1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
Permanent URI for this communityhttp://localhost:4000/handle/123456789/1
Browse
25 results
Search Results
Item Biostimulants for enhancing soil biological properties in wetland ecosystem(Department of Soil science and Agricultural Chemistry,, College of Agriculture, Vellayani, 2025-06-16) Kamali,B; Aparna,BThe study entitled “Biostimulants for enhancing soil biological properties in wetland ecosystem” was undertaken in Department of Soil Science and Agricultural Chemistry during the period December 2022 to October 2024. The objective of the study was to assess the effect of selected biostimulants in a wetland ecosystem on soil biological properties for crop growth and yield. The project was envisaged in four different parts, collection of geo-referenced soil samples from rice growing tracts of Southern Kerala, generation of thematic maps with highlighting Biological Fertility Index (BFI), characterization of biostimulants and evaluation of biostimulants through pot culture and field experiment. Geo-referenced soil samples (100 samples) were collected from five agroecological units (AEUs) viz. AEU 3 (Onattukara sandy soil), AEU 4 (Kuttanad soil), AEU 5 (Pokkali soil), AEU 8 (Southern laterites), and AEU 9 (South central laterites) of Southern Kerala at a depth of 0-15 cm. The collected samples were subjected to the characterization of soil biological properties. The biological properties of soil across the agroecological units (AEUs) exhibited notable variations. AEU 4 (Kuttanad soil) recorded the highest organic carbon (3.03 ± 1.19 %), microbial biomass carbon (628.57 ± 207.76 µg g-1), β-glucosidase activity (76.70 ± 14.88 µg p-nitrophenol g-1 soil h⁻¹) and acid phosphatase activity (111.60 ± 17.94 µg p- nitrophenol g-1 soil h-1). AEU 5 (Pokkali soil) noticed the highest microbial biomass nitrogen (197.30 ± 60.72 µg g-1), soil respiration (5.28 - 11.01 mg CO₂ g-1), dehydrogenase activity (682.54 ± 189.76 µg TPF g-1 soil h-1) and protease activity (111.09 ± 42.04 µg tyrosine g-1 soil h-1). In contrast, AEU 8 (Southern laterites) recorded the lowest microbial biomass nitrogen (50.17 ± 15.76 µg g-1), microbial biomass carbon (163.65 ± 84.16 µg g- 1), water soluble carbon, labile carbon, enzyme activities and microbial population. Using Principal Component Analysis (PCA), dehydrogenase was selected as PC1 (0.913), organic carbon from PC2 (0.669), microbial biomass carbon from PC3 (0.702), soil respiration from PC4 (0.847), and microbial biomass nitrogen from PC5 (0.721). The Biological Fertility Index (BFI) was computed using the procedure prescribed by Brookes et al. (1995). It was noted that AEU 5 recorded the highest biological fertility index, followed by AEU 4, AEU 9, AEU 3 and AEU 8 (AEU 5 > AEU 4 > AEU 9 > AEU 3 >AEU 8). The lowest biological fertility index (AEU 8) was selected for the pot culture experiment to evaluate the biostimulants. In Part II of the study, characterization of the biostimulants was carried out. As Part III of the study, a pot culture experiment was conducted in 2023 at the Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, to evaluate the effects of various biostimulants on rice (Oryza sativa L.) growth and yield. The rice variety used was Uma and the treatments consisted of RDF (100 % RDF: 90:45:45 kg N, P₂O₅, K₂O per hectare), supplemented with FYM and lime as per KAU POP. Treatments included T1 (RDF + Seaweed extract at 12.5 kg ha-1), T2 (RDF + Humic acid at 10 kg ha-1), T3 (RDF + Fulvic acid at 5 kg ha-1), T4 (RDF + Lignosulphatehumate at 10 kg ha-1), T5 (RDF + Protein hydrolysate at 2.5 kg ha-1), T6 (RDF + Panchagavya at 3 %), T7 (RDF + PGPR mix- 1 at 2 %), T8 (RDF + Pseudomonas consortium at 2 %), T9 (RDF as per KAU POP) and T10 (Absolute control). This study involved the evaluation of different treatments on soil chemical, biological and enzymatic properties across three crop stages. T2 (RDF + Humic acid) recorded the highest pH, organic carbon, available K, Mg, B and enzyme activities of β- glucosidase, amylase and the lowest EC. T7 (RDF + PGPR mix-1) exhibited the highest available N, available P, labile carbon, microbial biomass carbon, soil respiration, glomalin content and enzyme activities of dehydrogenase, acid phosphatase and protease, along with the highest microbial populations. The highest available S was noticed in T1 (RDF + Seaweed extract), whereas, water soluble carbon in T3 (RDF + Fulvic acid). In contrast, T10 (Absolute control) recorded the highest micronutrient content (Fe, Mn, Zn and Cu). The enzyme activity number was computed based on the activity of five different enzymes viz., dehydrogenase, catalase, acid phosphatase, protease and amylase proposed by Beck (1984). The highest EAN was in T7 (RDF + PGPR mix-1) at 20.28, followed by T2 (RDF + Humic acid) at 19.45, T1 (RDF + Seaweed extract) as 18.63. Growth and yield parameters, including plant height, tillers, thousand grain weight and yield were the highest in T7 (RDF + PGPR mix-1). Chlorophyll content was the highest in T7 comparable to T2 (RDF + Humic acid), while proline content was the highest in control. N and P content along with their uptake in straw and grain were the highest in T7 (RDF + PGPR mix-1) while treatment T2 recorded the highest K content and uptake. Micronutrient content (Fe, Mn, Zn and Cu) in straw and grain were the highest in controlwith significant difference compared to other treatments, but uptake was the lowest. However, the lowest micronutrient content was recorded in T2 (RDF + Humic acid). The root parameters such as active roots, root length, root dry weight, root volume were reported the highest in T7 (RDF + PGPR mix-1). SEM micrograph of rice roots revealed that PGPR mix-1 enhanced microbial colonization and root-microbe interactions, with biofilm-like structures. Treatment with Humic acid resulted in moderate microbial attachment. This was further confirmed by TEM with higher magnification, with the presence of PGPR within the epidermal layers and near the cell walls of rice roots. Bacterial colonization in the root tissues was absent in SEM and TEM images of the control samples. Root metabolites such as p-coumaric acid, vanillic acid, and syringic acid were observed and found that significant variation among the treatments with the highest concentrations found in T7 (RDF + PGPR mix-1), followed by T2 (RDF + Humic acid) and T1 (RDF + Seaweed extract). The standing water analysis showed a slight increase in pH from the 1st to 14th week and the highest pH was observed in T2 (RDF + Humic acid). Total Fe and Al were the highest in the absolute control while the CO2 evolution rate was highest in T7 (RDF + PGPR mix-1). From the interpretations of results of pot culture experiment, based on the enzymatic activities, nutrient uptake, plant growth, yield and root parameters, three best treatments were selected such T7 (RDF + PGPR mix 1), T2 (RDF + Humic acid) and T1 (RDF + Seaweed extract). In Part 1V of the study, the superior three treatments from the pot culture experiment were evaluated through a field experiment conducted at the College of Agriculture, Vellayani. The study included six treatments: T1 (Best treatment 1), T2 (Best treatment 2), T3 (Best treatment 3), T4 (KAU organic POP), T5 (RDF as per KAU POP), and T6 (Absolute control). The experiment was laid out in a Randomized Block Design (RBD) with four replications. The results revealed that T2 (RDF + Humic acid) noticed the highest pH, organic carbon, available Ca and Mg. Available N and P were the highest in T1 (RDF + PGPR mix- 1) and K in T2 while the highest available S was noticed in T3 (RDF + Seaweed