Browsing by Author "Beena, V I"

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Accumulation of heavy metals in typic sulfaquents of Kuttanad ecosystm
(Department of Soil Science and Agricultural Chemistry,College of Horticulture, Vellanikkara, 2016) Aneesa Beegum, M M; Beena, V I
An investigation entitled “Accumulation of heavy metals in Typic Sulfaquents of Kuttanad ecosystem” was conducted in the Department of Soil Science and Agricultural Chemistry, College of Horticulture, Kerala Agricultural University during 2014-2016. Sample collection was done from six acid sulphate soil series of Kuttanad viz., Ambalapuzha, Kallara, Thakazhi, Purakkad, Thottapally and Thuravur series. Twenty soil, sediment and water samples were collected from each series. Dominant aquatic macrophytes were also collected from each series. Mainly three mangrove species (Avicennia officinalis, Bruguiera gymnorrhiza and Rhizophora mucronata) were present in the area, and were collected for analysis. Soil and sediment samples were characterized for texture, pH, EC, organic carbon, macronutrients, micronutrients (Fe, Mn, Zn and Cu) and heavy metals (Pb, Cr, Hg and Al). Water samples were analysed for its irrigation quality parameters such as colour, temperature, turbidity, suspended solids, pH, EC, biological oxygen demand (BOD) and chemical oxygen demand (COD). Also the plant and water samples were analysed for its macronutrients, micronutrients (Fe, Mn, Zn and Cu) and heavy metals (Pb, Cr, Hg and Al). Based on the analytical data, maps were prepared by using specialized software ArcGIS ArcMap version 10 of ESRI. The soil samples from acid sulphate soil series of Kuttanad were extremely acidic whereas the sediment and water samples were slightly acidic. Highest EC values were recorded for soil, sediment and water samples collected from Purakkad series. Significantly higher OC and available N content were observed in soil and sediment samples collected from Kallara series, while the water samples taken from this series showed high ammoniacal N content. The available P content was low in all the series. Soil and sediment samples collected from Thuravur series exhibited highest content of N, P, K, Ca and Mg. In all the series, Cd and Hg were found to be below detectable levels in soil, sediment and water samples. The heavy metal accumulation was more in sediments when compared to soil and water. Toxicity of Fe and Al was recorded in soil and sediment samples of all series. Concentration of Zn and Mn was high in all soil samples of acid sulphate soil series. Even though accumulation of Pb and Cr were reported in soil and sediment samples, their availability were more in sediment samples than in soil samples. Soil pH and OC had significant influence on availability of heavy metals in soil and sediments. Concentration of Fe, Al and Cr in water samples were above the maximum permissible limit (MPL) as suggested by WHO, hence they are not suitable for drinking water purpose. The concentration of Pb was below maximum permissible limit in water samples of all series except Purakkad and Thottapally series. According to FAO, for irrigation water quality, all heavy metals were within the MPL in the water samples collected from study area and were safe for irrigation. Along with Cd and Hg, Zn and Cu were also below detectable levels in all water samples. The heavy metal content in Eichhornia crassipes were in the order of Fe >Mn > Al> Zn> Cr> Cu >Pb. Among the dominant macrophytes, Eichhornia crassipes accumulated high content of Pb. Hence it can be effectively used as a phytoremediator. Salvinia molesta contained high amount of heavy metals, especially Cr and Al. The content of Cd and Hg were below detectable level in all weed species. The content of Zn, Cd and Hg were found to be below detectable levels in all the three mangrove species. But these contained high concentration of Fe, Pb, Cr and Al in roots, while Cu and Mn were accumulated in aerial parts such as shoot and leaves. Hence the three mangrove species viz., Avicennia officinalis, Bruguiera gymnorrhiza and Rhizophora mucronata restricted the mobility of heavy metals to aerial parts but showed greater mobility of essential elements like Cu and Mn. Since they are having extensive root system, they can stabilise heavy metals within the roots. These plants can be effectively used for phytoremediation, especially for phytostabilisation of metals in mangrove ecosystem.
Effect of sulphur on yield, quality and uptake of nutrients by cowpea (Vigna unguiculata L. Walp) in a rhodig haplustox
(Department Of Soil Science And Agricultural Chemistry,College Of Agriculture, Vellayani, 2000) Beena, V I; Usha, P B
Influence of soil characteristics and fertility management practices on nutrient and antinutrient accumulation in amaranth (Amaranthus tricolor L.)
