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Open Access
Deterioration of oil cake by fungi
(Department of Plant Pathology, College of Agriculture, Vellayani, 1989) Naseema, A; KAU; Wilson, K I
Fungi causing deterioration of coconut, groundnut and sesamum oil cakes were studied. ficremonium implicatum, Asperdllus aculeatus, A. flavus, A. fumigatus, A. nlaer, A. terreus, A. versicolor, Bipolaris hawaiiensis, Curvularia clavata, Monascus ruber, Penicillium aurantioqriseum, P. Pinophilum, Pestalotiopsis palmarum, Rhizomucor £usillus and Ehizopus stolonifer were obtained from coconut oil cake. Aspergillus flavus, A. niaer, A. terreus, A. versicolor, Gliocladium sp. Penicillium pinophilum, RhizoEUS or^zae and Rhizopus stolonifer were noticed in groundnut and Aspergillus candidus, A. flavus, A. fumigatus, A. nlaer, A. tamarii, A. terreus, Curvularia clavata, Eurotium. chevalieri, F"sarium pallidoroseum, Monascus ruber, Fenicilliuiu pinophilum, Pestalotiopsls palmarum and Rhizopus or^zae in sesamum oil cake. Of these, Acremonium implicatum, Aspergillus aculeatus, A. caeslellus, A. .f"-igatus, Bipolaris hawaiiensis, Curvularia clavata, Monascus ru^, Penicillium anrantlogriseum, P. pinophilum, Pestalotiopsls palmarum and Rhizomucor pusillus from coconut oil cake, Aspergillus versicolor, Gliocladium sp., Penicillium pinophilum, Rhizopus oryzae and R. stolonifer from groundnut and Aspergillus candidus, A. fumigatus, A. tamarli, A. terreus, Curvularia clavata, Eurotium chevalieri, Fusarium pallidoroseum,Monascus ruber, Penicillium pinophilum, Pestalotiopsis palmarum and Rhizopus oryzae from sesamum oil cake have not been reported earlier. * Aspergillus flavus and A. niger were isolated from all the samples of groundnut and sesamum oil cakes. In coconut oil cake, these two fungi were present in 88.89 and 77.78 per cent of the samples. A. terreus was isolated from 66.67 per cent of groundnut and 55. 56 per cent of coconut and sesamum oil cake samples. Penicillium pinophilum was obtained from 66.67 per cent of groundnut, 44.44 per cent of sesamum and 27.78 per cent of coconut oil cake samples. Wide variation was noticed in the population of fungi present in the oil cakes collected from different regions during different periods of the year. Oil cakes collected during June-July had the highest population, of fungi. The central and the northern regions recorded higher population of fungi than the southern region. Positive and significant correlation could be obtained between weather parameters and population of fungi in different oil cakes. Maximum correlation was noticed in relation to total rainfall. Qood mycelial growth of fungi was obtained in all the oil cakes incubated at 27, 29 and 32°C. Maximum mycelial growth was noticed at 100 per cent relative humidity. This was followed by 96.1 per cent and 92.9 per cent in the descending order. The oil content of the oil cakes was considerably reduced due to the growth of all the fungi tested individually and in combination. Maximum reduction v/as noticed due to the growth of Pestalotiopsis palmarum in coconut oil cake, Rhizopus stolonifer in groundnut and Fusarium pallidorosem in sesamum oil cake. In the case of combinations, Aspergillus flavus, A. niger and Penicillium pinophilum together caused maximum reduction in oil content of coconut oil cake. In groundnut, combined growth of A. flavus, A. niger and A. terreus caused maximum reduction in oil whereas, A. niger and P. pinophilum together effected maximum reduction of oil in sesamum oil cake. Oil cakes inoculated with different fungi showed considerable reduction in total carbohydrates, crude protein, free amino nitrogen, crude fibre and ash to the extent of 6.11 to 76.95 , 4 . 28 to 68.03, 14.91 to 92.52, 1.25 to 92.55 and 0.17 to 65.16 per cent respectively. In the case of mineral nutrients like phosphorus, potassium, magnesium. calcium, copper and iron reduction ranging from 15.07 to 75.54, 23.13 to 94.41, 10.89 to 63.37, 28.78 to 90.20, 52.52 to 97.12 and 0.32 to 60.77 per cent respectively was noticed. Fourteen out of 2 0 isolates of Aspergillus flavus produced aflatoxins B^, and G2 in culture medium with maximum quantities being 1210, 1040 and 151 ppb respectively by the isolates from coconut oil cake. Eight out of 19 isolates of A. niger elaborated upto 222 ppb by the isolate from sesamum oil cake. When grown on the respective host material, A. flavus isolates from coconut oil