PG Thesis

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    Quantification and depth distribution analysis of carbon, nitrogen, and microbiomes in soils of Miyawaki forests in Kerala
    (Department of Soil Science, College of Agriculture, Vellayani, 2024-12-11) Sreelekshmi, M; Naveen Leno
    A study entitled “Quantification and depth distribution analysis of carbon, nitrogen and microbiomes in soils of Miyawaki forests in Kerala” was undertaken with the objectives of quantifying the levels of carbon and nitrogen in Miyawaki forest soils in Kerala, analysing the effect of increasing carbon sinks in achieving carbon sequestration and to investigate abundance of microbiomes in these soils. A preliminary survey was conducted to identify the locations where Miyawaki forests were established and is existent in the entire Kerala state. Altogether 58 Miyawaki forests have been established till date in Kerala. Five well established and oldest Miyawaki forests out of these were selected for further study. A survey was conducted during December 2023 in the selected study area and 20 georeferenced soil samples were collected from surface and subsurface layers from five Miyawaki forest and nearby undisturbed plots. The selected sites were located at Puliyarakonam, Peyad, Kanakakkunnu, Vilappilsala and Chalai. The soil samples were characterized for selected physical, chemical and biological attributes, carbon pools and nitrogen fractions. Various carbon indices like carbon pool index (CPI), lability index (CLI) and management index (CMI) were worked out. The carbon sequestration potential of each Miyawaki forest was also calculated. A metagenomic analysis of one sample each from Miyawaki forest and undisturbed plot was also conducted. A minimum data set (MDS) of indicators to assess soil quality index (SQI) was set up using Principal component analysis (PCA). The spatial variation in temperature within the confines of the Miyawaki forest as well as outside were recorded for a period of three months from March 2024 to May 2024 at two locations, viz., Puliyarakonam and Vilappilsala. The soils under study belong to sandy clay loam. The bulk density was found to be the lowest in the Miyawaki forest (1.15 Mg m-3) than the control. Other physical properties like water holding capacity (60.28%), soil moisture content (34.83%) and water stable aggregates (88.48%) were found to be higher in the surface soils of Miyawaki forest than the control plots. The soil acidity (pH 5.40) and EC (0.059 dSm-1) were found to be more in the Miyawaki forest. Soil biological properties like soil enzyme dehydrogenase activity (80.20 mg TPF g-1 soil 24 h-1), bacterial density (7.573 log cfu g-1), fungal count (5.507 log cfu g-1) and actinobacterial count (4.909 log cfu g-1) were also found to be higher in Miyawaki forest and decreased with depth. A higher total organic carbon of 10.31% was recorded in Miyawaki forest, which was observed to decrease with depth. Other carbon fractions like water soluble carbon (21.21 mg kg-1), labile carbon (4.51 mg g-1), particulate organic carbon (1.03%) and microbial biomass carbon (152.69 mg kg-1) were also observed to be higher in the Miyawaki forest when compared to the control plots. Total nitrogen content (0.36%) and available nitrogen (264.26 kg ha-1) was highest in Miyawaki forest. A higher C:N ratio was observed in Miyawaki forest (28.77) and was observed to increase with depth. The soil organic carbon stock (38.08 Mg ha-1) and carbon sequestration rates 9.05 Mg ha-1yr-1 were also found higher in Miyawaki forest soils compared to the control plots. A temperature difference up to 3.93°C and 4.21°C was observed between the mean maximum temperature between the inside and outside of Miyawaki forest during the summer months in Puliyarakonam and Vilappilsala respectively. No significant difference was observed for CPI, CLI, CMI, and SQI. The study on Miyawaki forests in Kerala reveal their substantial contribution to soil carbon storage and nutrient enrichment. The findings indicate that these forests not only enhance soil quality through increased organic carbon and nitrogen levels but also support a diverse microbiome, which is vital for soil health. Miyawaki forests in Kerala exhibit lower bulk density and higher water holding capacity compared to control plots, indicating improved soil structure and moisture retention. Additionally, the significant temperature regulation observed within the forests highlights their role in moderating local microclimates. Overall, the results underscore the potential of Miyawaki forests as effective carbon sinks and valuable ecological assets, advocating for their expansion as a strategy for carbon sequestration and soil restoration in the region. Further research is recommended to explore the long-term ecological impacts and management practices that can optimize these benefits.