(Department of Soil Science and Agricultural Chemistry, College of Agriculture ,Vellanikkara, 2024-05-18) Dharmendranaik, E.; Beena, V I
The research programme entitled “Influence of soil characteristics and fertility management practices on nutrient and antinutrient accumulation in amaranth (Amaranthus tricolor L.)” was carried out at the Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellanikkara, Kerala Agricultural University during 2017-2023. The study was programmed to determine the extent of accumulation of antinutrients viz., nitrate and oxalate in vegetable amaranth under different fertility management practices and to elucidate the relationship between soil characteristics and antinutrient accumulation. The investigation was carried out in three phases viz., (i) pot culture experiment with nine fertility management practices and two soil types, (ii) field experiment involving the best three fertility management practices selected from pot culture study and two varieties of amaranth viz., red (Arun) and green (CO-1) (iii) an evaluation of antinutrient status in the amaranth samples collected from farmer’s field. Initial steps included the characterization of electrochemical properties and nutrient status of soils collected from two different locations: (i) Chittur, Palakkad (Vertisol - alkaline soil: Typic Haplusterts) and (ii) Vellanikkara lateritic soil (Instructional Farm, Vellanikkara,very strongly acidic soil: Kandic Paleustalfs). A pot culture experiment was conducted from January to May 2019 in CRD with red amaranth variety “Arun” and 18 treatment combinations viz., nine fertility management practices and two soil types. The nine fertility management practices included in the experiment were: T1: Organic manure alone (Organic KAU-POP: FYM @ 25t ha-1); T2: KAU-POP (N: P: K -100:50:50 kg ha-1 + FYM + foliar spray of 1% urea); T3: T2 with foliar spray of amino acid-methionine 200 mg L-1 (instead of urea spray); T4: N: P: K - 100:75:75 + FYM + foliar spray of 1 % urea + lime as per soil test; T5: T4 with foliar spray of amino acid-Methionine 200 mg L-1 (instead of urea spray) + lime as per soil test based recommendation; T6: N: P: K -100:50:50 kg ha-1 in the form of Factamfos (basal), urea (top dress) and MOP +FYM +foliar spray of 1% urea; T7: T6 with foliar spray of amino acid -methionine 200 mg L-1(instead of urea spray); T8: Soil test based application of nutrients + foliar spray of 1%urea; T9: T8 with foliar spray of amino acid-methionine 200 mg L-1 (instead of urea spray). In all the treatments except T6 and T7, N and P were applied in the form of urea and superphosphate. In the treatments, T6 and T7, basal dose of 50: 50 kg ha-1 N and P were applied as Factamfos and the remaining 50 kg N as top dress in the form of urea. Potassium was applied in the form of MOP in all the treatments. In all the treatments,FYM was applied @ 25t ha-1 as per POP. The top-performing three fertility management practices were selected from the pot culture experiment based on two criteria viz., yield and antinutrient content (nitrate and oxalate). The field experiment was carried out in RBD with six treatment combinations from January to May 2022 at Agronomy Farm, College of Agriculture, Vellanikkara. For the evaluation of antinutrient status in the samples from farmers’ fields, fifteen amaranth samples each from two locations namely, Chittur and Madakkathara panchayat were collected. Fifteen soil samples pertaining to the sampled area were also collected. Soil and plant analysis for macro and micronutrients as well as antinutrients were also carried out. The data revealed that amaranth yield is comparatively lower in the first harvest. The second and third cuttings gave comparable yields. The total yield data from the three cuttings showed that the plant yield of amaranth did not differ significantly with soil type for the first and second harvests. However, Chittur soil exhibited a significantly higher yield than Vellanikkara soil for the third harvest. The total amaranth yield from the three harvests was significantly lower in organic manure alone treatment (109.16 g plant-1) and KAU POP (167.89 g plant-1) compared to the other treatments irrespective of the stage of harvest. Methionine spray gave a comparatively lower yield than urea spray. Soil test based application of nutrients performed better than KAU POP treatment. The treatments T4 and T6 (100: 75: 75 NPK and Factamphos treatments with urea spray) showed superiority over the other treatments in producing higher amaranth yield. Nitrate and oxalate contents in amaranth were significantly lower in Vellanikkara soil as compared to Chittur soil at all the three stages of harvest. Organic manure alone treatment registered the lowest value for nitrate as