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Open Access
Availability indices for stressed nutrients for coconut (Cocos nucifera L) in an ultisol
(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 2003) Priya, P; KAU; Sureshkumar, P
The present study was conducted with an objective to analyse the soil-plant system, the levels and interactions of nutrient ions in soil, soil solution and plant thereby / finding out the contributing factors to yield. The importance of the term relative intensity lies in the fact that the contribution of mineral elements to growth and yield of plants depend much on the relative amount of one element with respect to the others rather than the absolute content of individual elements. To study the ionic interactions and to unravel the role of Net Ionic Equilibrium based on Ratio Law on soil plant system, a sample of fifty phenotypically identical palms varying in yield from 14.4 to 84.4 nuts palm" year"! grown under an Ultisol were selected. Index leaf samples were collected during pre and post monsoon seasons from 25 palms each from high yielding and low yielding groups. Soil samples were also collected from the basins of these palms during the same seasons at 30 cm (surface) arid 60 cm (subsurface) depths. Soil solutions at saturation point were extracted from the surface samples by centrifugation technique. These leaf, soil and solution samples were analysed / . for different nutrient ions, and the NIE ratios in these three phases were worked out with respect to K and Na. The soil samples were acidic in nature and the variation in rhizosphere pH must have definitely influenced the solubility as well as absorption of different nutrient ions. In the case of available nutrients, the micro nutrients showed significant direct relation with yield both for high and low yielding populations. This might be due to their restricted availability due to aerobic oxidised condition where Fe and Mn might have been precipitated and got into unavailable forms. The BaCh exchangeable ions and the CEC derived from summing up of these exchangeable ions influenced yield directly. Exchangeable K had got a significant dominance in deciding the NIE ratio in soil, solution and in index leaves. Exchangeable K controlled the soil solution concentration of K which in turn controlled the NIE ratio in solution and the ratios in plant. Exchangeable K directly controlled the plant K content and plant K was positively and significantly correlated with the NIE ratios in plant and these ratios were positively and significantly correlated with yield. The negative significant correlation of exchangeable K with plant Mn and Zn revealed the antagonistic effect of exchangeable K in restricting the absorption of Mn and Zn by plants. Among the ionic concentrations in soil solution, Fe was positively and significantly correlated with yield in both the seasons. Soil solution concentrations of Ca and Mg were antagonistically and significantly related with plant Mn content. Potassium content and the NIE ratio in index leaves were found to have a significant direct relation with yield in the pre-monsoon season. Potassium, Ca and Mg were the dominant cations in plant deciding the total cation concentration in index leaves. The NIE ratios between the exchangeable ions, the ions in soil solution and the ions in index leaf samples were mutually, .positively and significantly correlated among themselves. This lead to the conclusion that there exists a constancy in the relative proportion of nutrient ions in the entire soil-plant system which followed Ratio Law. The study lead to the conclusion that the soil test values of the individual ions alone or the plant content of individual ions alone can't give a clear picture of optimum nutrient requirements for the plant. The relative concentration of K in soil through the ~ concentration in soil solution was found to govern the relative concentration in plant which in turn influenced the yield.
