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Open Access
Site specific nutrient management for chilli (Capsicum annum.L) in kalliyoor panchayath of kerala
(Department of Soil Science and Agricultural Chemistry,College of Agriculture,Vellayani, 2011) Priya, U K; KAU; Sudharmai Devi C R
Site Specific Nutrient management is a technology in precision fanning that offers chance for farmers to achieve the targeted yield taking into consideration the potential yield of the crop by application of apt amount of fertilizers. The technology is farmers' friendly, eco-friendly and also consumer friendly. In Indian scenario wherein farmers are suffering from yield losses up to 40% due to micronutrient deficiency of soils mainly zinc and boron deficiencies are the yield limiting factors of production. Kerala the soils are low in basic ions that are posing serious threat to crop production. The Judicious application of chemical fertilizers along with micronutrients is necessary for sustainable crop production. The present study "Site Specific Nutrient Management in" Chilli (Capsicum annuum.L.) in Kalliyoor Panchayath Of .Kerala" was carried out to satisfy the objectives viz. study the spatial variability of area, to find outtheindigenous nutrient supply via omission trials, fix a target yield based on the potential yield of the crop and formulate a site specific nutrient recommendation to obtain the targeted yield. In order to understand the spatial variability survey was conducted at 25 sites of Kalliyoor panchayath. The results of survey showed that the soils showed wide variation in terms of soil physical and chemical properties. Soil phosphorus status , was high in all cases other nutrient concentration ranged from low to high. The spatial variability necessitated carrying out the omission trials at four different sites that were ranked according to the nutrient status into high, medium first level, medium second level and low fertility soils. From the omission trials the recovery fraction and, indigenous nutrient supply were calculated. Utilising all these parameters in QUEFT model SSNJ\:1.--tre tments were fixed. /' / / - :l.33- The high yield target was fixed at 16 t ha that was 50% of the potential yield. The nutrient recommendation generated for HYT was 104.8: 13.6: 201 kg N, P205 and K20 ha-I. Medium yield target was fixed at 168:51: 230 kg N, P205 and K20 ha- I. Taking into account micronutrient and secondary nutrient deficiencies in the soil. In high yield target soil application of micro nutrients and secondary nutrients along with application of 1 % foliar spray of boron was recommended. Micronutrients for soil application were boron @ 5 kg ha-I in form of borax, zinc @ 20 kg ha-I in form of zinc sulphate. Secondary nutrients applied were calcium @ 30 kg ha-I in form of CaS04, magnesium @ 7.5 kg ha-I in form of MgS04. The requirement of sulphur was met from soil applied zinc sulphate, calcium sulphate and magnesium sulphate. In medium yield target only soil application of micro and secondary nutrients along with the application of QUEFT generated recommendations for the crop; POP + micronutrient recommendations were evaluated. Simultaneously an absolute control was also carried out. Soil analysis was carried out for all the physical and chemical properties of the soil initially before the crop was raised, and after each harvest. So that change in soil properties as a result of application of treatments could be evaluated, since the application of fertilizer coincided with each harvest. The results derived from the experiment proved the superiority of SSNM over other treatments with respect to the yield major nutrient and micronutrient uptake. , Where high yield target registered a cumulative yield of 17. 32 tons, medium yield target registered a cumulative yield of 11.75 tons this was _much superior to POP+SNMN that registered an yield of 9.83 tons, or the package of practice recommendation that registered an yield of only 8.3 tons . Farmers practice registered inferior yield data of only 5.2 tons. The study revealed that the site specific nutrient management is an efficient technology to increase the yield of crops and hence provide additional income to the farmers; this technique also provides a -134 - scope of increasing the yield without over application of fertilizers that would result in deterioration of the soil physical and chemical properties in long run.
Open Access
Nitrogen and sulphur interaction on their release pattern and use efficiency in ferralitic soils.
