PG Thesis

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    Characterisation and standardisation of biochar as a soil conditioner for okra[Abelmoschus esculentus(L.) Moench] in onattukara sandy plain
    (Department of Agronomy, College of Agriculture,Vellayani, 2024-03-06) Krishna vikram.; Atul Jayapal
    The study entitled ‘Characterization and standardization of biochar as a soil conditioner for okra [Abelmoschus esculentus (L.) Moench] in Onattukara sandy plain’ was conducted during 2020-2023 at the Department of Agronomy, College of Agriculture, Vellayani, Thiruvananthapuram, Kerala. The objectives of the experiment were characterization of biochar produced from different agro-wastes; standardization of rate of biochar as a soil conditioner and assessment of its effect on the growth and yield of okra in the sandy loam soils of Onattukara (AEU 3). The experiment was done in two parts. The part I of the experiment, characterization of biochar produced from different agro-wastes, was laid out in CRD, with five treatments and were replicated thrice. The treatments were t1 (biochar produced from rice stubbles), t2 (biochar produced from rice husk), t3 (biochar produced from tender coconut husk), t4 (biochar t produced from coir waste) and t5 (biochar produced from banana waste). Part II of the study was the field experiment for standardization of biochar as soil conditioner in okra and was laid out in RBD with nine treatments which were replicated thrice. The treatments were t1 (biochar @ 5 t ha-1 + 100% RDF), t2 (biochar @ 10 t ha-1 + 100% RDF), t3 (biochar @ 5 t ha-1 + 5 t ha-1 FYM + 100% RDF), t4 (biochar @ 10 t ha-1 + 5 ha-1 FYM + 100% RDF), t5 (biochar @ 5 t ha-1 + 75% RDF), t6 (biochar @ 10 t ha-1 + 75% RDF), t7 (biochar @ 5 t ha-1 + 5 t ha-1 FYM + 75% RDF), t8 (biochar @ 10 t ha-1 + 5 t ha-1 FYM + 75% RDF) and t9 (20 t ha-1 FYM + 100% RDF). Okra was raised in beds in lowlands at a spacing of 60 cm x 30 cm and managed as per Package of Practices recommendation (KAU, 2016). Among the biochar produced from different sources, recovery percentage (23.52%), pH (9.89), EC (0.013 dS m-1), total N content (0.95%) and total Cu (0.32 mg ha-1) were significantly higher in t3. Water holding capacity was significantly higher in t4 (235.74%) and was found to be on a par with t3 (232.34%). The CEC was significantly higher in t1 (16.60 (cmol (+) kg-1) and was on a par with t3 and t5. The total K (1.54%) and total Ca (0.67%) content was found to be significantly higher in t5. The total iron content was significantly higher in t4 (108.83 mg kg-1) and was found to be on a par with t3, t1 and t2. The total Mn was superior in t1 (10.42 mg kg-1). The recovery percentage, water holding capacity, pH, EC, CEC and N were found to be significantly higher for t3 (biochar produced from tender coconut husk). The treatment t3 (biochar produced from tender coconut husk) was identified as superior to the other biochars and was selected as the best and it was taken for evaluation in the field experiment. The results of the field experiment revealed that t4 (biochar @ 10 t ha-1 + 5 t ha-1 FYM + 100% RDF) produced superior growth characters viz., plant height (60 DAS and 90 DAS), number of leaves per plant (90 DAS) and root volume. The fruit yield per plant (544.93 g) was found significantly higher for t4 and was on a par with t3 (537.74 g). The fruit yield per hectare was found significantly higher for t4 (15.71 t ha 1 ). The treatment t3 recorded significantly higher harvest index (0.81). The highest crude fibre was recorded for t1 (21. 