levels of heavy metals except Ni (0.414 ppm) followed by the mixture of Water hyacinth and Composting Inoculum had comparable N, P , K, EC , C:N ratio, and heavy metal content below the detectable limit. Considering the effect of inoculants on different substrates, Composting Inoculum was concluded as the best in terms of moisture content, EC,N, P, K, dehydrogenase activity, cellulase activity, maturity period and C:N ratio. The resultant composts from the previous stage were evaluated for their performance as manure in a pot culture experiment with test crop amaranthus (variety - Arun). Application of 100 % N as compost water hyacinth and Composting Inoculum was noticed as the best treatment in terms of yield, plant height, number of branches, girth of stem, soil properties viz. water holding capacity, available N, available P, available K, available Mn, available Cu, bacteria population and plant content of micronutrients viz. Mn, Cu, and B. Major enzymes viz. dehydrogenase, urease and aryl sulphatase imposed significance on yield and yield attributes. Application of 100 % N as compost from water cabbage and Composting Inoculum was found to be good and on par with T13 in many of the characters. Application of various composts did not result any heavy metal accumulation in the soil Thus it was inferred from the study that water cabbage was the best substrate in terms of their chemical composition followed by water hyacinth. water cabbage + Composting Inoculum was recorded as the best compost followed by water hyacinth + Composting Inoculum. 100 % N as compost (water hyacinth + Composting Inoculum) was noticed as the best treatment in pot culture. With regards to inoculants used on different substrates,Composting Inoculum was found to be the most effective for composting the agrowastes.
Distribution, characterization and dynamics of soil enzymes in selected soils of kerala
(Department of Soil Science and Agricultural Chemistry,College of Agriculture, Vellayani, 2000) Aparna, B; Rajendran, P
Dynamics of iron and aluminium in rice based ecosystem of detrital laterites of AEU 11and mitigation strategies
(Department of soil science and agricultural chemistry, college of agriculture,Vellayani, 2023-11-11) Sreelakshmi, M M.; KAU; Aparna, B
A study entitled “Dynamics of iron and aluminium in rice based ecosystem of detrital laterites of AEU 11 and mitigation strategies” was carried out at the Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani during 2019-2023. The major objectives of the study were to assess Fe and Al dynamics in detrital laterites derived rice tracts of Northern Kerala (AEU 11), to suggest management strategies to mitigate acidity, and to maximize the yield of rice. The investigation was envisaged in six parts viz. survey and collection of geo referenced soil samples, characterization of geo referenced soil samples, generation of thematic maps using ARC GIS software, solution culture experiment, soil column studies for assessing the nutrient release pattern, pot culture experiment to screen the ameliorant for alleviating Fe & Al toxicity, field evaluation and validation. The salient research findings emanated are summarized below. In the first experiment, 10 geo referenced soil samples were collected from surface and subsurface depths of 0-15 cm (80 nos.) and 15-30cm (80 nos.) respectively from rice fields of AEU 11 (northern laterites). After surveying the study area, the soil samples were characterized for physical, chemical and biological parameters. Kalikkadavu series recorded the highest mean value for exchangeable acidity, potential acidity, pH dependent acidity, available Al content at 0-15cm and 15-30 cm. The highest available Fe content was observed in Kalikkadavu series at 0-15 cm and Naduvattom series at 15-30 cm. The order of contribution of Fe fractions to total Fe at 0-15 cm depth was observed as follows: Fe-re>Fe-or>Fe-ox>Fe-ex>Fe-c. At 15-30 cm, the order was as follows: Fe-re>Fe-ox>Fe-or >Fe-c>Fe-ex. Regarding Al fractions, the order of contribution of various Al fractions to total Al at both depths was observed as follows: Al-re> Al-ex>Al-c>Al-ox≥Al-or.The nutrient index of detrital laterite-derived rice soils of AEU 11 was observed to be medium to high for available N, available P, low to high for available K and medium to high for organic carbon content. Micronutrients like Fe, Mn, Zn and Cu were observed in the sufficiency range in all the soil