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201919
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Subject: Soil Science and Agriculture Chemistry × Author: KAU × End date: 2019 × Start date: 2019 ×
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    ThesisItemOpen Access
    Carbon pools in Lateritic soil amended with coirpith-vermicompost and its effect on Tomato (Solanum lycopersicum L.)
    (Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 2019) Aiswarya, R; KAU; Jayasree Sankar, S
    Soil organic carbon (SOC) is considered as the key indicator of soil quality and agricultural sustainability. Among the different management practices that are being followed, application of chemical fertilizers and manures has been recognized as the most systematic and effective means to either enhance soil organic carbon accumulation or reduce the rate of SOC loss. Hence, for studying the effect of coirpith based vermicompost on dynamics of carbon in a lateritic soil, a field experiment was laid out during October 2018 – February 2019, in RBD with 12 treatments replicated thrice, with tomato, variety Manulakshmi, as the test crop. The plot size was 3 x 3 m and plant spacing was 60 x 60 cm. The treatments consisted of an absolute control (T1), coirpith compost at 10 t ha-1 (T2), coirpith based vermicompost at 10 t ha-1 (T3), Coirpith based vermicompost at 10 t ha-1 + soil test based KAU POP (T4), , FYM at 20 t ha-1 + soil test based KAU POP(T5), T3 + 25 % of soil test based KAU POP (T6), T3 + 50 % of soil test based KAU POP (T7), T3 + 75 % of soil test based KAU POP (T8), FYM at 20 t ha1 + 25 % of soil test based KAU POP (T9), FYM at 20 t ha-1 + 50 % of soil test based KAU POP (T10), FYM at 20 t ha-1 + 75 % of soil test based KAU POP (T11), Adhoc KAU organic POP (T12). Raw coirpith was converted into compost using vermitechnology employing the compost worm Eisenia foetida .The composting process got completed within 64 days time span. Coirpith in the raw stage and after composting was characterized for physical, electro-chemical and chemical properties. Advantages of vermicomposting coirpith included a reduction in the content of lignin (32 to 16.7 %), cellulose (25.2 to 10.2 %), C: N ratio (113:1 to 20.5:1) and EC (0.98 to 0.51 dS m-1) and an increase in pH and total nutrients. Soil analysis after the experiment revealed the significance of treatments on electro-chemical and chemical properties as against the control. Significantly higher available K (281.0 kg ha-1) and Mn (75.33 mg kg-1) was obtained in coirpith based vermicompost at 10 t ha-1 + soil test based KAU POP (T4). In case of N, P, Ca and Fe the effect of the treatments T4, T5 (FYM + soil test based POP) and T8 (Coirpith vermicompost + 75 % soil test based POP) were comparable. The labile C fractions viz. water soluble carbon (WSC), hot water soluble carbon (HWSC), permanganate oxidizable carbon (POXC) and microbial biomass carbon (MBC) were also significantly influenced by the treatments and it followed the order POXC > HWSC > MBC = WSC. Further analysis revealed that the treatments T4, T5, T6 (Coirpith vermicompost + 25 % soil test based POP), T8 and T11 (FYM + 75 % soil test based POP) were comparable in influencing WSC, whereas T4 and T5 were similar in deciding HWSC and T4 and T8 in case of MBC. Significantly higher total C was registered by coirpith vermicompost + 75 per cent soil test based KAU POP. Dehydrogenase activity which is considered as an index of microbial activity in soil was significantly higher (146.3 µg TPF g-1soil 24hr-1) in coirpith based vermicompost at 10 t ha-1 + soil test based KAU POP. Integration of chemical fertilizers at different levels with organics, either coir pith vermicompost or FYM, increased microbial population which followed the order bacteria > fungi > actinomycetes. However, the impact of treatments was more pronounced in enhancing bacterial population due to the shift in pH towards neutral value. On considering biometric observations, it was seen that the plant height (104.7 cm), number of fruits per plant and fruit yield (1.84 kg/plant) were significantly higher for the treatment coirpith based vermicompost at 10 t ha-1 + soil test based KAU POP. The effect of coirpith based vermicompost and FYM along with fertilizers at different levels were comparable in determining fruit quality parameters like total soluble solids, ascorbic acid, lycopene and titrable acidity. Applying coirpith based vermicompost at 10 t ha-1 + soil test based KAU POP registered a higher B: C ratio of 2.43 in contrast to 1.57 recorded in the absolute control.
