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ThesisItem Open Access Comparative micromorphologial and physico- chemical study of the upland and midupland laterite soils of Kerala(Department of soil science and agricultural chemistry, College of Agriculture, Vellayani, 1986) Sankarankutty Nair, R; KAU; Aiyer, R SThesisItem Open Access Exchangeable aluminium as an index of liming for the acidic upland soils of Kerala(Department of soil science and agricultural chemistry, College of Agriculture, Vellayani, 1987) Meena, K; KAU; Alice, AbrahamAluminium toxicity is the major factor limiting crop production in the acidic soils and the usual practice of alleviating aluminium toxicity is liming* / The present investigation was carried out to find out the distribution of water s dluhle and exchangeable aluminium in the acidic upland soils of Kerala and to test the suitability of exchangeable aluminium as an index for liming them* It was further programmed to find out the growth, yield and nutrient uptake pattern of two acid sensitive crops namely cowpea and fodder maize in soils under different levels of exchangeable aluminium brought out by the use of different levels of lime* Chemical analysis of eighty soil samples representing the five major upland soil types of Kerala viz* laterlte, alluvial, red loam, sandy and forest a oil have indicated the highest amount of exchangeable aluminium and percentage aluminium saturation in the laterite soils* The soil with 3 high level of exchangeable aluminium and percentage aluminium saturation was selected for conducting a pot culture experiment to test the suitability of using exchangeable aluminium as an index of liming* The exchangeable aluminium content of this soil was maintained at different levels by applying different levels of lime and the performance of these crops in this soil was compared by making biometric observations and by chemically analysing plant and soil samples* From the results of the study it was seen that higher levels of exchangeable aluminium adversely affected the growth, yield and nutrient uptake In cowpea and fodder maize* Maintenance of exchangeable aluminium at 1*26 me/100 g with a corresponding percentage aluminium saturation valua of around 30, by the use of 500 kg lime/ha appeared to be the optimum for maximising the yield of cowpea* But in fodder maize this level of lime was found to be insufficient and complete elimination of aluminium toxicity appeared to be essential for maximising production* Since the critical levels of exchangeable aiuainiua appears to be different for different crop3, it is desirable that lias levels to reduce exchangeable aluminium to such a critical level alono be applied. The results of the present study thus point to the advantage in adopting the exchangeable aluminium level of soil as a better index of liming for various crops grown in the upland acidic soils of Kerala.ThesisItem Open Access Effect of submergence on the soil testing parameters of paddy soils(Department of soil Science and Agricultural Chemistry, College of Agriculture, Vellayani., 1986) Usha, Mathew; Alice, AbrahamThesisItem Open Access Factors governing response of rice to liming in Kerala soils(Department of soil science and Agricultural chemistry, College of Agriculture Vallayani , Trivandrum, 1986) Mary Kutty, K C; KAU; Subramania Aiyer, RA study has been conducted on the factors governing response of rice to liming in Kerala soils with a view to evolve suitable coliorative measures. A five pronged approach to the studies made are highlighted to enable a clear understanding of achievements as against the objectives and approaches made. A laboratory study with one hundred soil samples to assess the nature of acidity of four major rlce growing tracts of Kerala State viz.,Kuttanad, pokali, kole and latoritic alluvium has been carried out. The kuttanad soil lncludes karl, karapadon and kayal lands. Path coefficient anaysis of important fifteen acidity contributing factors against seven parameters for measurement of soil acidity and the inter-relation ships of 22 soil characters show that aluminium saturation of effective CEC is the best parameter for measurement of soil acidity. karapadon and hoyol land3. Path coefficient analysis of Important flftaon acidity contributing factors against seven parameters for racasurcsnont of soil acidity and tho intor-rclationahlpo of 22 soil characters show that aluminium saturation of effective CEG Is tho boot parameter for measurement of soil acidity. '*’*** fifteen factors ldontlflod as proton sources .ooount tor 95.9 por oont of th. mo.ourom.nt. vaulting th. 00. hundnd «il “ "P1” « • 9rOUp*S * pPln0lp*1 . —a erne seven clusters ire formed. This goipaMnt H ^ appliaatlan of prinoip.1 l» a probably th. ur district could however bo grouped together In a cluster with a range of aluminium saturation of effective CBC 70# 1 to 75,0 per cent. The fourth and fifth