Loading...
Theses
Browse
18 results
Search Results
ThesisItem Open Access Sulphur and boron nutrition and their foliar diagnosis in sesame(Department of Soil Science and Agricultural Chemistry,College of Agriculture, Vellayani, 2010) Jeena, Mathew; KAU; Sumam, GeorgeA laboratory cum field experiment was conducted to study the effect of S and B on the growth, yield and quality of sesame var. Thilarani and to standardize the foliar diagnosis of these elements in Onattukara sandy loam soil. The study included an incubation study and two field experiments. The treatments comprising the different levels of S and B laid out in 42factorial RBD. The treatments were T1(S0B0), T2(S0B1), T3(S0B2), T4(S0B3), T5(S1B0), T6(S1B1), T7(S1B2), T8(S1B3), T9(S2B0), T10(S2B1), T11(S2B2), T12(S2B3), T13(S3B0), T14(S3B1), T15(S3B2), T16(S3B3). The different levels of S were S0 (0 kg ha-1), S1 (7.5 kg ha-1), S2, (15 kg ha-1) and S3 (30 kg ha-1) and B0 (0 kg ha-1), B1(2.5 kg ha- 1), B2 (5 kg ha-1) and B3 (7.5 kg ha-1). The incubation study was conducted at College of Agriculture, Vellayani to understand the dissolution and release pattern of S and B from their sources gypsum and borax respectively in Onattukara sandy soil. The results revealed that the release of S and B was maximum at the 30th DOI. Increasing levels of S and B has a positive influence on the S content of the soil. T16 (S3B3) recorded the highest value at all the sampling stages for S whereas in the case of B, the treatment combinations which received B at the highest levels in combination with S3 or S2 showed the highest value. The field experiments were laid out at ORARS, Kayamkulam in 42 factorial RBD having two replications using Thilarani as the test crop. It was observed that application of S and B favourably influenced the yield and yield attributes of sesame. T16 was found to be the treatment which gave the highest grain yield and oil yield in both the years and was found to be on par with T14 (S3B1). S3 was the superior S level. As for the different levels of B, B1 can be inferred as the best level. The content of saturated fatty acids such as palmatic and stearic acid showed a decreasing trend with increasing levels of S and B whereas the content of the unsaturated fatty acids showed an increasing trend. The quality attributes of oil such as acid value, iodine value and saponification value was also studied and it was found that there is a decreasing trend with regard to acid and saponification value and an increasing trend for iodine number. The grain protein content also showed an increasing trend with the increase in rate of application of S and B. Regarding the content and uptake of N, P, K, S, B, Fe, Mn, Cu and Zn, a favourable influence for the different levels of S and B was recorded. Results regarding the S and B use efficiency and their apparent recovery showed that with increase in levels of S, an increasing trend was observed for S. In the case of B, increase was noticed up to B1 (2.5 kg ha-1) and there after showed a decreasing trend. This positive influence was also reflected on the available nutrient status of the soil such as organic carbon content, available N, P, K, S, B and DTPA extractable micronutrients. Correlation studies conducted to standardize the part and stage of sampling for the foliar diagnosis of sesame showed petiole at 30 DAS and 20 DAS in the case of S and B respectively. The same stages were found for the soil sampling also for both the nutrients. The critical nutrient level in the part standardised for these two nutrients were standardized using the graphical method proposed by Cate and Nelson (1965). In the case of S, it had been standardized as 0.088 per cent and for B, it had been found to be 28 mg kg-1. The critical nutrient level in soil was also estimated using the scatter diagram technique and was found to be 23 kg ha-1 at 30 DAS for S and 1.4 ppm at 20 DAS for B. Hence the application of S @ 30 kg ha-1 and B @ 2.5 kg ha-1 could faourably enhance growth of sesame with regard to the growth characters, yield and yield attributes and the quality aspects. Moreover, analysis of the plant and soil samples at the critical stages fixed for the respective nutrients will provide the necessary data for the sustainable management of the crop in Onattukara sandy loam soil.ThesisItem Open Access Silicon availability of tropical soils with respect to rice nutrition(Department of Soil Science and Agricultrural Chemistry, College of Horticulture,Vellanikkara, 2016) Arya Lekshmi, v; KAU; Jayasree Sankar, sSilicon (Si) is the second most abundant element in soil. The amount of silicon in soil depends on parent material, soil type, pedogenic process and landscape. In soil solution, Si is present as monosilicic acid which is the only form that the plant can absorb from soil. The productivity of rice is comparatively low in soils of Kerala. As a ̳Si – accumulator‘, rice can benefit from Si nutrition. The application of Si can enhance growth and yield of rice. With this background, studies were conducted to categorize major rice growing soils of Kerala according to plant available silicon and to evaluate the efficacy of different sources of silicon including rice straw in wetland rice. The release of silicon from different soils added with various silicon sources under different water regimes was also monitored. Soil samples were collected from five different locations representing major rice growing regions of