1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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Item Land use induced changes in cation anion balance of southern laterite soils of Kerala(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2026) Surya, G BThe study entitled “Land use induced changes in cation anion balance of southern laterite soils of Kerala” was conducted in the Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani during 2024-2025 with the objective of assessment of variability in the distribution of cations and anions as influenced by land use systems and seasons in the southern laterite (AEU 8) of Kerala. Georeferenced soil samples were collected from twenty different locations of four major land use systems (LUS) of the southern laterite soils of Kerala viz., banana, coconut, vegetable and uncultivated fallow lands, from the surface (0–15 cm) and sub-surface (15–30 cm) layers during both the pre- monsoon and post-monsoon seasons. The collected soil samples were analysed for physical properties, electrochemical properties, biological properties and cation- anion concentrations. An incubation experiment was conducted with the samples collected from the pre monsoon season to find out the effect of moisture content on cation anion concentration. During the incubation period, the concentrations of cations viz., NH₄⁺-N and Fe²⁺ displayed a pronounced decrease with the reduction in moisture content and the values recorded were statistically significant. Among the anions, NO₃⁻, SO₄²⁻ and PO₄³⁻ exhibited significant reduction with decrease in moisture content. Out of the five locations of the banana, coconut, vegetable and fallow land use systems, three were classified as sandy clay loam, one as silty clay loam and one as clay loam in texture. No variation in texture was observed in the sub surface layers. During the pre and post monsoon season in surface soil, significantly higher bulk density was noticed in the samples from banana LUS (1.20 Mg m-3) which was on par with coconut and uncultivated fallow LUS and lowest was observed in vegetable LUS (1.03 Mg m-3). Coconut LUS showed the highest pH (5.67) at 0-15 cm depth for pre and post monsoon. Significantly higher CEC (6.30 cmol(+) kg⁻¹) was recorded in the surface soils of coconut land use system. Conversely, vegetable LUS registered the maximum AEC (0.719 cmol(– ) kg⁻¹) in surface. Irrespective of the season and depth, the uncultivated fallow land showed the lowest values for pH, CEC and AEC. Coconut LUS recorded the significantly higher contents of Ca²⁺ (298 and 268 mg kg⁻¹, respectively), Mg²⁺ (98 and 78 mg kg⁻¹, respectively), Na⁺ (58 and 40 mg kg⁻¹, respectively) and Mn²⁺ (33.00 and 35.83 mg kg⁻¹, respectively) during pre- and post- monsoon seasons, with values generally on par with the vegetable LUS in surface soil. Surface Cu²⁺ content was also highest in coconut soils (2.66 mg kg⁻¹) and was comparable to banana and vegetable systems. Vegetable LUS showed significantly higher K⁺ (144.00 and 125.50 mg kg⁻¹, respectively) and NH₄⁺-N (34.72 and 52.08 mg kg⁻¹, respectively) in surface and sub-surface. It also had higher Fe²⁺ (28.52, 18.34 mg kg⁻¹) and Al³⁺ (7.37, 7.84 mg kg⁻¹), along with the highest surface Cu²⁺ (2.66 mg kg⁻¹, on par with banana and coconut) and consistently highest Zn²⁺ in both seasons. Uncultivated fallow land recorded the lowest concentrations of Ca²⁺, Mg²⁺, Na⁺, K⁺, NH₄⁺-N, Fe²⁺, Al³⁺, Cu²⁺, Mn²⁺ and Zn²⁺ during both the pre- and post-monsoon seasons. Irrespective of the land use systems, the concentration of cations tends to decrease with the depth. Irrespective of the season, concentration of anions like nitrates (84.56 and 64.40 mg kg⁻¹, respectively), sulphates (31.15 and 28.15 mg kg⁻¹, respectively) and silicates (29.69 and 32.54 mg kg⁻¹, respectively) were significantly higher in the surface soils of vegetable LUS. MoO₄²⁻ content was also greater under this system, measuring 389.85 μg kg-1 in surface pre and post monsoon and 350.10 μg kg-1 in sub surface pre and post-monsoon. However, banana LUS recorded the highest PO₄³⁻ levels in both seasons in surface, with 18.97 mg kg⁻¹ in surface soil and 16.55 mg kg⁻¹ in sub surface soil. Similarly, BO₃³⁻ concentrations were highest in banana LUS, with values of 0.667 mg kg⁻¹ in surface soil pre and post monsoon and 0.618 mg kg⁻¹ in sub surface pre and post-monsoon. Irrespective of the land use systems, the concentration of anions tends to decrease with the depth. Across the land use systems, CAB values remained positive which indicates surplus of cations over anions implying a change in ionic balance in these systems, which may lead to nutrient imbalances. The CAB values were in the order of coconut ˃ vegetable ˃ banana ˃ uncultivated fallow which signifies that CAB in soil is influenced by both soil and crop characteristics. Proper soil management practices are essential to maintain CAB and to optimize soil health and crop productivityItem Land use induced changes in cation anion balance of southern laterite soils of Kerala(Department of Soil Science and Agricultural Chemistry, College of Agriculture,Vellayani, 2026) Surya, G B; Raji SwaroopThe study entitled “Land use induced changes in cation anion balance of southern laterite soils of Kerala” was conducted in the Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani during 2024-2025 with the objective of assessment of variability in the distribution of cations and anions as influenced by land use systems and seasons in the southern laterite (AEU 8) of Kerala. Georeferenced soil samples were collected from twenty different locations of four major land use systems (LUS) of the southern laterite soils of Kerala viz., banana, coconut, vegetable and uncultivated fallow lands, from the surface (0–15 cm) and sub-surface (15–30 cm) layers during both the pre- monsoon and post-monsoon seasons. The