cake produced maximum quantity of B^^, B^ and being 1517, 1092 and 272 ppb respectively. A. niger isolate from coconut oil cake produced B^^ upto 419 ppb. oil cakes treated with calcium propionate (0.6 per cent, w/w) were free from fungus growth throughout the period (180 days) of observation and showed minimum number of fungal propagules whereas, those kept as control had higher population of fungi than the treated ones, at all period.of observation. Oil cakes stored in polythene lined gunny bags had the least population of fungi, whereas those stored in ordinary gunny bag had very high population of fungi. These results revealed that fungal deterioration and spoilage of oil cakes could be prevented or reduced to the minimum by treatment with 0.6 per cent calcium propionate- and by using polythene lined gunny bags for storage arid transport.
Open Access
Homeostatic analysis of components of genetic variance and inheritance of fruit colour, fruit shape and bitterness in bitter gourd (Momordica charantia L.)
(Department of Olericulture, College of Horticulture, Vellanikkara, 1989) Abdul Vahab, M; KAU; Gopalakrishnan, P K
Open Access
In vitro studies on the propagation of cardamom (Elettaria cardamomum maton)
(Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara, 1989) Reghunath, B R; KAU; Gopalakrishnan, P K
Open Access
Effect of phorate applied for the control of bunchy top vector of banana Pentalonia nigroneroosa Coq. on the plant and in the soil environment
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 1989) Sitarama Rao, D; KAU; Mohandas, N
A series of experiments were carried out for ascertaining the basic problems related to the current recommendations for managing bunchytop disease of banana through the application of phorate. The absorption, translocation and metabolism of phorate applied in the soil was influenced more by the condition and age of the plant than by the dose of the insecticide. Since the application of 2.50 g ai/plant did not result in corresponding increase in the residue content or the bioefficacy in the early phases of crop growth, when compared to the 1.25 dose, the latter can be used without significant loss in efficacy. A definite dose-effect relationship existed between the phorate content of plant and the mortality of P.nigronervosa confined at feeding sites. The median lethal doses of the insecticide content of the plant tissue were higher during declining phase of absorption as compared to those obtained during the active absorption phase. The result indicated the lesser toxicity of some components in the total residue during the later phase of the crop. Application of phorate granules in leaf axils was less effective than the treatment done in the soil and hence the current recommendation to use less quantity of insecticide when applied in the leaf axils has to be altered. A simple technique for the separation, identification and quantification of phorate and its metabolites was developed. Phorate and phorate sulfoxide contents of the total residue showed inverse relationship with each other while the other metabolites did not exhibit a clear relationship among them. Phorate and phorate sulfoxide exhibited more positive direct influences on the morality of the vector than the other metabilites. The absorption and toxicity of the insecticide content in plants did not vary significantly up to 174 DAP, when applied @ 2.50 g ai/plant at different intervals after planting. Absorption was very low when the insecticide was applied at 180 and 210 DAP. For ensuring residues within tolerance limits (0.10ppm) in raw fruits, the insecticide treatment has to be limited to 150 DAP and for ripe fruits the limit can be extended up to 180 DAP. The absorption and persistence of phorate and metabolites was significantly higher in plants grown in summer season than in those grown in rainy season. The absorption of insecticide was high in sandy soils and it was lowest in black cotton soils during the active absorption phase. The insecticide persisted at effective levels for 75 days in sandy, 90 days in lateritic upland and 105 days in black cotton soil. Sulfoxidation of the thioether moiety was the dominent metabolic pathway in sandy soil while desulfuration pathway was predominent in the other three soils. Application of phorate at planting, @ 2.50 g ai/plant, did not adversely affect the soil microflora as observed at the time of harvest of the crop.