Kerala viz., Kuttanad, Kole land, Pokkali, sandy and lateritic to categorize them according to plant available silicon. The available Si ranged from 7.70 mg kg -1 (sandy soil) to 34.91 mg kg -1 (Kole land soil) in the order Kole land > Pokkali > lateritic > Kuttanad > sandy soil. All the soils under study were categorized as low in available Si. The available Si had positive correlation with organic carbon, available N, Ca, Mg, Fe, Mn, Zn, exchangeable K, Ca, Mg and CEC and negative correlation with available boron, AEC and silica-sesquioxide ratio. These soils were subjected to fractionation of silicon. The major fractions of Si were mobile, adsorbed, organic, occluded, amorphous and residual Si. The percentage distribution of fractions of Si in these soils were in the order; residual Si > amorphous Si > occluded Si > organic Si > mobile Si > adsorbed Si. Quantity – intensity relationship of five major rice growing soils at two temperatures viz. 25 0 C and 40 0 C were studied. The highest buffer power was indicated by Kuttanad soil followed by Pokkali and sandy soils at 25 0 C. It clearly indicated that these soils have a higher power to retain Si on solid phase and replenish its concentration in soil solution as and when it is depleted through plant uptake or leaching. The equilibrium Si concentration and the amount of Si adsorbed by each soil were used to test the fitness of data to the adsorption isotherms viz., Langmuir, Freundlich and Temkin. The data obtained from the adsorption experiments fitted into Freundlich and Temkin equations, but not to Langmuir equation at 25 0 C. At 40 0 C no adsorption equations were obtained for any soil.An incubation study was conducted to know the extent of release of Si on addition of different sources of silicon such as rice husk ash, biodecomposed rice husk, calcium silicate and sodium silicate in five rice growing soils under submerged water regime (SWR) and field capacity water regime (FCWR). Addition of Si significantly increased the release of available Si in all soils except Kole land soil after a month. Kole land soil showed higher release of available Si after two months. The highest release of available Si was at SWR in case of Kole land and Kuttanad soil, where as Pokkali, sandy and lateritic soils showed more release of available Si at FCWR. Irrespective of soils, treatment with sodium silicate showed higher release of available Si. Total Si showed a decreasing trend over the period of incubation for three months in all the soils. A field experiment was conducted at Agronomic Research Station, Chalakudy to evaluate the efficacy of different sources of silicon including rice straw in wetland rice. Rice husk ash, biodecomposed rice husk, calcium silicate and sodium silicate were used as source of Si along with fertilizers as per package of practice recommendation (NPK alone). The maximum number of panicles per hill, number of spikelets per panicle, thousand grain weights and minimum number of unfilled grains per panicle were recorded in treatment with calcium silicate application. The maximum grain yield of 6.90 t ha -1 was recorded in treatment T 5 (T 2 + Calcium silicate) and significantly superior (fig.54) over all other treatments. This increase in yield may be due to the effect of application of Si on soil fertility, nutrient uptake, and plant growth. The direct effect of Si fertilization on increased number panicle per hill, number of spikelets per panicle, and thousand grain weight and decreased number of unfilled grains per panicle might be the reason for increased grain and straw yield in treatment with calcium silicate. The treatment with POP + sodium silicate showed the highest uptake of Si by grain and straw of rice. The sources of Si had no residual effect on grain and straw yield of succeeding rice crop. In general, sandy soil low in available Si had a high response to applied Si in achieving higher grain yield.ThesisItem Open Access Characterization and evaluation of on-farm liquid organic manures on soil health and crop nutrition(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2017) Sreya, U Parvathi; KAU; Ushakumari, KThe experiment entitled “Characterization and evaluation of on-farm liquid organic manures on soil health and crop nutrition” was undertaken at College of Agriculture, Vellayani during 2014-2017.The study was envisaged to characterize the on-farm liquid organic manures viz., cow urine, panchagavya, fish amino acid, vermiwash and jeevamrutha, to monitor the nutrient release pattern under laboratory conditions and to evaluate the efficacy of soil and foliar applications of these liquid manures on soil health and crop nutrition using bhindi as test crop. The study consisted of three parts. The first part comprised the preparation and characterization of above said on-farm liquid organic manures. These manures were prepared as per standard procedures and characterization study was conducted to determine the physical, chemical, biological and biochemical properties. Physical properties viz., colour and odour of different on-farm liquid organic manures were recorded. Among the liquid organic manures studied, fish amino acid and panchagavya showed acidic pH and other three liquid organic manures viz., cow urine, jeevamrutha and vermiwash recorded neutral pH. Regarding EC, jeevamrutha recorded the lowest value (1.53 dSm-1).The highest OC content (39.96%) was recorded by fish amino acid followed by