collected soil samples were analysed for physical properties, electrochemical properties, biological properties and cation- anion concentrations. An incubation experiment was conducted with the samples collected from the pre monsoon season to find out the effect of moisture content on cation anion concentration. During the incubation period, the concentrations of cations viz., NH₄⁺-N and Fe²⁺ displayed a pronounced decrease with the reduction in moisture content and the values recorded were statistically significant. Among the anions, NO₃⁻, SO₄²⁻ and PO₄³⁻ exhibited significant reduction with decrease in moisture content. Out of the five locations of the banana, coconut, vegetable and fallow land use systems, three were classified as sandy clay loam, one as silty clay loam and one as clay loam in texture. No variation in texture was observed in the sub surface layers. During the pre and post monsoon season in surface soil, significantly higher bulk density was noticed in the samples from banana LUS (1.20 Mg m-3) which was on par with coconut and uncultivated fallow LUS and lowest was observed in vegetable LUS (1.03 Mg m-3). Coconut LUS showed the highest pH (5.67) at 0-15 cm depth for pre and post monsoon. Significantly higher CEC (6.30 cmol(+) kg⁻¹) was recorded in the surface soils of coconut land use system. Conversely, vegetable LUS registered the maximum AEC (0.719 cmol(– ) kg⁻¹) in surface. Irrespective of the season and depth, the uncultivated fallow land showed the lowest values for pH, CEC and AEC. Coconut LUS recorded the significantly higher contents of Ca²⁺ (298 and 268 mg kg⁻¹, respectively), Mg²⁺ (98 and 78 mg kg⁻¹, respectively), Na⁺ (58 and 40 mg kg⁻¹, respectively) and Mn²⁺ (33.00 and 35.83 mg kg⁻¹, respectively) during pre- and post- monsoon seasons, with values generally on par with the vegetable LUS in surface soil. Surface Cu²⁺ content was also highest in coconut soils (2.66 mg kg⁻¹) and was comparable to banana and vegetable systems. Vegetable LUS showed significantly higher K⁺ (144.00 and 125.50 mg kg⁻¹, respectively) and NH₄⁺-N (34.72 and 52.08 mg kg⁻¹, respectively) in surface and sub-surface. It also had higher Fe²⁺ (28.52, 18.34 mg kg⁻¹) and Al³⁺ (7.37, 7.84 mg kg⁻¹), along with the highest surface Cu²⁺ (2.66 mg kg⁻¹, on par with banana and coconut) and consistently highest Zn²⁺ in both seasons. Uncultivated fallow land recorded the lowest concentrations of Ca²⁺, Mg²⁺, Na⁺, K⁺, NH₄⁺-N, Fe²⁺, Al³⁺, Cu²⁺, Mn²⁺ and Zn²⁺ during both the pre- and post-monsoon seasons. Irrespective of the land use systems, the concentration of cations tends to decrease with the depth. Irrespective of the season, concentration of anions like nitrates (84.56 and 64.40 mg kg⁻¹, respectively), sulphates (31.15 and 28.15 mg kg⁻¹, respectively) and silicates (29.69 and 32.54 mg kg⁻¹, respectively) were significantly higher in the surface soils of vegetable LUS. MoO₄²⁻ content was also greater under this system, measuring 389.85 μg kg-1 in surface pre and post monsoon and 350.10 μg kg-1 in sub surface pre and post-monsoon. However, banana LUS recorded the highest PO₄³⁻ levels in both seasons in surface, with 18.97 mg kg⁻¹ in surface soil and 16.55 mg kg⁻¹ in sub surface soil. Similarly, BO₃³⁻ concentrations were highest in banana LUS, with values of 0.667 mg kg⁻¹ in surface soil pre and post monsoon and 0.618 mg kg⁻¹ in sub surface pre and post-monsoon. Irrespective of the land use systems, the concentration of anions tends to decrease with the depth. Across the land use systems, CAB values remained positive which indicates surplus of cations over anions implying a change in ionic balance in these systems, which may lead to nutrient imbalances. The CAB values were in the order of coconut ˃ vegetable ˃ banana ˃ uncultivated fallow which signifies that CAB in soil is influenced by both soil and crop characteristics. Proper soil management practices are essential to maintain CAB and to optimize soil health and crop productivity.Item Evaluation of STCR based targeted yield equations of oriental pickling melon (Cucumis melo var. conomon) in Southern laterites(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2022) Archana Santhosh; Visveswaran ,SThe present study entitled “Evaluation of STCR based targeted yield equations of oriental pickling melon (Cucumis melo var. conomon) in southern laterites” was carried out in the Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani during 2020-2021. In this study, a randomized block design-based field experiment was conducted to test verify the targeted yield equation developed by STCR 2007 for oriental pickling melon for cultivating it at AEU 8. A farmer’s field was selected in Kalliyoor gram panchayath, Thiruvananthapuram for the field experiment. The variety used in the study was Mudicode. The test experiments included five treatments namely, POP KAU with organic manure management (T1), POP KAU based on soil test (T2), STCR recommendation for a targeted yield of 30 tonnes (T3), STCR recommendation for a targeted yield of 34 tonnes (T4) and STCR recommendation for a targeted yield of 38 tonnes (T5). The targeted yield equation used in the study is; FN = 3.24T – 0.095SN – 0.084ON FP2O5 = 1.64T – 1.332SP – 0.226OP FK2O = 3.16T – 0.068SK – 0.134OK Were, FN, SN and ON is fertilizer nitrogen dose, nitrogen contribution of soil and nitrogen contribution (in kg ha-1) of organic sources respectively. FP2O5, SP and OP are fertilizer phosphorus dose, phosphorus contribution (in kg ha-1) of soil and organic sources respectively. FK2O, SK and OK are fertilizer potassium dose, potassium contribution (in kg ha-1) of soil and organic sources respectively. Here T is the yield targeted in tonnes ha-1. Initial, soil fertility status, nutrient status of organic manures which was used in the field were analysed to calculate the fertilizer dose in T3, T4 and T5. Biometric