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    ThesisItemOpen Access
    Assessment of soil degradation and water quality in areas of small scale brick production and management of the degraded soil
    (Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 2019) Sophia, Baby; KAU; Betty, Bastin
    The utilization of clay for construction of habitations and buildings dates back to the period of ancient civilizations. Even though centuries had passed and civilizations changed, the basic raw material for brick production remained the same. Brick production requires fine clayey loam soil with plenty of water supply. With the increasing demand for construction material, clay mining had shifted from river banks to fertile agricultural lands. This change in land use had resulted in the deterioration of soil health and decrease in crop production. The entry of large number of small scale brick production units is causing irreversible damages to the soil, hydrology and ecosystem. Hence, this study was taken up to characterise the desurfaced (mined) soils and water resources and to identify suitable management methods of these soils. A comprehensive survey was conducted at Alathur Taluk of Palakkad District to identify locations with resurfaced soils. Soil and water samples were collected from 11 locations including a control location without mining activities during August to September, 2017. A total of 88 soil samples (eight samples per location) and 11 water samples (one sample per location) were collected for the study. Both soil and water samples were analysed for various physico- chemical properties. Biological properties of soil samples were also analysed. The physical properties of soil such as temperature and bulk density were found to be higher in desurfaced soils when compared to control. The water holding capacity, porosity and moisture content were found to be reduced in desurfaced soils. The texture of the soil changed from clay loam to sandy loam. The organic carbon content of desurfaced soils were in the range of 0.08 – 0.46 per cent with a reduction of 61 per cent when compared with control soil. The content of available nitrogen, phosphorus and potassium were also reduced to the extent of 43.70, 74.50 and 43.36 per cent respectively. The available magnesium content was found to be lower in desurfaced soils (55.6 per cent reduction). The content of plant available micronutrients (Fe, Mn, Cu and Zn) and heavy metals (Ni, Cr and Pb) were high in desurfaced soils. The presence of earthworms (13 nos. per m2) and termite mound were observed only in the xi control soil. The microbial biomass carbon and dehydrogenase enzyme activity were highly reduced in desurfaced soils. Water samples were also affected by small scale topsoil mining activity. The pH, electrical conductivity and TDS were in the safer limits for all water samples. The concentrations of sodium (W1 andW10) and calcium (W1 andW5) in certain water samples collected from mined areas were high and they were above safe limits to be used for irrigation purposes. Similarly the higher levels of nitrate, phosphate, bicarbonate and chloride in water samples from mined areas denote the possibility of the water bodies being polluted by mining activities. Based on the status of organic carbon and major nutrients, the soil with the lowest nutrient status (S5) was selected for pot culture study. The pot culture study was conducted with chilli (var. Anugraha) as the test crop. The effect of various organic and inorganic amendments on the properties of desurfaced soils were evaluated in this experiment. The treatment T2 (soil test based NPK + poultry manure) recorded the highest plant height (50.42 cm), number of leaves (221.78) and number of branches (6.11) at 60 days after transplanting. The yield attributes such as total number of flowers (95.33), total number of fruits (31.33) and per cent fruit set (32.95 per cent) were found to be higher for the same. The highest yield was obtained for the treatment T2 (soil test based NPK + poultry manure). The soils were also analysed after the harvest of the crop. The bulk density of soil after harvest was the lowest in treatment T3 (soil test based NPK + vermicompost) and was on par with T4 (soil test based NPK + coirpith compost). The content of organic carbon, available nitrogen, phosphorus and potassium recorded higher values in treatment T2 (soil test based NPK + poultry manure) than the other treatments. The biological properties such as microbial biomass carbon (374.133 μg g-1 soil) and dehydrogenase activity (3.630 μg TPF g-1 day-1) were the highest in treatment T2 (soil test based NPK + poultry manure) and T4 (soil test based NPK + coirpith compost) respectively. The study revealed that top soil mining for brick production predominantly affected bulk density, soil temperature and water holding capacity of the soils. The content of organic carbon and available nutrients such as N, P and K were also reduced. The biological properties like dehydrogenase enzyme activity and microbial biomass xii carbon reduced to a greater extent. Water samples from mined areas were polluted by cations like sodium and calcium and anions like nitrate, phosphate, bicarbonate and chloride to limited extent. Poultry manure application as an integrated nutrient management technique, followed by vermicompost application were found to be beneficial for the management of such desurfaced soils.
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    ThesisItemOpen Access
    Taxonomy and organic carbon-nutrient interactions in selected wetland soils of Kerala
    (Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 2019) Nideesh, P; KAU; Sreelatha, A K
    A study was undertaken with the objective to classify wet land soils in the agro ecological units AEU 10 (north central laterite), AEU 5 (Kole lands) and AEU 6 (Pokkali lands) of Kerala and to assess the organic carbon stocks and CNPS stoichiometry. The study also aimed in finding out the organic carbon - nutrient interactions and to predict the organic carbon turnover in these soils. Extensive field traverse was conducted to select sites for profile excavation in the lateritic, Kole and Pokkali wetlands. The excavated profiles were studied for their morphological, physical and chemical properties. Based on the results of the study, soils of lateritic wetlands were classified as fine loamy, mixed, super active, acid isohyperthermic, Fluventic Dystrustepts. Soils of Kole lands were classified as loamy, mixed, euic, isohyperthermic, Terric Sulfihemists and Pokkali soils as coarse loamy over sandy, mixed, active, isohyperthermic, Typic Sulfaquepts. Total soil organic carbon (SOC) stock in the north central laterite region (Fluventic Dystrustepts) was 218 Mg ha-1 up to the depth of 120 cm of which maximum amount was stored in the surface 30 cm (86 Mg ha-1). In the Kole land soil (Terric Sulfihemists) maximum SOC was stored in the 90-120 cm layer (1016 Mg ha-1) and a total SOC of 2261 Mg ha-1 was stored up to 120 cm depth. Pokkali soils (Typic Sulfaquepts) stored 209 Mg ha-1 SOC up to 120 cm depth which was almost uniformly distributed in the entire profile. The C/N, C/P and C/S ratios decreased with depth in lateritic soil profile, whereas in the Kole land soil these ratios except C/S ratio increased significantly in the sub surface horizons. In the Pokkali soils the CNPS stoichiometry suffered irregular variation with depth. An incubation experiment was conducted to study the organic carbon nutrient interactions in the three wetland soils. Treatments included control (T1), POP based fertiliser and lime application (T2), soil test based fertiliser and lime application (T3), FYM substituting nitrogen in the T3 treatment (T4) and soil test based fertiliser and dolomite application (T5). In the lateritic soils. the active carbon and organic reserves of N, P and S were high in T3 treatment. The organic N, P and S pools increased in treatment T5 whereas organic P and inorganic S increased in treatment T4. In the Kole land