panchagavya. Among the major nutrients, the highest N content (0.45%) was found in panchgavya followed by fish amino acid. The highest P content was recorded by FAA (0.41%). Maximum K content (0.17%) was recorded in cow urine followed by panchagavya, vermiwash and jeevamrutha. S content of all the liquid organic manures were higher compared to Ca and Mg content. The highest contents of Ca, Mg and S were recorded by fish amino acid. The Fe content (39.92mg L-1) was highest in jeevamrutha and the lowest in fish amino acid. Cow urine was found to be rich in Mn (0.400 mg L-1) and Cu (21.21 mg L-1).The maximum zinc content (2.00 mg L-1), IAA (6.00μg ml-1) and GA (35.00μg ml-1) were found in fish amino acid. Panchagavya was rich in cytokinin (2.82 mg L-1) whereas, ascorbic acid content (37.50 mg 100g-1) was the highest in vermiwash. Fish amino acid was registered the highest enzyme activities, except for dehydrogenase activity which was found to be maximum in cow urine (371.27 μg of TPF g -1soil 24 h-1) followed by fish amino acid (336.98 μg of TPF g -1soil 24 h-1). The maximum population of bacteria was observed in vermiwash and fungal population was presented in all liquid organic manures except cow urine. The highest azotobacter population was observed in fish amino acid. K solubilizers were found to be the highest in vermiwash whereas E.coli, P solubilizers, azospirillum and Pseudomonas sp. were not detected in any of the above liquid organic manures. The second part of the experiment was laboratory incubation study to monitor the nutrient release pattern from soil treated with the on-farm liquid organic manures for a period of two months. The study consisted of 6 treatments which included soil alone and soil treated with 10 per cent dilution of all the liquid organic manures separately and all the treatments were maintained at 60 per cent moisture level. In general increased pH and EC values were observed in all the treatments received diluted liquid organic manures compared to control. Regarding the release of major, secondary and micronutrients, there was significant difference in available nutrient contents between treatments during the periods of incubation. Regarding the release of N and P during incubation study, soil along with FAA 10 per cent recorded the highest release pattern whereas soil along with cow urine 10 per cent recorded the highest K release throughout the incubation period. There was increased release of Ca in the treatments received liquid organic manures. The highest Mg release throughout the incubation period was registered by the treatment received cow urine 10 per cent. Available iron content was higher in T5 (soil 5 kg + jeevamrutha 10 %) compared to other treatments. A significant difference was found among treatments with respect to available Zn content. Initially (0th day of incubation), all the treatments were recorded higher values compared to values recorded on 7th ,15th ,30th , 45th and 60th days of incubation. There was increasing trends in the Cu content of soil from 0th day of incubation to 60th day of incubation except in the case of T3 (soil 5 kg + FAA 10 %). Treatment T1 (soil without treatments) recorded the lowest values for all nutrients throughout the incubation period. The third part of the experiment was to evaluate the efficacy of soil and foliar applications of on-farm liquid organic manures in a pot culture experiment using bhindi as test crop. The treatments included were 75 per cent N as enriched vermicompost along with diluted liquid organic manures separately as soil and foliar applications. Plant height, LAI, dry matter production, number of flowers, number of fruits per plant and total fruit yield were found to be the highest in T5 (75 % N as EVC + panchagavya 3 % foliar application). Chlorophyll a, b and total chlorophyll content were the highest in T10 (75 % N as EVC + jeevamrutha 10 % soil application). T1 (KAU PoP) recorded the highest average fruit weight. T4 (75 % N as EVC + FAA 5 % soil application). registered the highest crude protein content while crude fibre content was lowest in T7 (75 % N as EVC + cow urine 10 % foliar spray). Ascorbic acid content was the highest in T5 (75 % N as EVC + panchagavya 3 % foliar spray) and was on par with T7, T2,T9 and T11. The results of the post harvest analysis of soil revealed that pH, EC, organic carbon and labile carbon contents varied significantly among the treatments. The highest organic carbon content of soil was recorded by T4 (75 % N as EVC + FAA 3 % soil application) and T12 (75% N as EVC + vermiwash 10 % soil application). The maximum labile carbon was recorded by T8. T5 (75 % N as EVC + panchagavya 3 % foliar spray) was rich in available N. Soil enzyme activities were influenced by the application of liquid organic manures. The treatment T5 registered the highest plant uptake of major nutrients. The treatment T3 registered the highest plant uptake of secondary nutrients. The highest value of Fe and Zn uptake was noticed in T11.