Open Access
Phosphorus management in a rice based cropping system
(Department of Agronomy, College of Agriculture, Vellayani, 1989) Annamma, George; KAU; Sasidhar, V K
In order to standardize an appropriate phosphorus management practice in a rice based cropping system involving rice-rice-cowpea/sesamum, field experiments were carried out in the rice fields of the Instructional Farm, College of Agriculture, Vellayani from June 1984 to September 1986. The experiment was laid out in a randomized block design with three replications. There were eight treatments. The treatments comprised of (1) continuous phosphorus application to all the three crops in the system (2) phosphorus application to the first and second crops of rice (3) phosphorus application to the first crop of rice and third crop of cowpea/sesamum (4) phosphorus application to the first crop of rice only (5) phosphorus application to the second crop of rice and third crop of cowpea/sesamum (6) phosphorus application to the second crop of rice only (7) phosphorus application to the third crop of cowpea/sesamum only (8) control plot with no addition of phosphorus to any of the crops in the system. The salient findings of the experiment are as follows: Phosphorus application had no significant influence on grain and straw yield of first crop of rice. But available nitrogen, available and total phosphorus and available potassium of the soil were increased with phosphorus application. Direct, residual and cumulative effects of phosphorus had no significant influence on grain and straw yield of second crop of rice. Phosphorus uptake could not show any variation due to the different treatments. Available and total phosphorus content of the soil were highest under cumulative phosphorus treatment. All the growth and yield attributes of third crop of cowpea and sesamum were increased by the direct and cumulative effects of phosphorus. Grain yield of cowpea was significantly increased by the direct application of phosphorus. Eventhough not significant the highest sesamum yield was accorded by the direct and cumulative application of phosphorus. Phosphorus uptake in all the growth stages of the crop was highest in direct phosphorus plots. Available and total phosphorus content of the soil was highest in continuous phosphorus applied plots. There was no significant influence on grain and straw yield of first crop of rice after cowpea and sesamum in the direct, residual and cumulative effects of phosphorus. Residual phosphorus was sufficient to maintain the available nitrogen status of the soil. Available phosphorus of the soil was increased by the direct, cumulative and continuous application of phosphorus and total phosphorus by continuous application of phosphorus. Balance sheet of available phosphorus revealed that the soil phosphorus level almost maintained, where phosphorus was applied only to the third crop of cowpea or sesamum. The highest net return and benefit-cost ratio for the rice-rice-cowpea and rice-rice-sesamum system was obtained when phosphorus was applied only to the third crop in the rice fallow and the residual effect being utilized by the succeeding rice crops.