soils, active carbon, organic nitrogen, inorganic P, organic S and inorganic S increased in T3; inorganic N and organic P increased in T4 and organic P and S pools increased in T5. In the Pokkali soils, active carbon content was high in T2 compared to other treatments while active carbon, organic N and inorganic N decreased in treatment T3. Liming decreased organic P in Pokkali soils due to conversion to available forms and higher utilisation. Application of FYM increased organic S in Pokkali soils and inorganic S in all soils. Temporal variation of the nutrient content (mg kg-1 soil) per organic carbon content (g kg-1 of soil) indicates the change in nutrient supply per unit change of organic carbon content. Treatment T1 favoured higher inorganic nitrogen per carbon content in laterite and Pokkali soils, where as in in Kole soils it was increased in T4. Inorganic phosphorus content per carbon was highest in laterite and lowest in Kole soil in control (T1). Inorganic sulphur per carbon content was highest in T4 for laterite, Kole and Pokkali soils. Organic nitrogen per carbon content was highest in the Kole land and minimum in the Pokkali land in the T3 treatment. Organic phosphorus per carbon content was maximum in FYM treatment in Kole and Pokkali soils and was minimum in T2 treatment in laterite and Pokkali soils. Treatment T3 had the highest organic sulphur per carbon content in the laterite and Kole soils and the treatment T1 gave the highest content in Pokkali soil. Wetland DNDC model was used to simulate the organic carbon turn over in the three wetland systems using the climatic data predicted by MarkSIM software. The results of modelling simulated for the year 2050 indicated that application of 100 per cent NPK along with FYM @ 5t ha-1 will ensure maximum organic carbon content in the Kole, Pokkali and lateritic wetlands. Fertiliser application improves the organic carbon storage in lateritic and Kole land soils. But in the Pokkali soils, fertiliser addition will not cause change in the organic carbon turn over processes whereas FYM application can improve the carbon content. Results of the study indicate that cultivation without any fertiliser and lime application causes gradual depletion of all organic and inorganic pools of nutrients in Kole land and lateritic wetland soils. Soil test based fertiliser and lime application along with FYM @ 5t ha-1 is appropriate in these soils for increased sustainability. The Pokkali soils are self-sufficient and can sustain its fertility status without any fertiliser application. However liming and FYM application may be considered as management options to improve sulphur availability and organic carbon turn over processes in these soils.
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    ThesisItemOpen Access
    Performance of Non-Conventional soil Ameliorants in Banana (Musa spp) var. Nendran
    (Department of Soil Science and Agricultural Chemistry, College of Agriculture,Padannakkad, 2019) Amalendu, M V; KAU; Jayaraj, P
    An investigation entitled “Performance of non-conventional soil ameliorants in banana (Musa spp) var. Nendran” was carried out at College of Agriculture Padannakad and Regional Agricultural Research Station (RARS) farm Nileshwar from 2017 to 2019. The objective was to study the performance of banana (Musa spp) var. Nendran in initial period with respect to the different non-conventional ameliorants and a subsequent field trial to confirm the importance of these ameliorants throughout the growing period in improving plant health and yield Pot culture study was carried out to evaluate the efficiency of different soil ameliorants in improving soil health as well as crop health with respect to availability of nutrients upto 4 months. The experiment was conducted in Completely Randomized Design (CRD) consisting of 5 treatments and 4 replications with the following treatments; T1 (basal application of Calcium silicate), T2 (Basal application of lime+ silica), T3 (Basal application of dolomite + silica), T4 (Basal application of Gypsum+ silica), control T5 (Basal application of lime as per KAU POP 2016). The biometric observations like the plant height, number of leaves, root length, root diameter and root CEC were periodically recorded. Considering the plant height, pseudostem girth and number of leaves T4 showed superior results. The root characters like root length, root thickness and root CEC were found superior in T4. The field experiment was carried out at Regional Agricultural Research Station (RARS) farm Nileshwar to study the effect of ameliorants on yield and quality of tissue culture banana var. Nendran. It was conducted in randomized block design comprising of 11 treatments and 3 replications. The treatments used in pot culture experiment were used in split doses to manage the soil acidity throughout the growing period of crop. Treatments were T1( Basal application of Calcium silicate), T2 (Basal application of lime + silica), T3 (Basal application of dolomite +silica), T4 (Basal application of Gypsum + silica), T5 (Lime+ silica in 2 splits at 1st and 2nd month after planting), T6 (Dolomite + silica in 2 splits at 1st and 2nd month 140 after planting), T7 (Gypsum + silica in 2 splits at 1st and 2nd month after planting, T8 (Lime+ silica in 3 split doses at 1st month, 2nd month and 4th month after planting),T9 (Dolomite + silica in 3 split doses at 1st month, 2nd month and 4th month after planting), T10 (Gypsum + silica in 3 split doses at 1st month, 2nd month and 4th month after planting), T11 (Application of lime as per KAU POP 2016) as the control. Biometric observations were recorded periodically. Soil and leaf analysis were also carried out at specific intervals of the experiment. The results of the field experiment revealed that among the vegetative characters, plant height, pseudostem girth at 90 cm height, number of leaves, number of functional leaves and number of suckers were superior for T10. Considering the yield attributes like number of hands per bunch (6.33) and number of fingers per hand (8.66) T10 recorded superior results. Treatment T10 recorded the highest bunch weight of 11.24 kg. Among the finger characteristics, average finger breadth (16.00 cm) and average weight of the fingers (225.00 g) is superior in T9 and the finger length (21.30 cm) is superior in T10. Among the treatments T10 recorded minimum days for bunch emergence (186 days), days to harvest (277 days) and days to ripening (4.33 days). Fruit characters like total soluble solids (29.90 0 brix), titrable acidity (0.27 %), reducing sugar (19.00 %), non reducing sugar (4.89 %), shelf life (4.40 days) were found superior in T10. Studies on the soil nutrient status was conducted at 3 months after planting, 6 month after planting and at harvest of the crop. It was revealed that T10 recorded superior results for soil pH and electrical conductivity. Considering the organic carbon content and cation exchange capacity T10 recorded superior results. Available nitrogen, potassium, phosphorus, calcium and sulphur, copper, zinc and silicon was found superior in T10 whereas highest available magnesium content was recorded in T9. In case of available Iron, manganese and exchangeable aluminium T10 gave superior results. Leaf analysis was carried out at bunching and at harvest of the crop and the following results were obtained. Nitrogen, potassium, phosphorus content in the leaf was found superior for T10. The calcium and sulphur content in the leaf was 141 superior for T10 while treatment T9 recorded the highest magnesium uptake. Uptake of micronutrients like zinc, copper and silicon were found superior in T10. Lowest concentration of iron and manganese were recorded in T10. The results from the investigation revealed that the application of non-conventional soil ameliorants increased the nutrient availability in soil thereby increasing the yield and quality of banana. Among them application of gypsum + silica in 3 splits dosses performed well and produced superior results in northern lateritic soils.