observations, yield parameters, pre- and post-harvest physicochemical properties of soil and the nutrient content in shoot, root, fruits and dry matter production were recorded to study their influence on yield. Among the treatments, T5 (STCR recommendation for a targeted yield of 38 tonnes) is found to be superior in the biometric and yield observations taken. The 123 targeted yield of 38 tonnes was achieved in this treatment. A maximum fruit length, girth and weight were observed in T5. The major contributing factor for yield increase was the increase in the number of fruits per vine. The vine length and internodal distance were maximum in T5 and days to the appearance of male and female flowers were found to be minimum in T5. There was no significant difference between the treatments while considering the particle density, bulk density, porosity, water holding capacity and porosity. The highest level of primary nutrients was observed in T5 and lowest was observed in T1. The plant nutrient content was analyzed for different plant parts to study the nutrient uptake. The highest uptake of primary nutrients was observed in T5 where the highest yield was also observed. The lowest uptake of nutrients was observed in T1 which yielded the least. This reveals that the fertilizer application can have a direct effect on nutrient uptake and thereby improve the yield of the crop as long as the supplied nutrient is well within the optimum range of crop as suggested in the Mistcherlich equation. The study concluded that the yield targets can be achieved using the targeted yield equations developed for oriental pickling melon in AEU 8. The crop responded positively to higher fertilizer doses in T5 which is reflected in the results obtained while analysing the nutrient content of the crop and the nutrient uptake studies. There was no significant difference between the treatments when the plant secondary and micronutrient content was studied. These nutrients were maintained in a sufficiency range. While considering the economic aspect too, T5 showed superiority over the treatments. The STCR- IPNS based targeted yield equations incorporating recommended organic manures for oriental pickling melon for target up to 38 tonnes per ha can be adopted in AEU 8 as the yield targets can be achieved with optimum use of fertilizers without deterioration of the soil quality and yield. . It also provides serious insights towards improving productivity by optimizing fertilizer dose. This will be useful in upgrading the existing package of practices and doing significant need based research in future which is a vital step towards perfecting the package of practices of KAU.Item 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, BThe 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.Item Standardization of cold plasma treatment for nitrogen fixation in major soil types of Kerala and its effect on seedling growth of cowpea(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellanikkara, 2025) Deepthi, P.; Prabha Susan PhilipPlasma, often referred to as the fourth state of matter is an ionized gas that can be generated in various gases or gas mixtures across a wide range of pressures and temperatures. Cold plasma assisted nitrogen fixation is a green technology to fix atmospheric nitrogen (N₂ ) through the generation of highly energetic electrons and reactive radicals and this also involves synthesis of ammonia and nitrogen oxides (NOx) or nitrates/nitrites (NO₃ ⁻ /NO₂ ⁻ ). A study titled “Standardization of cold plasma treatment for nitrogen fixation in major soil types of Kerala and its effect on seedling growth of cowpea” was conducted to explore the potential of plasma treatment for nitrogen fixation at the Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellanikkara during 2023-24. Surface soil samples were collected from seven major soil types of Kerala viz laterite soils, red loam soils, Onattukara sandy soils, coastal sandy soil, Kari soils, Pokkali soils and black soils. The soils were initially characterized for physico-chemical and biological properties and were subjected to cold plasma and Plasma Activated Water (PAW) treatments at low (5 kV), medium (10 kV) and high (15 kV) voltages for 10 minutes. Among the studied soil types, coastal sandy soil (7.34) was neutral; black soil (7.50) was of alkaline reaction and the other soils were acidic in reaction with pH varying from 2.95 (ultra-acidic) in kari soil to 6.32 (slightly acidic) in red loam soil. Pokkali soil recorded higher status with respect to EC (6.57 dS m-1), available N (570.75 kg ha-1), P (168.84 kg ha-1), K (442.55 kg ha-1) and B (2.00 mg kg-1). High values were recorded in Kari soil for parameters like organic carbon (99.60 g kg-1), Fe (1004.50 mg kg-1), S (651.30 mg kg-1) and Zn (4.18 mg kg-1). Soil pH and organic carbon content has significantly increased after cold plasma treatment in all the soil types under study except Kari soil, which showed reduction in both parameters. Electrical conductivity (EC) has decreased in all soils except Pokkali soil. Cold plasma treatment could enhance nitrogen status in all the selected soil types. Available nitrogen level was highest at 15 kV treatment for all the soils except Kari and coastal sandy soil, which have shown the peak value at 10 kV. The highest per cent increase in available nitrogen content has shown by coastal sandy soil at 5 kV (214.30 per cent) and 10 kV (457.20 per cent) and by black soil at 15 kV (269.56 per cent). Highest ammoniacal nitrogen content was observed at 5 kV in Kari (198.80 mg kg-1), coastal sandy (142.80 mg kg-1) and Pokkali soils (205.80 mg kg-1), at 10 kV in red loam soil (159.60 mg kg-1) and at 10 kV (161.00 mg kg-1) and 15 kV (155.40 mg kg-1) in laterite soil. Microbial activity has reduced in all soils after cold plasma treatment. Plasma Activated Water (PAW) has significantly