Open Access
Utilisation of dairy industry solid waste as an organic source in soil productivity
(Department of soil science and agricultural chemistry, College of Agriculture, Vellayani, 2004) Indu, B; KAU; Usha, Mathew
An investigation entitled ‘Utilization of dairy industry solid waste as an organic waste in soil productivity’ was carried out at College of Agriculture, Vellayani to study the feasibility of using dairy industry solid waste (dsw) as an organic source for improving soil productivity. The experiment consisted of four parts viz., characterization of dsw, vermicomposting of dsw, incubation study to monitor the changes in physical property, nutrient availability and microbial population in soil and pot culture experiment to study the influence of cdsw on amaranthus. The dairy waste collected from TRCMPU Ltd. at Ambalathara, Thiruvananthapuram was used in the present study. The physico-chemical and microbial analysis of dsw were done using suitable analytical procedures. Vermicomposting was carried out in pits of size 1 m x 0.5 m x 0.5 m using vegetable wastes, ground dsw and cowdung in the ratio 5:3:1 by the activity of earthworm Eudrillus eugeniae. Vermicompost was prepared according to package of practices recommendations of Kerala Agricultural University. Incubation study was conducted at the laboratory to monitor the nutrient release pattern and changes in physical properties and microbial population in soil. Two kg of soil was taken in plastic containers of uniform size and incubated at 60 per cent field capacity for three months after application of treatments. The experiment was laid out in CRD with seven treatments viz., T0 - absolute control, T1 – soil + 25 g fym, T2 – soil + 25 g dsw, T3 – soil + 12 ½ g fym + 12 ½ g dsw, T4 – soil 12 ½ g fym + 6 ¼ g dsw, T5 – soil + 12 ½ g cdsw, T6 –soil+ 6 ¼ g cdsw. Physico-chemical and microbilogical properties of soil were analysed at an interval of 1, 2, 4, 6, 8 and 12 weeks. The pot culture experiment was conducted to study the influence of dsw on growth, yield and quality of amaranthus. It was laid out in CRD with a treatments viz., T0 – absolute control, T1 – fertilizers and fym as per POP, T2 – POP fertilizers and 50 t ha-1 cdsw, T3 – POP fertilizers + fym 25 t ha-1 and cdsw 25 t ha-1, T4 – POP fertilizers and fym 25 t ha-1 and cdsw 12 ½ t ha-1, T5 – 2/3 N + full NPK of POP + fym 25 t ha-1 and cdsw 25 t ha-1, T6 – 2/3 N + full PK of POP and fym 25 t ha-1 + cdsw 12 ½ t ha-1, T7 – ½ N + full PK of POP + fym 25 t ha-1 + cdsw 25 t ha-1, T8 – ½ N + full PK of POP and fym 25 t ha-1 and cdsw 12 ½ t ha-1. Observations on various biometric and yield parameters have been recorded and analysis of plant sample were done at three stages of growth of plant viz., 30, 45 and 60 days after transplanting. The nutrient status of soil after the experiment was also analysed. Analysis of physico-chemical and microbial properties of dsw revealed that it had a near neutral pH (6.5) and it contained 37.5 per cent organic carbon, 5.80 per cent N, 2.04 per cent P, 0.71 per cent K, 1.69 per cent Ca, 1.58 per cent Mg, 1.71 per cent Fe, 159 mg kg 1 Mn and 1084 mg kg 1 Zn. Population of bacteria, fungi and actinomycetes in dsw were 13.3 x 106, 11.6 x 104 and 1.3 x 104 respectively. The results of the study revealed that vermicomposting can be successfully done in dsw using Eudrillus eugeniae. Vermicompost with a C : N ratio of 11.12 was obtained after 60 days of composting. The final compost contained 3.12 per cent N, 1.97 per cent P, 1.81 per cent K, 2.05 per cent Ca, 3.55 per cent Mg, 0.80 per cent Fe, 230 mg kg-1 Mn, 408 mg kg-1 Zn and 44 mg kg¬-1 Cu. Number of bacteria, fungi and actinomycetes in the compost at maturity stage were 42.6 x 106, 38.6 x 104 and 21.3 x 104 respectively. From the incubation study, it can be seen that nutrient content of soil increased upto 6-8 weeks in all treatments except T0 followed by a gradual decline. All nutrients except Cu were more on cdsw applied treatment in the initial period. Cu content was more in fym applied treatment. Nutrient availability was more from fym applied treatments during later periods of incubation. Bulk density of soil decreased in all treatments except T0 upto six weeks of incubation followed by a gradual increase in 8 and 12 weeks. Treatment in which cdsw was applied at higher dose showed the lowest bulk density. Upto six weeks the highest water holding capacity was noticed in cdsw applied treatments, after that fym applied treatments showed highest water holding capacity. Bacterial and fungal population reached the peak in sixth week and then declined. Upto eight weeks the effect of treatments was non significant with respect to actinomycete population. The pot culture experiment indicated the influence of cdsw on growth, yield and quality of amaranthus. Biometric and yield observation have proved the superiority of cdsw over fym. Beta-carotene content was more in cdsw applied treatments. Total yield and B:C ratio were the highest when cdsw was used as a partial substitute for fym. Physico-chemical properties of soil after the pot culture experiment revealed that pH, EC, organic carbon and available nutrients increased in all treatment except in T0 compared to the initial soil. pH, EC, organic carbon, available P, Ca and Fe were the highest in T2 which received cdsw at higher dose while the available N, K, Mg, Mn, Zn and Cu were the highest in T1 which received fym. From the results it can be concluded that effective biomanagement of dsw can be carried out using Eudrillus eugeniae. Better availability of nutrients especially nitrogen from cdsw compared to fym immediately after application as evidenced by incubation study is advantageous for short duration leafy vegetables. Use of cdsw can reduce the use of fym partially or fully in amaranthus. Fertilizer N can also be reduced to the extent of 1/3 of POP recommendation.