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    ThesisItemOpen Access
    Nutrient management in coconut based cropping system utilizing products from rapid conversion technology of biowastes
    (Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2019) Priya, U K; KAU; Sudharmai Devi, C R
    The study entitled “Nutrient management in coconut based cropping system utilizing products from rapid conversion technology of biowastes” was carried out at the Department of Soil Science and Agricultural chemistry, Vellayani and Farmers field in Onattukara , Kayamkulam ,Alapuzha during May 2016 to August 2018. The major objective of study was the nutrient management in coconut intercropped with banana (Njalipoovan) and tuber crop elephant foot yam (Amorphophallus paeoniifolius ) variety Gajendra using different products that are produced from rapid conversion technology of biowastes in AEU 3 of Kerala. In development and characterization of liquid formulation produced by rapid conversion technology, the segregated, ground biodegradable waste was subjected to thermochemical process and extracted using five concentrations (1%,2%, 3%, 6%, 10%) of four extractants KOH (0.1 N), KOH (0.25 M), KCl (2M), distilled water. The best extractant was chosen after screening for shelf life and phytotoxicity test using germination bioassay. KOH 0.25M, 2% and KCl 2M ,3% promoted seed germination, seedling vigour of okra and cow pea were selected. The two concentrations were then tested for their performance in pot culture using amaranthus and tomato. The results indicated that KOH 0.25 M, 2 % was superior to the KCl 2M, 3% solution. KOH 0.25 M 2 % was then fortified using modified Hoagland medium and GA3 1ppm. In banana and amorphophallus 0.1% dilution was given as foliar spray and in coconut 0.5% dilution was given as root feeding. Customisation of organic fertilizer was carried out on the basis of initial soil test results and crop requirements. 227 In order to find the effect of treatments in coconut intercropped system a field trial was conducted in RBD with eight treatments and 3 replications. The treatments had significant effect on the soil bulk density and WHC. There was lowering of bulk density in banana and amorphophallus for treatments that received POP and POP +STB. The highest WHC in coconut was for the treatment that received POP+STB. In banana and amorphophallus the WHC was highest for treatment that received POP and POP +STB followed by FFOF. There was a slight increase in the pH, for the treatments that received FFOF, QFOF+LF, HFOF +LF and LF alone. The second and third depths remained unaffected in terms of physical properties due to treatment effects. In soil carbon pools dynamics the results showed that TOC % was highest in surface soils for the treatments that received POP, POP +STB and FFOF in all the three crops. The labile carbon content was highest for treatment that received FFOF and LF, HFOF+LF, QFOF+LF in coconut for all the three depths. In amorphophallus and banana, the highest was for FFOF followed by the POP and POP+STB. Similar trend was followed in the case of oxidizable carbon, LI and CPI. The dehydrogenase activity was also high in treatments receiving FFOF ad those receiving LF. The earth worm count was mostly related to the rainfall pattern and not the carbon pool dynamics. There was a gradually increasing trend for soil available nutrients for subsequent years. In the case of coconut the primary nutrients shows a gradual increase in the April -May followed by a hike in August September in surface samples. the treatments that received FFOF was superior or on par with HFOF+LF or LF, POP, POP+STB. Second and third depths nutrient values were usually highest for treatment that received foliar fertilization and root feeding. In banana and amorphophallus POP, POP +STB and LF were either superior or comparable to FFOF. There was an initial increase in nutrient content of soil followed by a gradual decrease. In the case of micronutrients and secondary soil nutrient status FFOF was superior to all other treatments in terms of soil nutrient 228 availability that was mostly on par with POP+STB or HFOF +LF treatments for coconut, banana and amorphophallus. The foliar nutrient concentration in coconut showed a significant change only during the third season of treatment application. The highest foliar concentration was for treatment receiving FFOF, POP, POP+STB followed by the HFOF +LF, QFOF +LF, LF that was on par. In case of banana and amorphophallus a similar pattern was observed. The yield and yield contributing parameters in coconut showed a significant change during the third observation period of treatment application. The highest yield in terms of nut yield was highest for treatment receiving FFOF, followed by POP, POP+STB and HFOF +LF. A similar trend was seen in banana (18.01 kg) and amorphophallus (7 kg) wherein the yield was highest for treatment receiving FFOF followed by that receiving POP+STB, POP, that was comparable with yield in treatment receiving HFOF +LF. The Benefit cost ratio in coconut was highest for the treatments that received POP and POP+ STB, followed by the treatment that received half dose of FOF along with root feeding that was comparable with treatments that received QFOF +LF or LF alone. In the case of banana highest B:C ratio of 2.72 was for treatment receiving foliar fertilization alone, followed by FFOF, 2.60 during the first season. The second season the treatment with FFOF was on par with the treatment that received foliar fertilization. In amorphophallus the treatment that received FFOF was having the highest BC ratio followed by the treatment that received HFOF+LF during the first season. The same trend was found in second season. Hence it can be concluded that application of FFOF will increase the yield, soil nutrient availability and uptake in coconut and inter crops. Half dose of FOF along with LF was equally beneficial for annual crop. In case of coconut when the B:C ratio was calculated despite of the comparatively low yield in treatments that received liquid fertilization and POP, was on par with the treatment that received 229 FFOF, due to the high cost of FFOF. Therefore, if the unit cost of FOF is reduced can increase the B:C ratio for the treatment that receives FFOF, which can be recommended to the farmers for economic and ecologically sustainable intercropping of coconut with banana and amorphophallus.