well as oxalate in both soils. Methionine treatments exhibited nitrate and oxalate levels similar to that of urea spray. While examining the nitrate and oxalate levels across the different harvest stages and treatments, it was found that nitrate and oxalate concentration in amaranth ranged from 953.58 (T1 second cut) to 4486.66 mg kg-1 (T8 third cut) and 2791.24 (T1 and T6 second cut) to 3843.66 mg kg-1 (T2 first cut) respectively. In order to understand the extent of reduction in nitrate and oxalate concentrations due to cooking, fresh amaranth samples from the first cut were steamed for 3-4 min., air dried and the analysis of nitrate and oxalate was carried out. It was found that the cooked amaranth samples had nitrate levels in the range of 931.33 (Organic KAU POP) to 1793.66 mg kg-1 (KAU POP) and oxalate levels in the range of 2301.00 (Organic KAU POP) to 3211.42 mg kg-1 (Factamphos treatment) across the different fertility management treatments. However, in the raw amaranth samples from the first cut, nitrate content ranged from 1202.66 (T9) to 2044.00 mg kg-1 (T3) and that of oxalate ranged from 2881.28 (T1) to 3843.36 mg kg-1 (T2). Higher values of antinutrients were observed in KAU POP treatment even after cooking. Among the integrated nutrient management practices, significantly lower values of nitrate and oxalate were recorded in soil test-based nutrient (T8 and T9) treatments. The percentage reduction in nitrate and oxalate due to cooking ranged from 9.59 to 21.67 % and 15.50 to 36.05 % Total antioxidant activity was higher in Vellanikkara soil at the second and third harvest stages and its content decreased with advancement of harvest time. Higher values were observed in the first cutting and the values ranged from 3570.50 mg kg-1 (T1 – OM alone) to 3146.39 mg kg-1 (T5 - high P and K). However, all the treatments were on par. The same trend was obtained for the second and third harvests. Beta carotene content was lower in Vellanikkara soil as compared to Chittur soil and its content also decreased with harvest time. Organic manure alone treatment was significantly inferior to INM treatments, especially soil test-based application of nutrients at first and third harvest. The data on soil nutrients indicated that ammoniacal nitrogen decreased with harvest stages in both soils. Even though nitrate nitrogen decreased with the advancement of crop growth in lateritic soil, it showed an increasing trend in Chittur soil indicating no leaching loss of this nutrient in this soil type. Both the soils were inherently rich in nutrients and cattle manure is a source of key nutrients including N, P, K, S, Mg, and Ca as well as certain micronutrients. This would have been the reason for the lack of significant variation among the fertility management treatments.Based on the yield performance and antinutrient content (nitrate and oxalate) in amaranth the best three treatments were selected from the pot culture study so as to assess their performance under field condition. The field experiment was conducted at Agronomy Farm, College of Agriculture, Vellanikkara with two varieties of amaranth viz., Arun (red amaranth) and Co-1 (green amaranth) and the three treatments selected from the pot culture study. . The selected treatments were : T1 - N: P: K - 100:75:75 kg ha-1 + FYM+ foliar spray of 1% urea + lime as per soil test-based recommendation, T2 - N: P: K -100:50:50 kg ha-1 in the form of Factamfos (basal), urea (top dress) and MOP +FYM + foliar spray of 1% urea and T3 - Soil test based application of nutrients + foliar spray of 1% urea. Data on the effect of treatments on amaranth yield indicated that the varieties differed significantly. At the first and third harvests amaranth var: Co-1 had a significantly higher yield (9.19 and 8.43 t ha-1 respectively) than Arun (4.98 and 5.73 t ha- 1 respectively). However, there was no significant difference in yield between the varieties at the second harvest (9.20 and 8.08 t ha-1 respectively). The impact of various fertility management practices on amaranth yield was not significant. However, there were significant differences in nitrate and oxalate levels between the varieties . Red amaranth variety Arun registered higher levels of nitrate as well as oxalate. Analysis of nitrate and oxalate contents after cooking showed lower values. Nitrate and oxalate concentrations recorded in cooked amaranth var: Arun were 3190 .00 mg kg-1 and 3331.48 mg kg-1 respectively. Corresponding values noticed in Co-1 were 861.66 and 2783.73 respectively. The magnitude of reduction in nitrate and oxalate contents after cooking were in the range of 58.02 to 68.14 % and 10.38 to 12.19 % respectively. The potential toxic concentration of nitrate nitrogen in amaranth is 2100 mg kg -1 and that of