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Open Access
Land evaluation and suitability rating of the major soils of Onattukara region
(Department of soil science and agricultural chemistry, College of Agriculture, Vellayani, 1998) Premachandran, P N; KAU; Subramonia Iyer, M
The need for a scientific approach in inventorying and utilizing land resources most economically and efficiently is now universally accepted. Agricultural prosperity, to a great extent, depends on judicious use of soils and rational application of soils data. A reconnaissance soil survey of Onattukara region was undertaken to study the extent and distribution of the different soils for soil classification, land capability and irrigability classification and for subsequent land evaluation. The study reveals that Onattukara region extends over an area of 40,948 ha. The soil map showing the distribution of the identified twenty soil series has been prepared. The climatological data reveals that the soil moisture regime is , ustic and the soil temperature regime is isohyperthermic. The soils have been classified as per Soil Taxonomy (U.S. Soil Survey Staff, 1975) and Keys to Soil Taxonomy( U.S. Soil Survey Staff, 1994 and 1996). Ten series were classified under Entisols, SIX under Inceptisols, three under Ultisols and one under Alfisols. Based on the inherent soil characteristics and landscape features, the soils have been grouped into three land capability classes, nine capability subclasses and land capability map prepared. The soils were classified into five land irrigability classes, eight land irrigability subclasses and land irrigability map prepared. The soils were evaluated based on principles of land evaluation and rating of productivity parameters. The productivity rating of the soil propertIes agamst the productivity index for nee, coconut, sesamum ,cassava and banana were made and conclusions arrived at. Productivity rating shows that Kottakakam series is best suited for rice, Palamel, best for coconut and banana, Artuva and Mahadevikad, for sesamum and Palamel and Vallikunnam, for cassava. On the basis of the studies carried out, a land use is proposed for the twenty soil series of Onattukara region based on crop suitability ratings and crop suitability map prepared for the five crops taken for study. A proper soil survey interpretation provides information on soil potential, productivity and limitations in their sustained use. Soil survey information forms the major basis for land evaluation. A thorough knowledge of the potentialities and limitations of every piece of land is a prerequisite in its efficient utilization. A systematic survey is essential for the evaluation and classification of the soils based on their inherent soil characteristics, land capability, land irrigability and land suitability. A systematic survey and evaluation of the soils of Onattukara region was taken up to study, interpret, classify and to show their location and extent on base maps. It is hoped that the present study would open up avenues for further investigations on land evaluation, crop suitability and other management aspects for sustained use of soil resource data to the best advantage. This will also form the basis for microlevel planning for integrated and sustainable development of the region under Panchayat raj.
Open Access
Vermicompost as a potential organic source and partial substitute for inorganic fertilizers in sweet potato (Ipomoea batatas (L.) Lam.)
(Department of Soil Science and Agricultural Chemistry,College of Agriculture, Vellayani, 1998) Suresh Kumar, S N; KAU; Ushakumari, K
An investigation entitled "Verrnicompost as a potential organic source and partial substitute for inorganic fertilizers in sweet potato (Ipomoea batatus (L) Lam)" was carried out at the Instructional Farm, College of Agriculture, Vellayani during the period December 1995 to April 1996. The main objectives of the study were to study the efficiency of vermicompost as an organic manure, the extent to which inorganic fertilizers can be substituted when vermicompost was used as an organic source and the feasibility of reducing the dose of vermicompost. The experiment was laid out III randomised block design with seven treatments and four replications. The treatments consists of package of practices recommendations of Kerala Agricultural University for sweet potato (cattle manure + inorganic fertilizers) and vermicompost as organic source with graded doses of inorganic fertilizers. The growth parameters like vine length and number of branches did not show any significant variation. However highest vine length and number of branches are noticed in treatment which received vermicompost as a sole source of nutrient. Significant difference was observed in vine yield and highest vine yield was obtained when vermicompost was given as a sole source of nutrients. Yield attributing characters like length and girth of tubers and number of tubers did not show any