(Department of Soil Science and Agricultural Chemistry,College of Agriculture, Vellayani, 2011) Mariya Dainy, M S; KAU; Usha, P B
An experiment was carried out at College of Agriculture, Vellayani to investigate the interactive effect of nitrogen and sulphur on their release pattern and use efficiency in ferralitic soils with bhindi as the test crop. The experiment consisted of an incubation study and a field experiment. The incubation study was carried out to understand the release pattern of N and S from their sources viz. urea and gypsum in the soil at different sampling stages (30 and 100 days of incubation) using ferralitic soil kept at field capacity. The treatments consisted of M1N1S1, MINIS2 , M1N1S3 , M1N2S1 , M1N2S2 ,M1N2S3 ,M1N3S1 , M1N3S2 , M1N3S3 , M2N1S1 , M2N1S2 , M2N1S3 , M2N2S1 , M2N2S2 , M2N2S3 , M2N3S1 , M2N3S2 and M2N3S3 and M0N0S0 . Levels of N include N1 (50 kg ha-1), N2 (80 kg ha-1) and N3 (110 kg ha-1). M1 include P2O5 @ 8 kg ha-1+ K2O @ 25kg ha-1 (current POP) and M2 include P2O5 @ 35 kgha-1 + K2O @ 70 kg ha-1(modified POP). Different levels of S are S1 (10 kg ha-1), S2 (15 kg ha-1) and S3 (20 kg ha-1). Soil samples were collected and analyzed for pH, available N and available S content. There was increase in pH value to the neutral range at fifty per cent flowering stage (30 Days of Incubation) and all the treatments showed a decreasing trend in the pH value at 100 Days of Incubation. Available N and available S content increased to some extent at fifty per cent flowering and decreased at the final harvest stage. Application of N up to 110 kg ha-1 significantly increased the available N status of soil and S application up to 20 kg ha-1 increased the soil S status during incubation. The field experiment was laid out in 2×3×3+1 factorial RBD having three replications using bhindi variety Varsha Uphar as the test crop. The treatments were similar to that of the incubation study. S application @15 kg ha-1 significantly reduced the internodal length. N and S interaction N @ 80 kg ha-1 and S @ 15 kg ha-1 showed significant influence on fruit length. The maximum number of fruits and highest yield was obtained when the nutrients were applied @ 80 kg N ha-1 + 8 kg P2O5 ha-1 + 25 kg K2O ha-1 + 15 kg S ha-1. Considering the N and S interaction effects, combined application of N @ 80 kg ha-1 and S @ 20 kg ha-1 increased the number of fruits and yield. Application of N up to 80 kg ha-1 increased the crop yield and above this level, there was reduction in yield. The increase in number of fruits per plant by the application of N and S may be due to the highest uptake and efficient utilization of nutrients. N @ 110 kg ha-1 and S @ 20 kg ha-1 recorded the highest dry matter content. S application @ 15 kg ha-1 showed significant influence on N Use Efficiency (NUE) in bhindi. Application of 80 kg N ha-1 + 8 kg P2O5 ha-1 + 25 kg K2O ha-1 + 15 kg S ha-1 resulted in highest NUE. By the application of urea and gypsum, there was slight increase in the soil pH. After N and S application, there was increase in organic carbon content of the soil. At fifty per cent flowering all the nutrients showed an increase in availability and there was a decrease at the final harvest stage because of crop uptake and various losses. N application @ 110 kg ha-1 significantly increased the available N status in the soil. S application up to 20 kg ha-1 significantly increased the available P K and S content in soil. As the levels S increased, there was increase in the exchangeable calcium in soil. Higher levels of application of N recorded higher N content in both plant and fruit. Application of P and K at M2 (35 kg P2O5 ha-1 + 70 kg K2O ha-1) level significantly increased the content of P, K and Ca in plant and fruit. Increased S application increased the Ca content in plant since gypsum was used as the source of S. S application up to 20 kg ha-1 had significant influence on the fruit Ca and Mg concentration. The interactive effect of N and S was not significant in the case of S content in plant. But, N2S3 (N @ 80 kg ha-1 and S @ 20 kg ha-1) recorded the superior value. N application had got positive influence on the content of P, K, Ca, Mg and S in plant and fruit. By progressive increase in S application up to 20 kg ha-1and N application up to 80 kg ha-1, there was significant reduction in N: S ratio. N and S fertilization had significant influence on leaf chlorophyll content and application of 80 kg N ha-1, 35 kg P2O5 ha-1, 70 kg K2O ha-1 and 15 kg S ha-1 showed the superior value for chlorophyll content. An increasing trend was noticed with higher levels of N up to 80 kg ha-1 and S up to 20 kg ha-1. N and S application significantly enhanced the uptake of nutrients. Uptake of phosphorus, potassium, calcium, magnesium and S were highest when N, P, K and S were applied @ 80 kg N ha-1+ 35 kg P2O5 ha-1+ 70 kg K2O ha-1+ 20 kg S ha-1. N application @ 80 kg ha-1 significantly influenced the B: C ratio. Among the treatments M1N2S2 (80 kg N ha-1 + 8 kg P2O5 ha-1 + 25 kg K2O ha-1 + 15 kg S ha-1) which gave the highest yield showed the highest B: C ratio. Maximum B: C ratio was obtained when N and S were applied @ 80 kg ha-1 and 15 kg ha-1 respectively. As the levels of S increased, B: C ratio also increased. Fertilization of N, P, K and S @ 80 kg ha-1, 35 kg ha-1, 70 kg ha-1 and 15 kg ha-1 respectively recorded the minimum Percentage Disease Incidence (yellow vein mosaic). Among the treatments, yield, number of fruits per plant, N Use Efficiency and B: C ratio were highest for M1N2S2 (80 kg N ha-1 + 8 kg P2O5 ha-1 + 25 kg K2O ha-1 + 15 kg S ha-1) and it can be considered as the best treatment combination. Application of N significantly increased the yield and the yield was highest at N2 level (80 kg N ha-1). There was reduction in yield if we apply N @ 110 kg ha-1. By the application of S along with N increased the NUE and we can reduce the dose of N to 80 kg ha-1 instead of 110 kg N ha-1 for bhindi.