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    ThesisItemOpen Access
    Organic nano NPK fomulations for enhanching soil health and productivity
    (Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2019) Nibin, P M; KAU; Ushakumari, K
    The present investigation entitled “Organic nano NPK formulations for enhancing soil health and productivity” was carried out from July 2017 to February 2019 in the Model Organic Farm under the Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani. The objectives of the study were to characterize organic nano NPK formulations, assess the nutrient release pattern under laboratory conditions and study the effect of soil and foliar applications of organic nano NPK formulations on crop growth, yield, quality and soil health using okra as direct test crop and amaranthus as residual test crop. The first part of the experiment comprised characterization of granular and liquid nano NPK formulations. During characterization study physical, physico-chemical and biochemical properties of nano NPK formulations were estimated. The particle size of granular and liquid nano NPK formulations were 83.20 nm and 71.79 nm, respectively. The surface area of granular nano NPK formulation was 138.95 m2 g-1. The pH of granular nano NPK was neutral and that of liquid nano NPK was slightly acidic. Primary, secondary and micro nutrient contents (Cu, Zn, Fe, Mn and B) in both granular and liquid nano NPK formulations were analysed. Heavy metals such as As and Cd were not detected in the nano NPK formulations and Pb, Ni and Cr detected were below the permissible limit. Organic carbon, total amino acid and organic matter fractions of granular nano NPK were also determined. The second part of the experiment was a laboratory incubation study, conducted to assess the nutrient release pattern of granular nano NPK formulation for a period of 75 days. The study comprised of 8 treatments with 3 replications. Treatments included Soil alone (T1), Soil + FYM (12 t ha-1) (T2), Soil + nano NPK 12.5 kg ha-1 (T3), Soil + FYM (12 t ha-1) + nano NPK 12.5 kg ha-1 (T4), Soil + nano NPK 25 kg ha-1 (T5), Soil + FYM (12 t ha-1) + nano NPK 25 kg ha-1 (T6), Soil + nano NPK 50 kg ha-1 (T7) and Soil + FYM (12 t ha-1) + nano NPK.50 kg ha-1 (T8). In general, pH, EC and organic carbon content of incubated soil significantly increased throughout the incubation period. There was a significant difference in the available nutrient status of primary, secondary and micronutrients throughout the period of incubation. In general all the available nutrients increased upto 45th day of incubation and thereafter showed a decreasing trend except for K, where K showed an increasing trend upto 60th day and thereafter declined on 75th day. In the case of available Fe, Mn and Cu, the nutrient release increased upto 45th day of incubation and then declined. Zn showed a varying pattern of release. T1 (Soil alone treatment) recorded the least nutrient release pattern throughout the incubation period. The third part of the study consisted of four field experiments to study the efficacy of organic nano NPK formulations on crop growth, yield, quality and soil health using okra as the direct test crop and amaranthus as residual test crop. The field experiment on okra followed by amaranthus was repeated once again for confirmatory results. The field studies were carried out in a lattice design with 16 treatments and 3 replications. Treatments consisted of soil application of granular nano NPK at 3 levels (12.5 kg ha-1, 25 kg ha-1 and 50 kg ha-1) with and without FYM, foliar application of liquid nano NPK at 2 levels (0.2% and 0.4%) with and without FYM and combined application of granular and liquid nano NPK formulations with and without FYM. Growth, physiological and yield attributes of okra (direct test crop of first and third field experiment) viz., plant height, LAI, DMP, chlorophyll content, days to 50 % flowering, fruit length, fruit girth, number of fruits per plant, average fruit weight and total fruit yield were significantly influenced by the soil and foliar applications of organic nano NPK formulations. Treatment that received FYM + soil application of granular nano NPK formulation 12.5 kg ha-1 along with foliar application of liquid nano NPK formulation 0.4 per cent was found to be the best with respect to yield and yield attributes. Quality parameters of the fruit viz., crude protein, crude fibre and ascorbic acid contents were influenced by the application of organic nano NPK formulations. Post harvest analysis of soil for physical, chemical, biological and biochemical properties after the first and third experiments was done and was found to be significantly influenced by the treatments except for the bulk density of the soil. Highest NUE of 30.81 % and 31.38 % was recorded by the treatment T12 for the first and second direct crop, respectively. In general, microbial load viz., bacteria, fungi and actinomycetes were significantly influenced by the application of organic nano NPK formulations. With respect to nutrient uptake by the plants, T12 recorded the highest uptake of N, P, K, Ca, Mg, S, Fe, Mn, Zn and Cu for first and second direct test crop (okra). The highest B:C ratio of 2.27 was also recorded by T12 for both the okra crops. The residual effect of nano NPK formulations on growth, yield, quality and soil health was studied by raising amaranthus as test crop in the same field after the harvest of the direct test crops (okra). Highest plant height, DMP and yield were recorded in T12 in both residual crops. Quality parameters of residual crop were analysed and T12 registered the lowest oxalate and nitrate content. The highest vitamin C was recorded by T12. Post harvest analysis of soil revealed that pH, OC, labile carbon, available