oxalate is 2-5 g day-1. Therefore, it may be concluded that nitrate and oxalate concentration in cooked amaranth is not a serious issue if the fertilizers are applied along with organic manure as per the recommendations of Kerala Agricultural University Analysis of amaranth samples collected from farmer’s fields of Chittur taluk and Madakkathara panchayat revealed significant differences in nitrate and oxalate contents among the plant samples. The mean nitrate content in Chittur plant samples was 29148.94 mg kg-1, while in Madakkathara plant samples, it was notably higher at 39112.20 mg kg-1 indicating a significant variation in nitrate content between the two locations at a 0.05 % significance level. Similarly, the oxalate content (3595.95 mg kg-1) in plant samples from Chittur was found to be significantly higher than that of Madakkathara panchayat (2911.29 mg kg-1). Application of high doses of nitrogenous fertilizers without appropriate levels of organic matter, phosphorus and potassium would have been the reason for the accumulation of nitrate to extremely high level in amaranth cultivated by farmers. Considering the harmful effects of nitrate and oxalate and the benefits of the major nutrient potassium for human health, it was found that indicators viz., potassium nitrate ratio and potassium oxalate ratio in amaranth leaves may be used to assess amaranth nutritional quality. Among the two varieties tested, var. Arun displayed K/NO3 -and K/oxalate ratios of 5.24 and 9.54, respectively. Corresponding ratios for the Co-1 variety were 11.27 and 12.09, respectively. The present investigation revealed that Amaranthus dubius (Green amaranth var. Co-1 ) has higher nutritional value and lower levels of antinutrients viz., nitrate and oxalate as compared to Amaranthus tricolor L.( Red amaranth var. Arun ). Organic POP recommended by Kerala Agricultural University is a good practice to reduce antinutrients in amaranth. However, the yield and nutritional value of amaranth were higher under integrated nutrient management than in KAU organic POP in both the soils under study. Nitrate accumulation in both red and green amaranth could be reduced to a certain degree by the adoption of appropriate fertility management practices.
Interaction of phosphorous and sulphur in black cotton soil of Palakkad (AEU:23) under groundnut (Arachis hypogaea L.) cultivation
(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 2020) Shahana, C K; Beena, V I
Supply of nutrients in a balanced manner is one of the most important factors determining crop yield. Sometimes due to interaction between nutrients in soil, the applied nutrients may not be available for plant use. When the supply of one nutrient element affects the absorption and utilization of other nutrient element, the elements are said to be in interaction and interactions may be negative or positive. In Kerala, black cotton soils are seen in Chittur taluk of Palakkad district occupying an area of approximately 2000 ha. These soils are sandy clay loam, dark, calcareous, neutral to alkaline (pH 7.0 to 8.5), high in clay content and CEC. These soils are deficient in phosphorus (P) and sulphur (S). Finding the interaction between P and S in these soils will help to understand the factors determining the availability of these nutrients to crops. The present study was carried out at Nellimed in Chittur taluk of Palakkad district during 2017-19. The objectives of the study were to find out the interaction of P and S in black cotton soils of Palakkad and to assess the treatment level of phosphorus and sulphur for maximizing the yield. The study consisted of a field experiment with groundnut variety, K-6 in black cotton soils of Chittur, Palakkad followed by analysis of soil, plant and pod samples taken from the experimental field. Soil samples were collected from different locations of Chittur and analyzed for available P and S. Field experiment was carried out in the field deficient in both P and S. Experiment was laid out in factorial RBD with 17 treatments and 3 replications. Soil test based recommendation was taken as T1 and treatment combinations were made with four levels of P and four levels of S. The levels of N and K applications are kept same (based on POP recommendations of KAU) for all treatments, except for the first treatment where soil test based recommendation was given. P0 - 0 kg ha-1, P1 - 60 kg ha-1, P2 -75 kg ha-1 and P3 -90 kg ha-1 were the four levels of P and S0 - 0 kg ha-1, S1 - 10 kg ha-1, S2 - 20 kg ha-1 and S3 - 30 kg ha-1 were the four levels of sulphur. Physical characteristics of soil viz., texture and bulk density were analyzed before experiment and chemical characteristics viz., pH, EC, organic carbon, N, P, K, Ca, Mg, S, Fe, Mn, Zn, Cu and B were analyzed