series. From paired t-test analysis, significant variations of pHKCl, bulk density, organic carbon, labile organic carbon, carbon stock, available P, available Ca, available Fe, available Al, available B, pH-dependent acidity, and potential acidity were observed at two different depths of 0-15 cm and 15-30 cm. Principle component analysis (PCA) of surface soils showed that the first eight PCs eigenvalue ≥1 accounted for 73.914% of the total variance. In PC1, EC, organic carbon, labile carbon and available K had the highest factor loadings. Bulk density in PC2, mineralizeable carbon in PC3, exchangeable acidity in PC4, available Mn, Zn, and Al in PC5 available S in PC6, exchangeable H+ in PC7 and available Ca in PC8 reported highest factor loadings. PCA of soils at 15-30 cm showed that the first six PCs eigenvalue ≥1 accounted for 75.073 % of the total variance. In PC1, EC, organic carbon, carbon stock and available K had the highest factor loadings. Bulk density and mineralizeable carbon in PC2, water soluble carbon, exchangeable acidity and exchangeable H+ in PC3, exchangeable Al and exchangeable acidity in PC4, available P in PC5, and available Fe in PC5 exhibited highest factor loadings. The hierarchical cluster analysis of 80 locations was carried for two soil depths. At 0-15 cmand 15-30 cm, among the clusters, cluster II was the largest consisting of 57 soil samples including a majority of Naduvattom, Nanminda, Kalikkadavu, Kunnathura, Kunnamnagalam, and Payalam series. Analyzing the intra-cluster distance, it was found to be highest in Cluster V whereas, the inter-cluster distance was found to be highest between clusters III and IV. Interpretation of various statistical analysis revealed that Kalikkadavu series recorded the highest mean values for available Fe (979.61 ± 969.79 mg kg-1), Al (192.5 ± 65.25 mg kg-1), exchangeable acidity (1.66 ± 0.23cmol kg-1soil), potential acidity (45.8 ± 2.57 cmol kg-1) and pH dependent acidity. Hence this series was selected for conducting further experiments. A solution culture experiment was carried out using Hoagland nutrient solution to study the response of rice seedling variety Uma to 5 different levels of Fe and Al (control, 50 ppm, 450 ppm, 850 ppm, 1250 ppm).The relative decrease in root and root length with increase in Fe and Al concentration was observed. The control showed maximum root length of 8 cm and the minimum root length of 3 cm was observed in 1250 ppm Al. A maximum root length of 9.25 cm was observed in control and lowest value of 4.5 cm was observed in the treatment 1250 ppm Fe dose. Though the effect of Al doses on shoot length was non-significant, a decline in shoot growth was observed with increase in Al concentration. To conclude a significant reduction in root length and shoot length of rice seedlings was observed with increasing doses of Fe and Al. The representative Fe and Al rich soil samples from Kalikkadavu series were collected for setting up the soil column experiment. The treatments include KAU PoP, NPK as per PoP+ double dose of potassium (K), Phosphogypsm @ LR +NPK as per PoP, Phosphogypsm @ ½ LR + Lime @ ½ LR +NPK as per PoP, Calcium silicate as per LR+ NPK as per PoP, Rice husk ash + NPK as per PoP, Rice husk Biochar + NPK as per PoP, Vermicompost + NPK as per PoP and Absolute control. From the soil analysis, the lowest values for exchangeable acidity were noticed in rice husk ash (RHA) in the 21st week of sampling. The highest mean value for total Al was observed in control during the 1st, 7th, and 14th weeks of sampling while calcium silicate recorded the highest in the 21st weeks after sampling. Rice husk biochar (RHB) and RHA reduced the total Al content during the later stages of sampling. The lowest values for available Fe were noticed in RHA during the 1st and 7th week of sampling and RHB during the 14th and 21st weeks of sampling. A significant effect of RHB on lowering the available Al content was more pronounced during 1st, 14th, and 21st week while the lowest available Fe during the 7th week was exhibited by the treatment RHA. Regarding water analysis, the absolute control exhibited the highest value for exchangeable acidity at all the sampling periods while the lowest values were noticed by RHB treatment. A decrease in total Fe of water has been observed in all the treatments but the significant variation was observed only during 7th week. The significant effect of RHB in reducing total Al was