N, P, K, Ca, Mg, micronutrients and enzymatic activities were significantly influenced due to the residual effect of organic nano NPK formulations by soil and foliar application. Regarding the uptake of nutrients, T14 (FYM (12 t ha-1) + soil nano (25 kg ha-1) + foliar nano NPK (0.2%)) recorded the highest uptake of N, P, K, Ca, Mg, S and micronutrients (Fe, Mn and Zn). The highest B: C ratio of 1.99 was registered in T12 in first residual experiment. Similarly B:C ratio of 1.81 was recorded in the treatment T12 in second residual experiment. The present study revealed that both granular and liquid nano NPK formulations satisfied nano specifications having particle size less than 100 nm and high surface area. Organic nano NPK formulations contained primary, secondary, micronutrients, organic carbon, amino acid, humic acid etc. From the incubation study, in general, it was revealed that granular nano NPK formulation was found to be capable of releasing nutrients slowly for a period of 45 days and thereafter showed declining trend. Treatment which received Soil + FYM (12 t ha-1) + nano NPK (25 kg ha-1) was superior with respect to the nutrient release. Among the different treatments, application of FYM (12 t ha-1) + soil nano NPK (12.5 kg ha-1) + foliar nano NPK (0.4%) was found to be the best resulting in highest growth, yield and yield attributes of okra, the direct test crop. Similar trend was observed with respect to residual crop (amaranthus) also. But for the nutrient uptake of the residual crop, FYM (12 t ha-1) + granular nano NPK (25 kg ha-1) + foliar nano NPK (0.2%) showed a significant influence over the other treatments. From the study it was concluded that combined application of granular organic nano NPK at 12.5 kg ha-1 with foliar application of liquid nano NPK 0.4 per cent at biweekly intervals can substitute conventional fertilizers for sustainable crop production and healthy environment. Organic nano NPK formulations are ecofriendly and organically certified which can totally substitute conventional fertilizers and are considered as a boon for organic farming.
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    ThesisItemOpen Access
    Bio fortification of rice (Oryza sativa) with zinc under organic and integrated nutrient management practices
    (Department of Soil Science and Agricultural Chemistry, College of Agriculture, Padannakkad, 2019) Wayoolang Talang; KAU; Suresh, P R
    An investigation entitled “Biofortification of rice (Oryza sativa) with zinc under organic and integrated nutrient management practices” was carried out in Regional Agricultural Research Station (RARS), Pilicode during June to October 2018. The study was conducted in rice variety Uma (MO 16). The main objective of this research was to check the zinc nutrient content under organic and integrated nutrient management practices (INM). The field experiment was laid out under Randomized Block Design (RBD) with nine treatments and one control each replicated three times. The treatments consisted of soil application of Zn and combined soil and foliar application of Zn under organic (Organic Package Of Practice) and INM practices (Package Of Practice Kerala Agricultural University). Zn was applied as zinc sulphate (ZnSO4) at the rate of 1 per cent and 20 kg ha-1 as foliar application and soil application respectively. Foliar application of ZnSO4 was done at three growth stages of rice viz tillering, panicle initiation and flowering stage. Single foliar application of Zn was done at only tillering stage. Double foliar application of Zn was done at tillering and panicle initiation stages and triple foliar application of Zn was done at all the three growth stages. The effect of different treatments significantly influenced plant growth attributes like plant height, number of tillers per hill and panicles per hill. At harvest stage, the highest plant height (99.9 cm) was recorded in T8 (POP KAU + soil application of Zn + triple foliar spray of Zn) which was on par with T7. The minimum plant height was recorded in control (92.3 cm). Similarly, the maximum number of tillers per hill (15.5) and maximum number of panicles per hill (15.5) was recorded in T8 at harvest stage. Soil and foliar application of Zn along with soil application of NPK fertilizers as per POP KAU significantly improved the grain yield and other crop yield attributes. The treatment that recorded the highest grain yield was T8 (6.7 t ha-1) which was superior as compared to other treatments. The treatments that recorded the highest straw yield (6.5 t ha-1) and highest 1000 grain weight (27.1g) was with treatment T7. 127 The nutrient content in the plant samples (shoot and straw) analyzed at different growth stages of paddy was studied. The results revealed that nutrient content of N, K and Zn was highly improved in treatments under INM practices. At the harvest stage, treatments T7 recorded the highest N (0.62 %) and K (1.9 %) whereas Zn (85.7 mg kg-1) content in straw was highest with treatment T8. However, the nutrient content of P in plant samples declined with the increase in the number of foliar application of Zn. The treatment that recorded the lowest P content (0.19 %) in the straw at harvest was T5 (Organic POP + soil application of Zn + triple foliar application of Zn). The effect of treatments on Zn and P content in rice grains were also studied. Grain analysis results revealed that the treatment that recorded the highest Zn content (55.8 mg kg-1) was in T8 and the lowest Zn content (18.2 mg kg-1) was recorded in T10 (control). Similarly, P content was also analyzed in rice grains to study the interaction between Zn and P. The treatment that recorded the highest P content (0.61 %) in the grain was T2 and lowest P content (0.44%) was recorded in T5.