extract), while micronutrients (Fe, Mn, Zn and Cu) were the highest in the control except the boron. The labile and water-soluble carbon was the highest in T1 and T3 respectively. Enzyme activities were highest in T1 (RDF + PGPR mix-1). Humic acid fractions were the highest in T2 (RDF + Humic acid) treatmentThe study also assessed the effects of various treatments on rice growth, yield, nutrient uptake, root morphology and microbial interactions. RDF + PGPR mix-1 (T1) significantly recorded the highest EAN, improving growth, yield, root parameters, nutrient uptake (N, P, Ca and Mg), and microbial interactions. RDF + Humic acid (T2) recorded the highest K content and uptake. The control (T6) recorded the lowest growth, yield and nutrient uptake, but the highest Fe, Mn, Zn and Cu content. Root metabolites, chlorophyll, sugars and amylase were also the highest in PGPR mix-1, while proline content was the highest in the control. Standing water analysis showed the highest pH in RDF + Humic acid and the highest CO2 evolution rate in PGPR mix-1, indicating enhanced microbial activity. The economic analysis of treatments T1 (RDF + PGPR mix-1) recorded the highest net return, gross return and benefit-cost (B:C) ratio. The results suggest that T1 (RDF + PGPR mix-1) is the most cost-effective treatment, providing the highest profitability among all the treatments evaluated. The study concluded that biostimulants, particularly RDF + PGPR mix-1 @ 2 %, significantly improved rice growth, yield and nutrient uptake, while also enhancing soil biological properties, microbial interactions and nutrient dynamics in rice as evaluated through both pot and field experiments.Item Soil quality assessment and evaluation of rejuvenation strategies for coastal sandy soils of thiruvanathapuram district (AEU 1) through organics(Department of soil science and agricultural chemistry, college of agriculture,Vellayani, 2023-08-01) Athulya, B M.; Gowri PriyaA study entitled “Soil quality assessment and rejuvenation of coastal sandy soils of Thiruvananthapuram district (AEU 1) through organics” was carried out with an objective in assessment of soil quality of coastal sandy soils in Thiruvananthapuram district (AEU 1) and development of organics based rejuvenation methods. The study was carried out in two phases. As phase 1, characterization of southern coastal soils of AEU 1 in Thiruvananthapuram district was done. Based on the results of phase I, an area with low fertility was selected for phase 2 of the study. Different organic amendments were applied to study the effect on soil properties and crop growth in phase 2. Fifty geo-referenced surface soil samples, along with core samples were collected from coastal areas in AEU 1 of Thiruvananthapuram district and characterized for various physical (texture, bulk density, particle density, water holding capacity and soil aggregate stability), chemical (pH, EC, cation exchange capacity, exchangeable acidity, organic carbon, available macronutrients, available micronutrients such as Fe, Mn, Zn, Cu, B, Cl, Na and heavy metals (Pb and Cd)) and biological attributes (dehydrogenase activity and microbial biomass carbon). Principal component analysis was used to set up the minimum data set of indicators to compute the soil quality index. Six principal components were extracted from which ten indicators that highly influenced the soil quality were identified, viz. clay per cent, water holding capacity, bulk density, soil pH, organic carbon, available K, available S, available Zn, available Mn and available B. Scores and weights were assigned to each indicator, and were aggregated to compute the soil quality index. The relative soil quality index of the soils were also found. GIS techniques were used to prepare thematic maps of major soil attributes and relative soil quality indices of the coastal sandy soils of AEU 1. Correlations were worked out among the various analysed parameters. The analytical results for soil physical properties showed that the predominant soil textual class observed in the present study area was sand and loamy sand. Bulk 192 density was in the range of 1.37 - 1.86 Mg m- ³, particle density 2.22 - 2.89 Mg m- ³, with 22.7 – 56 per cent water holding capacity and 33.6-59.4 per cent soil aggregate stability. The soil pH ranged between 5.11 - 7.19, and 0.03 - 0.23 dS m-1 for electrical conductivity. Organic carbon was found in the range of 0.07 - 1.01 per cent, nitrogen 100 - 308 kg ha-1 , phosphorus 7.05 - 59.94 kg ha-1 and potassium 100 - 361 kg ha-1 . Secondary nutrients ranged as: calcium 80 - 360 mg kg-1 , magnesium 47 - 152 mg kg-1 and sulphur 4.5 - 20.5 mg kg-1 . The available micro nutrients ranged between: 6.63 - 81.57 mg kg-1 for iron, 2.53 - 36.01 mg kg-1 for manganese, 2.21 - 16.64 mg kg-1 for zinc, 0.11 - 6.07 mg kg-1 for copper and 0.11- 0.82 mg kg-1 for boron. Heavy metals such as Cd and Pb were below detectable limit. Soil biological activity in these soils were poor with dehydrogenase activity in the range of 5.57 – 20.29 µg TPF hydrolysed g-1 soil 24 hrs-1 and microbial biomass carbon of 9.18 - 29.96 µg g1 soil. So, generally the fertility status of this coastal sandy soils was found to be low. Majority of the soils belonged to medium soil quality (60 %), followed by good (36 %) and poor (4 %) quality. The soils of Kadakkavoor recorded the highest soil quality index and that of Anchuthengu, recorded the lowest. Based on the results of phase I, a pot culture experiment was done at Kochuveli, Industrial area, Thiruvananthapuram with Amaranthus (variety: Arun) as test crop. The experiment was completely randomized design (CRD) with 12 treatments and 3 replications. In the pot culture experiment, treatments included were; T1: Control, T2: Organic POP, T3 : Vermicompost, T4: Liming + Vermicompost, T5 : Coir pith compost, T6: Liming + Coir pith compost, T7: City compost, T8: Liming + City compost, T9: Suchitha, T10: Liming + Suchitha, T11: FYM 12.5 t ha-1 + Biochar 12.5 t ha-1 , T12: Liming + FYM 12.5 t ha-1 + Biochar 12.5 t ha-1 . In T2 (organic POP), FYM @ 25t ha-1 as basal dose and top dressing with fresh cow dung slurry @ 1kg per 10 litres (50 kg ha-1 ) was done. Along with that, 272.7 kg rock phosphate and 122.5 kg potassium sulphate ha-1 were applied. From T3 to T10, as per organic POP manure recommendation, basal dose of FYM was substituted with organic amendments @ 25 t ha-1 with or without lime application. 193 Soil management using organic manures had considerable impact on growth and yield characteristics of plant. Highest plant height was observed in T8, which was on par with T4 and T10. Highest dry matter and yield were recorded in T10 which was followed by T4. Effect of organic manures on quality parameters showed that highest β carotene and nitrate content were recorded in T10. Highest vitamin C content was recorded in T10 which was on par with T3 and T4. Being an antinutritional factor, T1 recorded the highest value of oxalate content and the lowest was seen in T10. Regarding the nutrient uptake in plants, T10 recorded the highest uptake of N, K, Ca and Mg, while T4 recorded the highest in P and S uptake. Analyses of post-harvest soil for nutrient parameters showed that the highest value of organic carbon was recorded in T10, which was on par with T8 and T9. The highest value for available nitrogen was recorded for T10 while the highest value for available phosphorous was recorded in T4. The potassium content was found to be the highest in T10. Also T10 showed the highest value in available secondary nutrients. Micronutrients analyses showed that highest content of available Fe was present in T3, while highest