noticed during 21stweek of sampling (0.267 mg kg-1).From the above results, a profound effect of rice husk ash, rice husk biochar, vermicompost and double dose of potassium on exchangeable acidity, Fe content and Al content was been noticed and thus these treatments were selected for conducting pot culture experiment. A pot culture experiment was conducted to evaluate the effectiveness of treatments to alleviate Fe and Al toxicity using rice as the test crop. From the experiment, the effect of RHB was found superior in reducing the Fe availability at growth stages. At active tillering stage, RHA recorded the lowest exchangeable acidity and at the harvesting stage, the effect of RHB was prominent. The highest dry matter yield of 126.83 g plant-1, grain yield of 48 g plant -1 and straw yield of 86.67 g plant-1, harvest index of 0.356 was noticed by RHB. From the interpretation of the results of pot culture experiment and by considering the potential ability of rice husk ash and rice husk biochar to reduce exchangeable acidity, available Fe and available Al content in soil under study, the aforesaid treatments were considered for field evaluation and validation. From the field experiment, the lowest value for available Fe was noticed in RHB (144.55 mg kg-1) at harvest stage. A highly significant and positive correlation was observed between available Fe and exchangeable Fe, oxide bound Fe, residual Fe and with total Fe content. With respect to available Al, lowest mean value was observed in RHB at panicle initiation and harvest stage. At harvest, the effect of RHA as on reducing exchangeable acidity was more pronounced. Available Al maintained highly significant and positive correlation with exchangeable Al, oxide bound Al, residual Al, and total Al content. The total Fe content of shoot, root and grain at active tillering and harvest were significantly low in plants treated with RHB. The total Al content of shoot at AT was significantly lower in plants treated with RHB while in roots; KAU PoP recorded the lowest value. At harvest, RHB outperformed by exhibiting the lowest value for Al content in shoot and root. In shoots, the highest Fe uptake was noticed by farmer’s practice. A significantly lower mean value was noticed by RHB. Regarding the Fe uptake by grain, RHB recorded the highest mean value. In shoot and root, a significantly lower Al uptake was noticed by farmer’s practice. The highest mean value for Al uptake in shoot and root was noticed in absolute control. Regarding plant observations, a significantly higher value of plant height, productive tillers was noticed by RHB at all stages. RHA recorded a significantly higher value for filled grains per panicle which was found statistically on par with RHB. A significantly higher value of grain yield, straw yield, and dry matter yield was observed in RHB which was found statistically on par with RHA. The significant mean value for Fe-deposited roots was found low in RHB. The highest lignin content, chlorophyll content, total sugars, and root spread were noticed in RHB. Also, RHB recorded a significant lower value for proline content. From the above results of the field experiment, the effect of application of rice husk biochar at 5 tha-1 on alleviating Fe and Al toxicity was more pronounced. Though the effect of RHB on soil nutrient status, crop nutrient content, nutrient uptake, plant growth characters and crop yield was found on par with the application of rice husk ash 2 tha-1, superior effect of rice husk biochar was more pronounced. From the above experiments, it can be concluded that the most common yield-reducing factors of rice production in northern laterites are high soil acidity preceded by Fe and Al toxicity. From the investigation, basal application of rice husk biochar at 5 tha-1 along with urea, rajphos, and muriate of potash can be recommended to alleviate Fe and Al toxicity, augment soil fertility, and enhance rice productivity in detrital-derived rice fields of northern Kerala
Effect of integrated plant nutrient system (IPNS) on the soil biological regimes in red loam soil
(Department of soil science and agricultural chemistry, College of agriculture, Vellayani, 2013) Neethu R Sathyan; Aparna, B
Effect of phosphorus solubilisers on the availability of native P in phosphorus rich soil
(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2018) Sreelakshmi, M M; Aparna, B
Effect of zinc fertilization on major plant and soil enzymes in southern laterites