Open Access
Soil test crop response studies on groundnut in laterite soils of Kerala
(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 2005) Sidha, P S; KAU; Betty, Bastin
The investigation entitled “STCR studies on groundnut (Arachis hypogaea L.) in laterite soils of Kerala” was conducted during 2003-2004 in the farm attached to College of Horticulture, Vellanikkara. Objectives of the study were to develop soil test based balanced fertilizer recommendation for specific yield targets to groundnut in laterite soils of Kerala, and to develop a basis for fertilizer recommendation for maximum and economic pod yield at varying STVs. The experiment consisted of FGE and STCR experiment. The aim of FGE was to create desired gradient in soil fertility in one and the same field by applying graded doses of N, P and K fertilizers and raising an exhaustive crop, fodder maize Co-1. After development of fertility gradient, the STCR experiment was conducted in the same field with the test crop groundnut variety TAG-24. The soil nutrient status before and after the experiment were analysed for both FGE and STCR. The nutrient requirements of groundnut variety TAG-24 were estimated as 49.46, 4.25 and 19.52 kg ha-1 N, P and K respectively to produce one tonne of pod. The soil efficiencies were worked out as 28.11, 7.70, 6.88 per cent for N, P and K respectively for groundnut in laterite soil. The contribution of nutrients from fertilizers were estimated as 45.61, 11.18 and 27.33 per cent for N, P and K respectively and the contribution from organic manure were 49.46, 4.25 and 19.52 per cent N, P and K respectively to produce one tonne of pod. Fertilizer prescription equations for specific yield targets of groundnut variety TAG-24 were derived by using the above basic data and the equations were as follows: Without FYM FN = 108.44 T - 0.616 SN FP = 38.01 T - 1.577 SP FK = 71.43 T - 0.305 SK With FYM FN = 108.44 T - 0.616 SN - 1.59 OM FP = 38.01 T - 1.577 SP - 1.87 OP FK = 71.43 T - 0.305 SK - 1.85 OK Multiple regression models were calibrated with yield as dependent variable and soil available and applied nutrients as independent variables. Among the three nutrients, P and K showed normal type (+, -, -) of response in both models with 15 and 17 variables. So equations were calibrated for these two nutrients. The equations were as follows: With 15 variables FP = 32.47 - 0.709 SP FK = 321.36 - 0.429 SK With 17 variables FP = 76.27 - 2.645 SP FK = 312.37 - 0.413 SK Simple correlation coefficient was worked out for nutrient uptake with yield, nutrient uptake and yield with available and applied nutrients and major plant nutrient content with yield. The study is useful to adjust fertilizer doses based on the specific objective and available resources of groundnut farmers of the state.
Open Access
Availability indices of potassium in an ultisol under coleus cultivation
(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 2007) Santhosh, C; KAU; Mariyam, K A
A field experiment was carried out in the main campus of College of Horticulture, Kerala Agricultural University, Vellanikkara to study the availability indices of potassium in an Ultisol under the coleus cultivation. The experiment was laid out in a randomized block design with eight treatments and three replications. The treatments consisted of eight different levels of potassium. All other crop management practices were done uniformly in all plots as per the recommendation of KAU. Observations on biometric parameters as well as yield attributes were recorded during the cropping period. The soil, shoot and tuber were analysed for the various nutrients. The quantity of potassium extractable by various reagents was also estimated at these three stages. The Q/I parameters were estimated for the soil under study and the thermodynamic parameters related to K supplying power of soil were worked out. Tuber number and tuber yield were significantly influenced by the potassium application up to 60 kg K2O ha-1. The size of the tuber was not significantly affected with potassium application. Available potassium status that increased linearly with the levels of K did not affect the availability of P where as availability of N increased during the active growth stage of the coleus. Available potassium increased significantly with the levels of K application. Availability of exchangeable Al and Mn in soil got reduced with the increased levels of K. Even though the nitrogen and potassium content in shoot increased with the levels of K application at active stages of crop growth it had not reflected in the final yield. Calcium and aluminium absorption were found to reduce with increase in available K. Nitrogen and phosphorous content in the tuber reduced towards the harvest of crop. Calcium and magnesium content in tuber was influenced by K application where as K content in tuber was not increased with the levels of K. At all stages of analysis the quantity of K extracted with all reagents increased with the levels of potassium application in the soil. The water soluble, exchangeable and non-exchangeable potassium were reduced from initial stages towards harvest indicating the crop utilization and the presence of dynamic equilibrium between the various forms of potassium. Correlation studies conducted between yield attributes and quantity of K extracted revealed positive correlation between tuber yields and tuber number with water soluble and exchangeable K. The quantity-intensity parameters estimated at temperatures viz. 25°C and 40°C showed that the desorption of potassium is more at higher temperature indicating the higher availability of K in summer season. The potassium adsorption of soil under study followed the Freundlich adsorption isotherm both at 25°C and 40°C.