(75 % N as EVC + vermiwash 10 % foliar spray). The highest value of Cu uptake was noticed in T1 (KAU PoP). The highest value of Mn uptake was noticed in T3 (75 % N as EVC + FAA 5 % foliar spray) . The lowest plant uptake of all nutrients were recorded by T13 (Absolute control). Economics of cultivation of bhindi indicated that cost benefit ratio was found higher for treatment T5, 75 per cent N as EVC + panchagavya 3 per cent foliar application (2.83) followed by T7, 75 per cent N as EVC + cow urine 10 per cent foliar spray (2.09). From the above study, it was concluded that the recommended dose of inorganics (KAU PoP) can be substituted with combined application of enriched vermicompost (enriched with azolla 10 %) to get 75 per cent N and foliar application of 3 per cent panchagavya or soil application of 10 per cent cow urine or 5 per cent fish amino acid at 10 days intervals. Soil health, in terms of physical, chemical, biological and biochemical properties of soil was more enhanced in the treatments received soil application of liquid organic manures. Liquid organic manures viz., cow urine, panchagavya, jeevamrutha, fish amino acid and vermiwash were easily preparable in the farmers’ farm, biodegradable, less expensive, eco-friendly and non-hazardous for human health and environment. From the study it was found that above liquid organic manures were very good organic sources for organic farming and sustainable agriculture.ThesisItem Open Access Chemistry and transformations of calcium and magnesium in tropical acid soils of kerala(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Thrissur, 2017) Bhindhu, P S; KAU; Sureshkumar, PCalcium and magnesium are indispensible as secondary nutrients for plant growth. Availability of these nutrients to plants depends on the form and quantity present in soil. Soils of the tropics normally pose the problem of acidity due to high rainfall and leaching of bases causing widespread deficiency of these nutrients. The study aims at characterization of soil samples from 23 agro ecological units of Kerala with respect to supplying power, chemistry, dynamics, transformations and availability indices of calcium and magnesium and also to optimize the level of calcium and magnesium for rice nutrition in lateritic soils. Sixty four representative soil samples from 23 agro ecological units under five agro ecological zones of the state were collected and characterised for physico-chemical properties. Among these soils, ninety two per cent were acidic in reaction, of which sixty three per cent were strongly to very strongly acidic (4.5-5.5). Lowlands of Kuttanad, Pokkali and Kaipad were extremely to ultra acidic. Twenty seven per cent of samples were deficient (< 300 mg kg-1) in available calcium, while sixty seven per cent samples were deficient in available magnesium (< 120 mg kg-1). Deficiency was negligible in soils from Attapady hills (AEU 18 and 19), Palakkad central and eastern plains (AEU 22 and 23) and the lowlands of Kuttanad, Pokkali, and Kaipad (AEU 4, 5 and 7). The availability of calcium and magnesium increased with pH, cation exchange capacity and decreased with increase in exchangeable aluminium. Forty one soil samples from different agro ecological units were subjected to sequential fractionation. The mean per cent contribution of different fractions to total calcium was in the order exchangeable > mineral > acid soluble > water soluble > organic complexed, whereas in the case of magnesium, it was observed as mineral > acid soluble > exchangeable > water soluble > organic-complexed. Exchangeable calcium and water soluble magnesium were the sole forms contributing directly to the available pool. The quantity-intensity relationship of calcium and magnesium in twenty- three soils belonging to different AEUs of Kerala were studied at 25oC and 40oC. Potential buffering capacity or the supplying power of soil had significant positive correlation with CEC and exchangeable cations in soil. The adsorption data of both calcium and magnesium at 25oC and 40oC were best explained by Tempkin adsorption isotherm indicating that the affinity for adsorption decreases linearly with degree of saturation. The change in free energy of adsorption for calcium and magnesium was negative in all the soils studied signifying the spontaneous nature of adsorption. The change in enthalpy (ΔH0) was negative in most of the soils indicating the process to be exothermic. The close correlation of enthalpy change with change in entropy proved that as the enthalpy change becomes more negative, stronger is the bond and more orderly is the adsorption. The incubation experiment conducted to study the effect of organic matter on the adsorption of calcium and magnesium revealed a positive influence of organic matter on availability of calcium and magnesium. The addition of organic matter improved the supplying power with respect to calcium and magnesium either through mineralization or formation of stable soluble complexes especially at higher pH. Two field experiments to optimize the level of calcium and magnesium nutrition for rice in low land of north central laterites (Pattambi) revealed the clear role of calcium and magnesium in improving the yield and yield attributing characters of the crop. Application of dolomite as per ΔpH was found to be effective in increasing the yield and maintaining optimum level of calcium as well as magnesium in soil. Application of lime was not found to influence the in situ soil pH. The response of crop to magnesium showed yield improvement to the tune of 1.18 t ha-1 by application of magnesium sulphate @ 120 kg ha-1. Residual effect of dolomite had significant influence on the yield of rice whereas no residual effect of applied magnesium sulphate was evident. The correlation studies and path analysis clearly indicated that plant absorption of calcium mainly takes place from exchangeable fraction