(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2019) Aswathy, U A; Aparna, B
Enzyme characterization of the acid sulphate soils of Kuttanad
(Department of Soil Science and Agricultural Chemistry, college of Agriculture, Vellayani, 2016) Arya Nath, V; Aparna, B
Regarding the enzyme status of the acid sulphate soils, the activity of urease was the highest in Thakazhi (L4-75.78 ppm of urea hydrolyzed g-1 soil h-1) in the surface layer. Acid and alkaline phosphatase activities were found to be the highest in Purakkad (L3-57.58 μg pnp released g-1 soil h-1) and Thakazhi series (L4-46.41 μg pnp released g-1 soil h-1) respectively in the surface layers. The highest activity of dehydrogenase was noticed in Thuravur series (L6-115.74 μg of TPF released g-1 soil 24 h-1) in the surface and Kallara series in the subsurface layers (L2-55.39 μg of TPF released g-1 soil 24 h-1). Karappadam and Kayal recorded the values of 145.73 and 114.80 μg of TPF released g-1 soil 24 h-1 for dehydrogenase activity respectively at surface layers. With regard to the microbial population, Thottappalli (L5) recorded the highest total bacterial count and fungal population in both surface and subsurface layers. Thiobacillus spp. recorded the highest population of 9.08 log cfu g-1 of soil at Kallara series (L2) while P solubilizers recorded the highest count at Ambalapuzha series (L1). Thuravur series recorded the highest actinomycetes population in subsurface soils. Micahelis – Menten constant, Km and the maximum velocity Vmax for different enzymes were determined and it was observed that for dehydrogenase Vmax value was found to be the highest in 6th week and for phosphatase only after 12th week of incubation. Thematic maps were prepared based on themes like microflora and enzyme status using GIS (ARC VIEW). Hence the study conclude that, with respect to biological fertility status of the study area, Purakkad recorded the highest enzyme activity number (23.69) at 0-15 cm, while Kallara series recorded the highest enzyme activity number in the subsurface layer and are observed to be biologically sustainable.
Latex sludge waste biocompost for management of soil fertility and productivity
(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2023) Sreeshna, T; Aparna, B
The study entitled “Latex sludge waste biocompost for the management of soil fertility and productivity” was carried out during 2021-23 at the Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani. The objective of the study was production and characterization of latex sludge waste compost; evaluation on soil physical, chemical and biological properties and crop productivity using bush cowpea (Vigna unguiculata L.) as test crop. The study comprised of three parts viz., production and characterization of latex sludge waste compost, soil incubation study for evaluating the nutrient release pattern and field experiment for evaluating the performance of latex sludge waste compost. The latex sludge waste for conducting the experiment was procured from HLL, Trivandrum. The latex sludge compost was prepared by aerobic heap method, wherein it was mixed with bulking agents such as sawdust, cattle manure and zeolite in different combinations as per ten treatments. To this, 5 per cent of composting inoculum was added uniformly to all treatments. The design followed was completely randomized design (CRD) with 10 treatments replicated thrice. The treatment combinations were T1- Latex sludge waste + Sawdust (1:1), T2-Latex sludge waste + Sawdust + Cattle manure (1:1:1), T3-Latex sludge waste + Zeolite (1:1), T4- Latex sludge waste + Zeolite + Cattle manure (1:1:1), T5-Latex sludge waste + Sawdust (2:1), T6-Latex sludge waste + Sawdust + Cattle manure (2:1:1), T7- Latex sludge waste + Zeolite (2:1), T8- Latex sludge waste + Zeolite + Cattle manure (2:1:1), T9- Latex sludge waste + Zeolite + Sawdust + Cattle manure (2:1:1:1) and T10- Latex sludge waste alone. The physico-chemical and biological properties of the produced latex sludge composts were analysed. Based on the analysed parameters viz., maturity of composts, clean index, fertilizing index, available major and minor nutrients, enzyme status and C:N ratio, four best treatments were identified. These treatments were subjected to an incubation study and a field experiment. The selected treatments were T2, T4, T6 and T9. Among these T9 (Latex sludge compost prepared from