before and after the experiment. Growth parameters such as plant height and number of leaves per plant were recorded at flowering, pegging, pod formation and harvesting stages and yield parameters like number of pods per plant and yield were recorded at harvesting stage. The nutrient contents in plant were analyzed and uptake was computed in critical growth stages. The nutrient content, protein and oil content in pod were analyzed. Soil nutrient status, plant nutrient content and uptake of nutrients were influenced by main effect and interaction effect of P and S. Application of P at 90 kg ha-1 and S at 30 kg ha-1 resulted in highest plant height and number of leaves per plant. Application of P at 90 kg ha-1 and S at 30 kg ha-1 resulted in highest number of pods per plant and yield. Highest protein and oil content were recorded by application of P at 90 kg ha-1 and S at 30 kg ha-1. Application of increased dose of P increased the availability of S. Application of P reduced the availability of Fe, Mn and Zn in soil due to the formation of insoluble compounds like Fe-P, Mn-P and Zn-P. Application of P enhanced the availability of N. The K content in soil was reduced with increased dose of P application. Ca content in soil was reduced due to P fertilizer application. Plant nutrient content showed a decreasing trend from flowering to harvest stage. Application of P and S enhanced content of P in plant and pod. Content of N, P, Mg and S was increased with increased levels of P and content of Fe, Mn, Zn, Cu and B was reduced with increased dose of P. The uptake of nutrients followed an increasing trend from flowering to harvest due to increased dry matter production. Uptake of S, Fe, Zn and Cu by kernel is higher compared to plant. P and S showed a positive interaction and P at 90 kg ha-1 and S at 30 kg ha-1 was found to be the best treatment in black cotton soils of Palakkad for high yield, protein and oil content in groundnut.
Land evaluation and crop suitability rating of the acid sulphate soils of Kuttanad for sustainable land use planning
(Department of soil science and agricultural chemistry, College of Agriculture, Vellayani, 2005) Beena, V I; Manorama Thampatti, K C
An investigation was carried out at College of Agriculture, Vellayani during 2001- 2004 to delineate acid sulphate soils of Kuttanad and to develop sustainable land use plan for the area based on land evaluation and crop suitability rating with the help of GIS technology. The study consists of generation of detailed soil maps of acid sulphate soils of Kuttanad, various thematic maps of acid sulphate soils of Kuttanad, interpretation of soil maps, qualitative and quantitative evaluation of land use systems of the area, and development of a sustainable land use model taking into account the climatology, productivity and socio- economic constraints of the area. Kuttanad is a lowlying deltaic region lying 0.6 to 2.2 m below mean sea level. The reconnaissance soil survey of the area was conducted according to the principles envisaged in IARI (1970). Two profile pits were dug from each series identified and morphological features were described and surface as well as subsurface samples were drawn for detailed laboratory examination. Soil classification was done based on field survey, soil correlation and laboratory investigation and soil map of acid sulphate soils of Kuttanad was prepared based on GIS technique. Land capability classification was done based on inherent soil characteristics, degree of limitations etc. Soil site suitability classificatio~ was done to find the suitability of different crops in the region and fertility capability classification was also done for evolution of sustainable agricultural management. These soils were thoroughly evaluated to study the present land use, its suitability and to suggest alternate land use plan for the area. The morphological and physico- chemical characteristics of the area showed great degree of variation. The soils were deep with a hue of7.5 YR to 10 YR, sticky and plastic, angular blocky to sub angular blocky in structure with textural variation from sandy to clayey with random deposits of lime shells and humus. Presence of faint to prominent reddish yellow or brown mottles in most of the soil layers. Some of the special characteristics observed were partially burned wooden logs and reddish brown root channels. The soils were extremely acidic with high organic carbon content. The CEC, ECEC and available nutrients except phosphorous were high for these soils. Due to P fixation, phosphorous deficiency is widespread. However the base saturation was below 50 per cent. As per USDA classification, the entire study area was classified under the order Entisols, with suborder Aquent, great group