of available Cu, Zn and B were recorded in T10. T9 showed the highest value in available Mn. T1 showed highest available Na and Cl content. Analyses of soil biological properties due to the effect of organic manure addition showed that the highest value of dehydrogenase activity was found in T8, which was statistically on par with T7 and T10. Also, the highest value in microbial biomass carbon was found in T8, which was on par with T7, T9, and T10. The highest B: C ratio was recorded by T10. From the study, it is concluded that soil test based lime application and basal application of Suchitha @ 25 t ha-1 , top dressing with fresh cow dung slurry @ 1kg per 10 litres, along with 272.7 kg rock phosphate and 122.5 kg potassium sulphate ha-1 was observed to be the best treatment to improve the soil quality, yield and quality parameters of amaranthus in coastal sandy soils of AEU 1 in Thiruvananthapuram district.Item Production and characterization of enriched NADEP composts and evaluation of manurial value(Department of Soil Science and Agricultural Chemistry, College of Agriculture , Vellayani, 2024-12-02) Aliya Shirin, K S.; Aparna, BThe study entitled " Production and characterization of enriched NADEP composts and evaluation of manurial value" was carried out during 2023-24 in the Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani. The objective of the study was the production and characterization of enriched NADEP composts using different organic sources and the evaluation of manurial value using the tomato variety Vellayani Vijai as test crop. The study comprised of two parts viz: the production and characterization of enriched NADEP composts from different organic sources and a field experiment for evaluating the performance of the enriched NADEP compost. NADEP compost was prepared in NADEP tanks using two commonly available aquatic weeds, yellow velvet leaf (Limnocharis flava) (S1) and water hyacinth (Eichhornia crassipes) (S2). Banana pseudostem was added to the aforesaid aquatic weeds in a 1:1 ratio. The matured composts were then enriched with minerals like calcium apatite (M1), epsom salt (M2) and calcium apatite + epsom salt (M3) at rate of 2 per cent in different combinations. The design followed was a Completely Randomized Design with 12 treatments and 3 replications. The treatment combinations were T1- NADEP compost prepared from 1:1 mixture of L. flava and banana pseudostem enriched with calcium apatite, T2- NADEP compost prepared from 1:1 mixture of L. flava and banana pseudostem enriched with epsom salt, T3- NADEP compost prepared from 1:1 mixture of L. flava and banana pseudostem enriched with calcium apatite and epsom salt, T4- NADEP compost prepared from 1:1 mixture of E. crassipes and banana pseudostem enriched with calcium apatite, T5- NADEP compost prepared from 1:1 mixture of E. crassipes and banana pseudostem enriched with epsom salt, T6- NADEP compost prepared from 1:1 mixture of E. crassipes and banana pseudostem enriched with calcium apatite and epsom salt, T7 - NADEP compost prepared from 1:1 mixture of L. flava and E. crassipes enriched with calcium apatite, T8- NADEP compost prepared from 1:1 mixture of L. flava and E. crassipes enriched with epsom salt, T9- NADEP compost prepared from 1:1 mixture of L. flava and E. crassipes enriched with calcium apatite and epsom salt, T10- NADEP compost prepared from 1:1:1 mixture of L. flava, E. crassipes and banana pseudostem enriched with calcium apatite, T11- NADEP compost prepared from 1:1:1 mixture of L. flava, E. crassipes and banana pseudostem enriched epsom salt and 166 T12- NADEP compost prepared from 1:1:1 mixture of L. flava, E. crassipes and banana pseudostem enriched with calcium apatite and epsom salt. To all the treatments (T1 – T12) zeolite was added at a rate of 0.5 per cent. The physico-chemical and biological properties of the produced composts were analysed. Based on the analyzed parameters like major and minor nutrients, enzyme activity, C:N ratio, fertilizing index and clean index the best six composts selected for field experiment were T3, T6, T7, T9, T10 and T12. Among these, T9 (NADEP compost prepared from 1: 1 mixture of L. flava and E. crassipes enriched with calcium apatite and epsom salt) was selected as the best compost with the highest values of most of the macro and micronutrients, N (3.03 %), P (0.62 %), K (1.80 %), Ca (0.32 %), Mg (0.26 %), S (30.00 mg kg-1), B (44.97 mg kg-1), Fe (1.40 %), Mn (179.00 mg kg-1), Zn (56.19 mg kg-1) Cu (26.00 mg kg-1) and enzyme activity (612.42 g TPF hydrolysed µg-1 compost 24 h-1). A relative lower C:N ratio was also observed for T9 (34.77%). In part II of the study, a field experiment was conducted from December 2023 to March 2024 with the tomato variety Vellayani Vijai as the test crop. In the field, 10 treatments were applied as follows: T1 to T6 - 6 selected enriched NADEP composts, T7- Bokashi compost prepared from L. flava enriched with calcium apatite, epsom salt and sylvinite, T8- KAU POP recommendation, T9- KAU POP (organic) recommendation and T10- Absolute control. Analysis of the postharvest soil for chemical properties revealed that the highest value of organic carbon (1.13%), nitrogen (311.09 kg ha-1) and phosphorous (80.54 kg ha-1) was recorded for T7 which was on par with T4, while the highest value of available potassium was recorded for T7 (260.55 kg ha-1). T7 recorded the highest values of iron (46.50 mg kg-1), manganese (22.41 mg kg-1), zinc (4.25 mg kg-1) and copper (1.66 mg kg-1), on par with T4, which exhibited iron (45.60 mg kg-1), manganese (21.37 mg kg-1), zinc (4.12 mg kg-1) and copper (1.57 mg kg-1). The highest value of dehydrogenase activity was recorded by T7 (292.31 µg of TPF hydrolysed g-1 of soil 24 h-1) which was on par with T5 (288.91 µg of TPF hydrolysed g-1 of soil 24 h-1) and T4 (278.22 µg of TPF hydrolysed g-1 of soil 24 h-1). The boron content was found to be highest for T7 (0.69 mg kg-1). 167 Analysis of the rhizosphere soil showed that the highest value of microbial biomass carbon (84.74 mg kg⁻¹ soil) was recorded by T4, followed by T1 (83.11 mg kg-1 soil), T6 (83.11 mg kg-1 soil) and T7 (81.48 mg kg-1 soil). The soil respiration (4.02 mg CO2 g-1) and microbial respiratory quotient (49.67) were highest for T7 which was on par with T4 with soil respiration (3.98 mg CO2 g-1) and microbial respiratory quotient (46.98). Treatment T7 recorded the highest values of bacteria (7.69 log cfu g-1 soil), fungi (5.32 log cfu g-1 soil) and actinomycetes (5.15 log cfu g-1 soil) which was on par with T4. Treatment T7 recorded the highest number of fruits per plant (62.00) which was on par with T4 (60.33). Fruit girth (14.50 cm) and fruit length (4.98 cm) were highest for T4, which was on par with T1 and T7. T7 recorded the highest value for yield per plant (1.67 kg), and total yield (43.97 t ha-1), which was on par with T4 and T3. The highest B:C ratio was reported by T4. From the study, T4 (NADEP compost prepared from 1:1 mixture of L. flava and E. crassipes enriched with calcium apatite and epsom salt) were concluded as the best compost. T4 (NADEP compost prepared from 1:1 mixture of L. flava and E. crassipes enriched with calcium apatite and epsom salt) and T7 (Bokashi compost prepared from L. flava enriched with calcium apatite, epsom salt and sylvinite) recorded the highest values for majority of the available macro and micronutrients, organic carbon and enzyme activity. Considering both soil parameters, yield parameters and B:C ratio, T4 (NADEP compost prepared from 1:1 mixture of L. flava and E. crassipes enriched with calcium apatite and epsom salt) was identified as the best treatment.Item