Open Access
Soil test crop response studies on coleus (Solenostemon rotundifolius Poir J.K Morton) in the laterite soils of Kerala
(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 2003) Nagarajan, M; KAU; Hassan, M A
Investigation entitled" Soil Test crop response studies on coleus in laterite soil of Kerala" consisting of two experiments namely fertility gradient experiment and STCR experiment was conducted during 2002 in the farm attached to the College of Horticulture, Vellan ikkara. Objective of the study was to develop soil test based balanced fertilizer recommendation for specific yield targets of coleus in laterite soils of kerala and provide a basis for fertilizer recommendation for maximum and economic tuber yield at varying soil test values. The fertility gradient experiment was conducted to create desired gradient in soil fertility in one and the same field by applying graded doses ofN, P, and K fertilizers and raising fodder maize var.Co.l. After development of fertility gradient, the STCR experiment was conducted in the same field with the test crop, coleus variety Nidhi.The treatment structure consisted of four levels of N (0,20,40, and 80 kg ha'), three levels of P20S (0,45 and 90 kg ha-I) and five levels of K (0, 25, 50, 100, 200 kg ha-I) along with three levels of FYM (0, 7.5 and 15 t ha-I) The nutrient requirement of coleus, variety Nidhi were estimated to be 9.15,1.38 and16.38 kg ha-I N, P20S and K20 respectively to produce one tonne of tuber. The soil efficiencies worked out as 21,46.85 and 40.85 per cent for N, . , P205 and K20 respectively for coleus in laterite soil. The contribution of nutrients from the fertilizers for coleus was calculated as 61.6,9.57 and 56.60 per cent for N, P205 and K20 respectively. From the above basic data, fertilizer prescription equation for specific yield targets of coleus variety Nidhi in the laterite soil were derived as follows, Without rVM FN =14.85T-0.34SN FP205 =14.42T-l J.21SP FK20 =28.98T-0.87SK FN, F P20S, F K20 - Fertilizer N, P20S and K20 respectively T - Target yield of tuber in t ha-I SN, SP, SK - Soil available N, P and K in' kg ha-I respectively . WithFYM FN 14.85 T - 0.34 SN - 0.34 ON 14.42 T - 11.21 SP - 3.25 OP F K20 = 28.93 T - 0.87 SK - 1.22 OK Where, ON, OP and OK are quantities ofN, P and K supplied through organic manure in kg ha" Multiple regression models calibrated with yield as dependent variable and STVs for available N, P and K and applied nutrients as independent variables had 67.4 per cent predictability. Among the three fertilizer nutrients, FN only showed the normal type (+, -, -) of response. The fertilizer adjustment equation fur v,!rying levels of soil available N for maximum tuber yield (t ha") of coleus in laterite soil was derived as FN= 168 SN, where FN is fertilizer N (kg ha"): SN is available N (kg ha-I) is soil. The behavior of applied p and K was found to produce responses other than normal and hence optimization coula not be done for fertilizer P and K at varying soil test values. Simple correlations coefficient was worked out for Nutrient uptake, soil available nutrients, applied nutrients with yield of coleus. Available nutrients -! showed higher positive correlation" than that of allied nutrients. The uptake of nutrients (N, P and K) also significantly correlated with yield of coleus. This study is useful to adjust fertilizer doses based on the specific objective and available resources of coleus farmers of the state.