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    Potential and prospects of fodder legumes in rice fallows
    (Department of Agronomy, College of Horticulture,Vellanikara, 1987) Meera Menon, V; Achuthan Nair, M
    An experiment was conducted in the Agricultural Research Station , Mannuthy during third crop season of 1985-’86 and first crop season of 1986-’87 to evaluate the relative performance of fodder legumes in rice fallows and their residual effect on the succeeding crop of rice under graded levels of N. The experiment, replicated thrice, was laid out in a split plot design with seven treatments – six fodder legumes (sannhemp, soya bean, rice bean, velvet bean, cowpea and black gram and a fallow- as main plot treatments and two N levels (52.5 and 70 kg/ha) applied to kharif rice as sub-plot treatments. The results revealed that sannhemp gave a fodder yield of 21 t/ha in rice fallows which was significantly superior to all other treatments. An increase in soil organic carbon, total and available N was also noticed. Soil organic carbon and total N was highest in the cowpea cropped plot. Available N in the soil was highest in the velvet bean cropped plot and the fallow plot recorded the lowest values. Increased rice grain yield was recorded after legumes compared to fallow and the highest grain yield was recorded after velvet bean followed by that after sannhemp cowpea and black gram. Application of N at the recommended dose of 70 kg/ha produced superior yields compared to N at 52.5 kg/ha. Rice crop succeeding fodder legumes with 75% N produced grain yield comparable to that after fallow receiving 100% N. The net income and returns per rupee invested were highest after the sannhemp-rice sequence followed by the cowpea-rice sequence. The results proved that 25% N could be saved in the case of rice after legumes. The study also showed the superiority of sannhemp and cowpea in fodder yield and residual effect in the succeeding rice crop.
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    Comparative efficiency of different phosphatic fertilizers in rainfed Nendran Banana
    (Department of Soil Science and Agricultural Chemistry, College of Agriculture,Vellanikara, 1990) Sheeja, V G; Harikrishnan Nair, K
    Though phosphorus is one of the key nutrients for plant growth, the consumption rate of phosphatic fertilizers in India is found to be comparatively low. The escalating cost of the imported raw material used for the manufacture of P fertilizers may be one of the possible reasons for the low intake. In this regard, the direct application of cheap native ground rockphosphate as a P source is a fruitful attempt especially in acid soils. The present investigation was conducted to compare the efficiency of different phosphatic fertilizers including rockphosphates in upland soils with ‘Nendran’ variety of banana as the test crop. The present study comprises of two aspects, field experiment and laboratory incubation study. The field experiment was conducted at two locations, viz. at the Instructional Farm attached to College of Agriculture, Vellayani and at Kattakada, in the cultivator’s field. The experiment was laid out in randomised block design with four treatments and five replications. The laboratory study was carried out in the soil, treated with different phosphatic fertilizers after incubation with organic matter under moist conditions to assess the influence of organic matter on the release of P from different P sources. The growth characters of banana plant such as height and girth of pseudostem, number of photosynthetically active leaves, leaf area and period taken for flowering were recorded and analysed upto shooting stages of the crop. The bunch characters like weight of bunch, length of bunch, number of fingers and hands bunch-1, and length and girth of finger were also recorded and analysed. Phosphorus application significantly influenced biometric characters of the crop while the differences between the various P sources were not statistically significant. In most of the growth and yield characters, comparatively higher efficiency was shown by plants treated with superphosphate, eventhough, it was statistically on par with the other sources in both locations. Thus, it indicates the possibility of using cheaper rockphosphates for meeting the phosphorus requirement of banana in upland soils of Kerala, rather than going in for the costly superphosphate. The effect of treatments on the drymatter production was significant at both locations. Phosphorus application significantly increased the P uptake. However the different P sources could not produce significant variation in the uptake of phosphorus in both locations. The phosphorus content in the leaf was found to be maximum from the late vegetative phase to shooting period of the plant growth. With respect to available and total P2o5 content in the soil, the differences between the various sources were not statistically significant though, addition of phosphorus increased the available as well as total P2o5 content of soil significantly over no P treatment. A significant positive correlation existed between the leaf P content and total P uptake. Similarly a significant positive correlation between yield as well as total drymatter content with P uptake was observed. The incubation study revealed that organic matter produced significant effect on the release of phosphorus from different P sources added to the soil under moist conditions. Upto 90 days of incubation, increased availability of phosphorus was recorded in all treatments, and the trend continued till 135 days. A gradual decline in the concentration of available P was noticed thereafter. However, a favourable influence of organic matter on the release of P from different sources has been brought out from this study. When the mean values of available P over all the periods were compared, maximum availability was recorded by soils incubated with organic matter and superphosphate. In general, various sources of P behaved similarly and were on par with respect to the release of phosphorus due to organic matter incubation.