and that of magnesium from water soluble fraction.ThesisItem Open Access Carbon sequestration and soil health under different organic sources in wetland rice(Department of Soil Science and Agricultural Chemistry, Vellanikkara, 2018) Rajalekshmi, K; KAU; Betty BastinIn the current scenario of global climate change, wetland paddy fields are considered as major sources of greenhouse gases (GHG), especially methane (CH 4) and carbon dioxide (CO 2) as they experience both dry and wet situations depending on water availability. On the other hand, wetland characteristics promote the accumulation of organic matter in the soil and sediment, serving as carbon (C) sinks and making them one of the most effective ecosystems for storing soil carbon. In this context, the present study was undertaken with the objective to assess the combined effect of organic and inorganic sources on carbon sequestration and soil health under rice –rice cropping system and to compare the carbon distribution and fluxes with that of adjoining fallow land. The experiment was conducted in the farmer’s field at Varadium, Thrissur with rice as test crop in sandy clay loam soil for two continuous cropping seasons viz., Virippu and Mundakan during April 2015 - January 2016. The treatments consisted of different organic sources like farm yard manure (FYM), jack tree (Artocarpus heterophyllus) leaves, daincha (Sesbania aculeata), rice husk biochar and no organic manure. These were applied in combination with four levels of nitrogen (N) viz., 0, 35, 70 and 105 kg ha -1 represented respectively as N 0, N 35, N 70 and N 105. The soil samples from surface (0-15 cm) and subsurface (15-30 cm) and plant samples were analysed at harvest stage in both seasons to assess the impact of treatments. Gas samples were collected during the second cropping season at three stages viz., active tillering, panicle initiation and near harvest of the crop from fifteen treatments (except N 0 level) so as to evaluate the GHG flux (CO 2 and CH 4) from the cultivated land and it was compared with that of adjoining wetland. Soil characterization of cultivated land (biochar treatment with N 0 level) and fallow wetland (1 m depth) was also carried out after the field experiment.Combined use of both organic and inorganic sources improved the physico-chemical properties of soil over inorganics alone. The impact was more pronounced with biochar + N 0 treatment and its effect on increasing soil pH was also note-worthy. The build- up of soil organic carbon (SOC) as well as total carbon (TC) contents were more in the surface layer compared to the subsurface. Irrespective of treatments, the carbon content decreased after Virippu season as a result of high temperature. The high carbon content noted in the biochar with all levels of N had positive effect even in the second season. The soil carbon storage was also high with this organic source. The distribution of organic C among physical pools of soil organic matter viz., coarse particulate organic carbon (cPOC), fine particulate organic carbon (fPOC), light fraction organic carbon (LFOC), intra light fraction organic carbon (iLFOC), heavy fraction organic carbon (HFOC) and mineral associated organic carbon (MinOC) separated on size and density basis using standard procedures were also studied. Though the organic sources had positive effect on various pools, biochar with all levels of N had a strong impact in the carbon content of cPOC, LFOC and iLFOC. The cPOC concentration decreased over time while the reverse happened with fPOC. However, in the density fractions with biochar treated soils, the LFOC had the highest C concentration followed by iLFOC and the effect was more prominent in the surface layer. Combined application of organic sources and inorganic fertilizers significantly increased the cation exchange capacity and nutrient availability in soil than that of inorganic fertilizers alone. The amount of nutrients decreased with increasing soil depth. Levels of N also had varied effect on these contents. The nutrient content in plant parts like grain, shoot and root of rice crop varied among treatments. Adequate improvement in soil physical, chemical and microbiological parameters on application of green manure contributed to increased grain yield at 35 kg N ha -1 in flooded rice soil while the straw yield was maximum in the treatment with biochar at N 105. Measurement of GHG emission during the rice growth stages showed that the level of CO 2 was high in the active tillering phase and near harvest phase of crop growth, while that of CH 4 was found to be higher in the panicle initiation phase. Application of biochar as well as green manure with 105 kg N ha -1 resulted in greatest emission of CO 2, whereas the FYM + N 105 showed highest emission of CH 4. Soil profile study carried out after the field experiment indicated that the soil profile in the fallow land had a depth of 115 cm and five horizons while a soil profile depth of more than 70 cm with six horizons in the cultivated land. The effect of biochar on distribution of carbon and available nutrients within 30 cm depth was maximum in cultivated land in comparison with fallow wetland. The study revealed that the application of biochar without N had great impact on soil pH and various pools of carbon but its effect at this level on soil available nutrients was reverse. The soil available nutrients were higher with FYM and daincha and their effects