significant variation. With respect to mean tuber weight and tuber bulking rate, the treatment differed significantly and maximum effect was observed when vermicompost was applied along with half the recommended dose of inorganic fertilizers. Significant treatment effect could be observed in total tuber yield and marketable tuber yield. Vermicornpost with half or 3/4th NPK produced highest yield. From this it could be deduced that by using vermicompost as organic manure in sweet potato, it is possible to bring down the usage of chemical fertilizers. Half or 3/4th dose of vermicompost along with recommended dose of inorganic fertilizers was equally effective as that of package of practices recommendations of Kerala Agricultural University (cattle manure + recommended inorganic fertilizers) in yield and yield attributes of sweet potato. The nitrogen and phosphorus content in the leaves and vmes did not show any significant difference by applying various treatments. But in tubers the nitrogen content was maximum when 1/2 inorganic fertilizers + organic manure as vermicompost was applied. The phosphorus accumulation in tuber was maximum in the combination of full inorganic fertilizers + organic manure as cattle manure was given. The treatment combination of full inorganic fertilizers + organic manure as vermicompost resulted m maximum accumulation of phosphorus in leaves, vines and tubers. Regarding calcium, magnesium and iron contents of leaves, vines and tubers there was no significant difference among various treatments. The application of full inorganic fertilizers + organic manure as vermicompost produced maximum manganese concentration in leaf and tuber. The starch content of tubers showed a decreasing trend with the reduction in the quantity of inorganic fertilizers. But by reducing inorganic fertilizer levels, the reducing sugar percentage increased. The crude protein, crude fibre and carotene contents showed the same trend as that of reducing sugar. The plant uptake of nitrogen, phosphorus and potassium was maximum when 112 inorganic fertilizers + organic manure as vermicompost was applied. The organic carbon level after the crop showed significant difference among various treatments. The maximum organic carbon percentage was noticed when nitrogen as vermicompost + organic manure as vermicompost was given. The growth characters like vine yield, number of branches were negatively correlated with yield. The yield components like number of tubers per plant, tuber weight, uptake of nitrogen, phosphorus and potassium showed positive correlations with yield. The economics worked out show that the highest net profit was obtained when 1/2 inorganic fertilizers + organic manure as vermicompost was given. The cost of cultivation while applying this treatment was minimum and it showed a B C ratio of 2.53.
Open Access
Effect of vermicompost enriched with rock phosphate on cowpea
(Department of Soil Science and Agricultural Chemistry,College of Agriculture, Vellayani, 1999) Sailajakumari, S; KAU; Ushakumari, K
An investigation was carried out at the College of Agriculture, Vellayani during 1998 to evaluate the effect of vermicompost enriched with RP on P availability yield and quality of cowpea and the feasibility of reducing the inorganic P. The variety used was Kanakamoni. All the growth characters, yield and yield attributes studied were significantly influenced by different treatments. Nodule number per plant, weight of nodules per plant and root shoot ratio were maximum by the application of enriched vermicompost. Yield attributes like number of pods per plant, number of seeds per pod and hundred seed weight and total grain yield were significantly increased by the application of enriched vermicompost. Vermicompost primed with full RP or with half RP produced no significant difference in grain yield. Thus the results revealed that inorganic phosphoate for cowpea coufd be reduced to half• of its recommended dose by priming vermicompost with RP. Analysis of plant samples at harvest showed that maximum content of macronutrients except Mg was recorded by enriched vermicompost. It showed its superiority over other treatments for protein and P content of grain. Enriched vermicompost also registered significant increase in soil available N, P and K after the experiment. ./ 2 Uptake of macronutrients was significantly influertced by different treatments. Enriched vermicompost registered maximum mean value for the uptake of all the macro nutrients. Priming of vermicompost with full RP or with half RP produced no significant difference in uptake of any macro or micronutrients. Grain yield was positively and significantly correlated with the growth characters. Yield and yield attributes showed positive and significant correlation with nutrient uptake. The study indicated the superiority of vermicompost enriched with RP on yield and quality of cowpea. P recommendation for cowpea can be reduced to half by priming vermicompost with RP.