Open Access
Nitrogen losses from the rice soils of Kerala with special reference to ammonia volatilization
(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 1989) Anila Kumar, K; KAU; Rajaram, K P
In order to get a deeper insight in to the N dynamics of selected submerged rice soils, an investigation entitled “Nitrogen losses from the rice soils of Kerala with special reference to ammonia volatilization” was carried at the Regional Agricultural Research Station, Pattambi during 1985 – 87 with the following objectives. 1. To estimate the magnitude of ammonia volatilization losses from submerged rice soils, representing major rice growing tracts of Kerala. 2. To study the factors which are responsible for accelerating the rate of ammonia volatilization under flooded soil conditions. 3. To evaluate the effect of submergence, organic matter application, complementary effect of P and K on ammonia volatilization from the rice soil ecosystem. 4. To identity suitable N carriers capable of reducing the loss of N due to ammonia volatilization from submerged paddy soils. 5. To find out the effect of continuous application of organic and inorganic manures in lateritic submerged paddy soils on the quantum of N loss through ammonia volatilization. 6. To find out the transformations and extent of mineralization of applied urea. With these objectives, in view, a serious of laboratory incubation studies, followed by pot culture trials were carried out and the results were finally verified under field experiment also. Besides these, the plots of permanent manorial trial (dwarf indica) were utilized for estimating the N loss through ammonia volatilization on long term application of organic manures and inorganic fertilizers. In the incubation study for estimating the magnitude of N loss though ammonia volatilization, eight rice soils of kerala viz., sandy, karapadam, kayal, kari, pokkali, kole, poonthalpadam and laterite soils representing the major rice growing tracts of Kerala were incubated with no N and 27 g N m-2 as urea. Air train and acid trapping device was utilized to collect the volatilized ammonia. The results showed that sandy soil collected from Onattukara region registered an increased N loss through ammonia volatilization, whereas in the kole soil of kattukampal, the process was retarded to the lowest level. More than 75 per cent of the volatilization loss was observed within 9 days after urea application. Significant negative correlation was observed between ammonia volatilization and organic matter content, clay fraction and cation exchange capacity of the soil, whereas the coarse sand fraction showed significant positive correlation. Soil sterilization had little influence on ammonia volatilization in any of the soil under study. Another incubation study to assess the impact of quantity of urea applied on the quantum of N loss through ammonia volatilization was carried out using four soil types (sandy, kayal, poonthlpadam and laterite soils) with four rates of N application (9, 18, 27 and 36 g N m-2 ). The results indicated that the N loss through ammonia volatilization had a positive relationship with increased rates of urea application, though not linear. The complementary effect of phosphorus and potassium on the extended loss of N through ammonia volatilization was estimated in another incubation study utilizing the same four soil types with treatment as N alone, N and P, N and K and N, P, K @ 27:13.5:13.5 g N, P, K m-2 respectively as urea, superphosphate and muriate of potash. The results revealed that combind application of urea and muriate of potash was found to be significantly better in reducing the volatilization loss to be significantly better in reducing the volatilization loss of ammonia compared to the treatments, N alone and N and P. The incubation study to find out the influence of depth of submergence on the rate of volatilization of ammonia was conducted using the same soil types and four treatments (soil saturation, 5,10 and 20 cm submergence). The results showed that the soil samples maintained at saturation point recorded double the values for ammonia volatilization, compared to samples kept under submergence of 20 cm depth. The effect of application of organic matter on N loss through ammonia volatilization was studied in the same four soil types with the treatments as no organic matter, 0.25, 0.50, 0.75 kg organic matter m-2 as farm yard manure. The results indicated that application of organic matter was found to reduce volatilization losses considerably in all the soils studied and the lowest value recorded was for the treatment receiving farm yard manure @ 0.75 kg m-2. The relationship between N sources and the extent of volatilization of ammonia was investigated in another incubation study employing the same four soil types and ten different N carriers to supply 27 g N m-2. The relative efficiency of different N carriers in reducing the ammonia volatilization loss was in the order sulphur coated urea > urea mudball > gypsum coated urea > rock phosphate coated urea = neem cake coated urea = ammonium sulphate = ammonium chloride > urea : coconut pith: soil = urea. The pot culture study to trace the pathway of transformation and extent of mineralisation of urea under flooded soil condition consisted of three soil types (laterite, kari and poonthalpadam soil) and two levels of N (no N and 90 kg N ha-1 as urea). The rate of mineralisation of applied urea followed the soil reaction and the mineralisation stopped at the stage of NH+4 formation and hence chances of N loss through denitrification is meagre, unless the soil is aerobic. The second pot culture experiment was conducted with a view to identify the different ways that result in minimum loss of N through ammonia volatilization in sandy and laterite soils. The study showed that the decreasing order of N loss through ammonia volatalization from different N carriers followed the order, urea basal = urea; coconut pith: soil = coaltar coated urea = gypsum coated urea = rock phosphate > coated urea > urea split > urea super granule > urea mudball > sulphur coated urea. The five treatments selected from this experiments viz., urea split, urea mudball, urea super granule, gypsum coated urea and rock phosphate coated urea on reduced ammonia volatilization and high grain yield were compared in another pot culture trial and finally it was verified under field experiments in trial and finally it was verified under field experiments in laterite soil. The results revealed that urea mudball placement in the anaerobic layer of soil was found to reduce the n loss through ammonia volatilization to negligible level. Treatments with surface application of rock phosphate coated urea and urea in split dose ranked second and third position respectively in reducing the volatilization losses. Treatment receiving split application (top dressing of urea at 20 and 40 DAT) reduced ammonia volatilization considerably. Significant positive correlation was found between the cumulative N loss through ammonia volatilization and flood water pH measured at 0800 hrs and 1400 hrs, flood water NH4 – N content and flood water bicarbonate content. The pH of flood water measured at 1400 hrs were significantly higher than the value recorded at 0800 hrs and highest diurnal variation was observed for treatment with urea super granule deep placement. The urea super granule deep placement treatment resulted in increased grain yield in both the pot culture trials and field experiment. However, in field experiment the effect of different N carriers on grain yield was found to be uniform. The periodical N uptake by plants as well as N accumulation in grain and straw at harvest were found to be higher in the case of treatments receiving USG deep placement and urea split application. The effect of long term application of organic and inorganic nitrogen sources in soil on the rate of n lose through ammonia volatilization was studied utilizing the permanent manorial experiments. Plots receiving combined application of cattle manure + green leaves + NPK @ 45:45:45 kg N, P2 o5, K2 o as ammonium sulphate, super phosphate and muriate of potash were recorded the lowest value of n loss via ammonia volatilization when compared to other treatment plots.
Open Access
Structural and functional linkages in the transfer of technology of improved rice varieties released by the Kerala agricultural university-a system analysis
(Department Of Agricultural Extension, College Of Agriculture, Vellayani, 1989) Abdul rahiman Kunju, O; KAU; Tampi, A M
The study aimed at analyzing the extent of existing structural and functional linkages between and among the Research Sub- system (RSS), the Extension Sub-system (ESS), the Client Sub- system (CSS) and the Input Sub- system (ISS) in the transfer of technology (TOT) of improved rice varieties released by the Kerala Agricultural University (KAU). The study was conducted in the Alleppey, Ernakulam, Trichur and Palghat districts of Kerala. Respondents of the study consisted of 52 researchers, 134 extension personnel, 110 farmers and 32 representatives from the input agencies. To delineate the structural linkages between and among the four sub- systems involved in the TOT process, detailed analysis of the existing formal mechanics of linkage were analysed. Linkage activities that could be performed by each sub- system were identified and relevancy rated for measuring the extent of performance and perception of importance of these linkage activities by the respondents. A linkage index was developed to measure the perception of importance of linkage activities by the respondents. Data from the RSS, ESS, and ISS were collected using separate pre-tested structured questionnaires. Data from the CSS were collected using a pre- tested structured interview schedule. In structural linkage, it was found that there were appreciable linkage forums for the RSS and the ESS. But there was lack of organized linkage forums for the CSS and the ISS. Representation for the ESS in the linkage forums of the RSS was found to be restricted to higher officials. There was no representation for the ISS in the important linkage forums of the RSS. The regularity and periodicity of convening of the package of practices workshops, Extension Advisory Committee (EAC) and State Level Technical Committee (SLTC) were also found not being strictly adhered to. In functional linkages, the extent of linkage of the ESS with CSS and the ESS with the ISS were significantly better and reciprocal. Though the RSS viewed its linkage with the ESS and the CSS as good, the ESS and the CSS did not subscribe to this view. Similarly, the ISS viewed that its linkage with the RSS and the CSS was good but the RSS and the CSS did not corroborate this. Based on these results the hypotheses set for the study were either rejected or accepted. In order to segregate the factors associated with the functional linkages between and among the four sub- systems in the TOT of improved rice varieties, principal- factor analysis was done and the factors were extracted and labeled appropriately. The perception about the importance of linkage activities of the ESS with the CSS and the ISS was significantly better and reciprocal. But the perception about the importance of linkage activities of the RSS with the ISS, the ESS with the RSS and the CSS with the RSS and the ISS were significantly poor and hence the hypotheses set for the study were rejected. Lack of infra- structural facilities for research followed by insufficient staff strength and lack of facilities to multiply seeds were the most- important constraints in evolving and spreading the improved rice varieties as perceived by the RSS. Susceptibility to pests and diseases followed by the need for heavy dose of fertilizers and pesticides and poor cooking quality were the most important constraints in spreading and adopting the improved rice varieties as perceived by the ESS, the CSS and the ISS. Based on the results of the study, certain important implications have been spelt out.