Open Access
Nutrient interactions in soil test crop response studies on cucumber ( Cucumis sativus L) in the laterite soils of Kerala.
(Department of Soil Science and Agricultural Chemistry,College of Horticulture, Vellanikkara, 2011) Sajnanath, K; KAU; Hassan, M A
A comprehensive approach has to be adopted for efficient fertilizer use, incorporating soil test, field research and economic evaluation of the results for providing a scientific basis for the process of enhancing and sustaining food production as well as soil productivity with minimum environmental degradation, it needs more. Soil testing is one of the best scientific means for quick and reliable determination of soil fertility status. Soil test crop response study in the field provides soil test calibration between the level of soil nutrients as determined in the laboratory and the crop response to fertilizers as observed in the field for predicting the fertilizer requirements of the crop. In Kerala, many studies have been conducted to get a fertilizer prescription equation for targeted yield in various crops like rice, banana etc. A programme was formulated to investigate the nutrient interaction in soil test crop response studies on cucumber (Cucumis sativus L.) in the laterite soils of Kerala. In this, the field works were conducted as per the pattern of soil test crop response correlation studies. A gradient crop experiment was conducted in the experimental field of AICRP on STCR using maize. The purpose is to create a fertility gradient in the field by applying different doses of fertilizers. The area was divided into three strips and the doses of nutrients were applied as per STCR pattern of fertilization for maize. The crop was harvested and the plant samples were taken for analysis. The pre and post experimental soil samples were analysed. It was found that fertility gradients were developed in the field. Using the data on dry matter production in various strips, the nutrient uptake was also determined. A test crop experiment was designed in the same field where the gradient crop was raised. There were 24 treatments with three control plots. The treatments included four levels of nutrients and three levels of farm yard manure. The crop, cucumber (Var.: AAUC-2), popularly known as salad cucumber, was raised and managed as per package of practices of KAU. The soil samples were collected before, at flowering and harvest stages during the experiment. The plant samples were collected at flowering and harvesting stages. The total dry matter production and yield were taken treatment wise at the harvest. The soil samples were analysed for various chemical parameters. The data on yield, uptake of nutrients, nutrient status, nutrient requirement, quantity of farm yard manure applied were used for formulating the fertilizer prescription equations for cucumber. Using these equations, the quantity of fertilizers to be used to get a target of yield can be calculated if the available nutrient status is known. The equations thus developed were verified in farmers' field at four locations; Pallikandam, Maraikkal, Ayiloor and Vithanassery. The fields were laid out with five treatments and four replications. The treatments were (i) farmers' practice (ii) KAU package, (iii) soil testing laboratory method, (iv) STCR method with a target of 30 t ha-I and (v) STCR method with a target of 35 t ha-I. The soil samples were analysed before raising the crop and the quantities of fertilizers to be applied were computed for various treatments. The plant and soil samples at flowering and harvest stages were analysed for pH, EC, CEC, Organic Carbon, available N, P, K, Ca, Mg, and micronutrients such as Fe, Mn, Cu and Zn. The total dry matter production and yield were taken treatment wise at the harvest. The data were used for- statistical analysis for assessmg direct and indirect effect of nutrients on yield and nutrient interactions. A positive correlation was observed between organic carbon' and soil parameters at flowering stage. At the harvesting stage, there was a positive correlation was found between yield and major nutrients. The interaction between available P in the soil and Nand K in the plant was observed. The availability ofP in plant was negatively correlated with Fe in the soil. The targeted yield equations for cucumber could produce the yields of 30 and 35 t ha-I from the verification experiments conducted at the different locations. The B:C ratio also was higher in the STCR methods over the farmers' practices, blanket recommendations and STL recommendations. The information generated in the project will help in making the soil testing programme scientifically sound in terms of achieving predicted yields, maintaining soil fertility and helping the extension agencies in ensuring balanced fertilizer use according to the soil fertility status and crop requirement.