Open Access
Evaluation of latex sludge as a phosphorus source in crop production
(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2004) Simi, Sathyaseelan; KAU; Sumam, George
A detailed investigation entitled ‘Evaluation of latex sludge as a phosphorus source in crop production’ was carried out at College of Agriculture, Vellayani, with chilli (Capsicum annuum L.) as the test crop. Preliminary studies in both India and abroad had shown this waste product of latex concentrate industry to be a rich source of plant nutrients especially P. Initially the basic physico-chemical properties of this sludge material were estimated followed by an incubation study in which its P release pattern was compared with that of two conventional P sources -SSP and RP. Then pot culture experiments were undertaken to study its direct and residual effects on the growth and yield characters of chilli var. Jwalamukhi. Chemically, latex sludge is magnesium ammonium phosphate. Analytical studies revealed it to be near neutral (pH 6.49) in reaction which is mainly due to the pH buffering effect of its magnesium phosphate component. So, no significant variation in soil pH was observed both in the incubation study as well as in the pot culture experiments and in this respect it is comparable with the conventional P sources- SSP and RP. The total P content is 35.98 per cent grading it superior to rock phosphates now popular in market as commercial fertilizers. Of the total P, 13 per cent is water soluble and 36 per cent citrate soluble, together accounting for nearly half of the gross P content. The presence of both fractions gives latex sludge an added advantage over SSP and RP, in that it can provide both readily available and slowly available forms of P, making it suitable for a wide range of crops and soils. Another positive property of latex sludge is the presence of Mg (6.86 per cent) and N (6.05 per cent) in it. Mg has been found to be required by many plants in about the same quantities as P to increase their photosynthetic efficiency. The N is present in readily available form too ie., as ammonium phosphate. The presence of about five per cent organic C is another advantage as it enhances phosphate dissolution capacity of the material. In addition, it can supply minute quantities of K and Ca (less than one per cent). On the basis of its chemical profile, latex sludge can be considered more or less as a complete complex fertilizer. The greatest advantage is its ability to act as a slow release fertilizer, a property bestowed on it by the encapsulation of nutrients by rubber residues present in low concentration. The dynamics of important soil chemical properties on incubation with latex sludge (T1), SSP (T2) and RP (T3) were studied against a control (T4, soil alone) for a period of 120 days. These sources were applied to one kg soil taken in plastic containers, to provide P @ 40 kg ha-1 and the soil was maintained at field capacity. The superiority of latex sludge in increasing the soil organic C content was very much evident from the incubation study, even though there was an initial delay. From the 30th day onwards latex sludge was significantly superior to RP and SSP, the values gradually increasing to a maximum by the 75th day followed by a slow decline. The available N values were the highest for latex sludge applied soil throughout the incubation period except on the 105th day. From 30th to the 90th day these values were significantly superior to those for SSP and RP applied soils. The different P sources exerted significant influence on soil available P contents throughout the incubation period. On the 15th day, the water soluble phosphates of SSP maintained its superiority by recording a value significantly higher than that of all other sources. The next highest value was recorded by latex sludge and was significantly superior to RP. But from the 30th day onwards, P release from latex sludge and SSP became statistically comparable and significantly superior to that from RP. The uniform release pattern of both latex sludge and SSP continued till the 90th day and thereafter the three sources became on par in their P release capacities. The superior effect of latex sludge in maintaining a high soil available P till about 90th day is therefore very much evident and is mainly due to the presence of both water and citrate soluble P fractions in it. The available K levels in soil remained unaffected throughout the incubation period despite P application in different forms. The various P sources could produce significant variations in soil exchangeable Ca and Mg levels only towards the middle period of the incubation. In general, latex sludge was seen on par with RP in increasing soil exchangeable Ca but the Mg release pattern showed high inconsistency. The agronomic efficiency of latex sludge was evaluated by conducting pot culture experiments laid out in CRD with a main and a residue crop