clusters °f soils studied except the kari soil and having tioir aluminium saturation of effective CCC in tho range of 40.1 to 70.0 por cent. Tho kayal soils of Kuttanad, poWcali and lstsritlc alluvium find a placo in tho sixth cluster with an aluminium saturation of effective CCC in tho range of 30.1 to 40.0 ~jCr cent. The seventh cluster nalnly of lateritic alluvium and a few loss acidic pokkali soils has aluminium saturation of effective CtC below 30.0 per cent. A pot cult ire experiment has been conductod in a highly acid soil hnri s o il o f Kuttanad having tho pH values 3.5 with 39 rico variotioo In or.lor to ocroon out a variety tolorant to acidity. Tho varlotlon hovo boon acroonod £or toloranco to acidltyunlng th. method of D2-0tatloticn. nolocting tho impor- , „h,.a throo cluotoro ora formed. Thoy hova tant character, ano . . flB toiorwit. tedium tolorant boon oharactori«od a and l.aat tolaa th. tolarant varlotl.. Jyothi variety acidity. ****** ^ .jvoc.cy of a p M of ia ranWd t *• • r method, of managmant ..... oowblnlng v.ri.ty 1 including lining and v»»vn>«ing for obtaining better productivity m hl3hly ^ soils of k« . u . liming la a hydro-an\eliorativo process, a pot culeKperlnon,. has been carried out to otudy the effect of 3 -eto^iaia coupled with washing with different levels of water and periods between washing in two highly acid soils. The fact that washing the ooil two or throe tinvas at an interval of 2 days maintaining 10 can water from tlio ooil surface after the application oa lino lu noro efficient often yielding better rerulta with a lower Lining done will certainly make the use of l-inin'1 materials in the management of acid soiis An economic promoaition. This further orroloins the preference for low rates L i •- *- of llmln already acca. tod try farm ra in Kuttanad in spite of oonorve 1 Lae"", of rosoon.sG to li.nin , in resGoj-cn st itions, where tho s o ils ire r.uc.i lesn acid than those confronted in cultivator’s f i e ld a. *, o t cult iroa»no?l.jant hao ixi'.n conducted to otudy tho ff o ' graded lovolo of lining (on dry and wot noli baoio) isingj tiio non'. tr- ,*l-rant vori ty in lour major ncld rlao noil ypon suc„h a-nn Lat-rltic alluvium, Uolo, i»kl;ali and tori soils (,.o f i r s t crop and tho subsequent thrco crons roo:>octivoly. Ml the ros >onso functions fittod hava l>oan in quadratic rxxlol .jcoopt those Involving lo t o r lt ic alluvium. in tolo soil. ti.o residual a££oct o£ limine, io much in , , in tho nocond succeeding avidence only m ^ crop.aCtor which a drastic decrease In ,y#i4enlldd has boon obtained. In th« case of __ r•siflual offoot, however, has been pronounce poWcali no . ^ crop8. In kari soil, th. maximum yl.ld In the second ^ ^ fcha ,uphoat rats of liming nor as could not be obta^ ^ for r.^du.1 effsct.. Th. r.al- • o o n s s ' j u e n o . , r a p i d l y b y t h . .M o n d o r o p dual »PP“ In the case of laterltic alluvium9 application of lime maximum ever* the yield decreases significantly and rapidly. Response functions for the first and second crops could not be worked out. This indicates that tho maximum yiold might have been attained at a lovol of liming bo low 1/4 La doso. However* for the third and fourth crops, at tho rate of liming tried, a quadratic residual response function could bo fitted. Tho results on residual effect of lime hnvo alco shown that higher rates of lirr.e application introduces problems of roacidification at a faster rate. Tho depressive effects of line at higher rate are again a pointer to the need to ac opt low lining rates ;?ut ’./ith frequent applicationsThesisItem Open Access Influence of applied nutrients and stage of harvest on the yield and physicochemical properties of essential oil of palmarosa (Cymbopogon martini Stapf var. motia)(Department of Soil Science and Agricultural Chemistry , College of Agriculture, Vellayani, Trivandrum, 1985) Chinnamma, N P; KAU; Aiyer, R SPalmarosa, an essential oil crop introduced in Kerala, from Maharashtra, nearly two decades ago, is spreading steadily la the pialas and midland regions of North Kerala. Several agro-techniques have yet to he standardised for the commercial cultivation of this crop in the State. The present studies were undertaken at the Aromatic pnfl Medicinal Plante Research Station, Odakkaly during 1980-'8 4 to obtain information on the nutrition of palmarosa, optimum harvest intervals to ensure maximum herbage and oil yields and the factors influencing the quality of oil. The treatments in the major field experiment (1980-'82) consisted of three levels of N, and KgO, each at 25, 50 And 75 kg/ha along with six intervals of harvest at 40, 45, 50, 55, 60 and 65 days. The total number of treatment combinations wore 162 in a 3^ x 6 confounded asymmetrical factorial design. Tho main experiment was continued for another two yoaro limiting tho observations, to the yield of herbage and oil. This was then followed by an