Browsing by Author "Sreelatha, A K"

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Assessment of soil quality in the post floods scenario of AEU 5 and AEU 9 of Ernakulam district of Kerala and mapping using GIS techniques
(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 2020) Neha Unni; Sreelatha, A K
Kerala state witnessed large scale devastating flood in 2018 due to excess rainfall, causing significant damage to agricultural sector and human life. One of the most affected districts was Ernakulam, especially AEU 5 and AEU 9. The AEU 5 - Pokkali lands, represent the lowlands, often below sea level, in coastal areas of Ernakulam district and extending to parts of Thrissur and Alappuzha districts. The soils are hydromorphic, often underlain by potential acid-sulphate sediments with unique hydrological conditions. Seawater inundation is not controlled and hence soils are acid-saline. The AEU 9 - south central laterites represent midland laterite terrain with typical laterite soils. The study aimed at the assessment of soil quality in the post flood scenario of AEU 5 and AEU 9 in Ernakulam district and to develop maps on soil characters and quality using GIS techniques and to workout soil quality index (SQI). For this purpose 100 geo-referenced soil samples were collected from different panchayats of AEU 5 and AEU 9 in Ernakulam district and were characterized for physical, chemical and biological properties. The Pokkali soils recorded low bulk density whereas porosity, water holding capacity and soil moisture were found high. Available N content was medium to high, available phosphorus and potassium was high in the soil. Among the secondary nutrients, available Ca and S were found sufficient for majority of the samples, while a deficiency of available Mg was noticed in Pokkali soils. In AEU 9, the soil pH varied from 5.01 to 7.69 and all the soils had an electrical conductivity less than 1.0 dS m-1. Organic carbon was noticed low to medium in the soils. Available N content was medium for 87 per cent of the samples, whereas all the samples were high in available P content. Available K was recorded low to medium values in AEU 9. Soil quality index was calculated using principal component analysis (PCA). There are three main steps involved in the soil quality index method which includes (i) selection of a minimum data set (MDS) of indicators (ii) formation of the MDS indicators and scoring of each indicators (iii) computation of index of soil quality. For developing minimum data set, principal component analysis (PCA) was performed for 23 soil attributes and resulted in 7 PCs. The indicators with high loading factors in each PCs were selected to develop minimum data set (MDS). MDS constituted 8 attributes for AEU 5 and 9 attributes for AEU 9 respectively. After the development of MDS, the soil indicators were converted to unit-less scores ranging from 0 to 1 using non-linear scoring function methods. Three types of scoring curves were used: i) more is better, ii) less is better, iii) optimum curve. Soil quality index ranged from 0.42 in Nayarambalam to 0.76 in Vadakkekkara in AEU 5, and 0.39 in Edathala to 0.92 in Aluva in AEU 9. The highest RSQI value was recorded in Aluva (69.7%) and the lowest in Edathala (29.55%) under AEU 9. In AEU 5 the highest RSQI was obtained in Vadakkekkara (71.58%) and the lowest in Nayarambalam (37.06%). Nutrient indices of flood affected areas in AEU 9 were low with respect to organic carbon and available potassium, medium with respect to available nitrogen and high with respect to available phosphorus. Nutrient index was high for nitrogen, phosphorus, potassium and organic carbon in AEU 5. Significant positive correlations were observed between organic carbon and available nitrogen, organic carbon and soil moisture content. Negative correlation existed between bulk density and porosity, organic carbon and bulk density in both AEUs. The present study revealed that soil fertility and productivity have been disturbed after the floods. In AEU 9 available potassium was found decreased after the flood. Prior to flood Kottuvally, Elamkunnapuzha, Edavanakkad and Kuzhuppilly panchayats in AEU 5 were medium in relative soil quality index (Joseph, 2014) and post flood assessment showed that these panchayats shifted to poor relative soil quality index.
Carbon dynamics of acid saline pokkali soil under long term fertiliser application in rice
(Academy of Climate Change Education and Research Vellanikkara, 2016) Sharon Mathew; Sreelatha, A K
The amount of carbon in the atmosphere has increased by 30 per cent. The rising temperatures and carbon dioxide concentration and uncertainty in rainfall associated with climate change may have direct relationship with increased levels of carbon dioxide. One proposed method to reduce atmospheric carbon dioxide is to increase the global storage of carbon in soils with an added benefit in simultaneous enhancement in agricultural production. Soil organic carbon (SOC) is one of the main carbon reservoirs in the terrestrial ecosystem. It is important to study SOC dynamics and effects of organic carbon amendments in paddy fields and saline soils because of their vast expansion Objectives of the study were to estimate the soil organic carbon (C) status in acid saline soil and to assess the influence of long term fertilizer applications on soil carbon dynamics. Samples were collected from the experimental plot laid out in randomized block design with 10 treatments, each replicated four times with pokkali rice variety Vytilla 4 at RRS Vytilla, Kerala. The study revealed the baseline soil characteristics especially the soil carbon and its counterparts. Vertical distribution of SOC showed the storage profile of carbon and in cultivated sites a topsoil carbon sink (mostly labile carbon) is identified owing to increased fertiliser inputs whereas a potential subsoil sink (non labile carbon) is identified vertically downwards. However, the high content of non labile carbon in the subsurface showed the ability of Pokkali soil for carbon sequestrations. The labile carbon present in the surface soil resulted in the availability of nutrients to the plants which was evident from the high nutrient status of the control plot .all carbon fractions in the present study indicates the ability of Pokkali soils to sequester carbon. Therefore, the Pokkali ecosystem has to be maintained as such to mitigate the ill effects of global warming in the present climate change scenario.