12 %). The N uptake by okra was significantly higher for t4 (101.35 kg ha-1) and was found to be on a par with t3 (95.93 kg ha-1), t2 (92.90 kg ha-1), t6 (92.70 kg ha-1) and t5 (91.93 kg ha-1). Higher P uptake was observed in t7 (24.76 kg ha-1) and was found to be on par with t8 (23.73 kg ha-1), t6 (22.57 kg ha-1), t5 (19.98 kg ha-1) and t3 (19.60 kg ha-1). Higher Ca uptake was noted in t6 (64.94 kg ha-1) and was found to be on a par with t3 (59.72 kg ha-1), t7 (59.38 kg ha-1) and t4 (58.61 kg ha-1). Higher Mg uptake in t4 (20.47 kg ha-1) was comparable with t3 (19.84 kg ha-1), t6 (19.61 kg ha-1) and t8 (19.60 kg ha-1). Higher Cu uptake was recorded by the t1 (1.82 kg ha-1) and was found to be on a par with t3 (1.73 kg ha-1). Higher Fe uptake was observed in t6 (0.96 kg ha-1) and remained at par with t1 (0.88 kg ha-1) and t3 (0.82 kg ha-1). Higher Mn uptake was recorded by t8 (1.69 kg ha-1) and was found to be on a par with t7 (1.68 kg ha-1), t4 (1.67 kg ha-1), t6 (1.61 kg ha-1) and t2 (1.46 kg ha-1). Among the soil parameters, the water holding capacity of soil was significantly higher for t4 (33.87%) and was on a par with t8 (33.02%), t3 (32.73%), t2 (32.65%) and t7 (32.61%). The bulk density of soil was found to be significantly lower for t8 (1.21 Mg m-3). Soil organic carbon was significantly higher for t4 (1.29 %) and remained at par with t8 (1.26%) and t3 (1.25%), t2 (1.23%), t7 (1.23%), t1 (1.19%) and t6 (1.17%). Available N was significantly higher for t4 (209.07 kg ha-1). Higher net income was observed in t3 (₹ 154292 ha-1) and was on a par with t5 (₹ 110728 ha-1) and t7 (₹ 108876 ha-1). Higher benefit-cost ratio was observed for t3 (1.78) and was on a par with t5 (1.65), t1 (1.59) and t7 (1.55) for okra. It could be concluded that, after characterization of biochar produced from different agro wastes, the biochar produced from tender coconut husk was the best by virtue of its higher recovery percentage, water holding capacity, pH, EC, CEC and total N. The rate of biochar as a soil conditioner for okra in Onattukara was standardized as 10 t ha-1. The soil application of biochar at the rate of 10 t ha-1 along with 5 t ha-1 FYM and 100 per cent recommended dose of fertilizer could be recommended for yield enhancement of okra while, the cost effective combination was biochar at the rate of 5 t ha-1 along with 5 t ha-1 FYM and 100 per cent recommended dose of fertilizer in the sandy loam soils of Onattukara.
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    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 V
    The 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.
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    Biochar based nano carriers for enhanced herbicide bio-efficacy
    (Department of Agronomy, College of Agriculture , Vellayani, 2024-03-25) Lisha Jose Kappen; Susha, V S
    The study entitled “Biochar based nano-carriers for enhanced herbicide bio efficacy” was undertaken at College of Agriculture, Vellayani, during 2021-2023. The objectives of the study were formulation and characterization of rice husk-biochar nano-carrier based 2, 4-D; assessing the bio-efficacy of the formulation on broad leaf weed and sedge and testing its efficacy for weed management in upland rice. Rice husk nano carrier (RHNC) and rice husk-biochar nano-carrier (RHBNC) were synthesized in the laboratory and loaded with the herbicide 2, 4-D sodium salt following a standard protocol. The characterization studies like X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and Scanning electron microscopy revealed an average size of 503.8 nm for the RHBNC. The bio-efficacy of RHNC and RHBNC based 2, 4-D formulations were assessed on Limnocharis flava (L.) Buchenau (broad leaf weed) and Cyperus rotundus (sedge) as a pot study at College of Agriculture, Vellayani during June 2023. The experiment comprised 10 treatments replicated thrice in a completely randomized design. The treatments were T1- RHNC based 2, 4-D in the weight ratio (1:0.10) at 0.8 kg a.i. ha-1, T2- RHNC based 2, 4-D in the weight ratio (1:0.25) at 0.8 kg a.i. ha-1, T3- RHNC based 2, 4-D in the weight ratio (1:0.10) at 0.6 kg a.i. ha-1, T4- RHNC based 2, 4-D in the weight ratio (1:0.25) at 0.6 kg a.i. ha-1, T5- RHBNC based 2, 4-D in the weight ratio (1:0.10) at 0.8 kg a.i. ha-1, T6- RHBNC based 2, 4-D in the weight ratio (1:0.25) at 0.8 kg a.i. ha-1, T7- RHBNC based 2, 4-D in the weight ratio (1:0.10) at 0.6 kg a.i. ha-1, T8- RHBNC based 2, 4-D in the weight ratio (1:0.25) at 0.6 kg a.i. ha-1, T9- conventional 2, 4-D at 0.8 