reduced soil pH in all soils except Onattukara sandy soil. Organic carbon content has shown significant reduction in all soils, except red loam soil. Available nitrogen content was highest at 15 kV for all soils except red loam soil, which has shown peak value at 10 kV. Coastal sandy soil has shown highest per cent increase at 5 kV (214.31 per cent), 10 kV (500.05 per cent) and 15 kV (557.20 per cent). Ammoniacal and nitrate nitrogen content was highest at 15 kV for all the selected soils except red loam soil, for which nitrate nitrogen was highest at 10 kV. Microbial activity and dehydrogenase activity has significantly reduced after PAW treatment, while urease activity has increased. A pot culture study was conducted to study the effects of plasma treatment on seedling growth of cowpea. Treatments included control (T1), plasma treatment (T2), plasma activated water treatment (T3) and cold plasma and plasma activated water treatment (T4). Total chlorophyll and protein content were significantly higher under treated conditions. Total nitrogen content was significantly higher in seedlings grown under plasma (T2) and plasma and PAW treated (T4) laterite (50.05 g kg-1) and black soil (50.05 g kg-1) and in plasma treated (T2) Kari soil (80.50 g kg-1). Seedlings grown under PAW treated black soil has shown significant increase in phosphorus (0.29 g kg- 1), zinc (94.44 mg kg-1) and copper (32.22 mg kg-1) content. Results of the study indicate that, cold plasma and plasma activated water treatment could assist nitrogen fixation in all the selected soils and treatment at a voltage of 5 kV can be considered as optimum for sufficient nitrogen fixing in the soils with low energy consumption and minimum impact on soil microbes. The feasibility and ease of application make plasma activated water more effective approach for enriching soil nitrogen.Item Diagnostic standards for compositional nutrients in banana cv. nendran for southern laterites of Kerala(Department of Soil Science and Agricultural Chemistry, College of Agriculture,Vellayani, 2025-04-21) Fathima Fairoosa, K T.An exploratory research work entitled "Diagnostic standards for compositional nutrients in banana cv. Nendran for Southern laterites of Kerala" was undertaken in Department of Soil Science and Agricultural Chemistry from December 2023 to October 2024 to formulate Compositional Nutrient Diagnostic (CND) standards for the identification of nutrient imbalances in the banana cultivar Nendran. The objective of the study was to develop CND norms to assess the nutrient imbalance in Nendran variety of banana for Southern laterite soils of Kerala (AEU 8). Geo-referenced soil samples were collected from the surface (0-15 cm) and subsurface (15-30 cm) layers of banana fields across 120 locations from 24 panchayats of AEU 8 viz., Parassala, Karode, Chenkal, Kulathoor, Thirupuram, Poovar, Perumkadavila, Kollayil, Kunnathukal, Athiyanoor, Aryancode, Kanjiramkulam, Kottukal, Vizhinjam, Venganoor, Pallichal, Vilappil, Malayinkeezh, Maranalloor, Kalliyoor, Balaramapuram, Vilavoorkal, Kattakada and Karakulam. Corresponding one-twenty plant samples were collected from the index leaves of banana plants at each location. The chemical analysis of soil samples showed that the surface soil pH ranged from 5.78 to 6.89, averaging 6.28, while the subsurface pH varied between 5.55 and 6.57 with a mean value of 6.08. Electrical conductivity values recorded varied from 0.16 to 0.60 dS m-1 for surface soil and 0.13 to 0.51 dS m-1 for subsurface soil. Organic carbon content ranged from 0.75 to 1.53 per cent in surface soil and from 0.58 to 1.63 per cent in subsurface soil, with the surface soil generally showing higher levels. The pH, electrical conductivity, and organic carbon content all showed a decrease with soil depth. Available nutrient content generally decreased with depth. The available nitrogen content in surface soil ranged from 253.38 to 481.69 kg ha-1, while in subsurface soil, it varied between 213.24 and 461.61 kg ha-1. Phosphorus availability in surface soil exhibited a range from 16.94 to 79.09 kg ha-1 whereas in subsurface soil it ranged from 14.37 to 71.64 kg ha-1. In the surface soil potassium had an average availability of 224. 46 kg ha-1 while in subsurface soil availability fell between 141. 12 and 226.24 kg ha-1. Calcium content in surface soil ranged from 190 to 386 mg kg-1 while in subsurface soil it varied between 154 and 336 mg kg-1. Magnesium levels in 148 surface soil were between 56 and 132 mg kg-1 compared to 39.6 to 103.2 mg kg-1 in subsurface soil. Sulphur content ranged from 17.4 to 30.60 mg kg-1 in surface soil and from 14.40 to 20.32 mg kg-1 in subsurface soil. Available iron content of surface soil ranged between 7.69 and 48.55 mg kg-1 and that of subsurface soil varied from 7.21 to 44.97 mg kg-1. Manganese levels exhibited a mean value of 22.50 mg kg-1 in surface soil and 19.86 mg kg -1 in subsurface soil. Zinc content was found a range from 2.10 to 9.92 mg kg-1 in surface soil while in subsurface soil it varied from 3.10 to 8.85 mg kg-1 averaging 4.05 mg kg-1. Available copper in subsurface soil ranged from 1.10 to 3.42 mg kg-1 and in surface soil it varied between 1.20 and 3.53 mg kg-1. Boron content in surface soil varied between 0.81 and 0.32 mg kg-1 while in subsurface soil it ranged from 0.27 to 0.69 mg kg-1. Available nickel ranged from 1.36 to 7.05 mg kg-1 in surface layer and 1.28 to 5.55 mg kg-1 in subsurface layer while molybdenum values exhibited a mean value of 0.29 mg kg-1 in surface layer and 0.28 mg kg-1 in subsurface layer. The nutrient composition of banana leaves in AEU 8 was analyzed revealing nitrogen levels between 2.05 and 4.36 per cent, phosphorus levels from 0.15 to 0.25 per cent, Potassium ranged from 1.35 to 2.85 per cent and calcium varied between 0.42 and 0.75 per cent. Magnesium showed a range from 0.15 