of chilli var. Jwalamukhi. The treatments included T1 (full P as LS), T2 (full P as SSP), T3 (full P as RP), T4 (¼ LS + ¾ SSP), T5 (½ LS + ½ SSP), T6 (¾ LS + ¼ SSP), T7 (¼ LS + ¾ RP), T8 (½ LS + ½ RP), T9 (¾ LS + ¼ RP), T10 (No P) and T11 (absolute control). Urea, muriate of potash and FYM were applied uniformly to all treatments except absolute control, as per Package of Practices Recommendations of Kerala Agricultural University. The P fertilizers were applied as per treatment schedule. The growth characters of chilli registered the maximum values when full P was given as SSP (T2). But, the effects were statistically on par with the combination treatment T8 (½ LS + ½ RP). Yield in general was favourably enhanced when latex sludge was applied along with RP. The highest yield was recorded by T7 (¼ LS + ¾ RP) but it was on par with T8 (½ LS + ½ RP). The economic analysis (benefit-cost ratio) also showed the same trend of yield. The quality traits of chilli also testified the suitability of latex sludge as an alternate P source. The treatment combination T8 (½ LS + ½ RP) registered values which were either the highest or on par with the highest. The plant uptake of nutrients, a major yield contributing factor, also showed trends in favour of latex sludge. The uptake of N, P, K, Ca and Mg which were significantly influenced by the treatments were the highest or on par with the highest for the combination treatment, T8. Chemical analysis of soil upon crop harvest indicated that the combination treatment T8 (½ LS + ½ RP) could maintain higher levels of available N, P and exchangeable Mg. Full P as latex sludge (T1) recorded the highest organic C content and was significantly higher than all other treatments. The residual effects of the treatments were studied by raising another crop of same variety of chilli in the same pots using the same soil following all the cultural operations as for the main crop except P addition. The highest residual effect of P was exhibited by the combination treatment T8 (½ LS + ½ RP) manifested by recording the highest fruit yield and thereby the highest returns. The high residual effect of T8 (½ LS + ½ RP) was also evident from its highest P uptake indicating adequate P availability inspite of its lack of application to the current crop. Moreover, the uptake of other nutrients was either the highest or on par with the highest value for the same treatment (T8). The present investigation, therefore, undoubtedly proves that latex sludge can be used as an alternate and cheap source of P in crop production. The combination treatment T8 (½ LS + ½ RP) emerges superior on the basis of its direct and residual effects on growth, yield and quality characters of chilli. Economic analysis substantiates this further. Moreover, use of this apparently ecofriendly material in crop production will be a boon in terms of its disposal also.
Open Access
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; KAU; Usha, P B
The proposed piece of research work entitled " Effect of sulphur on yield, quality and uptake of nutrients by cowpea (Vigna unguiculata L Walp) in a Rhodic Haplustox" was conducted at Instructional farm,College of Agriculture, Vellayani. The study WHS undertaken to evaluate the effect of different levels and sources of sulphur application on yield, quality and uptake of nutrients by cowpea using the var Kanakamoni. The experiment was laid out in RBD with three replications. Combination of three factors, organic manures (FYM), NPK fertilizers and sulphur constituted the ten treatments. Sulphur was applied through two sources viz gypsum and factamphos. Different levels of S application were I) no sulphur 2) S @ 15 kg ha,l and 3) S @ 30 kg ha,l. All treatments included normal NPK applied through urea,mussooriephos and MOP at the rates of 20:30: 1 0 kg ha". FYM application was also done at two levels i.e.treatrnents with FYM and without rYM. Growth characters like height of the plants, number of branches per plant, number and weight of effective nodules, chlorophyll content and NRA were significantly enhanced as a result of S fertilization.The treatment combination with 30 kg S ha,l along with POP recommendation recorded the maximum value in all these cases. Gypsum was found to be superior in all these cases execpt ip the case of number of branches per plant. Treatment with 30 kg S ha,l as gypsum along with POP recommendation recorded significantly minimum value for days to maximum flowering and N:S ratio. A 42 per cent increaese in yield over control was recorded by 30 kg ha" as gypsum along with POP recommendations. A significant increase in yield attributes and protein content (25.39%) was also noticed through S fertilization. Uptake of N,r, K, Ca, Mg and S was increased due to S fertilization indicating a synergistic effect. All the growth characters and yield attributes were best correlated with yield. Uptake of nutrients showed positive and significant correlation with yield, the best correlation being obtained at MFS. Yield is decided by the uptake of nutrients at MFS. N:S ratio and days to maximum flowering showed significantly negative correlation with yield. Field experiment revealed that S as well as combination of S with organic manures exerted significant effect on most of growth and yield attributing charecters of cowpea. The treatment combination with normal level ofNPK and FYM along with S @ 30 kg ha-I was found significantly superior to other treatments. Gypsum as the source was found to be superior to factamphos,