Sulfaquent, subgroup Typic Sulfaquent with six soil series viz., Ambalapuzha, Purakkad, Thotapally, Thuravur, Kallara and Thakazhi. As per FAO classification, these soils were included under Thionic Fluvisols. The region enjoys a humid tropical climate. Based on soil mapping of the area it is revealed that acid sulphate soils of Kuttanad cover an area of 14277.51 ha comprising of six soil series. Kallara series occupied the largest area of 6860.17 ha. The soils of the region were deep, poorly drained loamy soils in control section and are very gently sloping with slight erosion. Land capability classification of the area showed five soil senes ViZ., Ambalapuzha, Purakkad, Thuravur, Kallara and Thakazhi covenng an area of 13099.60 ha came under the class IV sw. The Thotapally series was grouped under III sw. While considering the soil site suitability for paddy, Thotapally and Thuravur series come under subclass S2 xf ie these are moderately suitable for paddy cultivation with limitations due to fertility and pH. For coconut cultivation, all the series except Thuravur are grouped under S2 xf. Soil site suitability for mango cultivation revealed that Ambalapuzha, Purakkad and ThotapalJy senes are moderately suitable with limitations due to excess wetness, low pH and fertility limitations. As per Fertility Capability Classification, the soils belong to the units Lgac, Lgac, LCgac, Cgaics, Lgac and LCgaic respectively for Ambalapuzha, Purakkad, Thotapally, Thuravur, Kallara and Thakazhi series. The modifiers that are relevant to the acid sui phate soi I condition are "g" which defi nes wet land soi Is, "a" aluminium toxicity, "i" denotes high P fixation by iron, "c" denotes the acid sulphate soil condition. Socio - economic, cultural and ecological traits were also taken in to account along with land, crop and climatological characteristics of the area for the development of a probable land use model. Based on the study the land use models that can be suggested for the area are rotational farming involving paddy, fish and livestock.
Phosphorus transformation in acid sulphate rice soils of Kerala
(Department of Soil Science and Agricultural Chemistry, College of Agriculture , Vellanikkara, 2024-09-29) Amrutha, K K; Beena, V I
Acid sulphate soils are lowland soils situated below the mean sea level along the coastal tracts of Kottayam, Alappuzha, Thrissur and Malappuram districts of Kerala, spread in two agro-ecological units namely Kuttanad (AEU 4) and Kole lands (AEU 6). These soils are characterised by high levels of organic matter, low pH and toxicity of iron (Fe) and aluminium (Al) with wide variability in available phosphorus (P) content. Acid sulphate soils generally contain substantial quantities of Fe sulphide minerals or the oxidation reaction products of these sulphidic minerals and the protonated/non-protonated surfaces of Al/Fe hydroxides and oxides, resulting in P sorption and formation of the complexes, thus decreasing P availability in soil. However, the recent fertility evaluations across the state showed high available P status due to solubilization of the accumulated applied P. To develop an economically viable phosphorus nutrient management strategy, a pioneer study on P transformations in acid sulphate soils is highly required. The study aimed to understand seasonal variation of nutrients and transformations of phosphorus in acid sulphate soils. The investigation was conducted at Radiotracer laboratory, College of Agriculture, Vellanikkara, with four experiments viz., collection and characterization of soil samples from the acid sulphate soils of Kerala in two seasons, fractionation of phosphorus, adsorption study and an incubation study. In the first experiment, 125 representative soil samples from Kuttanad (AEU 4) (15 each from Upper Kuttanad, Lower Kuttanad, Vechur Kari, Purakkad Kari and Kayal lands) and Kole lands (25 each from Thrissur and Ponnani Kole) in pre-monsoon (April) and post-monsoon (November) were collected and characterised. The experiments on the fractionation and adsorption of phosphorus were done in thirty-five samples ie., five each from the seven selected locations with varying available P status. Phosphorus fractionation was carried out to quantify different fractions of phosphorus and their contribution to the available pool. The inorganic P fractions includes saloid bound P, Fe-P, Al-P, reductant soluble P and Ca-P. Adsorption study was carried out to work out the quantity/ intensity (Q/I) relationship of phosphorus and the pattern of adsorption in acid sulphate soils. Finally, an incubation experiment of 90 days duration was conducted to understand the effect of phosphatic fertilisers, lime and farmyard manure at different levels in low and high available P soils collected from