Open Access
Characterisation of Soils Under Reed (Ochlandra Travancorica Benth.) In the Western Ghats
(Department Of Soil Science And Agricultural Chemistry,College Of Horticulture,Vellanikkara, 1999) Sujatha, M P; KAU; Jose, A I
A study was carried out at the Kerala Agricultural University and the Kerala Forest Research Institute during 1993-1996 mainly to characterise the reed growing soils of Western Ghats. The study comprises four parts, viz., pedological / taxonomical characterisation of reed growing soils, evaluation of fertility status of reed growing soils, assessment of growth performance of reed in relation to soil fertility and study on litter decomposition and nutrient release from reed leaf litter. The pedological / taxonomical characterisation was carried out by digging representative soil profile (with 3 replications) at two different types of topography (flat-undulating and sloping) in two different elevations (200-300 m and 600-800 m) at four locations viz. Vazhachal, Pooyamkutty, Adimali and Pamba. Reed growing soils were found to carry litter on soil surface which was. under varying stages of decomposition. The colour of the surface soils was mostly in the hue of 7.5 YR and subsurface layers were dominated by either 5 YR or 10 YR. Fine fibrous roots were found to mat the soil surface giving granular and crumb structure. The subsurface layers were generally massive without any distinct structural development. Reeds were found to flourish on both shallow and deep soils. In pure reed brakes where upper canopy was closed, the undergrowth was completely absent. The content of gravel, especially the secondary gravel, was very low in these soils. In most of the cases the textural make up turned from sandy loam to sandy clay loam from top to bottom of the profiles. Bulk density was found to increase with increase in depth of the profiles while porosity and water holding capacity to showed a diminishing trend. These soils were strongly to moderately acid in reaction and in pure reed areas surface soils were more acid than subsurface soils. But in areas where reed was growing as undergrowth in teak and moist deciduous forest, surface soils were less acidic than subsurface soils. In general, exchangeable bases, exchange acidity, cation exchange capacity and percentage base saturation were found to show a diminishing tendency from surface to bottom of the profiles. Distribution of organic carbon, total and available N, total and available P and available K was in a decreasing trend with increase in depth of the profiles while total K was found concentrated in lower layers. In general, the change in location, elevation and topography was not found to exert any definite impact on the depth wise distribution of soil properties in these soils. These soils were classified under Ustic Kandihumult, Ustic Palehumult, Ustic Haplohumult,' Ustic Kanhaplohumult, Typic Kanhaplustult, Ustic Hurnitropept, Ustoxic Hurnitropept, Ustic Dystropept, Ustoxic Dystropept, Oxic Ustropept and Lithic Dystropept at sub group level. The content of gravel, especially the secondary gravel was low in the 'Surface soils of reed growing soils. These soils were sandy loam in texture with low bulk density and moderately high water holding capacity and porosity. In general, these soils were strongly acidic in reaction with high content of organic carbon and available N and K. But the status of available P was very low. Contents of available Ca and Mg were in moderate quantities. Cation exchange capacity was also high, but the percentage base saturation was low. Significant variation with respect to various soil properties viz., gravel, silt, clay, bulk density, porosity, water holding capacity, pH, organic carbon, available N, K, Ca, Mg and percentage base saturation was observed due to change in location. Change in elevation was found to exert significant impact on bulk density, porosity, organic carbon and cation exchange capacity. In general variation in topography was not found to exert any significant and definite impact on various soil properties. Results in general reveal that reed bamboo play a significant role in conserving soil and its fertility. Number of matured culms / ha was found to be a better parameter injudging the growth performance of reed and Class I reed was found to have higher number of matured culms / ha than Class II and Class Ill. Soils of Class I reed was significantly acidic and contained higher organic carbon but lower available N and K than the class Ill. The model fitted through stepwise regression relating number of culms to different soil properties viz., soil pH, organic carbon, available N, P and K was Y = 501.0420 - 179.881920xI + 16.1516x12 + ! .9450XIX2 where Y= number of culms / ha, XI = soil pH and X2 = organic carbon. Dry weight of both culms and leaves per hectare and uptake of N, P and K were significantly high in Class I than the other two classes. The models fitted through stepwise regression relating dry weight of culms and leaves with the uptake ofN, P and K were YI=-1294.29 + 37.265N + 321.410 P + 226.442K, Y2=2.1 + 38.403 + 187.2 K where YI is the dry weight ofculms / ha and Y2 is the dry weight of leaves / ha. Reed growing soils were found to conserve comparatively higher content of soil moisture. Mass loss during decomposition of reed leaf litter was highly influenced by rainfall and the annual decomposition rate constant did not vary significantly (0.229 and 0.234) at two sites studied. The time required for 50 per cent and 95 per cent decomposition was 3 and 13 months respectively. Based on the concentration and absolute content, the nutrient mobility from decomposing reed leaf litter was in the order K > N > Mg > Ca > P.