Utilization of biochar from different bioresources for soil health and crop production(Vellayani Department of Soil Science and Agricultural Chemistry, College of Agriculture,Vellayani, 2024-01-20) Diya Rajendran; Meera, A VThe study entitled “Utilization of biochar from different bioresources for soil health and crop production” was carried out during 2021-2023 in the Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani and Integrated Farming System Research Station, Karamana. The objectives of the study were characterization of biochar produced by pyrolytic conversion of bioresources generated in farming systems and assessing their influence on soil health and crop production. The study comprised of four parts viz., production and characterization of biochar from different bioresources, bioassay study for selection of best four biochar, incubation experiment to study the nutrient release pattern and field evaluation of the effect of biochar on crop performance and soil health. Biochar was produced from seven different organic residues viz., teak leaf, coconut leaf, banana pseudostem, crop residue of vegetables, Eichhornia crassipes, Limnocharis flava and Colocasia esculenta, by the process of pyrolysis and the synthesized biochar were analysed for physical and chemical properties using standard procedures. Temperature of pyrolysis and residence time for various organic residues ranged between 250-5000C and 30-120 minutes, respectively. Highest recovery percentage of 46.53 % was recorded for coconut leaf biochar and lowest, 24.93 % for E. crassipes. Teak leaf biochar recorded the highest bulk density (0.48 Mg m-3) and EC (4.70 dS m-1), while banana pseudostem biochar had a higher water holding capacity (327.74 %). The produced biochar has an alkaline characteristic, with pH values ranging from 8.19 (C. esculenta biochar) to 10.40 (Banana pseudostem biochar). CEC (14.10 cmol kg-1), total carbon (67.52 %), N (1.34 %), K (2.24 %), S (0.33 %) and Zn (69.37 mg kg-1) content were highest for banana pseudostem biochar while P (0.77 %), Mn (173.76 mg kg-1), Cu (37.12 mg kg-1) and B (47.40 mg kg-1) were highest for L. flava biochar. Calcium (0.57 %) and magnesium (0.43 %) content were highest for crop residues of vegetable biochar while iron (2314.15 mg kg-1) content was highest in biochar produced from C. esculenta. C: N ratio was highest in C. esculenta biochar (128.35) and lowest in banana pseudostem biochar (50.38). 159 Bioassay study was carried out for 28 days using okra seedlings to select best four biochar for field study. The biochar produced from seven different bioresources were mixed with 2 kg soil @ 0.5 and 1 % w/w basis and FYM @ 1 % w/w basis and 10 okra seeds were placed in each pot. Coconut leaf, banana pseudostem and L. flava biochar recorded the highest germination percentage (96.67 %) and it was on par with biochar derived from crop residues. Banana pseudostem biochar recorded the highest values for shoot length (33.04 cm) and shoot biomass (2.23 g plant-1) and it was on par with L. flava biochar and FYM treated soil. Root length (23.97 cm), root biomass (0.60 g plant-1) and root volume (4.90 cm3) of the okra seedlings were highest in L. flava biochar treated soil and it was found to be on par with crop residue of vegetables biochar and FYM supplied treatments. Teak leaf biochar applied @ 1 % recorded the lowest values for germination percentage, shoot length, shoot biomass, root length, root biomass and root volume. Based on the results obtained from bioassay study, four biochar viz., coconut leaf, banana pseudostem, crop residue of vegetables and L. flava were selected for the incubation and field experiments. The nutrient release pattern from the selected four biochar was monitored after incorporation to soil based on a 90 day incubation study. Biochar and FYM were added @10 g kg-1 of soil. Periodic sampling and analysis of samples were done at 0, 30, 60 and 90 days of incubation. The incubation study revealed a slow and sustained release of nutrients from biochar. Biochar treated soils showed significantly higher value for pH and EC compared to FYM treated soil till the end of the incubation period. The pH was significantly higher for banana pseudostem biochar treated soil while EC was higher in soil applied with crop residue of vegetables biochar. During initial period of incubation, the mean values for available N, K, S and Zn content were highest for FYM treated soil but as incubation period progressed, banana pseudostem biochar treated soil recorded the highest values. The mean value for P, Fe, Cu and B were significantly higher for FYM treated soil during initial period and later stages, it was for L. flava biochar applied soil. Similarly, exchangeable Ca and Mg content were highest in FYM treated soil during initial period and as incubation period progressed, the crop residue of vegetables biochar treated soil recorded the highest values. A field experiment was conducted during 2023 to compare the effect of biochar from different bioresidues and FYM application on soil health and crop production using okra as the test crop. The treatments consisted application of selected four biochar viz., coconut leaf, banana pseudostem, crop residue of vegetables and L. flava biochar @ 25 t ha-1 along with 100 and 75 % of recommended dose of fertilizers (RDF) and FYM @ 25 t ha-1 along with 100 % RDF and soil with 100 % RDF only. The physical, chemical and biological properties of soil were markedly improved by the application of biochar. Reduction in bulk density, increase in water holding capacity, pH, EC, CEC, organic carbon and nutrient availability were observed with biochar application compared to FYM incorporation. Banana pseudostem biochar application recorded the highest values for organic carbon (1.92 %), available N (334.56 kg ha-1), K (258.45 kg ha-1), S (23.27 mg kg-1), Zn (3.73 mg kg-1) and dehydrogenase (192.78 µg of TPF g-1 soil 24 h-1) and microbial biomass carbon (81.97 mg kg-1) content of post harvest soil. Available P (91.78 kg ha-1), Fe (132.08 mg kg-1), Mn (34.89 mg kg-1) Cu (2.77 mg kg-1) and B (0.667 mg kg-1) content were higher in soil applied with L. flava biochar. Biochar application had significantly influenced the biometric and yield parameters of okra. Plant height, biomass yield and fruit yield were highest in treatments supplied with banana pseudostem biochar and it was on par with the treatments received L. flava biochar. Nutrient content of index leaf at harvest also indicated the beneficial effect of biochar in comparison to FYM and conventional fertilizers. Plant biometric attributes, fruit yield and soil health parameters for biochar application @ 25 t ha-1 and RDF at 100 and 75 % were on par. The highest B: C ratio (1.70) was recorded in treatment supplied with banana pseudostem biochar @25 t ha-1 along with 75 % RDF, which indicated that 25 % reduction in fertilizer application is possible through biochar application. There was 21 % increase in yield by banana pseudostem biochar application compared to FYM. It may be inferred that physico-chemical properties of biochar varies with the source material and their assessment for phytotoxicity is essential for ensuring the safety for agricultural use. Coconut leaf biochar, banana pseudostem biochar, crop residues of vegetable biochar and L. flava biochar had ideal physical and chemical 161 properties that qualify them to be used as good soil amendments which improve the soil physical, chemical and biological properties. FYM and biochar application had a positive effect on soil properties during incubation and field study. However biochar application exhibited sustainable