Impact of soil compaction on the productivity of Onattukara soils
(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2001) Sreelatha, A K; Pushkala, S
An investigation was carried out at Rice Research station, Kayamkulam to study the effect of soil compaction with organic manure and amendments on soil physical properties, nutrient availability, rooting pattern, yield and quality of crops like rice, sesamum, green gram and cowpea under rice based cropping system of Onattukara tract of Kerala. The compaction treatment with four passes of a 400 kg roller significantly improved the soil physical properties, nutrient availability and yield of all the crops. The available water content, microporosity, available N, P and K, root volume and root density significantly increased in compacted treatments for all the crops. Application of coirpith and kayaJ silt improved the field moisture content in kharif rice. The hydraulic conductivity and infiltration rates decreased in compacted plots. The compacted plots recorded less number of days for 50 percent flowering of sesamum, green gram and cowpea. The rabi crop of rice, sesamum and cowpea recorded the highest grain yields of 2.72 t ha-I, 529.79 kg ha-I and 594.78 kg ha-I in the compacted treatment along with coirpith and farm yard manure (@2.5 tha-I) combination, where as the kharif crop of rice recorded the highest grain yield of 3.15 t ha-1 in the compacted and coir pith treatments along with 5 t ha-1 farm yard manure. The seed yield of green gram was highest in compacted and 5 t ha-l farm yard manure treated plots with no amendments. Thus it can be concluded that compaction of coarse textured soils along with the application of 2.5 t ha-1 farm yard manure and 5 t ha-l coir pith significantly improved the soil physical properties, nutrient availability and inturn the yeild of different crops under rice based cropping system of Onattukara.
Ion interactions and rice nutrition in acid saline pokkali soils
(Department of Soil Science and Agricultural Chemistry,College of Horticulture, Vellanikkara, 2016) Aditya Mohan; Sreelatha, A K
Management of soil salinity with calcium salts in rice-prawn farming system in pokkali lands
(Department of Soil Science and Agricultural Chemistry College of Horticulture, Vellanikkara, 2018) Divya, P V; Sreelatha, A K
Pokkali is the unique system of rice cultivation in the water-logged coastal saline acid soils of Kerala. These are tidal wetlands characterized by multi stressed conditions such as acidity, salinity and waterlogging. Pokkali soils are the major salt affected soils in Kerala. Plant growth is affected by salinity at all stages of development resulting in reduced grain yield, dry matter production and total decrease in productivity. Excess sodium present in the saline environment creates adverse conditions for plant growth. High salinity in the root zone results in osmotic imbalance and ionic toxicity and thereby modifies nutritional status in soil and plant. In this context, the present study entitled “Management of soil salinity with calcium salts in rice–prawn farming system in Pokkali lands”, was conducted with the following objectives (i) to manage the soil salinity by application of calcium salts in pokkali lands (ii) to assess the effect of calcium salts on the growth and nutrition of rice, yield of prawn and soil properties. The experiment was conducted in the Thathapilli padasekharam (10º12’N, 76º26’ E) of Kottuvally Panchayath in Ernakulam district, during June 2017 to April 2018. The experiment was laid out in randomized block design with six treatments and four replications having plot size of 100 m². The treatments consisted of absolute control, calcium nitrate, calcium chloride, calcium sulphate, rock phosphate and dolomite at the rate of 45, 30, 34, 27 and 25 kg per plot so as to adjust the ratio of 1:5 for Na : Ca in the exchange complex on the basis of content of Na and Ca in soils. The Ca salts were applied before the rice crop only. Rice variety, Vyttila 6 was raised in the first crop season. Soil samples were collected from the treatment plots during three stages; before the sowing of crop, after the harvest of rice and after the harvest of prawn and analyzed for various physical (soil texture, bulk density), chemical (pH, EC, organic carbon, available N, P, K, Ca, Mg, S, Fe, Cu, Mn, Zn, B and exchangeable Na and Al) and biological parameters (microbial biomass carbon). Plant samples were collected at the time of harvest and analyzed for N, P, K, Ca, Mg and Na separately for shoot and root so as to assess the source sink relationship. Initial soil analysis revealed that texture of soil was sandy loam with a bulk density of 1.25 Mg m־³. Initial soil pH was 6.74 and electrical conductivity was 1.51 dSm¹־. Soil was deficient in available N, Ca, Mg and Cu and all other nutrients were in sufficiency level. Data on analysis of soil samples after the harvest of rice revealed that, all the treatments showed a superiority over control with respect to chemical parameters and biological parameter. The EC values ranged from 1.59 dSm־¹ to 1.75 dSm־¹. Exchangeable Na and Al content were highest in control. Among the different treatments, calcium nitrate registered peak values of organic carbon and available nutrients especially nitrogen and it reduced the available Fe content to an extent. Application of calcium nitrate significantly increased the grain yield (3300 kg ha־¹) and dry matter content and plant nutrient uptake. Increased shoot and root N content was also recorded and increment was reflected in the case of other plant nutrients also. Consequent reduction in the shoot Na content was observed as a result of reduced salinity. Highest Ca:Mg and K:Na ratio observed in plant samples of calcium nitrate treatment revealed better plant survival rate under salt stress. Next to calcium nitrate treatment, calcium chloride and dolomite treatments recorded higher in grain yield of 2192 kg ha־¹ and 2098 kg ha־¹ respectively and also the nutrient uptake. Soil analysis after the harvest of prawn recorded an increase in available major and secondary nutrients and reduced the Fe and Mn content in all the treatment with slight variation from control. Yield of prawn was highest in calcium treated plots as a whole than control plot and these variations in the productivity was a result of calcium salt treatments during rice cultivation and its residual effect retained in soil. Thus it can be concluded that application of calcium salts in pokkali soils increased the yield of rice and prawns, improved the soil properties and nutrient uptake by plants. Increase in grain yield was higher in calcium nitrate followed by calcium chloride and dolomite treatments. The highest B:C ratio was recorded in dolomite treatment because of the less input cost.