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    ThesisItemOpen Access
    Carbon: nitrogen dynamics in acid sulphate and acid saline rice soils of Kerala
    (Department of Soil Science and Agricultural Chemistry, Vellanikkara, 2019) Irene Elizabeth, John; KAU; Sureshkumar, P
    The present study was undertaken to unravel the chemistry of Carbon: Nitrogen dynamics in submerged acid sulphate and acid saline soils, to identify the labile fractions of these elements contributing to soil fertility and to modify the organic carbon based fertility ratings for nitrogen recommendation in Kale lands. Forty-five representative soil samples from 4 different rice growing acid saline and acid sulphate soils of Kerala were collected and characterized for pH, EC, OC, total carbon, total nitrogen, available nutrients (N, P, K, Ca, Mg, S, Fe, Cu, Mn, Zn and B) and microbial biomass carbon. The soil samples were analysed as such after sampling on wet basis and the results were expressed on moisture free basis to have uniformity. The organic carbon status of the soils varied from 0.81 to 7.58 per cent. Soils from Kaipad recorded the lowest and soils from Vechoor Kari of Kuttanad recorded the highest value of organic carbon. The total nitrogen ranged from 0.05 per cent in upper Kuttanad to 0.42 per cent in Vechur Kari. The highest available nitrogen content of281.38 kg ha' was recorded in sample from Vechoor Kari and the lowest of 19.84 kg ha in Purakkad Kari. The C:N ratio varied from 13:1 to 24:1. Widest C:N ratio was recorded in soils of Upper Kuttanad and the lowest in soils from Thrissur Kale. The organic carbon was significantly and positively correlated with total nitrogen and available nitrogen status. Total nitrogen was the single most independent factor explaining 94 per cent variability of organic carbon. Soil samples were subjected to fractionation studies (both physical and chemical) to quantify the carbon and nitrogen that is associated with different inorganic and organic constituents in soil. In physical fractionation, soil carbon and nitrogen preferentially recovered from the sand, silt and clay size fractions were estimated. Of this, carbon recovered from clay size fraction was the dominant independent variable that explained 64.6 per cent variability of organic carbon. The different chemical carbon fractions studied were water soluble carbon (WSC), hot water extractable carbon (HWEC) and permanganate oxidizable carbon (POC). The water soluble carbon being derived from completely decomposed organic matter was not associated with nitrogen in soils. The HWEC being the most labile pool of carbon had significant influence on mineralisation process thereby contributing to total and available nitrogen content. The permanganate oxidizable carbon being a stabilized pool might not undergo further decomposition to release nitrogen and hence, its contribution to available pool was negligible. Among the organic pools of nitrogen, the total hydrolysable nitrogen contributed significantly to mineralizable N. Among the inorganic fractions of nitrogen, ammoniacal nitrogen was contributing more to the available pool of nitrogen than nitrate nitrogen fraction probably because of high solubility and losses of latter by leaching. A field experiment was conducted to investigate the response of rice to different levels of nitrogen in Adattu Kole with an initial C:N ratio of 20:1. The treatments with increased levels of nitrogen based on C:N ratio (treatments Ts-TlO) produced significant effect on plant height, number of productive tillers, number of grains per panicle, straw yield and grain yield. The total nitrogen content both in soil and plant were significantly influenced by higher doses of nitrogen fertilizers prescribed as per the C:N ratio. Among the carbon fractions, hot water extractable carbon contributed more to the mineralizable pool than water soluble carbon. The direct effect of total hydrolysable nitrogen on total and available nitrogen was very high. Ammoniacal nitrogen being a dynamic and time dependent variable, though contributing significantly to available N content, its effect on total nitrogen was negligible. This was in conformity with the results of experiment in characterization of soil samples collected from 45 locations. The maximum grain yield of 8.22 Mg ha" was recorded in the treatment where nitrogen was applied based on C:N ratio (wet analysis). An increase of 1.15 Mg ha of grain yield was recorded over the treatment where soil test based fertilizer recommendation was applied. The highest straw yield of 17.47 Mg ha was recorded in treatment where nitrogen applied was double that of C:N ratio based recommendation. The highest net return was obtained in treatment where nitrogen was applied as per the C:N ratio in soil.