effects than FYM. From the study, it can be concluded that banana pseudostem biochar @ 25 t ha-1 along with 75 % RDF is the economically viable and best treatment.Item Soil carbon stock estimation and prediction of aggregate associated carbon under different land use systems in Palakkad central plain using reflectance spectroscopy(Department of Soil Science and Agricultural Chemistry, College of Agriculture , Vellanikkara, 2025-01-09) Abdul Hadi, K; Divya Vijayan, VThe distribution of soil organic carbon (SOC) across various aggregates and its changes over time is crucial for monitoring carbon dynamics and optimising nutrient management. Reflectance spectroscopy is a fast, non-destructive and economical solution for estimating SOC in the soil. In this context, the present study was proposed to identify the potential of different land-use systems for the sequestration of SOC and distribution of SOC among various aggregates of selected land-use systems (LUS), where the selected aggregates were macroaggregate (> 0.25 mm), micro aggregate (0.25-0.053 mm) and clay and silt fraction (< 0.053 mm). It also aimed to evaluate the predictive potential of reflectance spectra for estimating SOC associated with soil aggregates. The study was conducted in the Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellanikkara during 2023-24. The selected land use systems were natural forest, coconut plantation, rubber plantation, vegetable field, and paddy field, in the Palakkad Central Plain (AEU 22). Georeferenced surface (sample no. = 9), subsurface soil samples (sample no. = 9) and one profile sample were collected from each land use system. A total of 105 samples were collected. The soil samples were pre-processed and analysed for the different physico-chemical properties, wet aggregate analysis, soil carbon stock (SCS) and SOC in aggregate fraction. A part of the macroaggregates and microaggregates obtained from wet sieving was utilised to record the spectral signatures. Prediction models were then developed using the SOC content of these aggregates as the dependent variable, while the spectroscopic bands corresponding to each aggregate type served as the independent variables. The raw spectra obtained from the spectroradiometer underwent four preprocessing steps viz logarithmic transformation, Savitzky-Golay filtering (SG), first-order derivative (FOD), and second-order derivative (SOD) before model development. Correlation analyses were then performed to identify the most relevant wavebands associated with SOC. It reduced the number of bands needed for modelling. The prediction of aggregate-associated SOC was performed using a Partial Least Squares Regression (PLSR) model. The efficiency of developed models was analysed using the coefficient of determination (R2), root mean square error (RMSE), and the ratio of prediction deviation (RPD). The subset prediction models were also developed to identify which region is best for prediction. Finally, the variable importance in the projection score (VIP) was used to find which wavelengths are contributing the most of the variance in the PLSR model. The result showed that the perennial systems such as forest (47.95 Mg ha-1) and rubber (43.08 Mg ha-1) showed higher soil carbon stock. In contrast, annual cropping systems like paddy (SCS = 16.55 Mg ha-1) and vegetable (SCS = 19.14 Mg ha-1) exhibited lower soil carbon stock. The distribution of water-stable aggregates revealed that greater proportion of macroaggregates in rubber (96.05 %) and forest systems (95.18%), followed by coconut (83.12 %). Lower aggregate fractions, including microaggregates and clay-silt fractions, were more abundant in paddy (micro aggregate = 30.72 %; clay and silt fraction = 2.29 %) and vegetable fields (micro aggregate = 26.60 %; clay and silt fraction = 2.53 %). Mean weight diameter was highest in forest (2.65 mm) and rubber systems (2.44 mm) and lowest in paddy (0.73 mm) and vegetable systems (0.99 mm). These findings suggest that intensive tillage and lower SOC levels significantly degraded soil structure. The key spectral bands for predicting bulk SOC spanned the entire spectrum (400–2500 nm), whereas bands relevant to aggregate-associated SOC were primarily located in the shortwave infrared (SWIR) region (1000–2500 nm). These findings indicate that bulk SOC predictions were more influenced by the chromophore effect, while aggregate SOC predictions depended on chemical bonds in specific spectral regions. The preprocessing steps influenced the prediction ability of the model. second-order derivatives (SOD) produced the best models for the prediction of microaggregate SOC (MiSOC) and macroaggregate SOC (MaSOC), while Savitzky Golay-filtered full spectra were most effective for bulk soil SOC. Prediction accuracy was higher for MiSOC (R² = 0.84, RMSE = 0.25, RPD = 2.21) compared to MaSOC (R² = 0.92, RMSE = 0.25, RPD = 1.74). The R2 value of the test dataset further validated the prediction efficiency of the model. The R2 value of the test dataset were 0.79, 0.66, and 0.84 for MiSOC, MaSOC, and bulk soil SOC, respectively. The superior predictive performance for MiSOC can be attributed to the higher organic carbon content in microaggregates and the difference in the type of organic functional groups between the two fractions. The result shows that spectroscopy can be effectively exploited for the prediction of aggregate-associated carbonItem Evaluation of STCR based targeted yield equations for cowpea (Vigna unguiculata L) in southernlaterites(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2023-04-27) Mary Shyna , J.; Visveswaran ,SThe study entitled ‘Evaluation of STCR based targeted yield equations for cowpea (Vigna unguiculata L.) in southern laterites’ was conducted at the Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani during 2020-2021. The targeted yield equation developed by AICRP on STCR during 2018 for cowpea was test verified for southern laterites (AEU 8) in this study. A farmer’s field in Kalliyoor gram panchayath, Thiruvananthapuram was selected for the experiment. The variety used in the study was Anaswara and the design followed was RBD. The experiment consisted of five treatments viz., POP-KAU with organic manure management (T1), POP-KAU on the basis of soil test (T2), STCR recommendation for a targeted yield of 15 tonnes (T3), STCR recommendation for a targeted yield of 16.5 tonnes (T4) and STCR recommendation for a targeted yield of 18 tonnes (T5). The targeted yield equation followed in this study is as follows; FN = 3.88 T – 0.098 SN – 0.02 ON FP2O5 = 4.34 T – 0.619 SP – 0.01 OP FK2O = 16.53 T – 0.489 SK – 0.08 OK Here, FN, FP2O5, and FK2O are nitrogen, phosphorus and potassium contributions from the fertilizers respectively. SN, SP and SK are nitrogen, phosphorus and potassium contributions from the soil respectively. Similarly, ON, OP and OK are nitrogen, phosphorus and potassium contributions from the organic sources respectively. T in the equation represents the targeted yield. Different soil and plant parameters were analysed to study the performance of the crop under each treatment. This includes initial and post harvest physico-chemical characteristics of the soil, biometric observations, nutrient content of pod and stover, yield parameters and dry matter production. The biometric observations viz., average length of the pod, average weight of the pod, the number of pods per plant and the number of seeds per pod were found to be the maximum in T5. Also the number of days to first flowering and the number of days to 50% flowering was the least in this treatment. All the three yield targets in STCR treatments