Pottassium dynamics in Neyyattinkara soil series under coconut cultivation
(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 1993) Sreelatha, A K; Saifudeen, N
Practical manual:BSc Hons(Ag)
(Kerala Agricultural University, 2013) Beena, V I; Sreelatha, A K; Sindhu, S
Quality assessment of pokkali soils under different land uses
(Department of Soil Science and Agricultural Chemistry,College of Horticulture, Vellanikkara, 2014) Chris Joseph; Sreelatha, A K
The present study entitled ‘Quality assessment of Pokkali soils under different land uses’ was undertaken to evaluate the soil and water quality of acid saline Pokkali soils under different land uses and to develop geo-referenced database and maps on soil characterization. For this purpose, surface soil samples and water samples were collected from the selected panchayaths representing five land use pattern in the Pokkali tracts. Initial survey was conducted on Pokkali area and five panchayaths were selected from Ernakulam district namely, Kuzhippally, Nayarambalam, Elamkunnappuzha, Edavanakkadu and Kottuvally with all the selected land use patterns. The land use patterns under study were i) paddy alone ii) paddy – shrimp iii) shrimp alone iv) fallow and v) mangroves. The soil samples were analysed for their physical (texture, bulk density, soil moisture constants, aggregate stability), chemical (pH, EC, CEC, base saturation, available N, P, K, Ca, Mg, Fe, Cu, Mn, Zn, S, B) and biological (organic carbon, dehydrogenase activity, microbial biomass carbon) attributes. Water samples were also characterized for parameters like pH, EC, TSS and heavy metals. Measured attributes were analyzed by one-way analysis of variance using statistical package MSTATC to examine the effect of land use type on soil properties. Soil quality evaluation was done by the method described by Andrews et al. (2002). Three main steps of this technique includes, i) selection of minimum data set (MDS), ii) scoring of the MDS indicators based on their performance of soil functions, and iii) integration of the indicator scores into a comparative index of soil quality. Analysis of variance revealed that land uses have significant effect on most of the measured attributes except fine sand percent, base saturation percent, content of Mg, Zn, organic carbon and dehydrogenase activity. The statistical analysis resulted in selection of minimum data set which highly influenced the quality of the soil. Indicators in the MDS included available water content, pH, fine sand percent, aggregate stability, silt percent, available Mg, bulk density, available S, microbial biomass carbon, available Mn, organic carbon, base saturation and EC. The highest soil quality index (4.92) was observed in paddy- shrimp land use system in Nayarambalam panchayath and least value (2.07) was observed in shrimp alone land use pattern in Kottuvally panchayath. The observed soil quality index value was in the order, paddy- shrimp> paddy alone> fallow> mangrove> shrimp alone. Based on the relative soil quality index value, all land uses were categorized into three groups, ie, poor, medium and good. Paddy- shrimp land use system in Nayarambalam panchayath was the only one land use system coming under the ‘good’ category. For all the panchayaths and RRS, Vyttila GIS based soil quality index maps were prepared.
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; 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.
Taxonomy and soil carbon sequestration potential of altered natural wetland ecosystems (AEU 6 and AEU 7) of north Kerala
(Department of soil science and agricultural chemistry, Vellanikkara, 2023-09-14) Purandhar, E.; Sreelatha, A K
The present investigation entitled ‘Taxonomy and soil carbon sequestration potential of altered and natural wetland ecosystems (AEU 6 and AEU 7) of north Kerala’ was formulated with the aim of classifying the soils of selected altered and natural wetlands in Kerala as per the USDA soil taxonomy and to find out the soil carbon sequestration potential of such soils. The study also compared carbon pools, carbon storage potential and mineralization at different soil depths in these natural and altered ecosystems. Three experiments were envisaged to achieve the above objectives of the research program