Open Access
Assessment of some phosphatic sources for possible accumulation of heavy metals in chilli (Capsicum annuum L.)
(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 1998) Jidesh, C V; KAU; Sam, T Kurumthottical
Rock phosphate sources collected from different locations were analysed for both phosphorus content and heavy metals namely cadmium and lead. Those sources which analysed relatively higher content of heavy metals were included for conducting a pot culture experiment using chilli (Capsicum annuum L.) as test crop. To derive meaningful comparison in the study, partially acidulated rock phosphates as well as direct water soluble source of cadmium and lead were also applied to assess their bioavailability to plants. The influence of organic matter when applied alone or in conjunction with heavy doses of heavy metals was also assessed in the study. The pot culture experiment was conducted in the Vegetable Research Farm, Department of Olericulture, Vellanikkara during the kharif season of 1996, with chilli as the test crop. The entire fertilizer management was based on package of practice (N, P and K at 70, 40 and 25 kg ha-1) recommendation. Five different sources of P selected for the pot culture experiment were (1) Maton rock phosphate, (2) Mussorie rock phosphate, (3) Gafsa rock phosphate, (4) Rajasthan rock phosphate and (5) Single superphosphate. The maximum content of cadmium (55 mg kg-1) was recorded in Gafsa rock followed by 25 mg Cd kg-1 for the Maton rock and single superphosphate analysed the least concentration of cadmium (15 mg kg-1 Highest lead content of 230.5 mg Pb kg-1 was analysed in Maton rock while lowest (38 mg kg-1) in Musoorie rock. All the other sources maintained their heavy metal concentration in between these extremes. In general, the shoot portion of test crop chilli recorded highest cadmium uptake while root portion noted the maximum lead uptake. The least uptake of heavy metals was noted in the chilli fruit, which is the edible part of the plant. This indicates that the heavy metal load in the fruit portion is much less when compared to other plant parts, irrespective of the sources used. The same trend was evident when either partially acidulated P sources or direct source of heavy metals (through water soluble salts) were applied. However, the uptake of cadmium and lead from those sources remained higher in plant parts. Application of organic matter in conjunction with a heavy dose of heavy metals to soil resulted in a significantly higher uptake of cadmium and lead in all plant parts. Analysis of the available cadmium and lead in the post-harvest soil samples indicated negligible build-up of these metals in soils. However, direct application of higher levels of heavy metals permitted higher cadmium and lead extraction in the post-harvest soil samples. Application of partially acidulated rock sources to soils, though could cause enhanced uptake of heavy metals, could not show higher residual effects of heavy metals in post-harvest soil samples.
Open Access
Regulation of major plant nutrients and organic matter for improving the nutritive quality of banana grown in laterite soils
(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 1999) Binu Thomas; KAU; Hassan, M A
An investigation was taken to study the regulation of major plant nutrients and organic matter for improving the nutritive qualities of banana. The expriment was laid out at Banana Research Station, Kannara, Kerala Agricultural University during the period 1996-97. The result of this study revealed that application of fertilizer and organic matter is essential for getting better yield and quality of banana. All the food nutrients studied were increased by the application of fertilizer and hence the quality is much improved. Regarding bunch yield the fertilizer dose of 12.5 kg FYM, 200: 125:300 g N, P205 and K20 per plant obtained maximum yield. The treatments receiving medium level of FYM and nitrogen recorded higher content of carbohydrate. Protein content of banana was increased by the application nitrogen and potassium. Application of farmyard manure enhanced the fat content of banana. Sugar content of the banana fruit is increased by the application of nitrogenous and potassium fertilizers. Acidity is increased by the application of farmyard manure and nitrogen. Nitrate accumulation in banana was high in plots receiving highest dose of nitrogen. Nitrogenous fertilizers increased the carotene content of banana. Fertilizer application enhances the total mineral content of banana due to increased uptake and availability of nutrients. Fibre content was high in fertilized plots compared to absolute control. The nitrogen content of edible portions of banana was high in plots receiving higher doses of nitrogen. The treatment T6 and T\3 which received highest dose of phosphorus (200 g/plant) recorded highest content of phosphorus. Vitamin C content was enhanced by the application of nitrogenous fertilizer and farmyard manure. Correlation studies revealed that the content of l1ajor nutrients in soil at 2, 4 and 6 months after planting has got much influence on the quality parameters studied. Hence fertilizers should be applied in split doses commencing from 2 months after planting. Path coefficient analysis revealed that the direct effect of the three major nutrients on quality parameters was maximum at 6 months after planting. The direct effects at 2 months after planting and 4 months after planting were also significant. This indicated that the requirement of these nutrients is essential through out the growth of the plant.