kg a.i. ha-1, T10- Control (weedy check). The growth parameters of the weeds L. flava and C. rotundus were adversely affected by RHNC and RHBNC-based 2, 4-D formulations. In L. flava, significantly higher per cent reduction in population (62.06) was recorded in RHBNC based 2, 4-D in the weight ratio (1:0.25) applied at 0.8 kg a.i ha-1 (T6) which was on par with T1 (57.46), T9 (57.46) and T8 (53.93). In C. rotundus, T6 recorded significantly higher per cent reduction in population (66.66), shoot and tuber dry weight and was on par with T9. This treatment resulted in highest weed control efficiency of 95.33 per cent and 98.74 per cent in L. flava and C.rotundus respectively. The chlorophyll content of L. 128 flava (0.25 mg g-1 fresh weight) and C. rotundus (0.44 mg g-1 fresh weight) was significantly lower in T6. In L. flava, regeneration was observed in T2, T3, T4 and T5 at 28 days after treatment. However, in C. rotundus was no regeneration was observed in any of the treatments. The efficacy of RHNC and RHBNC based 2, 4-D formulations for weed management was tested under field condition in upland rice at the Instructional Farm, College of Agriculture, Vellayani from August 2023 to November 2023. The experiment was laid out in randomised complete block design with nine treatments, replicated thrice. The treatments were T1- RHBNC based 2, 4-D in the weight ratio (1:0.25) at 0.6 kg a.i. ha-1, T2- RHNC based 2, 4-D in the weight ratio (1:0.10) at 0.8 kg a.i. ha-1, T3- RHBNC based 2, 4-D in the weight ratio (1:0.10) at 0.6 kg a.i. ha-1, T4- RHNC based 2, 4-D in the weight ratio (1:0.10) at 0.6 kg a.i. ha-1, T5- RHBNC based 2, 4-D in the weight ratio (1:0.25) at 0.8 kg a.i. ha-1, T6- RHBNC based 2, 4-D in the weight ratio (1:0.10) at 0.8 kg a.i. ha-1, T7- Conventional 2, 4-D at 0.8 kg a.i. ha 1 , T8- hand weeding (HW) twice at 15 and 30 days after sowing (DAS), T9- weedy check. The variety KAU Manuratna was dibbled at a spacing of 20 cm x10 cm in upland and managed as per KAU POP. Broad leaf weeds and sedges dominated the weed flora composition. At 40 DAS, dry weight of sedges and broad leaf weeds was the lowest in T8 which was followed by T5 and at 60 DAS it was statistically on par with T5. The treatment, T8 recorded higher weed control efficiency (84.95%, 72%) and weed control index (56.33%, 49.28%) at 40 and 60 DAS respectively and was on par with T5. Rice husk nano-carrier and rice husk-biochar nano-carrier based 2, 4-D formulations significantly influenced the growth attributes of rice including plant height, leaf area index, number of tillers m-2 and total dry matter production at all growth stages. Among the formulations, T5 recorded significantly taller plants (72.03 cm, 74.08 cm) and leaf area index (3.80, 4.29) at 40 DAS and 60 DAS respectively and was comparable with T8. The treatment, T5 exhibited higher yield attributes like number of productive tillers per m-2 (389.33) and filled grains per panicle (100.96) which was on par with T8. Grain yield was significantly higher in T8 (3103 kg ha-1) and was comparable with T5 (2840 kg ha-1). Higher harvest index was recorded in T5 129 (0.441) which was on par with T8 (0.440) and T2 (0.440). Weed index which signifies yield loss due to weeds was the lowest in T5 (17.96). Nutrient uptake by crop (N, P and K) was higher in T8 and was comparable with T5. Also, the treatment, T8 exhibited lower nutrient removal by weeds and was on par with T5. Dehydrogenase enzyme activity at 40 DAS and 60 DAS was higher in treatments T5, T2 and T6. Microbial population showed enhanced growth in all herbicide treated plots when compared with T8 and T9 (weedy check). The study identified RHBNC based 2, 4-D in the weight ratio (1:0.25) applied at 0.8 kg a.i. ha-1 as the most effective formulation for the management of L. flava and C. rotundus in terms of weed control efficiency and lower regeneration count. The formulation was found to enhance the bio-efficacy of 2,4-D for weed management in upland rice improving yield and weed control efficiency than conventional 2, 4-D herbicide.