Open Access
Nutrient management for sustainable rice production in the black soils of Kerala.
(Department of Soil Science and Agricultural Chemistry,College of Horticulture, Vellanikkara, 2011) Danish, Tamuly; KAU; Betty, Bastin
A field experiment was carried out to find out the best nutrient management system suited for sustainable rice production in black soils of Chittur, Palakkad district. The study also aimed to know the influence of zinc on the yield of rice in such soils. These black soils though fertile, the nutrient imbalances, as well as the poor physical condition may adversely affect the yield of crop. The soil selected for the study had a mean pH value of 6.4 and electrical conductivity of 0.1dSm-1. The organic carbon content was 0.74%. The status of available N, P and K were 310.5, 5.67 and 154.36 kg ha-1 respectively. It was found that, except for available P and B, all other soil nutrients were present either in the medium level or adequate. The field experiment consisted of eleven treatments and three replications each. The treatments were- Absolute control (T1), farmer’s practice (T2), recommendation of KAU (T3), Soil Test Laboratory recommendation of Kerala (T4), STCR recommendation (T5), STCR + FYM @ 5 t ha-1 (T6), T2 + zinc sulphate @ 25 kg ha-1 (T7), T3 + zinc sulphate @ 25 kg ha-1 (T8), T4 + zinc sulphate @ 25 kg ha-1 (T9), T5+ zinc sulphate @ 25 kg ha-1 (T10) and T6 + zinc sulphate @ 25 kg ha-1 (T11). Soil as well as plant nutrient status were recorded at critical growth stages viz, maximum tillering, panicle initiation, flowering and harvest stage for the content of N, P, K, Ca, Mg, S Na, Si, Fe, Mn, Zn, Cu and B. Biometric parameters such as the height of the plant, number of tillers and number of leaves at critical growth stages were also recorded. Simple correlation co-efficient were worked out for soil nutrients, plant nutrients, grain nutrient and uptake with yield. Among the available soil nutrients, N content was found to be highest followed by available K and P during different growth stages. Available Ca was higher than Mg during all the growth stages. Among micronutrients, available Zn reduced while B increased from maximum tillering to harvest. A sharp decline in soil Fe content was observed with the advancement of growth stages. Available Na increased while, Si remained almost uniform throughout the different growth stages. Among plant nutrients, the content of N decreased from maximum tillering stage to harvest. A higher concentration of Mg compared to Ca was observed during maximum tillering stage. The plant content of Fe showed a sharp decrease from maximum tillering to panicle initiation and thereafter increased. The range varied from 5000 mg kg-1 at maximum tillering stage to 3000 mg kg-1 towards the harvest stage. The plant content of Na increased from panicle initiation to harvest stage while, that of Si declined from flowering to harvest. The number of leaves and tillers were found to be significantly higher for STCR treatments (with or without FYM) and zinc sulphate at the flowering stage. The highest benefit cost ratio was obtained for T1 (absolute control). It was also observed that the yield of both grain and straw reduced on addition of ZnSO4. Positive and significant correlation was observed between uptake of almost all the nutrients with grain and straw yield except Ca, Cu and Si. The uptake of the major nutrients, N and K was found to be significantly and negatively correlated to the contents of Na and Ca in soil. This supports the fact that excess amount of basic cations are hindering the uptake of major nutrients. Prediction of yield based on content of soil, plant and yield attributes could not be obtained from the present study. It can be concluded that black soils of Chittur are fertile. But the productivity of these soils are constrained by factors like high content of basic cations such as calcium and sodium and subsequent low uptake of major nutrients. High plant content of Fe was also observed during the maximum tillering and panicle initiation stage. The content of Si in soil as well as uptake of Si by the crop was also comparatively less. So management practices have to be adopted to reduce the soil content of the basic cations as well as nutrient imbalances in soil and plants by drainage, leaching and incorporation of FYM, crop residues rice husk etc. the interaction between macro and micronutrients have to be examined in detail and further studies have to be conducted for sustainable rice production in these poonthalpadam (black) soils.