increased with higher levels of N which subsequently improved the plant nutrient contents and rice yield. However, the organic sources with higher doses of N had enhanced emission of CO 2 and CH 4. Hence a suitable balance between the organic + inorganic N sources is advocated.ThesisItem Open Access Impact assessment of landfill on soil health and water quality in a waste disposal site(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2017) Fasila, E K; KAU; Sam, T KurumthotticalThe study entitled “Impact assessment of landfill on soil health and water quality in a waste disposal site” was undertaken with an objective to assess the impact of dumping Municipal Solid Waste (MSW) on soil and water quality, spatial variability in the level of biological and chemical contamination along the leachate zone and identification of a few bioremediators and their possible effectiveness in decontaminating the landfill materials. As a part of this study, geo-referenced sampling points have been identified initially for dumped waste materials (from the existing two landfill sites), soil (from two depths) and leachate samples along the leachate flow zone at a regular interval of 50 m within the plant area and ground water samples outside the area were collected. All the samples were monitored from these geo-referenced sampling points in three successive seasons, viz., pre-monsoon, monsoon and post-monsoon. The values for all the physico-chemical parameters in landfill materials were high during pre-monsoon period and only a marginal variation observed in heavy metal content in three seasons of study. Soil samples were acidic in reaction and a reduction in N, P, K and heavy metals were observed as the depth of sampling increased. Comparatively high values were observed in all parameters during pre-monsoon period than the other two seasons both in soil and leachate samples. Fe, Al and Hg content in leachates were very high and the concentrations of Fe, Al, Pb, Cd and Hg in ground water exceeded the acceptable level insisted by BIS. The leachate samples also recorded a high value for biological oxygen demand, chemical oxygen demand and coliform count than the ground water samples. Fifteen profusely growing weed species were identified and collected along the leachate flowing zone and the shoot and root portions were analyzed separately for various heavy metals to assess their selective retention capacities. Most of the weed species except Sphagneticola trilobata, Commelina diffusa, Ricinus communis, and Mikania micrantha were found to retain more toxic metal load in the root portion than the shoot portions. Among them, Alternanthera tenella was identified as the best hyper accumulator with respect to its gross uptake of the metals like Mg, Mn, Pb, Cd, Ni, Co and Cr. Hence, this plant was selected for the sand culture study along with other established hyper accumulator plants namely; Indian mustard, sunflower, globe amaranth and marigold analyzed for selective retention capacity under four graded doses of lead, cadmium and nickel. This study identified three best plants species (sunflower, globe amaranth and marigold) showing highest hyper accumulation capacities and hence they were carried forward to another pot culture study employing contaminated and degradable landfill materials for the final revalidation of claims. The experiment consisted of ten treatments and the treatments where the growing medium was re-constituted with different proportions of degradable landfill materials and virgin soil with and without the AMF inoculation. The plants which were grown for three months were analyzed separately for root and shoot portions for the exact quantum of selective retention status of metals like Al, Zn, Cu, Fe, Pb, Cd, Ni, Co, Cr and Hg. Lower levels of metal accumulation was recorded in all the plant parts where AMF had been inoculated in the media than its pairing treatment without inoculation, indicating the specific effect of AMF in preventing the uptake of heavy metals by plants and at the same time permitting the absorption of other ions needed for growth. Sunflower had been adjudged as the best plant that removed maximum load of studied heavy metals from the contaminated growing media except nickel and chromium. Similarly globe amaranth had been specifically identified as an excellent accumulator of nickel. Marigold was identified to be efficient accumulator of chromium. From the investigation it can be concluded that the soil and water bodies near the dumpsite sufficiently contaminated with the heavy metals like Zn, Mn, Cu, Fe, Pb, Cd, Ni, Co, Cr and Hg. As the distance from the dumpsite increased the extent of various chemical and biological contaminations showed a decreasing trend. Sunflower, globe amaranth and marigold were found to be effective hyper accumulators for the area in decontaminating the soils.ThesisItem Open Access Technology refinement for biochar production and evaluation of its effect on soil health and crop productivity(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2017) Sainath Nagula; KAU; Usha, P BA study entitled ‘Technology refinement for biochar production and evaluation of its effect on soil health and crop productivity’ was carried out at the Department of Soil science and Agricultural Chemistry, College of Agriculture, Vellayani, during March 2015 to June 2016. The objective of the study was refinement of technology for micro level biochar production from