to 0.24 per cent and sulphur content ranged from 0.53 to 0.69 per cent. Iron concentrations were between 150.20 and 223.30 mg kg-1, manganese content ranged from 129.0 to 308.70 mg kg-1, zinc from 10.92 to 16.67 mg kg-1 and copper between 3.60 and 14.20 mg kg-1. Boron levels ranged from 8.80 to 23.60 mg kg-1. Nickel content in plant samples ranged from 0.92 to 3.73 mg kg-1 while molybdenum varied between 0.86 to 3.07 mg kg-1.The average banana bunch yields per panchayat varied from 9.63 kg plant -1 to 14.00 kg plant-1 with an overall average of 11.04 kg plant-1. Following the procedure by Parent and Dafir (1992), CND norms were developed. The nutrient content in banana leaves were first converted to percentages. Then, nutrient concentrations, residue values, simplex, and row-centered log ratios were calculated. The database was then divided into two sub-populations using the Cate-Nelson procedure, based on ranked yield values. The cumulative variance ratio is calculated by combining variance ratios at each iteration. This cumulative variance ratio function, FiC (VX), is expressed as a proportion of the total sum of variance ratios across all iterations. For yield Y, FiC (VX) exhibited a cubic pattern, with the inflection point indicating a change in model concavity, as identified by the second derivative. The yield cut- off value is determined at this inflection point. To classify a high and low yield subpopulation, the highest yield cut-off value was derived from cumulative values of the variance ratio for each nutrient. The maximum yield cut-off value was found for nitrogen which was 12.29 kg plant-1. CND norms are formulated by calculating the means and standard deviations of row-centered log ratios (VX) of nutrients in high-yield groups, denoted as V*N, V*P, V*K, etc., as well as their corresponding standard deviations (SD*N, SD*P, SD*K, etc.). The computed CND norms are as follows: V*N = 4.15± 0.35, V*P= 1.52± 0.16, V*K = 3.88± 0.32, V*Ca = 2.46± 0.33, V*Mg = 1.44± 0.21, V*S = 2.60± 0.18, V*Fe = -0.95± 0.19, V*Mn = -0.89± 0.27, V*Zn = -3.50± 0.17, V*Cu= -4.10± 0.38, V*B= -3.4± 0.51, V*Ni= -5.36± 0.37, V*Mo= -5.37± 0.28, V*Rd= 7.60± 0.11. The CND indices (IX) are computed using row-centered log ratios of the survey population VX, V*X, and SD*X values. These indices can be either positive or negative. Nutrient indices close to zero indicate an ideal nutrient balance. Negative values of CND indices suggest a deficiency of that nutrient with lower values indicating a greater deficiency. The CND indices calculated for banana cv. Nendran for AEU 8 (Southern laterites) are, IN = 0.20, IP = 0.30, IK = -0.03, ICa = 0.02, IMg = -0.58, IS = 0.06, IFe = 0.14, IMn = 0.19, IZn = 0.78, ICu= -0.12, IB = -0.15, INi= 0.19, IMo = -0.30 and IRd = -0.81. The calculated CND indices revealed magnesium as the most limiting nutrient, establishing the order of limiting nutrients as Mg > Mo > B > Cu > K > Ca > S > Fe > Mn > N > P > Zn.Item Chitosan -zeolite composite fertilizer formulation for sustained nutrient release and enhanced crop production(Department of Soil Science and Agricultural Chemistry, College of Agriculture,Vellayani, 2025) Adithya, M G.; Gladis, RThe study entitled “Seed invigoration studies in okra [Abelmoschus esculentus (L.) Moench]”was conducted at the Department of Seed Science and Technology, College of Agriculture, Vellanikkara, during 2022-2024. This research investigated the effects of osmopriming with PEG 6000 (13.5% at -0.25 MPa for six hours) and biopriming with Pseudomonas fluorescens @10g/kg on growth, yield, seed quality and seed longevity of five okra varieties—Aruna (V1), Anjitha (V2), Pusa-5 (V3), Salkeerthi (V4), and Varsha Uphar (V5). The study comprised two experiments. Experiment 1 focused on the effects of priming treatments on the varietal performance of okra in terms of growth, yield, and seed quality, while experiment 2 examined seed longevity under storage conditions. Experiment 1 followed a Randomized Complete Block Design (RCBD) with three replications, resulting in 15 treatment-variety combinations. Seeds of the five okra varieties were subjected to three priming treatments: T1 (osmopriming with PEG 6000 solution at -0.25 MPa for six hours), T2 (Pseudomonas fluorescens at 10 g/kg of seed), and a control (non-primed seeds). Experiment 2 followed a Completely Randomized Design (CRD) with the same priming treatments and varieties replicated three times. Seed initial quality parameters were assessed immediately after priming treatment. Among the varieties Salkeerthi (V4) achieved the highest germination rate followed by Varsha Uphar and showed superior performance over other varieties due to high seed vigour indices and lowest EC. The combination Salkeerthi-PF (V4×T2: 93.66 %) followed by Varsha Uphar-PF (V5xT2: 90.66%) showed superiority in seedling vigour and growth attributes of okra In the Experiment 1, the results indicated that both priming treatments significantly enhanced field performance across all varieties compared to the control. Varieties displayed significant variation in growth, yield, and seed quality traits. Varsha Uphar (V5) emerged as the top performer for field emergence, early flowering plant height and seed yield per plant under priming conditions. Pusa-5 (V3) showed superior fruit weight and yield per plant, with the combination Pusa-5 x Pseudomonas fluorescens recording the highest number of fruits per plant and Pusa-5 x PEG producing the highest fruit weight and yield. Salkeerthi (V4) exhibited the highest seed count per pod. Among the treatments, T2 (Pseudomonas fluorescens) consistently demonstrated a greater positive impact on growth, fruit yield, and seed quality compared to T1 (PEG 6000 (13.5% at -0.25 MPa for six hours). In the Experiment 2, storage study was conducted with the same five okra varieties, using the same priming treatments along