the mixture of latex sludge waste, zeolite, sawdust and cattle manure in 2:1:1:1 ratio) showed highest values of nitrogen (1.66%), phosphorus (0.96%), potassium (0.42%), calcium (3.91%), sulphur (0.61%), iron (1876 mg kg-1), manganese (189 mg kg-1), zinc (290 mg kg-1), copper (35.36 mg kg-1), dehydrogenase (554.86 µg TPF hydrolysed g -1 compost 24 h -1) and the lowest value for C:N ratio (12.39). The nutrient content of T6 (Compost prepared from latex sludge waste, sawdust and cattle manure in 2:1:1 ratio) is comparable with T9. In part 2 of the study, a soil incubation experiment was carried out to investigate the nutrient release pattern of selected composts. One kg of 2 mm sieved soil was taken from the site of field experiment and incubated at field capacity for 3 months. The best treatments selected after characterization were imposed at the surface of the soil @ 10 g kg-1 and thoroughly mixed. Soil samples were drawn at initial, 1st, 4th, 8th and 12th weeks of incubation and analysed for evaluating the nutrient release pattern. The treatments include four composts selected from part 1 and absolute control. From the incubation study, it was observed that pH and EC was increased during incubation over a period of three month. Phosphorus, potassium, calcium, sulphur, copper, organic carbon and dehydrogenase activity were found to be maximum at 4th week of incubation. Zinc, iron and magnesium content were observed to be maximum at 12th week of incubation while manganese availability was maximum during 8th week of incubation. Latex sludge waste, zeolite, sawdust and cattle manure in 2:1:1:1 ratio and latex sludge waste, sawdust and cattle manure in 2:1:1 ratio recorded the highest values for the available nutrient status during incubation period. A field experiment was carried out using bush cowpea var. Bhagyalakshmi as test crop from March to May 2023, in RBD with 7 treatments replicated thrice. In the field experiment 7 treatments were imposed viz., T1- Latex sludge waste + Sawdust + Cattle manure (1:1:1), T2- Latex sludge waste + Zeolite + Cattle manure (1:1:1), T3- Latex sludge waste + Sawdust + Cattle manure (2:1:1), T4- Latex sludge waste + Zeolite + Sawdust + Cattle manure (2:1:1:1) and T5- FYM as per KAU POP, T6- KAU organic POP and T7- Absolute control. Analysis of the postharvest soil for chemical properties revealed that the highest values for organic carbon (1.17%), available nitrogen (322.31 kg ha-1), calcium (314.39 mg kg-1), sulphur (22.72 mg kg-1), iron (39.97 mg kg-1), copper (1.82 mg kg-1), zinc (5.26 mg kg-1) and dehydrogenase (195.23 µg of TPF hydrolysed g -1 of soil 24 h -1) were recorded for T4. The highest value for phosphorus (96.56 kg ha-1), potassium (268.25 kg ha-1), magnesium (57.78 mg kg-1) and manganese (25.54 mg kg-1) were observed for T2. Analysis of the rhizospheric soil showed the highest values of soil respiration (30.14 mg CO2 100g -1 soil) and microbial biomass carbon (78.30 mg kg -1 soil) for T3. T4 recorded the highest value for microbial respiratory quotient (40.15) which was on par with T3 (38.06). Bacterial population in the rhizosphere soil was found highest for T3 (7.79 log cfu g-1 soil), fungi in T4 (4.81 log cfu g-1 soil) followed by T3 (4.79 log cfu g-1 soil) and actinomycetes in T2 (4.69 log cfu g-1 soil). Application of latex sludge waste compost had significantly influenced the biometric and yield parameters of bush cowpea. The root weight (13.5 g) and root volume (18.67 cm3) were found to be highest in T3 which was on par with T4. The highest number of effective nodules were noticed in treatment T4 (29.13) which was on par with T3 and T6. T4 recorded the highest yield (7526 kg ha-1) followed by T3 and drymatter production (4641 kg ha-1) was found highest in T4. Highest B:C ratio was recorded in T3 (2.15). It may be inferred that the compost produced from latex sludge waste, zeolite, sawdust and cattle manure in 2:1:1:1 ratio had the highest values of N, P, K, micronutrients and enzyme activity. The nutrient content of latex sludge waste with sawdust and cattle manure in 2:1:1 ratio is comparable with latex sludge waste with zeolite, sawdust and cattle manure in 2:1:1:1 ratio. Latex sludge waste compost application had a positive effect on soil properties during incubation and field study. From the study, it can be concluded that latex sludge waste, sawdust and cattle manure in 2:1:1 ratio is economically viable and best treatment.