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    Suitability of Tunisia rock phosphate for direct application in acid rice soils of Kerala
    (Department of Soil Science and Agricultural Chemistry, College of Horticulture,Vellanikara, 1997) SanthoshKumar, V C; Mariam, K A
    A study was conducted at College of Horticulture during the period 1993-95 so as to assess the suitability of Tunisia rockphosphate for direct application in acid rice soils of Kerala as a source of P compared with single superphosphate (SSP) diammonium phosphate (DAP) and Mussoorie rockphosphate (MRP). In addition to above sources a control treatment (with no P fertilizer) and another treatment with SSP of the rate of 45 kg P2O5 ha-1) given twice (conventional practice) were also included. The P release from all the sources was monitored with an incubation experiment. In order to evaluate the residual effect of fertilizers two continuous pot culture experiments were undertaken using Triveni variety of rice. The acids soils of Kerala namely Kuttanad alluvium and laterites were used for the study. The soils showed variation in pH with submergence irrespective of the treatments. The different nutrients like N, K, Ca, Mg were higher in Kuttanad soil compared to laterite soil and was found to decrease with period of incubation. The available phosphorus content gradually increased with period of incubation and reached a peak .fit 60 to 90 days for water soluble phosphates and 90th to 120th day for rockphosphates. Comparing the two extractants, Mathew's triacid extracted more available P than that of Bray solution in both soil types. In general, Kuttanad alluvium recorded higher content of available nutrient as compared to laterite. The extent of fixation of P was higher in Kuttanad soil with Fe-P as dominant fraction while in laterite soil it was Al-P which was dominated. While evaluating pot culture experiment the different nutrients showed a decrease in soil and increase in uptake with the advancement of crop. Of the different soils Kuttanad alluvium registered a higher yield compared to laterite soil. It was found that TRP registered a comparable uptake of phosphorus and gave a comparable yield of grain and straw with other sources in laterite and Kuttanad alluvium. The residual effectiveness of rockphosphate was found to be higher than that of water soluble sources and TRP gave the highest. Of the two different type of soils Kuttanad soil showed a higher residual effectivenes and resulted in higher yield for 2nd crop while laterite soil registered a lower yield.
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    Spatial arrangement & nutrient management of grain cowpea - Fodder maize intercropping in summer rice fallows
    (Department of Agronomy, College of Agriculture, Vellayani, 1990) Sunitha, S; Lekha Sreekantan
    An investigation was carried out during the summer season of 1988-'89 in the Instructional Farm attached to the College of Agriculture, Vellayani to determine the best crop arrangement for a grain cowpea + fodder maize intercropping system in summer rice fallows under different fertility levels. The different crop arrangements tried were pure crop of cowpea at normal row arrangement, pure crop of maize at normal row arrangement, cowpea and maize in alternate rows, paired row of cowpea with one row of maize in between and triple row of cowpea with one row of maize in between. The fertilizer levels tried were 100, 75 and 50 per cent of the recommended doses of nutrients of cowpea, maize and cowpea+ maize, depending on the crop arrangement and the area occupied by each crop. The experiment was laid out in split plot design with four replications. The crop arrangements were allotted to main plots and the fertility levels to the subplots. Plant height of cowpea was maximum in the crop arrangement where cowpea was alternated with one row of maize where as the pure crop of cowpea produced the maximum number of leaves. In the case of maize, plant height and number of leaves were maximum when cowpea and maize were grown in alternate rows. Pure crops of cowpea and maize recorded the highest for their respective LAI values at flowering. Plant height, number of leaves and LAI of both cowpea and maize were affected by different fertility levels. Higher doses of fertilizers were found to be the best. The crop arrangements did not show pronounced variation in the uptake of nutrients by cowpea except potassium. Potassium uptake by cowpea and maize were maximum for their respective sole crops. For maize, nitrogen and phosphorus uptake were maximum when grown in alternate rows with cowpea plants. Full dose of fertilizers recorded the highest uptake values. Number of pods per plant, length of pods, number of seeds per pod, hundred grain weight, pod yield as well as grain yield of cowpea were not affected by different crop arrangements or fertilizer levels. The fodder yield of maize was affected by different crop arrangements and the pure crop of maize was on par with the crop arrangement where cowpea and maize were alternately grown. Hundred per cent recommended dose of fertilizers recorded the highest value for fodder yield of maize. The treatment where cowpea and maize were grown in alternate rows resulted in the greatest protein content of cowpea grains. Seventy five percent dose of fertilizers resulted in the highest crude protein content of maize fodder. The various indices like LER, LEC, IER, net profit, benefit/cost ratio, return per rupee invested on labour and return per cropping day were found to be superior in the crop arrangement where cowpea and maize were grown in alternate rows and at full dose of fertilizers. Hundred per cent and seventy five per cent dose of fertilizers were on par with regard to LER, LEC, IER, net profit and benefit/ cost ratio. From a detailed analysis it is seen that cowpea alternated with one row of fodder maize under 75 per cent of the recommended level of nutrients, is the best in providing higher profit to the farmer.