with control. Seed quality parameters were monitored for six months. All varieties and treatments maintained germination rates well above the Indian Minimum Seed Certification Standard (IMSCS) threshold of 65 percent. However a progressive decline in seed quality was observed over time. This decline was evident in reductions in key traits such as shoot length, root length, seedling dry weight, vigour indices, and enzymatic activities including dehydrogenase, α-amylase, and catalase. Concurrently, negative trends were noted, with increases in parameters such as electrical conductivity (indicating membrane deterioration), mean germination time, time to 50 percent germination, seed moisture content, and the percentage of microflora contamination, all of which are indicators of seed aging and reduced vigour. Among the varieties evaluated, Salkeerthi (V4) consistently emerged as the top performer in maintaining superior seed quality during the storage period followed by Varsha Uphar. This was particularly notable when the seeds were treated with T2 (Pseudomonas fluorescens). Seeds treated with T2 retained higher enzymatic activity, including significantly enhanced levels of dehydrogenase, α-amylase and catalase, which are critical for metabolic processes during germination. These enzymes are known to play essential roles in energy production, starch breakdown, and oxidative stress management, contributing to better seed vigour and viability. This superior performance highlighted the potential of biological priming with Pseudomonas fluorescens not only improved seedling vigour during cultivation but also mitigate the negative effects of storage, ensuring sustained seed quality over time.Item Synthesis and evaluation of biochar based zinc oxide(ZnO) composite as a slow release fertilizer(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellanikkara, 2025) Malavika, J.Biochar is a carbon-rich material produced from organic residues through the pyrolysis process under limited oxygen supply. The versatile properties of biochar include high porosity, high surface area, and an abundance of surface functional groups, making it beneficial as a soil amendment, for carbon pool, for heavy metal adsorbent, as well as slow-release fertilizer. The study entitled “Synthesis and Evaluation of Biochar-Based Zinc Oxide Composite as a Slow- Release Fertilizer” was conducted in the Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellanikkara during 2022-2024. This study comprised of two experiments. The first experiment, the coconut fronds (CF) were used as feedstocks for biochar production at two different temperatures, viz 450℃ and 650℃. The biochar obtained at respective temperatures was evaluated for their physicochemical properties, including pH, EC, volatile matter, ash content, and macro- and micronutrient composition, to determine variations based on temperature. The finely sieved biochar undergone surface characterisation techniques such as Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Brunauer-Emmett-Teller (BET) analysis, and X-ray Diffraction (XRD) to assess surface morphology, functional groups, surface area, and crystallinity, respectively. In the experiment, from CF 450 and CF 650 biochar, corresponding biochar composites (BBZOC 450 and BBZOC 650) were prepared using a biochar-sodium hydroxide solution and a zinc nitrate-starch solution in a 1:1 ratio. The prepared BBZOC were also analysed for their physicochemical properties. The physical properties showed that CF 450 biochar had a higher recovery percentage (35.80%) than CF 650 biochar (28.30%). CF 650 biochar exhibited higher ash content (17.90%), bulk density (0.131 g/cm³), pH (10.70), EC (6.7 dS/m), and pHzpc (10.80), while CF 450 biochar had lower values for these parameters (16.66% ash content, 0.13 g/cm³ bulk density, pH 10.34, EC 4.50 dS/m, and pHzpc 9.50). The macro- and micronutrient concentrations decreased with increasing pyrolysis temperature. The mineral composition of CF 650 biochar were 55.95% carbon, 1.63% hydrogen, 0.56% nitrogen, 25.20% oxygen, 0.25% S, 0.28% P, 1.142% K, 1.54% Ca, and 2.52% Mg, along with trace amounts of Fe, Mn, Zn, Cu, and B. CF 450 biochar contained 50.86% carbon, 2.36% hydrogen, 0.4% nitrogen, 28.14% oxygen, 0.22% S, 0.22% P, 0.90% K, 1.25% Ca, and 2.26% Mg, along with trace amounts of Fe, Mn, Zn, Cu, and B. The FTIR characterisation techniques depicted the presence of more functional groups in CF 450 biochar as compared to CF 650 biochar. The XRD spectra confirmed the presence of KCl and SiO₂ in both CF 450 and CF 650, with the indication of broad wide spectra. The BET analysis exhibited a greater surface area for CF 650 biochar, with more number of pores concentrated below the 10 nm range, whereas CF 450 biochar showed more number of pores concentrated in the 10– 100 nm range. The elemental ratio analysis of biochar exhibited higher aromaticity, hydrophilicity, and polarity for CF 650 biochar than CF 450 biochar. The physico-chemical analysis of BBZOC showed a decline in the pH, with values viz. 7.36 for BBZOC 650 and 7.91 for BBZOC 450. The results also showed an increase in bulk density in the BBZOC (from 0.13 to 0.23 g/cm³ in BBZOC 650 and from 0.131 to 0.19 g/cm³ in BBZOC 450) due to the formation of zinc oxide. The surface characterisation techniques revealed an enhanced surface area with a decreased pore diameter in BBZOC 450, whereas BBZOC 650 exhibited a decreased surface area. The presence of white deposits on the BBZOC surface in SEM analysis and the appearance of 536 cm⁻¹ and 499 cm⁻¹ peaks in FTIR spectra confirmed ZnO bonding and the formation of zinc oxide on the biochar. Elemental ratio analysis indicated increased aromaticity, hydrophilicity, and polarity in BBZOC due to oxygen addition. Water absorbance, swelling ratio, equivalent water content, and water retention studies showed that