observation trial with intervals of harvest longer than tho maximum of 65 doye tried in the main experiment. In the main experiment the herbage yield vns significantly increased by application of P2°5 ^2°* Nitrogen did not have any eignifioant offeot on herbage yield poaeibly due to tha medium level etatua of soil N in the ABSTRACT ^erimental plots. The oil yield was Bignifioantly enhanced by P205 application at 50 kg/ha. Different levels and K showed no significant influence on the yield of oil. Harvest intervals showed significant influence on herbage yield, oil yield and oil content and the maximum value was recorded by the 65 day interval. A path analysis of the herbage yield with related cnaracters has shown that the height of the plant is the most important yield attribute influencing directly the yield of herbage. Path analysis of oil yield showed that oil yield is mainly dependent upon herbage yield. The direct effects on oil yield by yield attributes are found to be in the decreasing order of number of tillers with inflorescence, height of the plants and length of inflorescenoe. Maximum indirect affect via herbage yield is expressed by the height of the plant and length of inflorescence. All these directly and indirectly contributing factors arc soon to be markedly influenced by tho applioation of phosphorus and intervals of harvoat* Herbage yield and oil yield for various harvest lntorvalo obtained In the flrot two years wore fit tod In a Cobb-Dcughlua reoponoo function and tha expooted values «leulat«d were found to be very olooe to tho actual observed values• In thethird and fourth year of the experiment, the ghest herbage and oil yields were recorded by 60 day interval followed by the interval of 65 days, A quadratic Sanction for the data pooled over for four years was fitted to see if the data show a diminishing return with an increase in harvest interval and it was found that the optimum herbage yield and oil yield were obtained when the harvest was done at 62 and 63 days interval respectively. The final observational trial also indicated that the herbage and oil yields were maximum for a harvest interval of 65 days beyond which it decreases. Increase in the levels of both N and P tended to increase the content of geraniol and to decrease the content of geranyl acetate which are the price determining quality attributes of the essential oil. But the maximum interval of harvest viz., 65 days tried in the main experiment was not sufficient for moot of the physico-chemical properties of oil ouoh os specific gravity, refractive index, geraniol content, geranyl acotato content etc. to reach the minimum limit prescribed by 131. The observational trial showed that the oil obtained at intervale of 95 days and above satisfied the 131 specification with respect to all the phyalco-ohemioal properties of the oil. However, at thle herveat Interval the yield Itself wae considerably depressed compared to the yield at 65 day Interval. Th, eoonomloe worked out for different Intervale of harveab baaed on the ourrant market prloe of the oil paeein« as above the I SI limits as fe. 240/- per kg (oil from harvest intervals at and above 95 days) and those below them at Fs.220/- per kg (oil from harvest intervals of 55, 65, 75 and 85 days) it has been found that a wider cost benefit ratio and net return per rupee investment are obtainable for harvest intervals ranging from 65 to 85 days. However, 65 day interval has the advantage of early returns from the investment. Application of 50 kg PgO^/ha in view of its significant effect on herbage yield, oil yield and oil quality increase the net profit per rupee invested for the harvest interval of 65 days. The average removal o f II, P, K, Ca and Mg from the s o i l by palmarosa per h ecta re per year lias a lso been worked o u t . The optimum f e r t i l i s e r le v e l fo r palmarosa i s 25 kg II, 50 kg P?05 and 25 kg K20 per h ectare over an a p p lic a tio n o f spent g ra ss at 5 tonnes per h ectare per y e a r . The optimum h arvest in to r v a l i s 65 days. TIiIb would give maximum horbago y io ld , o i l y io ld ond ea rly return from in v e stm e n ts.ThesisItem Open Access Potassium utilization in cassava (Manihot utilissina pohl) as influenced by neem cake - urea blend(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 1985) Manorama Thampatti, K C; KAU; Padmaja, PPotassium utilization in cassava (manihot utilissima pohl.) as influenced by neem cake – urea blend. An investigation was carried out at the College of Horticulture, Vellanikkara, during the year 1983-84, which include a soil column study to understand the dynamics of NH4+- N and K+ ions when applied as urea or urea-neem cake blend either alone or along with muriate of potash. The columns were filled with soil collected from the field surface upto 60 cm depth. Each 15 cm was taken as a separate layer maintaining the same bulk density as observed in the