Mineralization of soil nitrogen, carbon and kinetics of enzymes under coconut based cropping system
(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2017) Usharani, K V; Aparna, B
Production and characterization of enriched NADEP composts and evaluation of manurial value
(Department of Soil Science and Agricultural Chemistry, College of Agriculture , Vellayani, 2024-12-02) Aliya Shirin, K S.; Aparna, B
The study entitled " Production and characterization of enriched NADEP composts and evaluation of manurial value" was carried out during 2023-24 in the Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani. The objective of the study was the production and characterization of enriched NADEP composts using different organic sources and the evaluation of manurial value using the tomato variety Vellayani Vijai as test crop. The study comprised of two parts viz: the production and characterization of enriched NADEP composts from different organic sources and a field experiment for evaluating the performance of the enriched NADEP compost. NADEP compost was prepared in NADEP tanks using two commonly available aquatic weeds, yellow velvet leaf (Limnocharis flava) (S1) and water hyacinth (Eichhornia crassipes) (S2). Banana pseudostem was added to the aforesaid aquatic weeds in a 1:1 ratio. The matured composts were then enriched with minerals like calcium apatite (M1), epsom salt (M2) and calcium apatite + epsom salt (M3) at rate of 2 per cent in different combinations. The design followed was a Completely Randomized Design with 12 treatments and 3 replications. The treatment combinations were T1- NADEP compost prepared from 1:1 mixture of L. flava and banana pseudostem enriched with calcium apatite, T2- NADEP compost prepared from 1:1 mixture of L. flava and banana pseudostem enriched with epsom salt, T3- NADEP compost prepared from 1:1 mixture of L. flava and banana pseudostem enriched with calcium apatite and epsom salt, T4- NADEP compost prepared from 1:1 mixture of E. crassipes and banana pseudostem enriched with calcium apatite, T5- NADEP compost prepared from 1:1 mixture of E. crassipes and banana pseudostem enriched with epsom salt, T6- NADEP compost prepared from 1:1 mixture of E. crassipes and banana pseudostem enriched with calcium apatite and epsom salt, T7 - NADEP compost prepared from 1:1 mixture of L. flava and E. crassipes enriched with calcium apatite, T8- NADEP compost prepared from 1:1 mixture of L. flava and E. crassipes enriched with epsom salt, T9- NADEP compost prepared from 1:1 mixture of L. flava and E. crassipes enriched with calcium apatite and epsom salt, T10- NADEP compost prepared from 1:1:1 mixture of L. flava, E. crassipes and banana pseudostem enriched with calcium apatite, T11- NADEP compost prepared from 1:1:1 mixture of L. flava, E. crassipes and banana pseudostem enriched epsom salt and 166 T12- NADEP compost prepared from 1:1:1 mixture of L. flava, E. crassipes and banana pseudostem enriched with calcium apatite and epsom salt. To all the treatments (T1 – T12) zeolite was added at a rate of 0.5 per cent. The physico-chemical and biological properties of the produced composts were analysed. Based on the analyzed parameters like major and minor nutrients, enzyme activity, C:N ratio, fertilizing index and clean index the best six composts selected for field experiment were T3, T6, T7, T9, T10 and T12. Among these, T9 (NADEP compost prepared from 1: 1 mixture of L. flava and E. crassipes