tender coconut husk and evaluation of its effect on soil health, yield and quality of banana (Musa spp.) in the field. A modified design of micro biochar kiln for the pyrolysis of tender coconut husk to biochar was developed. The micro kiln consists of a temperature monitoring enabled, double barrel reactor unit with chimney and a cooling assembly for condensation and cooling of syngas. The reactor unit had a biomass capacity of 30 kg. The pyrolytic conversion happened at temperature >350 oC and time required was 90 minutes. Characterization of biochar produced was done by standard procedures and it had an alkaline pH (8.53), CEC (15.26 cmol kg-1), AEC (5.64 cmol kg-1), C: N (46.11), C:P (175.25), C:S (259.62) and C:N:P:S (350:7.5:2:1) ratios. Electrical Conductivity, total C, N, P, K, Ca, Mg, S, Fe, Mn and B were 1.70 dS m -1, 70.10 %, 1.52 %, 0.40 %, 2.26 %, 0.54 %, 0.46 %, 0.27 %, 89.9 mg kg-1, 2.84 mg kg-1 and 6.78 mg kg-1 respectively. The heavy metal contents (Pb, Cd, Ni, Cr, Zn and Cu) were very low when compared to the maximum allowed threshold levels. The syngas produced during pyrolysis was analyzed by gas chromatography and its composition was carbon dioxide (67.70%), methane (22.89%), oxygen (8.74%), hydrogen (0.66%) and n-Butane (0.001%) on normal mol % (dry) basis. Carbon monoxide and nitrogen were absent. The biochar recovery percentage was 50 %, which was 17 % more than the previous model of biochar kiln. The quantity of syngas produced was comparatively less. The composition of syngas produced revealed that it can not be used as a bioenergy source because the methane content is less. There was no production of bio oil during pyrolysis. All these advantages qualifies this refined technology as the most effective in carbon sequestration and safe waste management. In order to find out the effect of biochar on soil health and crop productivity, a field experiment was carried out with nendran banana as test crop in Loamy, Kaolinitic, Isohyperthermic, Typic Kandiustults belonging to Vellayani series. Treatment combinations were T1- Package of practices recommendation, T2- BC @ 5 kg plant-1 + NPK as per POP, T3- BC @ 10 kg plant-1 + NPK as per POP, T4- BC @ 5 kg plant-1 + 75% NPK as per POP, T5- BC @ 10 kg plant-1 + 75% NPK as per POP, T6- FYM 10 kg plant-1 + (NPK + secondary and micronutrients as per Soil test based recommendation), T7- BC @ 5 kg plant-1 + (NPK + secondary & micronutrients as per STBR), T8- BC @ 10 kg plant-1 + (NPK + secondary & micronutrients as per STBR), T9- BC @ 5 kg plant-1 + 75% (NPK + secondary & micronutrients as per STBR), T10- BC @ 10 kg plant-1 + 75% (NPK + secondary & micronutrients as per STBR) and T11- BC alone 10 kg plant-1. Plant biometric characters like plant height at 2, 4, 6 and 8 months after planting, number of leaves per plant at 2 and 6 MAP and pseudostem girth at 4 and 8 MAP were highest in the treatment (T10) where biochar @ 10 kg plant-1 + 75% (NPK + secondary & micronutrients as per STBR) was applied followed by 5 kg biochar + 75% of NPK as per POP (T4). The total dry matter production was significantly higher with biochar @ 10 kg plant-1+ 75 % of STBR. Biochar @ 10 kg plant-1 added with 75% of STBR resulted in the highest bunch weight, number of hands per bunch, number of fingers per bunch and both length and girth of the index finger. 10 kg biochar along with 75% STBR enhanced the physical properties of the soil by imparting 57.11 % increase in the WHC, 35.32 % increase in porosity and 7.31 % decrease in the bulk density than application with FYM + NPK as per POP. A significant increase in soil pH was observed in the biochar based treatments as compared to the FYM applied treatments with a 0.6 units increase in pH in the treatment which received 10 kg biochar + 75% STBR. The highest OC content of 1.45 % and a 100 % increase in CEC of the soil was realized when biochar @ 10 kg along with 75 % of STBR were applied instead of FYM based POP recommendation. The biochar application @ 10 kg with 75 % of STBR significantly increased the soil available N, K, Mg and B at the active growth and harvest stages of banana. Zn content was highest in this treatment throughout all stages. The superiority of biochar based treatments as compared to FYM based treatments in promoting the growth and development of soil microorganisms in the rhizosphere was evident with a 55.9 % enhancement in soil dehydrogenase activity in the treatment where biochar @ 10 kg plant-1 + 75% STBR was applied. Biochar @ 10 kg plant-1 with 75 % STBR (T10) recorded highest foliar N, K, Mg, S, Fe, Mn, Zn content, as well as highest nutrient use efficiency of 50.4 %. Fruit quality parameters like TSS, ascorbic acid content and shelf life of fruits were found to be superior for the same treatment. The highest B:C ratio of 2.38 was also found in T10 treatment. Based on this a biochar based nutrient mix was prepared by mixing 10 kg biochar with urea 260.21g, MOP 528.75g and MgSO4 23.44g for Typic Kandiustults of Vellayani series. Hence it may be concluded that the biochar produced by modified micro biochar kiln had ideal physical and chemical properties that qualify it to be used as a good soil amendment which is environmentally safe and contributing to the soil carbon pool. Biochar application in general, and biochar (10 kg plant-1) along with 75 % soil test based recommendation in particular, enhanced the soil physical properties, decreased soil acidity, promoted rhizospheric