Kuttanad and Kole lands. The treatment details of the incubation study were three levels of phosphatic fertilisers (as SSP - 0, 35 and 70 kg ha-1), two levels of lime (as CaO - without lime and lime as per POP recommendations) and two levels of farmyard manure (0 t ha-1 and 5 t ha-1). The observations were made on 30th, 60th and 90th days of incubation. Seasonal characterisation of soil samples during the two seasons revealed that among the collected samples, 50 per cent was sandy clay loam and 40 per cent was sandy loam in texture. The acidity characterisation of soil samples reaffirmed the extreme acidity condition of acid sulphate soils with 40 per cent of samples coming under extremely acidic class and 20 per cent under very strongly acidic. Among the collected soil samples, 37.60 per cent was low in available P, 23.20 per cent and 39.20 per cent under medium and high P respectively. The soil sample from Vechur Kari region showed the highest value of organic carbon (11.46 %). The available micronutrients viz., Fe and Mn showed very high concentrations. Among the acidity fractions, potential acidity was dominant followed by pH-dependent acidity in both seasons. Seasonal variation in electrochemical properties like pH and EC was noticed between two seasons. Ultra acidic soil reaction with high electrical conductivity was noticed during pre-monsoon period which reaffirm the salt water intrusion in these locations. Oxidation of pyrite mineral resulted in high amount of available sulphur as well as potential acidity during pre-monsoon. Reduced condition prevailing in the post monsoon resulted in high concentration of available iron. The fractionation study of phosphorus indicated that the per cent distribution of different phosphorus fractions followed the order, Fe- P > organic P > reductant soluble P > calcium P > aluminium P > saloid bound P. The contribution of dominant fraction (Fe-P) to the available P is mainly through saloid bound P. The phosphorus fixing capacity was significantly and positively correlated with clay, organic matter content, and negatively correlated with the available P. In the adsorption study, high buffer power indicated the ability of acid sulphate soils to replenish the depleted available P. Freundlich adsorption isotherm was found to be the best to explain P adsorption followed by Langmuir and Temkin adsorption isotherms. The Freundlich adsorption constant, KF was found to be correlated with organic matter which confirmed the fixation of phosphorus by organic matter in acid sulphate soils. In most of the soils, Langmuir adsorption constant (KL) increased with rise in temperature, indicates chemisorption behaviour of P adsorption. The incubation study affirmed that in soils with low available P, the addition of SSP at doses of 70 kg ha-1 and 35 kg ha-1 along with lime and FYM showed a significant increase in pH. In these soils, the addition of SSP (70 kg ha-1) along with lime and FYM registered the highest available P of 51.63 and 73.33 kg ha-1 respectively in Kuttanad and Kole soils at 60th day of incubation. In the same treatment, Fe bound P fraction was found to be highest with a decreasing trend towards 60th day of incubation, which increased after that. In the case of soils with high available P, the treatment combination with the addition of the highest dose of SSP (70 kg ha-1) along with lime and FYM showed the highest pH with an increasing trend towards 60th day. On the contrary to low P soils, in high P soils, the addition of SSP at 35 kg ha-1 along with lime and FYM registered the highest available P of 309.44 and 126.94 kg ha-1 respectively in Kuttanad and Kole at 30th day of incubation followed by a reduction towards 60th day of incubation. Phosphorus, a widely varying nutrient in acid sulphate soils is prone to high adsorption and fixation in soil depending upon the type of clay, organic matter content and amount of oxides and hydroxides of Fe and Al. There was no significant seasonal variation of P in soil samples from AEU 4 and AEU 6. In acid sulphate soils, the most dominant fraction, Fe-P contributed to available P mainly through saloid bound P, which is the water-soluble and loosely bound P fraction. The reduction of available P with the increase in P fixing capacity necessitates its estimation at least for the grouping of soils for the efficient management of phosphorus. In soils with high available P, addition of lower dose of SSP (35 kg ha-1) along with organic manure (FYM @ 5 t ha- 1) and lime (POP recommendations) is sufficient to enhance the P availability. Where as, in soils with low available P, addition of higher dose of SSP (70 kg ha-1) along with organic manure (FYM @ 5 t ha-1) and lime (POP recommendations) enhanced the P availability than its sole application. In this regard, field experiments in acid sulphate soils have to be conducted to confirm the results of incubation study in rice under natural system and more investigation is needed to know the interaction between organic matter and organic P fraction. As the organic matter plays the dual function in the environment- as a link and as a bottleneck for phosphorus availability, detailed study should be undertaken to know the complex formed by P fixation and its degree of crystallinity for developing better P management strategies in acid sulphate soils