field. Fertilizer treatments comprising, no fertilizer, urea or urea-neem cake blend to supply 100 ppm N and muriate of potash to supply 100 ppm K either alone or in combination were applied to the surface 15 cm soil and mixed thoroughly. The study indicated that under natural conditions NH4+ - N was concentrated more in the lower layers of soil beyond the root zone of cassava whereas potassium was concentrated more in the surface layers of 0-30 cm depth. Application of muriate of potash either alone or in combination with urea-neem cake blend increased potassium in the surface layer within eight hours after fertilizer application. When untreated urea granules were applied along with potassic fertilizer, a major part NH4+ - N was found either concentrated in lower layers, or nitrified and lost. But when urea-neem cake blend was applied along with potassic fertilizer a major part of nitrogen was retained as NH4+ - N in the surface layers upto two weeks and later it moved downwards. There was a drastic reduction of NH4+ - N status in the surface layers upto 45 cm after one week in untreated urea, whereas urea-neem cake blend maintained much of NH4+ - N in the surface 30 cm upto three weeks. Application of muriate of potash maintained highest potassium status followed by urea-neem cake blend along with muriate of potash. The maximum leaching loss of potassium was observed from untreated urea when applied along with muriate of potash. The loss was reduced considerably when potassic fertilizer was applied along with urea-neem cake blend. A field experiment was conducted as a continuation of the study carried out at the College of Agriculture, Vellayani, when urea-neem cake blend at 5:3 ratio increased nitrogen availability, nitrogen uptake and yield. But it had an adverse effect on potassium utilization of the crop resulting in poor quality tubers and the yield increase observed was not significant. The present experiment was planned to tide over this difficulty either by changing the time of application or increasing the rate of potassic fertilizer. Results of the experiment clearly showed that urea-neem cake blend increased nitrogen use efficiency of cassava as evident in higher soil available nitrogen and higher nitrogen uptake by the crop. When muriate of potash was applied one month after application of urea-neem cake blend, the uptake of potassium was not reduced considerably in the initial stages and at the same time uptake was comparatively higher at the sixth month and harvest stages. Potassium at 75 kg K2O ha-1 increased uptake of all nutrients and also produced maximum tuber yield of 21.39 tonnes ha-1, whereas application of potassium one month after application of urea-neem cake blend recorded 19.76 tonnes ha-1 of tuber yield which was on par with the former treatment. Potassium uptake at all major growth stages were significantly correlated with plant dry weight and tuber yield. Maximum benefit per rupee invested was obtained when the rate of potassium was raised from 50 kg K2O ha-1 to 75 kg K2O ha-1 along with 50 kg N as urea-neem cake blend. Changing the time of application of potassic fertilizers to one month and three months after planting also increased the benefit obtained. Both three treatments were on par with each other and significantly superior to others.ThesisItem Open Access Characterization of Kerala soils into fertility classes with respect to available P and K extracted by a common extractant(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 1988) Kamalam, P V; KAU; Jose, A IA laboratory study was undertaken to evaluate the suitability of Mathew’s triacid extractant (0.06 N H2SO4 + 0.06 N HCI + 0.05 N oxalic acid) for the combined extraction of available P and available K in soil. The suitability of this triacid extractant was confirmed on a large number of soil samples. Precise relationships between triacid K and NH4OAc K were established. The ten fertility classes for available P and K currently followed in the soil testing laboratories are based on Bray-1 P and NH4OAc K. By making use of suitable regression equations the class intervals in terms of triacid P and triacid K values have to be formulated for the purpose of fertilizer recommendation. The use of this extractant can simplify the work in soil testing procedures thus enabling considerable savings of time and labour. A large number of soil samples was collected representing the entire state of Kerala. The available phosphorus of soil was extracted by Bray No.1 solution (1:10 soil solution ratio with an equilibration period of 5 min) and by Mathew’s triacid extractant (1:10 soil solution ratio with an equilibration period of 30 min). Phosphorus in the extract was then determined colorimetrically by the chlorostannous reduced molybdophosphoric blue colour method in HCI system. The available potassium of the soil was determined by neutral N NH4OAc with a soil solution ratio of 