microorganisms, increased the soil fertility status enabling efficient nutrient use and resulted in higher growth, profitable yield and superior fruit quality of banana.ThesisItem Open Access Phytoremediation of inorganic contaminants in Vellayani wetland ecosystem(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2017) Meera, A V; KAU; Manorama Thampatti, K CAn 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.ThesisItem Open Access Evaluation of a customised organic fertilizer in relation to labile carbon dynamics nutrient release characteristics and productivity of banana(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2017) Naveen Leno; KAU; Sudharmaidevi, C RA study entitled ‘Evaluation of a customised organic fertilizer in relation to labile carbon dynamics, nutrient release characteristics and productivity of banana’ 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 evaluate the customised organic fertilizer obtained from biodegradable urban garbage by rapid thermochemical conversion technology, in relation to labile carbon dynamics, nutrient release characteristics and productivity of banana in agro- ecological unit 8 of Kerala. Characterisation and assessment of the maturity parameters of degradable solid waste and the organic fertilizer produced from it were done. Organic fertilizer produced by thermo chemical treatment was odourless, with a particle size of < 4mm, low moisture content and bulk density compared to raw waste. It recorded a neutral pH, low electrical conductivity and total organic carbon. The content of major nutrients was higher in the organic fertilizer. Status of secondary and micronutrients was sufficient and heavy metal contents were within safe limits. Cellulose content in organic fertilizer decreased by 38.14% whereas hemicellulose and lignin contents increased. Organic fertilizer recorded lower C:N ratio, C:P ratio, NH4+/NO3- ratio, water soluble carbon/total organic carbon ratio and a higher cation exchange capacity in comparison to degradable solid waste. The humification indices were higher and was non phytotoxic. Fertilizing Index of 4.7 and Clean Index of 5.0 qualify it to be a Class A marketable organic fertilizer. Customisation of the organic fertilizer was done on the basis of soil test and crop requirement for Nendran banana in AEU 8. A laboratory incubation experiment to study the nutrient release characteristics of the customised organic fertilizer was done for a period of 300 days with seven treatments, of which three were FYM based, three customised organic fertilizer based with a soil alone (control) treatment. Regardless of the source of organic manure, the organic carbon content remained high in all the manured treatments than in soil alone. N release pattern indicated steady and constant supply of the nutrient. A phase of total immobilization of P was observed from 180 to 240 days in all treatments. Ca also exhibited a similar trend. The release pattern of K and Mg was identical with a progressive mineralization up to 240 days. Trend in release pattern of S was almost similar to N with a 90 days immobilization-mineralization cycle. Micronutrient kinetics exhibited a series of shorter mineralization-immobilization cycles at 60 days interval. However an increasing trend in release of B and Fe was observed till the end. Mn and Zn followed a homogenous release pattern with highest availability at 20 days after incubation. A field experiment of Nendran banana was laid out with 8 treatments in RBD to study the effect of customised organic fertilizer on labile carbon dynamics and yield. Temporal variation in organic carbon revealed long duration cycles with smooth curves representing heterogeneous and buffered field condition. The treatment in which customised organic fertilizer was used for basal and top dressing, contained high labile carbon, non labile carbon and carbon pool index. Soil reaction (pH) and water holding capacity of customised organic fertilizer based treatments and EC of FYM treatments increased with the growth stages. Antagonism between K and Ca was evident. The availability of micronutrients increased initially and reached the lowest at harvest stage. B steadily decreased up to harvest. Application of customised organic fertilizer enhanced dehydrogenase activity. Foliar concentration of N and P were highest in the initial stages in these treatments while that of K was highest at the later stages of crop growth. Foliar Ca and S also recorded higher values in these treatments. A synergistic effect was observed in the uptake of B and Mg and similarly between Mn and Zn. While Cu absorption was more during vegetative phase, Fe absorption coincided with flag leaf formation. The treatment where customised organic fertilizer was used for basal application as well as top dressing recorded highest plant growth characters, total dry matter production, shelf life of fruits and B:C ratio but was on par with the treatment which received FYM (soil test basis) in bunch weight, number of fingers per bunch and length of peduncle. Hence it can be concluded that the customised organic fertilizer obtained from degradable solid waste is of class A marketable quality, capable of a steady and constant supply of all essential nutrients to banana and realising profitable net returns, ensuring immediate energy source to rhizospheric microorganisms and promoting long term carbon sequestration in agro-ecological unit 8 of Kerala.