were achieved. The maximum yield was observed in T5 and the minimum in T1. In the case of the weight of the stover, the highest value was shown by T5 and the lowest by T1. Dry matter production of the above ground portion also showed the same trend. For the particle density, bulk density and porosity of the post harvest soil, there was no significant difference found among the treatments. The pH and OC content of the soil showed slight increase after the harvest. The maximum N, P and K content was found in T5 and the minimum in T1. The highest dehydrogenase activity was observed in T1 and the lowest was observed in T5. The nutrient status of the stover and the pod was analysed. In both stover and pod samples, the treatments T5 and T1 showed the highest and the lowest N, P and K contents respectively. The chlorophyll content in the leaf samples showed significant difference among all the treatments where the highest chlorophyll content was recorded in T5 and the lowest was observed in T1. The pesticide residue analysis done for the presence of quinalphos in soil showed the maximum value in T2 and the minimum in T4. The pesticide residue level for quinalphos in the harvested pods was below the detectable level. Correlation studies were carried out to find the correlation between yield and other different parameters. A significant negative correlation with yield was found for the number of days for first flowering and the number of days for 50% flowering. There was significant positive correlation between the average length of the pod, the average weight of the pod, the number of pods per plant and the number of seeds per pod with yield. Similarly, the weight of the stover showed a significant positive correlation with yield. In the case of N, P and K contents in soil, stover and pod samples, there was a significant positive correlation with yield. The analysis of nutrient status of the plant parts showed that, higher nutrient contents was observed in plants which were grown under treatment having higher amount of fertilizer doses. This shows a direct proportion of fertilizer applied and the nutrients absorbed. The micro nutrient status of the samples did not show significant difference among the treatments. The treatment T5 was economically superior to the other treatments as it has the maximum B: C ratio. Therefore, it can be concluded that STCR- IPNS based targeted yield equations for cowpea can be extended to AEU 8 for successful cultivation. This ensures the maximum utilization of the fertilizers and the maximum profit to the farmer without disturbing the soil quality.Item Multinutrient pellets for organic farming in rice (Oryza sativa L.) for acid sulphate soils of Kuttanad(Department of Soil Science & Agricultural Chemistry, College of Agriculture, Vellayani, 2023-04-04) Rohith A K.; Biju JosephThe current work entitled “Multinutrient pellets for organic farming in rice (Oryza sativa) for acid sulphate soils of Kuttanad” was conducted at the Department of Soil Science, College of Agriculture, Vellayani and Rice Research Station, Moncompu, during the year 2022. In this study, organic multinutrient pellets were prepared and investigated for its nutrient release characteristics through laboratory incubation study. Simultaneously a field experiment was conducted during puncha season in a randomized block design with Pournami rice variety to evaluate the effect of organic multinutrient pellets on organic rice cultivation in acid sulphate soil. Pellets were prepared using N, P and K organic nutrient sources permitted in NPOP, taking into account the nutritional requirement of rice and the fertility status of the experimental soil. The pellets were P1 (blood meal +rock phosphate +potassium sulphate), P2 (blood meal +rock phosphate +langbeinite), P3 (blood meal +steamed bone meal +potassium sulphate), P4 (blood meal +steamed bone meal +langbeinite), P5 (groundnut cake +rock phosphate +potassium sulphate), P6 (groundnut cake +rock phosphate +langbeinite), P7 (groundnut cake +steamed bone meal +potassium sulphate), and P8 (groundnut cake +steamed bone meal +langbeinite).Bentonite clay and humic acid were used as binding agents. On the characterization of pellets, all the pellets were found physically stable with high water holding capacity and bulk density. N content (8.47) was highest in pellet 3 (blood meal +steamed bone meal +potassium sulphate) while pH (5.98), organic carbon (23.13%), P (4.24%), K (4.21%) and Ca (5.08%) content were highest in pellet 1 (blood meal +rock phosphate +potassium sulphate). A laboratory incubation experiment was carried out to investigate the nutrient release pattern of the pellets after addition to soil. The organic multinutrient pellets were added into pots containing 5kg of acid sulphate soil, depending on the weight of soil taken and the nutritional requirement of rice. The pots were maintained at saturated condition. Samples were drawn at 15th, 30th, 45th, and 60th day of incubation, and analyzed for chemical parameters such as pH, EC, organic carbon, available N, P, 177 K, Ca, Mg, S, B, Fe, Mn, Zn, Cu, dehydrogenase activity, humic acid and fulvic acid using standard procedures. Soil pH and EC increased with days of incubation while organic carbon decreased. The availability of all nutrients increased from 15th day to 60th day and the maximum value was observed on 60th day of incubation. The dehydrogenase activity of soil and humic acid content increased with days of incubation while fulvic acid content decreased. In the field experiment 11 treatments were included such as, T1- Organic nutrient management as per KAU POP recommendation (organic crops), T2- Nutrient management as per KAU POP recommendations, crops 2016. T3- Organic nutrient management using pellet I, T4- Organic nutrient management using pellet II, T5- Organic nutrient management using pellet III, T6- Organic nutrient management using pellet IV, T7- Organic nutrient management using Pellet V, T8- Organic nutrient management using pellet VI, T9- Organic nutrient management using pellet VII, T10- Organic nutrient management using pellet VIII, T11- Absolute control. Analysis of post-harvest soil for chemical properties showed that, highest quantity of available Ca (410 mg kg-1), Mg (116 mg kg-1), S (19.83 mg kg-1) and P (24.59kg ha 1 ) were reported in T4. While the highest quantity of available N (291.68 kg ha-1), K (174.47 kg ha-1), Mn (2.54 mg kg-1) and Cu (1.25 mg kg-1) were observed in T2 followed by T3. T10 reported highest values in B (0.40 mg kg-1) and Zn (2.00mg kg-1). pH (5.21) and EC (0.120 dS m-1) of soil were the highest in T4 and T3 respectively. Regarding the nutrient content and uptake in plants, the treatment T2 (nutrient management as per KAU POP recommendations, crops 2016) registered the highest content and uptake of the most nutrients, which was followed by T3 (organic nutrient management using blood meal, rockphosphate and potassium sulphate) and T4 (organic nutrient management using blood meal, rock phosphate and langbeinite). The content and uptake of N and P and the uptake of K were highest in the T2. T3 recorded the highest content of N in grain, uptake of N in straw and the content and uptake of K in grain and straw. 