Open Access
Availability indices of boron in major soil groups of Kerala.
(Department of Soil Science and Agricultural Chemistry,College of Horticulture, Vellanikkara, 2011) Anu, George; KAU; Suresh, Kumar P
Representative surface samples (0-20 cm) of eight soil types each from three locations (total 25 samples-including one additional sample from Kuttanad) covering nine agro-ecological units representing the major rice growing tracts of the state were collected for the present study on “Availability indices of boron in major soil groups of Kerala”. The agro-ecological units (AEU) included were Kuttanad (Kuttanad, AEU 4), Kole (Kole lands, AEU 6), Pokkali (Pokkali lands, AEU 5), Black cotton (Palakkad central plains AEU 23 and Palakkad eastern plains, AEU 10), Onattukara (Onattukara sandy plains, AEU 3), Palakkad rice soil (North central laterite, AEU 10), Laterite soils from Kozhikode, Vellanikkara and Pattambi (Midland laterite, AEU 11 and North central laterite, AEU 10)and Wayanad Plateau soils (Northern High hills, AEU 15 and Wayanad central plateau, AEU 20). The soils were characterized with respect to pH, EC, CEC, PBS and exchangeable cations, total sesquioxide and available nutrient status (Organic carbon, available B, P, K, Fe, Mn, Cu and Zn). Among the 25 soils, 15 soils showed acute boron deficiency chances (Critical limit: <0.5 mg kg-1 soil ). Fractionation of soil boron was done to separate the different forms of boron existing in soil viz. nonspecifically adsorbed plus water soluble B (NSA-B), specifically adsorbed B (SPA-B), manganese oxy-hydroxide bound B (MOH-B), B occluded in amorphous Fe-Al oxides (AMO-B), B occluded in crystalline Fe-Al oxides (CRO-B) and residual boron. Amount of boron existed in different fractions was in the following order, Residual > CRO-B > AMO-B > MOH-B > SPA-B > NSA-B. Among these fractions, MOH-B and NSA-B contributed to available B directly as well as indirectly through each other. Electrical conductivity or rather salinity is the single most important factor influencing B availability. Adsorption studies were conducted with all the soils to study the adsorption pattern of B in the above soils. The data obtained from boron adsorption experiments were fitted into different adsorption isotherms like Freundlich, Langmuir and Tempkin isotherms. 22 soils followed Freundlich adsorption pattern where as only one each of Black cotton soils (Black cotton 1) and Onattukara soils (Onattukara 2) fitted with Langmuir and Tempkin as well. Onattukara 1, the soil which recorded the lowest available B of 0.04 mg kg-1 was used to conduct a pot culture experiment using rice as test crop with three levels of B (0,10 and 20 kg ha-1) with and without 5t of FYM per hectare. The data on soil as well as plant analysis at panicle initiation and harvest stages indicated that available B status improved with increasing levels of B. Grain and total DM yield increased with the increase in boron doses without FYM. It was also noted that FYM alone could meet the B requirement. FYM with borax was found to have antagonistic effects with respect to yield as well as the nutrient contents in rice.
Open Access
Dynamics of pesticide residues in cardamom growing soils of Iddukki district.