Open Access
Rock dust as a nutrient source for coleus (solenostemon rotundifolius (POIR) morton)
(Department Of Soil Science And Agricultural Chemistry,College of Agriculture, Vellayani, 2008) Divya, S S Rose; KAU; Shehana, R S
The effect of application of rock dust at different rates alone as well as in combination with FYM and chemical fertilizers and the resultant effect on growth and yield of Coleus (Solenostemon rotundifolius) var. Sreedhara was evaluated by conducting a laboratory incubation study and field experiment at College of Agriculture , Vellayani during 2006- 2007. The results of the incubation study revealed that increasing the rate of application of rock dust resulted in an increase in the available nutrient contents of soil. Application of rock dust in conjunction with an equal quantity of FYM also enhanced the availability of all the major as well as minor nutrients. The pattern of release of available N was found maximum during 30th day of incubation and for P, the highest value was recorded during 120th day of incubation. The release of K was found to increase over time reaching the maximum during the later part of the study. The pattern of solubilisation of micronutrients viz. Fe, Mn and Zn revealed that there was a gradual increase in their concentration from the start of experiment, reaching the highest values during the later stages of incubation. Application of rock dust at a higher rate i.e.12 t ha -1 along with an equal quantity of FYM resulted in the maximum release of almost all the nutrients viz. N, P, K, Fe, Mn, and Zn through out the incubation period. Addition of rock dust along with an equal quantity of FYM resulted the percentage increases from 7 to 17.5, 19.50 to 29.22, 22.95 to 45.38, 10.47 to 14.14 15.58 to 26.36 and 1.3 to 8.6 respectively for available N, P, K, Fe, Mn and Zn when compared to the application of rock dust alone. The results from the field experiment conducted to evaluate the efficiency of rock dust revealed that the plant growth characters like number of branches per plant at 90 DAP and plant spread at 60 DAP showed significant variation due to the application of rock dust @ 10 t ha -1 mixed with equal quantity of FYM and kept for 15 days before the field application. Leaf chlorophyll concentration was increased by 47.36 per cent due to the application of rock dust when compared to POP recommendation. Yield component like number of tubers per plant was also increased by 14.81 per cent due to the application of rock dust. Application of rock dust @ 10 t ha -1 along with equal quantity of FYM and 50 per cent of the chemical fertilizers NPK @ 30:30:50 kg ha -1 also produced yield (17.26 t ha -1, B. C ratio 2.63) equivalent to POP (19.55 t ha -1, B. C ratio 2.39). This treatment also produced the highest number of tubers per plant, dry matter content of plant parts and total dry matter production. The highest yield of 19.55 t ha -1 was obtained for POP recommendation. But application of rock dust along with half the recommended dose of NPK and FYM also produced the similar yield as (17.26 t ha -1) that of POP recommendation. This shows that partial substitution (50 per cent) of chemical fertilizers with rock dust can be recommended to the farmers where ever it is locally available. The starch content and cooking quality of the tubers were also favoured by the application of rock dust @ 10 t ha -1. Starch content increased by 35.02 per cent due to the application of rock dust. Priming rock dust with FYM two weeks prior to field application resulted in the maximum release of P, K, Ca, Mg, Fe, Mn and Zn from rock dust. Rock dust application resulted in the percentage increases of 34.55 to 43.12, 47.96 to 58.49, 20, 17.55 to 55.00, 74.50 to 78.69 and 20 for P, K, Mg, Fe, Mn and Zn respectively when compared to the application of inorganic fertilizers for coleus. Rock dust @ 10 t ha-1 along with equal quantity of FYM resulted in the highest returns per rupee invested (B.C ratio 2.89). It can be concluded from the results of the study that the present recommended dose of in organic fertilizers for coleus can be reduced to half provided it is applied along with rock dust @ 10 t ha -1 . 100 per cent substitution of chemical fertilizers with rock dust 10 t ha -1 and FYM 10 t ha -1 can be recommended for coleus wherever rock dust is locally available.