BBZOC 450 exhibited slightly better water absorbance and retention compared to corresponding CF 450 biochar. In the second experiment, biochar and its corresponding BBZOC were used to study the slow-release pattern of zinc in both water and soil. In the water column study, leachates were analyzed at 1, 3, 5, 10, 15, and 30 days. Similarly, in the soil column study, leachate were analyzed at 1, 3, 5, 10, 15, 30, and 60 days using five different treatments (10 g, 20 g, 30 g, and 40 g of BBZOC). The results of soil column showed a cumulative release of zinc and zinc content were estimated as 1665.53 mg/L and 2054.09 mg/L for BBZOC 650 and BBZOC 450, respectively. In the water column study, cumulative zinc release was 273.608 mg/L and 411.480 mg/L for BBZOC 650 and BBZOC 450, respectively. The data thus obtained from both the soil and water column study picturizes that the BBZOC 450 exhibited greater zinc release compared to BBZOC 650, with the highest release at an application rate of 40 g BBZOC treatment. The results confirmed that BBZOCs can function as an efficient slow-release fertilizer, providing gradual zinc release over time.Item Standardization of production technique of liquid organic manure (Panchagavya) for soil health and crop productivity(Department of Soil Science and Agricultural Chemistry, College of Agriculture,Vellayani, 2025) Raseena Mol.; Gowri PriyaThe study, “Standardization of production technique of liquid organic manure (Panchagavya) for soil health and crop productivity,” aimed at standardizing Panchagavya production to reduce local variability, evaluating its chemical properties, and assessing its impact on soil health and crop productivity using bhindi (var. Anjitha) as a test crop. The research was divided into two parts: standardizing the Panchagavya production method and evaluating its influence on soil health and crop productivity. To determine the optimal composition, the study used eight ingredients in 81 combinations, testing four key components (cow urine, ghee, milk and curd) in varying amounts, while keeping the levels of cow dung, coconut water, jaggery and banana constant. The design followed a Completely Randomized Design (CRD) with two replications. The Panchagavya preparations were analyzed for physical and chemical properties, and a germination study evaluated their phytostimulant potential. Based on this, the 20 most effective treatments were selected, and their biochemical constituents were analyzed. Principal Component Analysis (PCA) was then conducted to select the top ten treatments, followed by a microbial count analysis. The Panchagavya preparations from all treatments had an acidic pH, ranging from 5.11 to 5.76. Electrical conductivity (EC) ranged from 6.00 dS m-1 to 7.15 dS m-1, and nutrient content varied significantly across treatments, with T81 generally having the highest values. The nitrogen levels varied from 1.12 per cent to 2.66 per cent, phosphorus from 0.12 per cent to 0.39 per cent, and potassium from 0.35 per cent to 0.66 per cent. Calcium content ranged from 186.30 mg L-1 to 256.60 mg L-1, while micronutrients like Fe, Mn, Zn and Cu were also measured, with T81 often exhibiting the highest concentrations. All Panchagavya preparations improved bhindi seed germination compared to the control, though differences between treatments were not statistically significant. Root length ranged from 2.40 cm in T1 to 4.98 cm in T81 which showing a 114.66 per cent increase over the control. Based on the germination study, the top 20 treatments were selected. Indole acetic acid (IAA) and Gibberellic acid (GA) concentrations were highest 187 in T81 and lowest in T54 among these treatments. Ten treatments were further screened through PCA: T59, T60, T61, T62, T67, T68, T69, T70, T76 and T77. Among these, T70 showed the highest bacterial, fungal, and actinomycetes counts, indicating a robust microbial presence. To evaluate field-level effects, a pot experiment was conducted using the selected treatments (as T1–T10), a KAU POP recommendation (Crops, 2016) (T11) and a control without the application of any fertilizers of manures (T12). Post-harvest soil analysis indicated that Panchagavya-treated soils had lower bulk density and higher organic carbon content compared to the control. Treatments T8, T4, T7 and T10 showed the highest nutrient availability, including N, P and K and high values for microbial counts and soil enzyme activities like urease and dehydrogenase, enhancing soil health. Plant growth parameters in the pot experiment showed that T8 produced the tallest plants (137 cm), with the highest dry matter (73.93 g/plant) and chlorophyll content. Yield parameters, including fruit length, girth, number of fruits and average fruit weight, were also highest in T8, resulting in the highest total fruit yield per plant (365.04 g). Treatments T4, T7 and T10 performed in a similar manner with high protein content, low crude fibre, and high ascorbic acid in fruits. Nutrient analysis of bhindi shoots and fruits revealed that T8-treated plants had the highest concentrations of essential macro- and micronutrients (N, P, K, Ca, Mg, S, Fe, Mn, Zn and Cu), indicating enhanced nutrient uptake with no significant difference between treatments T4, T7 and T10. The highest Benefit-Cost (B:C) ratio was recorded in T8 and T4 (1.69). The results of the pot culture experiment indicated that treatment T8 (U12G1M3C2.5) exhibited superior quality effects on bhindi productivity, with no significant difference between the treatments T4, T7 and T10. Based on the B:C ratio analysis, treatment T4 was found to have a lower cost compared to treatment T8, making it a more economically viable option for farmers, which comprises of Panchagavya prepared with 2 L of cow urine, 0.75 kg of ghee, 4 L of milk, 2 L of curd, 7 kg of cow dung, 3 L of tender coconut water, 3 kg of jaggery, and 0.5 