(Department of Soil Science and Agricultural Chemistry,College of Agriculture, Vellayani, 2011) Siji N, Nath; KAU; Thomas George
The pesticide use pattern in cardamom growing tracts of Idukki district shows that the farmers are applying plant protection chemicals aggressively and the liberal and continual use of pesticides has disturbing consequences on the ecosystem. The decision regarding the type of chemicals to be used, dosage, frequency of application are fixed by the farmers themselves or as per the directions of company representatives and they are not following the recommendation of KAU or Spices Board. The improper usage of these chemicals resulted in pollution of the cardamom ecosystem especially the soil and water with toxic xenobiotics. Hence in order to assess the residue level and to study the extend of pollution due to pesticides, soil and water samples were collected from the cardamom growing plantations of Idukki district. In multi residue method validation, soil samples were spiked at five different levels (0.01 µg g-1, 0.05 µg g-1, 0.1 µg g-1, 0.5 µg g-1, 1 µg g-1) and extraction was carried out using various solvent/ solvent system and the method which gave 70-110 per cent recovery with RSD <20 per cent was selected. The same procedure was adopted for further estimation of residues from soil samples. The pesticide hot spots, were selected mainly in three locations, Kattappana, Pampadumpara and Nedumkandam Panchayath in Idukki district and five farmers were identified randomly from each location. Soil and water samples were collected before and after spraying of insecticides for a period of six months starting from December to May at two different depth at 0-15 cm and 15-30 cm depth from the selected plantations. In the monitoring study, samples collected at 0-15 cm depth were found to contain higher level of pesticide residues. The samples were frequently detected with residues of organophosphorus insecticides like phorate, chlorpyriphos, quinalphos, profenophos, methyl parathion and relatively lower number of samples were found to contain residues of endosulphan and synthetic pyrethroids. The samples collected from the lower depth 15-30 cm were contaminated with residues at a lower level. The physico chemical properties of the soil were analysed and it was found that the soils were rich in organic matter content (3.63-3.74%), acidic to near neutral pH (5.72-6.04) and have higher fertility status. The higher organic matter content of the soil favours higher rate of adsorption of the insecticide. Water samples were collected from the selected locations and analysed for the presence of pesticide residues and it was found that none of the samples were contaminated with pesticide residues. A field dissipation study was carried out with the neonicotinoid group of insecticide, imidacloprid applied at three different levels (0.05 ml l-1, 0.10 ml l-1, 0.20 ml l-1) in cropped and non-cropped condition. The half life of the chemical calculated under both the situation. The highest half life (4.25 days) was obtained when imidacloprid applied in non- cropped situation at double the recommended dose (0.20 ml l-1) and the lowest half life (2.55 days) was obtained in cropped situation when the insecticide was applied at the lowest dose (0.05 ml l-1). The half life value obtained in cropped condition was lower compared to the non cropped situation. The faster degradation of the chemical under the cropped situation may be due to the higher activity of soil microorganisms and rhizosphere effect in addition to other soil factors like pH and organic carbon content.
Open Access
Influence of organic matter and moisture on adsorption of chloroacetanilide herbicides in laterite soil.
(Departmental of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 2011) Hasna, K; KAU; Durga Devi, K M
Experiments were carried out to study the influence of organic matter and soil moisture on the adsorption of chloroacetanilide herbicides, viz., butachlor and pretilachlor, in laterite soil. The technical programme consisted of an incubation experiment and a pot culture study. In the incubation experiment, two moisture levels viz., air dry and field capacity were included along with two herbicides, butachlor and pretilachlor, and three organic matter sources, FYM, vermicompost and soil. The pot culture experiment consisted of six treatments with two herbicides and three organic matter sources. The herbicides, butachlor and pretilachlor were applied @ 1.25 kg ha-1 and 0.45 kg ha-1 respectively and the manures were applied @ 5.0 t ha -1. The soil sample collected for the study belongs to Ultisol order, the major characteristics of which are low pH, low CEC (4.7 and 4.67 C mol (+) kg-1 respectively ) and high sand content (73.13 % sand, 16.88 % silt and 10.00 % clay). Organic carbon content was in the medium range (0.61 %). Dissolved organic carbon (DOC) is the most active fraction of organic matter and hence the procedure for DOC estimation in soil, FYM and vermicompost was standardized. Quantity of herbicides adsorbed by soil was determined by gas chromatography using standard protocols developed at AICRP on Weed Control, College of Horticulture, Vellanikkara. In the incubation experiment, the degree of adsorption of butachlor and pretilachlor was evaluated using the Kd (distribution coefficient) values. The Kd values followed the order of organic carbon content in the soil samples taken from the treatments. The Kd values were higher for pretilachlor with the order being FYM > vermicompost > soil. Only slight variations were observed between air dry and field capacity levels indicating that moisture levels had no significant influence on the Kd