1:5 and an equilibration period of 5 min as well as by the triacid acid method. Potassium in the extract was determined flame photometrically. Soils were also analysed for organic carbon, pH and EC. Suitable correlation was worked out between Bray-1 P and triacid P. A linear regression equation was fitted to predict triacid P values from Bray-1 P values. Suitable relationship was also established between NH4OAc K and triacid K. The linear regression model worked out between NH4OAc K and triacid K was used to predict triacid K values from NH4OAc K. Most of the soils were acidic and non-saline. The pH showed a negative correlation with Ec and organic carbon content of soil. Soils varied in the content of organic carbon from 0.04 per cent to 4.41 per cent but in general was rich with a mean organic carbon content of 1.14 per cent. Electrical conductivity was positively correlated with organic carbon content of soil. A positive correlation was observed between organic carbon and available K. Mineralisation of organic matter contributed significantly to the increasing acidity of soil. The available P estimated by Bray-1 was found to range from 0.46 to 370.30 ppm whereas triacid P ranged from 1.73 to 462.50 ppm. The triacid extracted larger amounts of available P than the Bray-1. A significant correlation was observed between triacid P and Bray-1 P (r = 0.9575**). By fitting the regression equation y = 1.15x, where y represented triacid P and x represented Bray-1 P, the triacid P values of the ten fertility classes have been worked out. The available K as estimated by neutral N NH4OAc ranged from 10.0 to 425.0 ppm whereas triacid K ranged from 4.0 to 154.0 ppm. Triacid extracted lower amounts of available K (42.38 ppm) than the neutral N NH4OAc K (105.23 ppm). Although triacid showed less efficiency for releasing K from soil it was found to have high correlation with neutral N NH4OAc (r = 0.9235**). The linear regression equation of the form y = 0.44x was worked out where y represented triacid K and x represented NH4OAc K. This was employed to redefine the ten fertility classes in terms of triacid K values. The increase in precision obtained by the relationship between P estimated by Bray 1 and triacid as well as K estimated by neutral N NH4OAc and triacid by grouping the soils into separate textural classes was only marginal. The present study therefore confirmed the suitability of the triacid for estimation of both available P and K in the soil of Kerala. The revised class intervals for the ten fertility classes followed in the soil testing laboratories of Kerala have been formulated in terms of triacid P and triacid K values which will serve as a guide for giving fertilizer recommendations for various crops.ThesisItem Open Access Foliar diagnosis, yield and quality of pepper (Piper nigrum L.) in relation to nitrogen, phosphorus and potassium(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 1982) Sushama, P K; KAU; Jose, A IPepper vines of variety, Panniyoor-1, of the NPK fertilizer trial maintained at the Pepper Research Station, Panniyoor, Canncanore District were selected for the collection of tissue samples under the present study during 1979-81. The experiment was laid out in a 33 factorial design in a randomized block design, confounding the effect of NP2K2 totally. In order to standardize the best leaf position for foliar diagnosis, the mature leaves of fruit bearing laterals were numbered from the youngest to the oldest, taking the youngest fully matured leaf as the first and they were collected separately. The most suitable season for the collection of leaf intended for foliar diagnosis was also standardized by drawing samples of first mature leaf at different stages of growth of the vine. The suitability of different types of stem of the plant such a runner shoot, top shoot, fruit bearing lateral and hanging shoot for tissue analysis was also examined. For studying the variations in the oleoresin content of berry as influenced by fertilizer nutrients, the berries were sampled at different stages of maturity. The first mature leaf better reflected variation in the levels of application of nitrogen to the vine. As the phosphorus and potassium contents of the first mature leaf established significant positive correlation with yield of pepper, it is recommended as an index for foliar diagnosis in pepper in relation to nitrogen, phosphorus and potassium status of the vine. The period just prior to flushing is the most suitable season for the collection of leaf samples intended for foliar diagnosis. During this period, the first mature leaf is sensitive to application for different levels of nitrogen and its potassium content established significant positive correlation with yield. For assessing the phosphorus status of the vine, the runner shoot appeared to be a better tissue as its phosphorus content established a high degree of correlation with yield. As