kg of ripe poovan banana.Item Soil phosphorus dynamics and its interactions in red sandy loam soils(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Padannakkad, 2025-06-19) Shiv Prasad, T; Nideesh, PThe study entitled “Soil phosphorus dynamics and its interactions in red sandy loam soils” was carried out at the instructional farm II, College of Agriculture, Padannakkad, to assess the short-term dynamics of phosphorus in the sandy loam soils cultivated with cowpea as modified by different amendments and to study its impact on growth and yield parameters of cowpea. The study was carried out in two parts; an incubation experiment and a field experiment. Soil samples collected from the instructional farm II were incubated at field capacity for three months, and analysis was done after the incubation period. Treatment combinations were T1 (Control), T2 (Soil test-based P fertilizer), T3 (T2 + ZnSO4 @ 20 kg ha-1), T4 (T2 + Borax @ 10 kg ha-1), and T5 (T2 + Lime @ 250 kg ha-1). Analysis of the soil samples before incubation experiment showed that the soil is very strongly acidic, non saline and high in organic carbon. Soil sample analysis after incubation showed a significant effect of lime application on the soil pH. Available P was also significantly affected by treatments and was highest in T4 (T2 + borax) and T5 (T2 + lime) treatments. Treatments have significant effect on the Phosphorus activity coefficient (PAC) also having higher values of 15.82% and 15.79% in T4 and T5 treatments respectively, indicating better conversion of total P to available P in those treatments. On analysing the different P pools, Ca-P and Fe-P pools were found at significantly higher levels in treatment T5 (T2 + lime), whereas the Al-P, loosely bound P, and reductant P were significantly higher in T4 (T2+ borax). The incubation study revealed that boron and lime application could help in enhancing the available P content in the soil. The application of borax has a significant effect on the soil P pools also indicating its role in enhancing the reserve soil P pools. The field experiment was laid out in a randomized block design with eight treatments and three replications. The treatment combinations were T1 (KAU POP based lime and fertilizers), T2 (Soil test-based fertilizers and lime), T3 (KAU organic POP ), T4 (T2 + ZnSO4 @ 20kg ha-1), T5 (T2 + Borax @ 10 kg ha-1), T6 (T2 + PSB), T7 (T3 + PSB) and T8 (T2 excluding P + Nano P @ 10ml L-1). The cowpea variety Kanakamony was used as a test crop for the field experiment. Results of the field experiment showed significant changes in the soil chemical properties and phosphorus pools. At flowering, T3 ( KAU organic POP) treatment showed significantly higher soil pH which was on par with T1 (KAU POP) treatment. Phosphorus pools were significantly affected by treatments. Available P content was significantly higher in T1 (KAU POP) and T2 (KAU organic POP) treatments, Fe bound P and Al bound P were significantly higher in T4 ( T2 + ZnSO4) treatment. Ca bound P and reductant P were significantly higher in T2 (Soil test-based fertilizer and lime) and T3 (KAU organic POP) treatments respectively. Loosely bound P was significantly higher in T1 (KAU POP) and Organic P content was higher in T3 (KAU organic POP) treatment. Total P was significantly higher in T7 (T3 + KAU organic POP) treatment. At post-harvest, there was no significant change in the soil pH, EC and OC. Available P was significantly higher in T1 (KAU POP) treatment which was on par with T2, T3 and T4 treatments. Fe bound P and Al bound P were significantly higher in T4 (T2 + ZnSO4) treatment, whereas Ca bound P and Reductant P were significantly higher in T3 (KAU organic POP) treatment. Organic P was significantly higher in T1 (KAU POP) and T3 (KAU organic POP) treatments. Loosely bound P was significantly higher in T7 ( T3 + KAU organic POP) and total P was highest in T3 and T7 treatments. Treatment T2 (soil test based fertilizer and lime) had significantly higher PAC (Phosphorus activation coefficient) values at flowering and post-harvest stages (14.977 and 11.443% respectively) than the other treatments. The plant analysis results revealed that higher N and P were recorded in treatment T8 and K content was highest in treatment T1. Total Ca, Mg and Fe were highest in treatment T2. Total S was highest in treatments T1 and T7. Total Cu and Mn were highest in treatment T3. Total Zn was highest in T4 and T7 treatments, whereas B was highest in T5. Application of amendments had no significant effect on the growth parameters of cowpea, while yield parameters like pod weight per plant, pod yield and grain weight were significantly affected by treatments. Pod weight per plant was highest in T3, T7 and T8 treatments while pod yield was maximum in T8. Grain yield was significantly higher in T7 and T8 treatments compared to other treatments. The study results revealed a change in the dynamics of phosphorus pools and soil properties with the application of different amendments. Application of lime helps in increasing available P in the soil. The synergistic and antagonistic behaviour of added amendments such as B and Zn were also seen affecting different pools and hence the available P. Even though the available P is very high in the coastal sandy soils, a small amount of fertilizer addition is necessary to ensure the sustainable release of phosphorus from the reserve pools, as is evident from the PAC values. The addition of amendments such as Borax, ZnSO4, etc., could help in fixing excess P in the soil and can thus reduce the negative impact on the environment and soil. Borax can also help in the sustainable release of fixed P from the reserve pools. Foliar application of nano P fertilizer (DAP) was found to increase the yield parameters and is an alternate option for ensuring P supply to plants without adding P to the soils.