178 Organic multinutrient pellet prepared using blood meal, rock phosphate and potassium sulphate on application in T3 significantly influenced the number of tillers (296.52), number of panicles meter-2 (280.27), spikelets panicle-1(111.67) and height of plants (100.53 cm) and provided highest value for them. Length of panicle (17.33 cm), filled grain percentage (90.07%) and 1000 grain weight (27.30g) were highest in T2 (nutrient management as per KAU POP recommendations, crops 2016). Chlorophyll content (1.23 mg g-1) was found highest in T6 due to the application of pellets prepared with langbeninte which contained magnesium. Nutrient management using organic multinutrient pellets had considerable impact on grain yield and straw yield. Highest grain yield (6167 kg ha-1) and straw yield (9012 kg ha-1) were recorded in T2 (nutrient management as per KAU POP recommendations, crops 2016) which was followed by T3 (organic nutrient management using blood meal, rock phosphate and potassium sulphate). The nutrient use efficiency of major nutrients were found to be highest in T2 receiving inorganic fertilizers, which was on par with the treatment T3 receiving blood meal, rock phosphate and potassium sulphate. Organic multinutrient pellets significantly influenced harvest index of rice. T2 and T3 registered the highest index value (0.41), while T4, T6 and T10 reported harvest index of 0.40. T2 with KAU POP recommendation of inorganic fertilizers reported the highest BC ratio of 3.79. However, T3 (Organic nutrient management using blood meal, rockphosphate and potassium sulphate) was on par with T2 with BC ratio of 3.02. Organic nutrient management in rice can be easily done by using multinutrient pellets prepared using nutrient sources permitted under NPOP. Pellets prepared using bloodmeal, rock phosphate and sulphate of potash (T3) produced on par yield to the treatment receiving inorganic fertilizers (T2). It was able to significantly improve the uptake of most of the nutrients in plant and could also maintain significantly higher levels of nutrients in the post-harvest soil. T2 was superior with respect to economics of cultivation with a BC ratio of 3.79 compared to a BC ratio of 3.02 in T3. It can be concluded that T3 (organic nutrient management using blood meal, rock phosphate 179 and potassium sulphate) is a viable option for nutrient management in organically grown paddy in acid sulphate soils of Kuttanad. 180Item Fortifid organic matrix pellets for crop nutritional resilience in Onattukara sandy loam soils(cultural Chemistry, Department of Soil Science and Agri College of Agriculture , Vellayani, 2023-05-15) Neema, V H.; Mini ,VA study on “Fortified organic matrix pellets for crop nutritional resilience in Onattukara sandy loam soils” was carried out during 2020-2022 in the Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani. Objective of the study was to fortify the organic matrix developed from agro wastes with macro and micro nutrients and to evaluate the effect of this fortified organic matrix pellets on yield and quality of chilli in the sandy loam soils of Onattukara. The study comprised of three parts viz., development of fortified organic matrix, nutrient leachate experiment and evaluation of the effect of fortified organic matrix pellets on growth and yield of chilli. Biodegradable agro waste materials viz., rice husk, rice husk ash, cow dung, coir pith compost, vermicompost, poultry manure, neem cake and ground nut cake were combined in 1: 4: 5: 1: 2: 1: 1: 1 ratio to develop the organic matrix. The developed organic matrix was fortified with essential nutrients viz., N (1.2%), P (0.4 %), K (0.82%), Ca (0.12%), Mg (0.13), S (0.10%), Fe (0.04%), Mn (0.02%), Zn (0.06%), Cu (0.02%), B (0.10%) and Mo (0.01%), considering the nutrient requirement of chilli and general soil status of Onattukara. Carriers of various macro and micro nutrients viz., urea, rajphos, muriate of potash, calcium nitrate, magnesium sulphate, ferrous sulphate, manganese sulphate, zinc sulphate, copper sulphate, borax and ammonium molybdate were used for fortifying the organic matrix. Fortified matrix was converted into pellet forms for soil application. Onattukara soils are generally coarse textured with low organic matter content. Nutrient supplying capacity of this sandy plain is declining due to nutrient loss through surface runoff and leaching. Nutrient leachate experiment was conducted to assess the leaching loss of nutrients and the leachates were collected to analyse macro and micro nutrients. Four saturation times were evaluated viz., 10 min, 1 day, 5 days, and 10 days. The 10-min saturation was designed to mimic precipitation that runs through the soil immediately following a short duration rain event. The 1-day saturation was designed to mimic a longer rain event, which might cause localized ponding due to saturated subsoil. The 5-day and 10-day saturation events were designed to mimic the leaching during flood events. Four treatments viz. T1- organic matrix mixed with soil, T2-fertilizer mixed with soil, T3-fortified organic matrix mixed with soil and T4-control (soil alone) were taken (20 parts water to 1part solid ratio) for nutrient leachate study. An increase in nutrient content in the leachate was observed during the study and the average increase in nutrient content was less in T1 and T3 compared to T2 and T4. This indicated the effect of organic matrix in reducing the leaching loss of nutrients. 122 A field experiment was conducted to evaluate the effect of various doses and time of application of fortified organic matrix pellets on growth and yield of chilli in the Onattukara sandy plains during January,2022 to April, 2022.The experiment consisted of eight treatments and they were T1 (Recommended dose of fertilizers and organic manure (as FYM) as per POP), T2 (Recommended dose of fertilizers and organic manure (as organic matrix) as per POP) ,T3 (Fortified organic matrix pellets @ 500g/plant in three splits) ,T4 (Fortified organic matrix pellets @ 500g/plant in two splits) T5 (Fortified organic matrix pellets @ 400g/plant in three splits), T6 (Fortified organic matrix pellets @ 400g/plant in two splits), T7 (Fortified organic matrix pellets @ 300g/plant in three splits) and T8 (Fortified organic matrix pellets @ 300 g / plant in two splits).Growth, yield and quality of chilli increased significantly due to the application of fortified organic matrix pellets. The highest plant height (67.0 cm) was recorded in the treatment T4 and it was on par with T3. Treatment T4 recorded the highest fruit set percentage (77.60 %) which was on par with treatments T3 and T6. The highest root length (42.6 cm), root volume (48.3 cm3) and root dry weight (19.0 g) was also recorded in T4. The treatment T4 (Fortified organic matrix pellets @ 500g/plant in two splits) recorded significantly higher values for number of fruits per plant and fruit weight and recorded the highest yield (0.63 kg per plant). The highest values for the quality parameters such as ascorbic acid (42.0 mg 100 g -1) and capsaicin (0.77%) were also recorded in T4. Soil analysis after the experiment showed that there was as improvement in water holding capacity of the soil and treatment T4 recorded the highest value (29.42 %) and it was on par with T2, T6 and T7. The treatment did not show any significant influence on pH of soil and the electrical conductivity was also in the non-saline range. The highest organic carbon (0.71 %) was recorded for T4 and it was on par with T1 and T2. In the case of available N, treatment T4 recorded the highest values (225.80 kg ha -1) and it was on par with T3 and for available P, the highest value (52.53 kg ha -1) was recorded for T4 which is significantly superior to all other treatments. Treatment T4 recorded the highest value for available K, (148.26 kg ha -1) and it was on par with T1, T2, T3, T6, and T8. The highest content of secondary and micronutrients were also recorded in T4. The treatment T4 (fortified organic matrix pellets @ 500g/plant in two splits) improved the status of microbial biomass