Open Access
Nutrient dynamics in the rice based cropping systems
(Division of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 1989) Sundaresan Nair, C; KAU; Subramonia Aiyer, R
The experiment consisting of five cropping sequences viz. rice - rice – rice (A1), sweet potato – rice – rice (A2) cowpea – rice – rice (A3) daincha – rice – rice (A4) and fallow – rice – rice (A5) and six treatments with varying doses of N P and K were conducted to study the performance of the sequences in relation to the nutrients required for optimising the out put from the sequences. The field experiment was laid out at R.R.S., Pattambi in 1980 – 81 and the experiment was conducted for two consecutive years ie. For six seasons. The experiment was started with the summer crop of 1981, namely summer rice (Triveni), sweet potato, cowpea, daincha and a summer fallow wherein the land was ploughed twice and left as such without any crops. The component crops were raised with five treatment variations modified from the recommended doses for each crop. The biometric observations for the summer crops, virippu and mundakan crops were recorded. The indications were that treatments have a significant effect on summer crops virippu and mundakan rice crops of 1981 and 1982. The yield shows that both treatments and sequences have a significant effect. The sequence daincha – rice – rice and the cowpea – rice – rice sequence gave the highest yield. The chemical analyses of plant parts of the summer crops, virippu and mundakan rice crops of both 1981 and 1982 show that the treatments have no effect on the NPK content. The soil study shows that the cropping sequences have a significant effect on soil pH. A pH decrease was noticed in all the sequences, the highest decrease being in the rice – rice – rice sequence. The organic carbon level of the soil is also affected due to the cropping sequence. The rice – rice – rice sequence shows a maximum decrease in organic carbon level and the daincha – rice – rice – rice shows a gain in organic carbon level of the soil. The total nitrogen of the soil shows a decrease in all the sequences and maximum decrease was noticed in sweet potato – rice – rice sequence. The available nitrogen level also was influence both by the sequences and treatments. A decrease in available nitrogen was noted to be a maximum in the rice – rice – rice sequence. The total P and available P levels show an increase in all the sequences and were high in daincha – rice – rice and cowpea – rice – rice sequences. The treatments also have a significant effect in maintain the P level in soils. The total K status of the soil as well as the exchangeable status of K shows a decrease after two year of cropping. The nutrient uptake studies reveal that the maximum NPK uptake takes place in the sequences sweet potato – rice – rice followed by rice – rice – rice and cowpea- rice – rice – rice followed by rice – rice – rice and cowpea - rice – rice. The balance sheet of nutrients reveals that nitrogen and available phosphorus in all sequences show a decrease and increases with decrease in fertilizer levels. The balance sheet of K shows that the soil maintains K levels. The sequence daincha – rice – rice is the best in maintaining a high K status in the soil. An analysis of the economics of cropping sequences reveal that the sequence sweet potato – rice – rice with full recommended dose of fertilizers gave the highest net return, which was followed by Cowpea in – rice – rice and rice – rice – rice. From nutrient balance studies, yield and economic analysis it is clear that any attempt in reducing the quantity of fertilizer for the component crops of the sequences affects the yield, besides deleteriously affecting the fertility of the soils. Any decrease in the fertilizer doses in the sequences will not be economical. With a long range view of enhancing crop output from cropping sequences and maintaining soil fertility, it becomes necessary to enhance and maintain higher fertility levels.