enriched with calcium apatite and epsom salt) was selected as the best compost with the highest values of most of the macro and micronutrients, N (3.03 %), P (0.62 %), K (1.80 %), Ca (0.32 %), Mg (0.26 %), S (30.00 mg kg-1), B (44.97 mg kg-1), Fe (1.40 %), Mn (179.00 mg kg-1), Zn (56.19 mg kg-1) Cu (26.00 mg kg-1) and enzyme activity (612.42 g TPF hydrolysed µg-1 compost 24 h-1). A relative lower C:N ratio was also observed for T9 (34.77%). In part II of the study, a field experiment was conducted from December 2023 to March 2024 with the tomato variety Vellayani Vijai as the test crop. In the field, 10 treatments were applied as follows: T1 to T6 - 6 selected enriched NADEP composts, T7- Bokashi compost prepared from L. flava enriched with calcium apatite, epsom salt and sylvinite, T8- KAU POP recommendation, T9- KAU POP (organic) recommendation and T10- Absolute control. Analysis of the postharvest soil for chemical properties revealed that the highest value of organic carbon (1.13%), nitrogen (311.09 kg ha-1) and phosphorous (80.54 kg ha-1) was recorded for T7 which was on par with T4, while the highest value of available potassium was recorded for T7 (260.55 kg ha-1). T7 recorded the highest values of iron (46.50 mg kg-1), manganese (22.41 mg kg-1), zinc (4.25 mg kg-1) and copper (1.66 mg kg-1), on par with T4, which exhibited iron (45.60 mg kg-1), manganese (21.37 mg kg-1), zinc (4.12 mg kg-1) and copper (1.57 mg kg-1). The highest value of dehydrogenase activity was recorded by T7 (292.31 µg of TPF hydrolysed g-1 of soil 24 h-1) which was on par with T5 (288.91 µg of TPF hydrolysed g-1 of soil 24 h-1) and T4 (278.22 µg of TPF hydrolysed g-1 of soil 24 h-1). The boron content was found to be highest for T7 (0.69 mg kg-1). 167 Analysis of the rhizosphere soil showed that the highest value of microbial biomass carbon (84.74 mg kg⁻¹ soil) was recorded by T4, followed by T1 (83.11 mg kg-1 soil), T6 (83.11 mg kg-1 soil) and T7 (81.48 mg kg-1 soil). The soil respiration (4.02 mg CO2 g-1) and microbial respiratory quotient (49.67) were highest for T7 which was on par with T4 with soil respiration (3.98 mg CO2 g-1) and microbial respiratory quotient (46.98). Treatment T7 recorded the highest values of bacteria (7.69 log cfu g-1 soil), fungi (5.32 log cfu g-1 soil) and actinomycetes (5.15 log cfu g-1 soil) which was on par with T4. Treatment T7 recorded the highest number of fruits per plant (62.00) which was on par with T4 (60.33). Fruit girth (14.50 cm) and fruit length (4.98 cm) were highest for T4, which was on par with T1 and T7. T7 recorded the highest value for yield per plant (1.67 kg), and total yield (43.97 t ha-1), which was on par with T4 and T3. The highest B:C ratio was reported by T4. From the study, T4 (NADEP compost prepared from 1:1 mixture of L. flava and E. crassipes enriched with calcium apatite and epsom salt) were concluded as the best compost. T4 (NADEP compost prepared from 1:1 mixture of L. flava and E. crassipes enriched with calcium apatite and epsom salt) and T7 (Bokashi compost prepared from L. flava enriched with calcium apatite, epsom salt and sylvinite) recorded the highest values for majority of the available macro and micronutrients, organic carbon and enzyme activity. Considering both soil parameters, yield parameters and B:C ratio, T4 (NADEP compost prepared from 1:1 mixture of L. flava and E. crassipes enriched with calcium apatite and epsom salt) was identified as the best treatment.