Practical manual:BSc Hons(Ag)
(Kerala Agricultural University, 2013) Beena, V I; Sreelatha, A K; Sindhu, S
Soil test based fertilizer prescriptions for tomato (Solanum lycopersicum L.) in magnesium deficient ultisols of kerala
(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 2017) Remya, K N; Beena, V I
Substrate impact on biogas production and manurial value of slurry
(Department of Soli Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 2015) Anooja C Lonappan; Beena, V I
The growing population of the world increases energy demand and waste generation. Due to lack of proper recycling technology, large quantities of biodegradable wastes are being produced. Biogas production is a good technology for mitigating both the problems. The slurry produced after biomethanation is a good manure which provides balanced nutrition for crops and improves soil quality. There are large varieties of biodegradable wastes which can be used as feed stock for biogas production. The quality and quantity of biogas and slurry generated are based on the nature and composition of feed stock. In order to find out an efficient substrate from the available substrates in Kerala and to determine manurial value of different types of slurry, the present study was undertaken at College of Horticulture, Vellanikkara during 2012 – 2014. To elucidate the impact of different substrates on biogas production, an experiment was laid out with three replications and six treatments viz., cow dung alone and co digestion of cow dung with poultry manure, goat manure, biodegradable house hold waste, elephant dung, and pulse residue in 1:1 ratio with equal quantity of water. The biogas generated from different treatments were analysed for CH 4 and CO 2 . The highest CH 4 production was recorded for the treatment combination of pulse residue with cow dung which was on par with cow dung and elephant dung combination, while the highest CO 2 was recorded in the biogas produced from poultry manure and cow dung combination. The hydraulic retention time recorded was lowest for elephant dung and cow dung combination. The highest organic carbon content was recorded in the slurry generated from cow dung alone, which was on par with the combination of goat manure with cowdung. The highest ammoniacal nitrogen content was recorded for biodegradable house hold waste - cow dung combination followed by pulse residue - cow dung combination. The highest total nitrogen content was observed for cow dung - poultry manure combination and cow dung - goat manure combination.157 A pot culture experiment was conducted to find out the manurial value of the slurry obtained from the treatments for biogas production with three replications and six treatments. This experiment was done by irrigating the pots with the slurry obtained from the treatments along with absolute control, as per Package of Practices and Recommendations of KAU (both were irrigated with fresh water) and with fresh undigested cow dung slurry with cowpea (var. Bhagyalakshmy) as test crop. The highest number of pods per plant and the highest yield were obtained from the plants which were irrigated with biogas slurry produced from pulse residue and cow dung combination. After harvest, the highest organic carbon content was noted in soil which was irrigated with biogas slurry produced from elephant dung and cow dung combination. The highest available nitrogen and available phosphorus content was recorded for soil irrigated with slurry produced from cow dung alone and cow dung - pulse residue combination. Available potassium content in soil was highest for in the soil which was irrigated with slurry produced from poultry manure and cowdung combination which was on par with slurry produced from elephant dung- cow dung combination. The plants irrigated with the slurry produced from cow dung-pulse residue combination and cow dung-elephant dung combination had recorded highest uptake of total nitrogen. Plants raised from the seeds obtained from these treatments showed greater shoot length, seedling length and vigour index. However elaborate studies are necessary to monitor the hormones present in different types of slurry generated from different substrates.