values. This could be explained by hydrophobic character of the herbicides under study. The pot culture study showed that adsorption as well as dissipation of herbicides were more in vermicompost treatment. The results also indicated that initial adsorption of herbicides was lessened by dissolved organic carbon released from the farmyard manure. However, the half life of herbicides was more in FYM treatment when compared to vermicompost and control (soil alone). The half life of butachlor was 17.00 days and that of pretilachlor was 19.00 days in FYM treatment. The results indicated the superiority of FYM in retaining the herbicides for the desired period of weed control in rice. Phytotoxicity due to herbicide application was more with vermicompost treatment than that of FYM and soil alone treatments. This was due to the higher initial adsorption of herbicides by the soil matrix. Biometric observations on plant height, productive tillers, yield of grain and straw showed that FYM is superior to vermicompost in improving the growth and yield of rice. From the above study, it could be concluded that butachlor and pretilachlor are strongly adsorbed on soil organic matter and their adsorption onto soils is affected by the presence of soluble organic matter. Presence of high levels of dissolved organic carbon in the FYM treatment at the time of application of herbicides resulted in a reduction in the magnitude of adsorption. On comparing two organic matter sources, it was noticed that total as well as dissolved organic carbon were higher in the FYM applied soil. The dissolved organic carbon would have facilitated movement of chemicals while the particulate organic carbon improved their retention. Therefore, it is essential to consider both these factors when pre -emergence herbicides are applied to rice.
Open Access
Evaluation of aquatic pollution and identification of phytoremediators in Vellayani lake
(College of Agriculture, Vellayani, 2011) kavitha, Kamal; KAU; Manorama, Thampatti K C
A study entitled “Evaluation of aquatic pollution and identification of phytoremediators in Vellayani lake” has been carried out at the College of Agriculture, Vellayani during the year 2009-2011 to assess the extent of pollution and to identify the phytoremediators in Vellayani lake. Vellayani wetland ecosystem comprising a fresh water lake and surrounding padasekharams, extends through three panchayaths viz., Kalliyoor, Pallichal, Venganoor and two zones of Thiruvananthapuram Corporation namely Nemom and Thiruvallam. It is the sole drinking water source for the above area. Vellayani and adjoining areas is undergoing drastic reduction in area and water quality. Samples of water, sediment and macrophytes found in the lake were collected during pre monsoon, monsoon and post monsoon seasons, from 15 sites within the lake and were subjected to physical, chemical and biological analysis. The physical properties of the lake water viz., colour, turbidity and the amount of suspended solids showed significant variation among seasons and with locations showing higher values during monsoon season. All the chemical properties of lake water were also significantly influenced by the season and location. On evaluating the water as per ISI/WHO criteria, it was found that the chemical characteristics like EC, NO3-N, K, Ca, Mg, S and Zn were within the maximum permissible limits. P and Cu were not detected in water in any of the seasons. pH of the lake water was within safe limits only during the monsoon season and it was highly contaminated with organic load. The NH4-N content of water exceeded the MPL at certain locations during pre and post monsoon seasons. With regard to the heavy metals, one location was contaminated with Fe, six locations with Cd and eight locations with Pb. During monsoon season, the water quality is generally good. Al content of water was always above the safe limits fixed by ISI/WHO. Hence suitable treatments for improving water quality should be advocated for its use as drinking water/ for domestic purposes. With regard to the microbiological properties, the bacterial count was lowest during monsoon and highest during post monsoon season. Regarding the Coliform count, a gradual increase in number from pre monsoon to post monsoon season was observed. Algal population was seen uniformly distributed in all the 15 sites throughout the three seasons. All the chemical properties of lake sediment were significantly influenced by the season and location. Among the chemical characteristics organic carbon, extractable K, Ca, Mg, S, Fe, Cu, Zn and Pb were higher during pre monsoon season while pH and NH4-N were higher during monsoon season. Most of the chemical characteristics like EC, NO3-N, extractable K, S, Fe, Cu, Zn and Pb recorded their lowest values during monsoon season, while organic carbon, extractable Ca, Mg and Cd were at their lowest during post monsoon. NO3-N and extractable Al recorded their highest value during post monsoon season. Carbonates and bicarbonates were not detected in the sediment samples. The texture of sediment ranged from sandy to sandy clay loam. Fourteen species of aquatic macrophytes were found within the lake. Maximum number of plant species (12) was found during pre monsoon and minimum (9) during monsoon season. All the macrophytes showed higher elemental composition in shoot compared to root. Among the macrophytes, Eichhornea crassipes was found to be a good phytoextractor for N, K, S, Al, Fe, Cu and Cd and Pistia stratiotes for N, K, S, Al, Zn, Cu and Pb. Nymphaea odorata was found to phytoextract Cu and Cd and Nymphoides indicus for Cd and Pb. For S, Limnocharis flava and Scirpus grossus can be used as phytoextractors.