Studies on the chemo dynamics of phosphorus in the laterite soils of Kerala and utilization of fixed phosphorus for crop production
(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2024-02-05) Kota Adilakshmi; Aparna, B
A study entitled “Studies on the chemo dynamics of phosphorus in the laterite soils of Kerala and utilization of fixed phosphorus for crop production” was carried out at the Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, during 2018-2021, with the objectives to characterize in detail the dynamics of inorganic phosphorus and phosphorus fractions in the laterite soils of Kerala, identify the dominant phytoaccumulators of phosphorus, screening of suitable extractants for available P, and evaluate various organic and inorganic solubilizers/mobilizers on the solubility and availability of fixed phosphorus. The study was carried out in four parts. The first part consisted of the collection and characterization of georeferenced soil samples and the identification of dominant phytoaccumulators of phosphorus (P). For that, by following a preliminary survey, a total of 100 georeferenced representative soil samples (0-15 cm depth), 25 from each of the four agro-ecological units (AEUs), viz., southern laterites (AEU 8) of Thiruvananthapuram district, south central laterites (AEU 9) of Kollam district, north central laterites (AEU 10) of Thrissur district, and northern laterites (AEU 11) of Kozhikode district of Kerala were collected for assessing its fertility status. From scrutiny of the data, it was observed that among the four AEUs, AEU 8 reported the highest values for electrical conductivity (EC), organic carbon (OC), available P, sulphur (S), iron (Fe), manganese (Mn), exchangeable hydrogen (H+), anion exchange capacity (AEC), microbial biomass carbon (MBC), microbial biomass phosphorus (MBP), and population of P solubilizers, AEU 9 for available boron (B), exchangeable aluminium (Al3+), hydrogen (H+), acidity, and MB C/P ratio, and AEU 11 for pH, available nitrogen (N), potassium (K), calcium (Ca), magnesium (Mg), zinc (Zn), and copper (Cu). According to the results of frequency distribution, it was observed that, among the four AEUs (8, 9, 10, and 11), sandy clay loam was the prevalent soil textural class. Data on the mean values of pH revealed that the pH ranged between 5.42 and 6.21 among the four AEUs, and the majority of the collected soils were found to be strongly acidic (37%) and moderately acidic (40%) in nature. The EC values of the four AEUs were found to be within the critical limit. The mean values of OC varied from 0.63 From the present study, it can be concluded that the soils of southern laterites (AEU 8) exhibited the highest values for available P. Amaranthus viridis from AEUs 8, 9, and 10, and Synedrella nodiflora from AEU 11, were identified as dominant phytoaccumulators of P. Among the various fractions of P, with respect to the Po fractions such as the labile Po fraction, HCl extractable Po fraction, fulvic acid Po fraction, moderately labile Po fraction, humic acid Po fraction, residual Po fraction, and non-labile Po fraction, the soils collected from AEU 8 showed the highest values compared to other soils. It was also observed that the soils treated with vermicompost @ 15 t ha-1 showed the highest values for all the Po fractions when compared to soils without any manure, including total Po. Similarly, for Pi fractions, the soils collected from AEU 8 treated with vermicompost @ 15 t ha-1 showed the highest values for saloid-Pi, Al-Pi, and Fe-Pi, while the soils collected from AEU 8 without manure showed the highest values for residual/occluded Pi. Furthermore, soils treated with vermicompost @ 15 t ha-1 displayed the highest values for Ca-Pi in AEU 10 and reductant-soluble Pi in AEU 11. Notably, the soils of AEU 8 exhibited the highest capacity for P fixation among all studied soils. From the study, it was also observed that ion exchange resins were found to be the best extractants for available P determination, and biochar was the best amendment for alleviating P fixation, thus augmenting soil fertility