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    Nutritional requirement of pre-release sesamum culture 42-1 in garden land
    (Department of Agronomy, College of Agriculture, Vellayani, 1987) Raveendran Nair, P; Chandrasekharan, P
    A 4 raise to 3 fatorial experiment confounding NPK (3 df) totally in replication I and II was conducted under garden land condition at the Instructional Farm, College of Agriculture, Vellayani, during semirabi season 1984, to study the effect of graded doses of nitrogen (10, 30, 50 and 70 kg/ha), phosphorus (5, 15,25 and 35 kg P2O5/ha) and potassium (10, 30,50 and 70 kg K2O/ha) on the growth , yield , quality, content and uptake of mineral nutrients and also to work out the economics of production with the pre-release sesamum culture 42-1 (now released as Soorya or ACV-2). The study revealed that application of nitrogen significantly influenced growth , yield and yield attributing characters. Phosphorus and potassium produced significant influence on number of leaves and leaf area index on 40 and 60 days after sowing. Significant effect of phosphorus was also observed on number of branches, pod-seed ratio, bhusa yield, thousand seed weight and total dry matter production. Applied potassium significantly influenced the yield and yield attributing characters like number of pods , weight of pod per plant, pod seed ratio, seed yield and harvest index.
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    Effect of different forms and levels of phosphorus on the growth, yield and composition of three yielding varieties of rice (IR 8, Taichung Native I and Culture 28)
    (Division of Agricultural Chemistry, Agricultural College and Research Institute, Vellayani, 1968) Jagadeeschandran Nair, M P; Koshy, M M
    To study the effect of different forms and levels of phosphorus on the growth, yield and composition of three high yielding varieties of rice, a pot culture experiment was carried out in the Agricultural College and Research Institute, Vellayani, in a randomised block design with 39 treatments and 3 replications. The different forms of phosphorus used were superphosphate, ultrafos, defluorinated rock phosphate and Thomas phosphate. The levels of application were 0,25, 50 and 75 kg P2O5/ha. The rice varieties studied were Culture 28, IR 8 and Taichung Naive 1. The main findings of the experiment are summarised below: 1) The height of plants was a maximum for IR 8. This growth character was not influenced by the form of phosphorus used, but it increased significantly with increase in the rate of phosphorus application, 2) In the matter of tillers, Taichung Native 1 was superior to IR8 and Culture 28. Of the different forms of phosphorus applied, superphosphate and deflurinated rock phosphate produced the maximum number of tillers. As regards the effect of level, the number of tillers increased with increase in the level of phosphorus application.
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    Fertilizer management in rice variety cheradi
    (Department of Agronomy, College of Agriculture, Vellayani, 1986) Vaijayanthi, C P; Ramachandran Nair, V
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    Spacing cum fertilizer investigation on rice variety, Mashuri, in the Onattukara tract
    (Department of Agronomy, College of Agriculture, Vellayani, 1983) Sobhana, S; Chandrasekharan, P
    With a view to investigate the influence of different fertilizer levels, spacings and their combinations on the growth and yield of rice variety, Mashuri, in the sandy loam tracts of Onattukara, an experiment was conducted at the Rice Research Station, Kayamkulam, during the second crop season of the year, 1981-82. The response of the variety to four fertilizer levels (50 : 25 : 25, 60:30:30, 70:35:35 and 80:40:40 kg/ha NPK), four spacings (10cm X 5 cm, 10cm x 10 cm, 15 cm x 10 cm and 20 cm x 1o cm) and their combinations was studied. The experiment was laid out in randomised block design , as a 4 x 4 factorial experiment with three replications.
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    Effect of drying and wetting on the physical, Physico-chemical and chemical properties of the submerged soils of Kuttanad
    (Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 1988) Raju, P V; Koshy, M M
    A study was undertaken at the College of Agriculture, Vellayani to know the effect of drying and wetting on the physico-chemical properties of submerged acid sulphate soils of Kuttanad which are known locally as Kerapadom, Kari and Kayal soils. Random soil samples were collected from various parts of Kuttanad and their physico-chemical properties such as pH, conductivity, available NPK status and different forms of iron and aluminium were estimated in moist state itself. Texturally Kuttanad soils were predominantly of clayay nature. Bulk and particle densities were significantly lower in Kari soils due to high organic matter as compared to Karapadom and Kayal soil. The pH values of Kayal soils were significantly higher than that of Kari and Karapadom soils which were extremely acidic. The conductivity of all soil groups were negligible probably due to seasonal effects and also due to the commissioning of Thaneermukkom bund and Thottapally spillway which prevented the ingress of sea water. The availability of major nutrients was fairly high and no significant differences existed between soils. Exchangeable iron and aluminium varied greatly.