carbon (140.53 mg kg -1) and dehydrogenase activity (29.98 µg TPF g -1 24h- 1 soil) and it was on par with T1, T2 and T3. Labile carbon pools were also high in T4 and it was on par with T1 and T2. The results of the shoot analysis revealed that the treatment T4 recorded significantly higher content of N (3.73 %). The highest P content (0.38%) in the shoot was recorded in T4 123 and it was on par with T1, T2, T3, T5 and T6. The highest potassium content (2.74 %) was recorded in T4 and it was on par with T3. Status of secondary nutrients also improved in all the treatments and recorded the highest values for treatment T4. In case of micronutrients, highest value of B (11.22 mg kg -1), Cu (5.15 mg kg -1) and Zn (26.24 mg kg -1) were recorded for T4 and was significantly superior to all other treatments. The results of the fruit analysis revealed that the treatment T4 recorded the highest N (2.39 %), P (0.25 %) and K (1.81 %) content and similar observation was recorded for secondary and micronutrients. There was no major pest and disease incidence in the crop. Treatment T4 recorded the highest net return (Rs.8,54,185/ ) and B:C ratio (2.22). Present study revealed that, treatment T4 (Fortified organic matrix pellets @ 500g/plant in two splits) is the best treatment for improving the yield and soil nutrient status. Application of fortified organic matrix made from agricultural wastes and macro- and micronutrients decreased the leaching loss of nutrients, increased the yield and quality of chilli and enhanced soil health in Onattukara sandy loam soils. Use of fortified organic matrix fertilizer pellets improved the physical, chemical and biological properties of the soil. From the investigation, it can be concluded that the application of enriched organic matrix pellets @ 500g/plant in two splits at basal and 45 days after transplanting was the best treatment for increasing production, soil nutrient status and to ensure crop nutritional resilience in Onattukara sandy loam soils. 12Item Geotechnical characterisation of lateritic soil profiles in midland and highland plateaus of Kerala(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellanikkara, 2023-04-13) Mridul , V; Divya Vijayan, VThe soils of highland and midland laterites in Kerala are unique in characteristics due to the various soil formation processes in the landscape. The midland laterites are often underlain by plinthite and contain appreciable quantities of gravel, which holds against supersaturation where as the highland laterites are devoid of plinthite. The hill zones of Kerala are witnessing frequent landslides during every monsoon. Landslides are induced by several factors and the soil-rainfall interacting process is one of the important processes, wherein the soil susceptibility increases landslide hazards by triggering slope failure due to the draining of water through infiltration, percolation and saturation of soil at an extreme level. Geotechnical properties / Atterberg limits are the basic measure of soil plasticity as a function of moisture variation. It includes the Plastic Limit (PL) which is the limit at which soil changes from semi-solid to plastic and the Liquid Limit (LL) which is the limit at which soil changes from plastic to liquid state as the water content increases. Atterberg properties of soil of a region depend on soil physico-chemical properties (soil textural dynamics, porosity, soil mineral types etc) which strongly influence landslides. To understand the physical and geotechnical properties of the laterite soils of hill and midland with respect to their behaviour on progressive saturation with water, the study “Geotechnical characterisation of lateritic soil profiles in midland and highland plateaus of Kerala” was carried out in the Department of Soil Science & Agri. Chemistry, College of Agriculture, Vellanikkara during 2021-22. The soil profiles for the study were collected from Mulagunnathukavu, Attoor and Kuranchery (AEU 10) of Thrissur district, Kokkayar, Koottikkal (AEU 14), Koottar and Pampadumpara (AEU 16) of Idukki district for elucidating morphological, physical, chemical and geotechnical properties. The results of the physico-chemical analysis showed that, the soils were acidic in reaction with values ranging from (4.78 to 6.53) in midland and (4.17 to 6.49) in highland laterites. The Cation Exchange Capacity (CEC) of the soils ranged from 6.2 to 15.3 cmol (+) kg-1 in midlands and 10.40 to 19.60 cmol (+) kg-1in highland laterites. Based on the morphological and physico-chemical properties, the midland and highland were classified under the order Ultisols. The dominant suborder in all the midland laterites was ustults and the dominant suborder of highland was humults except for the Kokkayar profile which was under the suborder ustults. Among the midland profiles studied the Mulagunnathkavu soil profile was unique with plinthite formation in the lower horizon and the soil contained appreciable quantities of gravel and clay per cent. The Atterberg limits of highland soil was higher compared to midland soil and it ranged from 31.62 to 54 per cent for liquid limit, 22 to 35 per cent for plastic limit and 6.79 to 23.61 per cent for the plasticity index. The Atterberg limits of midland soil ranged from 23.99 to 45 per cent for liquid limit, 18.55 to 29 per cent for plastic limit and 4.71 to 19 per cent for plasticity index. The higher value of Atterberg limits in the highlands can be attributed to the presence of more fine earth clays in the highlands compared to the midlands. Comparison of soil properties between midland and highland soil profiles for the surface and sub soil horizons showed significant differences in the soil properties like organic carbon, extractable iron oxides, exchangeable sodium, potassium, liquid limit and plastic limit, coarse sand, gravel per cent and bulk density. The per cent of coarse sand, gravel per cent and bulk density were higher in midland laterites compared to highland laterites and the content of organic carbon, extractable iron oxides, sodium, potassium, liquid limit and the plastic limit was higher for the highland soil compared to midland. A correlation between plastic limit and liquid limit with different soil properties of highland profiles showed that the clay has positive correlation and sand has a negative correlation with Atterberg limits. The random forest classification-regression model ranked clay as the most important variable affecting the plastic limit. The high clay content contributed to a directional arrangement of soil particles leading to the increase in weakly bound water increasing the plastic limit. The X-ray diffraction analysis results revealed that kaolin, gibbsite, feldspar, quartz and mica were found in both midland and highland laterites, which showed the different stages of weathering. Thus, it can be concluded that, the high rainfall, soft lateritic deposits, highly plastic clay and intensively weathered rocks, will saturate the entire mass and can cause loss of shear strength and this can be one of the reasons for landslides in highlands (AEU 14 and 16). The midland laterites (AEU 10) though it contains high illuvial clay the hard plinthite layer (hardened mix of iron bearing minerals with honeycomb structure and voids with kaolin) holds against supersaturation and resist clay movement. Thereby ensuring protection against landslides and piping in this AEU 10.Item Geotechnical characterisation of lateritic soil profiles in midland and highland plateaus of Kerala(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellanikkara, 2023-04-13) Mridul, V; Divya Vijayan, V
- «
- 1 (current)
- 2
- 3
- »