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    Production, characterisation and quality assessment of biochar
    (Department of Agronomy, College of Horticulture, Vellanikkara, 2015) Ammu Punnoose; Anitha, S
    Crop residues in fields can cause considerable crop management problems if they accumulate. Composting is a viable option for crop residue management. However composting of plant twigs and woody plant residues is difficult as they take longer time for decomposition. Conversion of crop residue biomass into biochar and using it as a soil amendment is a nascent approach and then suggested as an alternative to composting and crop residue burning. Biochar is produced by controlled burning of biomass with little or no oxygen, known as pyrolysis. Research information on biochar in agricultural use in India is scanty. Very few reports are available on production, characterization and use of biochar as soil amendment. The present study was proposed against this backdrop to produce biochar from crop residues and to study the effect of biochar on the performance of crops. The investigation entitled ‘Production characterisation and quality assessment of biochar’ was conducted to assess the effect of production methods and materials used on the character of biochar and to study its suitability as soil amendment for amaranth. Woody wild growth, coconut petiole and herbal waste residues left after composting were the three materials used for biochar production. Biochar was produced using heap and drum methods. Biochar was characterised by percentage mass recovery and by physical and chemical distinctiveness. Methods of production and materials used had significant influence on the characteristics of biochar. Drum method gave higher biochar recovery compared to heap method. Porosity, water holding capacity and carbon content were higher in biochar produced from woody wild growth. All biochars showed alkaline pH with the highest pH in coconut petiole biochar. An increase in NPK content was noticed in biochar compared to the materials used. A pot culture experiment was conducted to study the soil amendment effect of biochar on crop performance. The treatments consisted of six biochars produced from three materials using two methods of production, along with three levels of fertilizers ie, 100 per cent recommended NPK, 75 per cent NPK and absolute control( without any fertilizers). Biochar materials were mixed at a 1:1 ratio on volume basis with soil and assessed their effect on the growth and yield of amaranth. They were also compared with treatment of ordinary potting mixture receiving FYM and 100 per cent NPK. A residual crop was raised in the same pot after the experiment and the yield of the crop was noted. For the first crop, the highest yield was obtained in the ordinary potting mixture which received 100 per cent NPK when compared with the biochar treatments. For the second crop, the highest yield was observed in the woody wild growth biochar receiving 100 per cent NPK. This indicated the nutrient retention property of biochar and its long term benefit. Biochar from woody wild growth recorded the highest carbon content, porosity and water holding capacity and produced better yields, among the different biochar materials. Biochar along with 100 per cent NPK recorded the highest yield compared to biochar treatments without fertilizers. Because of the high water holding capacity of biochar, irrigation could be given to the crops once in three days for the biochar applied treatments instead of twice daily as was done in ordinary potting mixture. Increase in pH of the soil was noticed after the experiment indicating its efficiency as a soil amendment in acidic soil. Beneficial properties of biochar like high carbon content, alkaline pH and high water and nutrient holding capacity revealed the suitability of biochar as a soil amendment.
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    Climate resilient product development from seaweeds kappaphycus alvarezii, gracilaria corticata and water hyacinth eichhornia crassipes
    (Academy of Climate Change Education and Research, Vellanikkara, 2018) Shamiya Hasan; Zacharia