Open Access
Yield maximisation in rice (Oryza sativa L) in the acid sulphate soils of Kuttanad through systematic approach in fertilizer use
(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2007) Annie, Koruth; KAU; Venugopal, V K
Cereals are the world’s major source of food for human nutrition. Among these, rice is very important and represents the staple diet for more than two-fifths (2.4 billion) of the world’s population, making it the most important food crop of the developing world. Rice is the staple food of Kerala and is the only cereal crop of significance to the food basket of the State. Kuttanad is the rice bowl of Kerala producing nearly 30% of the State’s rice output. The entire area is now planted with high yielding rice varieties adopting all improved agricultural practices including higher doses of fertilizers and pesticides. The problems associated with the application of heavy doses of fertilizers, leading to nutrient imbalance and economic loss to the farmer is a major constraint. Therefore improvement in soil health through balanced fertilization, leading to productivity increase and economic benefit to the farmer, will have a measurable impact on rice production in the state. With a view to realize the maximum economic yield in rice by optimizing the nutritional status of the soil, a series of experiments were undertaken under the present study entitled “Yield maximisation in rice (Oryza sativa L.) in the acid sulphate soils of Kuttanad through ‘systematic approach’ in fertilizer use”. This involved preliminary soil analysis, nutrient fixation study and green house nutrient survey to demarcate the nutrient constraints and also to optimize the soil nutrient status. The critical level of P & K for the soils of Kuttanad were also done since the basic concept of systematic approach is based on the critical level of nutrients in soil. Pot culture studies were undertaken to find out the critical level of P & K using maize as indicator crop. The soil test values of P & K were correlated with the per cent yield and a significant correlation was obtained only for P with yield. A quadratic relationship was observed with per cent yield and soil test P values. This relationship gave a critical level value of 11.17 mg I' 1 for P. But in the case of K, no such relationship was obtained. Fixation study conducted for P, K, Cu, Zn, Mn, S & B to find out if any of the applied plant nutrients, fixed or complexed abnormally with the soil indicated P, K, Zn, S & B as the limiting nutrients, and the optimum quantities of these limiting nutrients were determined as 224 mg f 1 P, 122 mg l"1 K, 5.8 mg f 1 Zn, 2 mg I' 1 S & 1.52 mg I' 1 B. The green house nutrient survey conducted to arrive at the optimum treatment revealed that, for formulating the optimum treatment, lime @ 0.07 g CaCC>3 100 ml' 1 soil, Ca @ 822.4 mg I'1, Mg @ 349 mg f 1, P, K, Zn, S & B at the above concentrations, Mo @ 2 mg I' 1 & N @ 100 mg I' 1 has to be added. There were 16 treatments. This experiment was conducted with Sorghum as indicator crop and the relative yield calculated from the biomass yield, recorded on the 45th day of planting revealed P only as the limiting nutrient for this particular soil. The quantity of P to be added to the optimum treatment was 224 mg I'1, which is 602 kg P ha'1. Since this is a very high and uneconomic dose for farmers to adopt, the Package of Practices Recommendations: Crops (POP) for medium duration rice variety, 45 kg P2O5 ha’1 was opted as the base and since P is the limiting nutrient, two higher doses, 60 & 75 kg P2O5 ha' 1 were tested as the three levels of P application. As balanced fertilization is a must for the rice crop, three levels of K were also included. Since K was not limiting, the POP recommended dose and two lower levels were tested, i.e., 15, 30 & 45 kg K2O ha'1. Thus the design for the field experiment was 3x3 Factorial RBD with an absolute control. Total 9+1 treatments. N @ 90 kg ha' 1 was applied to all treatment plots. The main effect of P & K and their interactions were studied. The field experiment was laid out for two consecutive seasons, Puncha (Rabi) 2004-05 (Nov. ’04 - March ’05) and Additional Crop (,Khan/) 2005 (May ’05 to Oct. ’05) in the experimental field of Rice Research Station (RRS), Moncompu, Kuttanad, Kerala. The medium duration rice variety, Uma (MO. 16) released from RRS, Moncompu with an average grain yield of 4.5 - 5.0 t ha' 1 was used for the experiment. The effect of these treatments on dry matter yield of shoot & root, soil & plant nutrient content and nutrient uptake of N, P & K at the critical stages of rice growth were studied. Biometric observations, yield and yield components were also recorded. For P, the limiting nutrient, significant differences in the phosphorus content of plant were observed when different doses of P were applied. The P content and uptake of grain and straw were not influenced during the Puncha season, while during the Additional Crop season it was significantly influenced by the varying doses of P. All the control plots recorded a significantly lower P content and uptake & low P soil status compared to treated plots on an average during both seasons. An increase in the application of K doses, resulted in a significant increase in the K status of soil during Puncha season, while during the Additional Crop season, this was not noticed and the treated plots were on par with control. With an increase in applied K, there was a significantly corresponding increase in K content in plant during the Puncha season, while during the Additional Crop season this was not so. The K content and uptake of grain and straw was not influenced during both seasons by the different doses of K but the treated plots recorded a significantly higher uptake

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