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    ThesisItemOpen Access
    Effect of zinc fertilization on major plant and soil enzymes in southern laterites
    (Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2019) Aswathy, U A; KAU; Aparna, B
    The study entitled “Effect of zinc fertilization on major plant and soil enzymes in southern laterites” was carried out in the Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani during the period 2017-19. The study was envisaged to assess the effect of various sources and methods of application of zinc on the activities of major plant and soil enzymes, biochemical and microbial parameters in laterite soils using tomato (Solanum lycopersicum var. Anagha) as a test crop. From the soil test database developed by the Department of Soil Science & Agricultural Chemistry under the project RF-Soil Testing Lab, laterite soils in Neyyatinkkara series with Zn deficiency were identified. Soil samples were collected from these locations and analysed for confirming Zn deficiency. Soil with low Zn status (0.506 ppm) was selected for the study. The second part of the experiment was a field study aimed at evaluating the efficacy of different sources of Zn using tomato (var. Anagha) as the test crop. The study was laid out in Randomized Block Design with eight treatments replicated thrice. The treatments were Absolute control (T1), N, P, K as per POP- 75:45:25 kg ha-1 (T2), N, P, K+ Soil application of Zn as ZnSO4- 10 kg ha-1 (T3), N, P, K+ Foliar application of Zn as 0.5 per cent ZnSO4 (T4), N, P, K+ Zn as Zn EDTA-18 kg ha-1 (T5), N, P, K+ Zn solubilizer -5 per cent (T6), N, P, K+ Zn Humate- 44 kg ha-1 (T7), N, P, K+ K solubilizer 5 per cent (T8). From the study, it was observed that the treatment T7 with the application of N, P, K+ Zn Humate (44 kg ha-1) recorded the highest plant growth and yield attributes such as number of branches per plant (8.3), days to first flowering (31.7), fruits per plant (46.7), fruit length (3.5 cm), total fruit yield (35833.36 kg ha-1) (1.29 kg plant -1) and total dry matter production (0.108 kg plant -1). The same treatment reported the highest value for enzymes such as carbonic anhydrase, peroxidase and catalase viz., 910 EU g-1, 48.17 activity min-1 g-1 and 27.06x103 units ml-1 respectively. The results of indole 3- acetic acid (IAA) (217.83 μg g-1) and lycopene analysis (26.11 μg g-1) also revealed that the same treatment T7 recorded the highest values. It was observed that the treatments did not have a significant effect on plant pigments chlorophyll a and b. The results of post harvest soil analysis revealed a marginal increase in available nutrient content compared to initial status. The treatment T7 with the application of N, P, K+ Zn Humate (44 kg ha-1) recorded the highest mean value for electrical conductivity (EC) (0.172 dS m-1), exchangeable Ca (436.67 ppm) and Mg (166 ppm), available B (0.221 ppm), soil respiration rate (177.14 mg CO2 100 g-1 d-1), microbial biomass carbon (186.67 μg g-1) and enzymatic activities (dehydrogenase and β- glucosidase). Similarly, T7 with the application of N, P, K+ Zn Humate (44 kg ha-1) recorded the highest value for available Zn (5.123 ppm) which was on par with treatment T5 (4.860 ppm).The uptake analysis revealed that the nutrient uptake varied significantly with the treatments. The treatment T7 registered the highest plant uptake of N, Mg, Zn and B (87.87, 75.29, 0.187 and 0.57 kg ha-1 respectively). An incubation study was conducted to monitor the pattern of activity of enzymes such as dehydrogenase, peroxidase and carbonic anhydrase and to evaluate their kinetic parameters for a period of three months. The study was carried with five treatments each replicated four times in CRD pattern. The treatments included were Soil alone (T1), Soil + Zn as 0.5 ppm ZnSO4 (T2), Soil + Zn as 1 ppm ZnSO4 (T3), Soil + Zn as 1.5 ppm ZnSO4 (T4) and Soil + Zn as 2 ppm ZnSO4 (T5). It was observed that the activity of enzymes were significantly influenced by the treatments. The enzymes peroxidase and carbonic anhydrase showed an increasing trend in activity while peroxidase registered a decreasing trend. Treatment T4 with the application of Soil + Zn as 1.5 ppm ZnSO4 registered the highest value for peroxidase (11.98 activity min-1 g-1) and carbonic anhydrase activity (385 EU g-1). The enzyme kinetics study revealed that the lowest km value was noticed for peroxidase (0.17 activity min-1 g-1) and dehydrogenase (0.77μg TPF g-1 24 h-1) on the 84th day. The peak value for Vmax was observed on the 28th day for enzyme dehydrogenase (75.23 μg TPF g-1 24 h-1) and peroxidase (59.43x103activity min-1 g-1). The treatment T5 corresponding with the application of Soil + Zn as 2 ppm ZnSO4 registered the lowest value of Km for carbonic anhydrase (0.89 EU g-1) and dehydrogenase (0.77μg TPF g-1 24 h-1), and the highest Vmax values for peroxidase. A significant positive correlation between soil enzyme (dehydrogenase), plant enzymes (peroxidase and catalase) and Zn with correlation coefficients 0.942**, 0.950** and 0.726** respectively was noticed. Similarly, in the case of regression analysis, the plant enzymes (peroxidase and catalase) and soil enzyme dehydrogenase were dependent on zinc with coefficients (0.001*, 0.001* and 0.041* respectively). From the study it was observed that treatment T7 with the application of N, P, K+ Zn Humate (44 kg ha-1) registered the highest values for soil parameters (EC, available nutrients and soil enzymes) and plant parameters viz., growth, yield and uptake. Similarly it was also observed to be the best source for available Zn followed by T5- N, P, K+ Zn as Zn EDTA (18 kg ha-1). The incubation study revealed that for highest activity of peroxidase and carbonic anhydrase, the rate of Zn application is 1.5 ppm. In enzyme kinetics study, the treatment T5 with the application of Soil + Zn as 2 ppm ZnSO4 was found to be superior than all other treatments. Hence it can be concluded from the present study that the most efficient source of Zn was Zn Humate with an ideal rate of 44 kg ha-1 along with the recommended levels of N, P, K nutrients.