compared to other types of stem, the highest content of potassium was found in the fruit bearing laterals. The periods of maturity significantly influenced the phosphorus, potassium and oleoresin contents of the berry. Their contents increased from four to six months after flowering and then decreased. The graded doses of nitrogen, phosphorus and potassium and their interaction failed to influence the percentage of oleoresin content of pepper.ThesisItem Open Access Evaluation of available phosphorus and potassium in soil using a common extractant(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 1986) Durga Devi, K M; KAU; Jose, A IA laboratory evaluation and an uptake study using Neubauer seedling technique was carried out for evolving a single extractment suitable for extracting both available P and available K, so as to simplify the process of extracting these available plant nutrients in soil testing works. Eighty seven soil samples from different parts of the State were used to evaluate the performance of the selected number of extractants based on a 3 step evaluation i.e., (i) an initial study consisting one soil, 18 extractants at a single soil solution ratio (1:10) and two equilibration periods (30 and 60 min); (ii) a preliminary screening consisting of 9 soils, 15 extractants at a single soil solution ratio (1:10) and 5 equilibration periods (5, 10, 15, 30 and 60 min). An uptake study was also conducted using Neubauer seedling technique and correlation coefficients were worked out between the amount of P extracted by the various extractants and the P and K uptake by rice; (iii) a final selection of the common extractant consisting of 10 extractants with suitable equilibration periods, at 1:10 soil solution ratio and 87 soils. In combination of NH4 F and DTPA, increasing concentration of NH4 F retarded the extraction of both P and K and they extracted much smaller quantities of P and K as compared to that of Bray No.1 and neutral normal NH4 OAC. Use of ammonium acetate along with Bray No.1 inhibited the release of P drastically. Mathew’s triacid extractant viz., 0.06 N H2 SO4 + 0.06 N HCL + 0.05 N oxalic acid extracted relatively large amounts of P and K. The pattern of P and K release when examined together as a function of period of equilibration found that the equilibration period for different extractants was varying. The suitable equilibration period for 0.1 M NH4F + 0.001 M DTPA, 0.1 M NH4F + 0.003 M DTPA, 0.5 M NH4F + 0.005 M DTPA, 0.05 M NH4F + 0.05 M acetic acid, and Dray No. 1 is 5 min. for 0.3 M NH4F + 0.001 M DTPA combination and Bray No.1 + 0.005 M DTPA an equilibration period of 10 min is found to be the optimum. An equilibration period of 30 min is suitable for Mathew’s triaced extractant, Olsen’s extractant and neutral normal ammonium acetate. Since the initial and preliminary studies established the suitability of Bray No.1 for available P and the neutral normal ammonium acetate for available K and because the coefficient of correlation between the amount of K extracted by the extractants and the K uptake by rice were highly significant at all the equilibration periods the final selection of the common extractant was based on the correlation of the P and K values of the selected extractants with that of Bray No. 1 P and neutral normal ammonium acetate extractable K. The correlation coefficients with Bray No.1 P established by the various extractants have shown the following decreasing order of efficiency. 0.5 M NH4F + 0.005 M DTPA > 0.05 M NH4F + 0.05 M acetic acid > NH4OAC > Olsen > Mathew’s triacid > Bry No.1 + 0.005 M DTPA > 0.3 M NH4F + 0.001 M DTPA > 0.1 M NH4F + 0.001 M DTPA > 0.1 M nH4F + 0.003 M DTPA. All the extractants were not significantly and positively correlated with NH4 OAC (std) K. The three extractants viz., Mathew’s triacid, 0.1 M NH4F + 0.001 M DTPA and Olsen’s extractant have given significant positive relationship with NH4 OAC (std) K. Highest correlation was obtained with Mathew’s triacid followed by 0.1 M NH4F + 0.001 M DTPA and Olsen’s extractant. Thus it is confirmed that Mathew’s triacid extractant is the best common extractant for available P and available K. No analytical difficulty in the determination both P and K was observed while using this extractant. Inter-correlations worked out between the various soil properties have cleared the following facts. Mathew’s triacid P and Bray No.1 P were significantly and positively correlated with total P and negatively correlated with P fixing capacity. NH4 OAC (std) K and Mathew’s triacid K gave significant positive correlation with total K as well as CEC. Mathew’s triacid extractant viz., 0.06 N H2SO4 + 0.06 N HCL + 0.05 N oxalic acid with a soil solution ratio of 1:10 and an equilibration period of 30 min is recommended as a commom extractant for available P and available K by the present study, since it saves considerable time and materials in soil testing.