Open Access
Potassium supplying capacity of Neyattinkara- Vellayani soil association and its relationship with potash nutrition of major crops on them
(Department of soil science and agricultural chemistry, College of Agriculture, Vellayani, 1989) Valsaji, K; KAU; Subramonia Aiyer, R
Detailed study on the potassium supplying capacity of Neyattinkara-Vellayani soil association and its relationship to potash nutrition of major crops on them namely coconut and cassava has been made. This soil association represents the red loam soil type and consists of Neyattinkara series tentatively classified under Typic Eutropepts and Vellayani series under Typic Tropudalfs. Soil samples were collected from selected fields under coconut and cassava for the dominant soil types namely sandy clay loam and sandy loam soils under Neyattinkara and Vellayani series. To find the most suitable depth and location of soil sampling for coconut samples were also drawn at two different depths of 0-30 and 30-60 cm from basins and interrows. Empirical methods, quantity intensity studies, electro ultrafiltration studies and foliar diagnostic techniques were employed to decide on the most suitable method for plant available K. The various intensity, quantity and capacity factors which relate the readily available, difficultly available and storage or buffer capacity were assessed for a proper appraisal of the K status and supplying capacity. The various soil K parameters such as total K, water soluble K, exchangeable K, available K, nonexchangeable K, HNO3 extractable K, H2SO4 extractable K, sodium tetraphenylboron extractable K and percentage K saturation were found to be low. The water soluable K formed higher proportion of available K than exchangeable K. Interrelations showed that water soluble K, exchangeable K and available K are in dynamic equilibrium. Nonexchangeable K did not show any relationship with available K indicating that it is a poor source of available K. Quantity-intensity studies showed that the shape of the Q/I curve was similar in all types of soil since they belong to a group of related soils. The Q/I parameters like Are.K, Ko, Kx. KL and potential buffering capacity values were low. The KL values were higher than NH4OAc.K. The free energy values were found to be high indicating easy release rates of K. For both coconut and cassava, the leaf K did not show any consistent relationship with the soil K parameters. Among the Q/I parameters, KL had significant relation with leaf K of coconut. EUF 10 and EUF 35 showed significant relationship with leaf K of both coconut and cassava. Electro-ultrafiltration studies showed that the easily desorbed K was more than the strongly desorbed K indicating easy supply rate. The EUF 30-35 values were related to HNO3.K showing that this fraction included some initially nonexchangeable K. EUF 10 had significant relation with exchangeable K and EUF 35 had significant relation with exchangeable and available K. The buffer parameters BK (EUF 10/EUF 30) and EUF.Q (EUF 30-35/EUF 30) values were low indicating low buffer capacity. The EUF desorption pattern showed that the first peak was within 10-20 minutes and prominent than the second peak. This indicated low reserve K but easy supply rates. The EUF desorption curve of soils with high NH4OAc.K was above that of soils with low NH4OAc.K. This indicated that with increase in NH4OAc.K the easily desorbed K also increased. The yield of coconut and cassava were related to the various K parameters to evaluate the suitability of different methods for available K. In most of the cases NH4OAc method was found to be suitable for both coconut and cassava. Leaf analysis was also found to be suitable. For cassava the result obtained after 41/2 months is meaningless for the current crop. For coconut collection of index leaf is laborious. It was also found that the Q/I and EUF were suitable for coconut. But these methods cannot be followed in routine soil testing because of the high input of laboratory work involved. Considering these aspects it was found that NH4OAc method is the most suitable one because it is simple, cheap and easy to adopt. Based on the NH4Ac.k content the fertility status was found to be low to medium. The various intensity, quantity and capacity factors of soil K, Q/I and EUF parameters revealed that this soil association has low K supplying capacity. Hence heavy dose of K fertilizers is required. Split application is preferable especially in sandy loam soils to reduce leaching losses. NH4OAc.K which was found as a suitable indicator of plant available K varied significantly in basin and inter-row samples of sandy clay loam soils. This K fraction did not vary with depth in both sites. In general, the K nutrient index indicated that the basin samples had a higher level than inter-row and surface samples. Thus basin sampling at 0-30 cm depth was found to be the ideal site of soil sampling for coconut tree.

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