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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 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 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.ThesisItem Open Access Fertility investigations on the soils of South Kerala in relation to their physiographic positions(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 1986) Wilfred Godwin, G; KAU; Alice AbrahamA study of the soils of South Kerala has been undertaken to investigate the variation in fertility status in relation to their physiographic position. Twelve locations from the districts of Trivandrum and Quilon were selected and from each location soil samples from upper, middle and lower reaches were collected from depths of 0 to 20 cm and 20 to 40 cm. The elevation of the location varied from 20 to 150 meters and the degree of slope from 6 to 27. The lower reaches of all the location were or less level paddy fields. The middle reaches were cultivated to banana, pepper, coconut and tapioca and the upper reaches in addition to the above crop perennials like coconut and rubber.ThesisItem Open Access Nitrogen balance studies in the rice soils of Kerala(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 1986) Meera, K; KAU; Ramasubramonian, P RNitrogen balance studies were carried out under pot culture conditions in CRD to assess the rate of efficiency of applied nitrogen in five diifferent soil types viz., karapadam, kole, sandy loam, low level laterite and black soils and two irrigation levels, viz., 5 and 10 cm with respect to short and medium duration varieties of rice viz., Triveni and Jaya. The effect of soil type, submergence levels and fertiliser nitrogen application on growth and yield of rice, nitrogen uptake and NPK content in soil, plant, grain and straw were studied and the recovery and loss of nitrogen were computed.ThesisItem Open Access Assessment of the factors governing response to phosphorus in the rice soils of Kerala(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 1986) Harikrishnan Nair, K; KAU; Subramonia Aiyer, RAn attempt to asses the various factors and arrive at an integrated picture on response of rice to phosphorus application In rice soils of Kerala has teen made. To reach certain conclutions on some of the possible reasons for response of rice to phosphorus in the acid rice soils of Kerala, the following approaches have been resorted to. Categorising the rice soils with special reference to phosphorus and factors affecting them. Detailed studies on the various phosphorus fractions, both inorganic and organic as well as toe relationships between the p fractions and important soil parameters have been worked out. Elaborate studies have been undertaken on the p fixing capacity of rice soils and the factors governing it. Phosphorus transforation studies, both inorganic p fractions and available f due to waterlogging have also been conducted. Two rice varieties, a medium end a short duration have been tested under pot culture conditions -lO with graded levels of B and finally two p labelled sources of phosphorus, a water soluble monocalcium phosphate and water insoluble tricalcium phosphate have been evaluate in 7 soil types representing the major rice soil types of KeralaThesisItem 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; KAU; Alice AbrahamLaboratory Incubation atudiea were conducted to quantify the changes in pH, EC, lime requirement and availability of important nutrients such as N, P, K, Ca & Mg due to submergence of alluvial, acid saline acid sulphate and saline rice soils of Kerala The study has revealed that pH of all the soil types increased immediately after flooding of the. air dried soils, reached a maximum and remained more or less steady throughout the period of three months submergence. Consequent to the increase in pH, a corresponding decrease in lime requirement was observed In all the soils. Maximum reduction in lime requirement was noticed for the saline and acid saline soils. A rise in EC was observed in all the soil typos due to submergence during the first four to six weeks. It showed a decreasing tendency afterwards All the soils showed a progressive increase in available nitrogen content with increase in the period of flooding. The increase was in the range of 75 - 393% for the various soil types. Maximum increase was,recorded by saline soils (395%) and minimum by alluvial soils (75%). The levels of available phosphorus recorded for the four soil types in the air dried state were in the low to medium range for rice. Submerging of these soils has resulted in a manifold increase in the content of available phosphorus. The increase was maximum for acid saline soils (700%) and minimum (55%) for alluvial soils. The availability of exchangeable cations like potassium calcium and magnesium, however, showed a periodical increase and decrease on flooding in all the four soil types. The results of the study have clearly brought out the magnitude of the changes that result in the status of each nutrient upon flooding of soils for wetland paddy cultivation. The manifold increase in the statue of major nutrients like ft and P upon flooding of soils indicates that addition of fertilizer ft and P under such conditions is not likely to produce any significant effect on rice unless the rice varieties are highly responsive to these nutrients. The feasibility of reducing the quantity of fertilizers to be applied or even skipping of fertilizers for one or two seasons may be considered taking into account the responsiveness of the rice variety as well as other economic factors.ThesisItem Open Access Use of cheaper and efficient sources of Phosphatic Fertilizer for cowpea In rice fallows(Division of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 1986) Omana, M; KAU; Ramasubramonian, P RAn experiment was conducted in a farmer's field at Kalliyoor in Trivandrum District with a view to study the effect of different cheaper sources of phosphorus application on growth, yield and composition of cowpea. The residual effect of these sources of phosphorus was also studied by raising a paddy crop during the subsequent season. The trial was laid out in a randamised block design with five treatments and four replications. The treatments included Mussoorie phosphate, Udaipur phosphate, rock phosphate (Madhya Pradesh) and single superphosphate. The subsequent trial was laid out in split plot non-factorial structural design with five mainplots, two subplots and four replications. The study revealed that phosphorus application significantly influenced the growth characters of cowpea viz. plant height, number of leaves per plant and number of branches per plant. Yield contributing factors viz. number of pods per plant and grain yield per plant were also significantly increased by different sources of phosphorus. Application of superphosphate resulted in heighest value for all these yield characters of cowpea. Maximum grain yield of 658 kg/ha could be obtained from the superphosphate treatment and this was followed by Mussoorie phosphate. Studies on the effect of residual phosphorus on the subsequent paddy crop indicated that height of plant and the tiller number per plant at maximum tillering stage and grain ripening stage were significantly influenced by rock phosphate application. The yield contributing factors such as number of filled grains per panicle, thousand grain weight and grain yield of paddy were also significantly influenced by the residual effect of rock phosphates applied to cowpea plus superphosphate applied to paddy than that of superphosphate alone applied to both cowpea and paddy.