Open Access
Utilization of elephant dung for vermicompost production
(College of Horticulture, Vellanikkara, 2011) Rekha, V R Nair; KAU; Sushama, P K
The study on Utilization of elephant dung for vermicompost production was undertaken at College of Horticulture Vellanikkara during the period 2009-11. The experiment was done to understand the influence of macro and micro fauna on the in situ decomposition of elephant dung and to investigate the manurial value of biotically enriched elephant dung. In order to attain the objective three separate experiments were conducted in a phased manner. The first experiment included the investigation of the role of macro and micro fauna on the in situ decomposition of elephant dung and isolation of native microbes efficient in lignocellulose degradation. In order to study the effect of macro and micro fauna on the in situ decomposition of elephant dung, a field monitoring was undertaken by identifying six stages of degradation of dung viz. more than one year old (E1), one year old (E2), eight months old (E3), four months old (E4), and fresh sample constituting of body washings (E5) and faecal bolus (E6). The results revealed that the temperature of degrading dung was always higher than atmospheric temperature indicating that natural decomposition was a continuos process. Higher microbial activity was observed in fresh dung which resulted in lowering the C: N ratio of old dung. Among the native microbes isolated from the dung, bacteria were found to have a predominant role in lignocellulose degradation. The second experiment mainly included the characterization of physico chemical and biochemical properties of elephant dung. The manurial value of elephant dung was estimated as 48.18% C, 0.86% N, 0.34% P, 0.37% K+, 0.19% Ca2+, 0.05% Mg2+ and 0.25% Na+ with a pH value of 6.9. Dung was rich in crude fibre (21.4%) and low in crude fat (2.8%). Cellulose, hemi cellulose and lignin fractions were accounted as 35.8, 30.1 and 17.5 per cent respectively. The third experiment was vermicomposting which was done to identify the suitable microbial decomposers for pre-composting and the best substrate controlled environment for the same. The experiment was conducted in factorial CRD with two factors and two replications. Eudrillus euginae was used as the compost worms. The different factors involved are the microbes and substrates at different levels. The factor without microbes was compared with Pleurotus platypus, combination of Aspergillus flavus and Bacillus subtilis and native microbes. Different substrate levels used for vermicomposting included FYM and banana pseudostem in 1:1 and 1:8 proportion, FYM and elephant dung in 1:1 and 1:8 ,elephant dung and FYM in 1:1 and 1:8. Based on the daily observation of the compost pile of elephant dung, four stages of composting namely thermophilic (10-15 days), mesophilic (25-30 days), cooling (5-8 days) and maturity (5-10 days) were identified. After thermophilic stage worms were introduced and found that substrate combination of FYM: ED (1:8) recorded seven to eight fold multiplication in earth worm population and a maturity period of 56 days which was on par with the substrate composition of FYM: ED (1:1), recording 54 days (on an average). The biotically enriched dung also recorded the manurial value of 10.78% C, 1.34% N, 0.66% P, and 0.61% K+. 0.67% Ca2+. 0.04% Mg 2+and 0.12% Na+ with a pH value of 7.3. Among the microbes used, consortium of Aspergillus flavus and Bacillus subtilis, was found to be efficient in lignocellulose degradation which was on par with Pleurotus platypus. The FYM & elephant dung in the ratio 1: 8 must be pre composted with Aspergillus flavus and Bacillus subtilis in order to reduce the maturity period of compost. Moreover the same treatment recorded high rate of microbial activity, maximum earth worm multiplication rate and high nitrogen, phosphorous and calcium status with minimum maturity days for composting. Regarding the practical utility of work, it was found that a benefit cost ratio of 1.2 was estimated for vermicomposting of elephant dung using a tank (1m3 ) of 300 kg capacity and with the introduction of 1500 earthworms for a period of 50- 60 days with the help of effective lignocellulose degraders, Aspergillus flavus and Bacillus subtilis

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