Open Access
Comparative study of soils of cardamom plantations and virgin forests
(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 1998) Gladson, D` Cruz; KAU; Babukutty, K
The investigation entitled "comparative study of the soils of cardamom plantations and virgin forests" was taken up at the College of Agriculture, Vellayani, during 1994 - 96. The study has been made on the soils of cardamom plantations of the Idukki district of Kerala with a view to assess and compare physico-chemical and nutritional status of cardamom cultivated soils and virgin forests. A comparison was also made between healthy cardamom plantation with those where a decline in yield is observed. For this, surface soil samples and soil profiles excavated from various selected locations were subjected to detailed chemical analysis. The plant samples were also collected from the cardamom plantations and subjected to chemical analysis to find out whether any plant nutrient factors are involved in the yield decline in cardamom. A study of the soils of cardamom plantations in comparison with adjacent forests has shown that considerable variation in the physico-chemical properties of the forest soils did not take place due to the influence of the cardamom plantations. In all these soils, the sand and silt content decreased and clay content increased with depth. The soils of cardamom plantations have higher sand content and lower clay content compared to the soils of adjacent forests. A higher content of the clay in the forest soils compared to cardamom plantation indicates a greater degree of weathering and clay formation. Healthy cardamom plantation soils contained a significantly higher amount of coarse sand and lower content of fine sand than the soils of the location which show a decline in yield. 12D The physical properties such as bulk density, particle density and WHC and exchangeable properties such as CEC, ECEC, exchangeable acidity were found to be positively influenced by organic matter content of the soils and were . more or less similar in all the locations. Total P and K content of soils of the cardamom plantations were lowwhen compared to the adj acent forest indicates inefficient bio-cycling associated with the cardamom plantation and loss of bases from the system by leaching and soil erOSIOn. A lower P content of the soils of the cardamom plantation which show a decline in yield when compared to the healthy plantation is due to t,he inherent properties of the former. Inspite of the similarity in the content of total nitrogen, the available N of the adjacent forest soils was significantly higher indicating a rapid rate of mineralisation of organic matter in the soils of adjacent forest. The total P content of the soils of the healthy cardamom plantations was significantly higher than that of the location which show a decline in yield.~\.Jhe specific influence of --' the plantations m making more of available P from the unavailable pool is evident. The total and exchangeable potassium status m the soils of the cardamom plantation recorded a lower value than the soils of the adjacent forest. This situation may indicate a lower release as well as grater uptake of this element. The content of micronutrients such as Fe, Mn, Zn and Cu were more or less same in the soils of cardamom plantation and adjacent forest indicating the same parent material and similar climatic conditions prevailed in the locations under study. The analysis of plant leaves showed a higher content of P, K, Ca, Mg, Fe, Mn, Zn and Cu in the leaves of the healthy cardamom plantation. This point to a situation where the soil nutrient factors are not a single factor for declining the yield of cardamom but the plant nutrient factors were also responsible for the decline in yield. 1:Z t
Open Access
Status and impact of heavy metals in selected soils and crops of Kerala
(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 1999) Usha Mathew; KAU; Alice Abraham
Status of Cu, Zn, Ni, Pb and Cd in samples of selected soils, fertilizers, manures and crops were estimated. A critical analysis of the total content of these heavy metals in the soils studied here revealed that Cu arid Cd are existing beyond the critical level in the some of the samples. In the wetland soils, content of all heavy metals was lowest for phytotoxicity and food safety in samples from absolute control plots of rice PME at Pattambi, Moncompu and Kayamkulam and highest in samples from plots receiving maximum quantity of organic manures and inorganic fertilizers. The DTPA extractable form is only a very minor part of their total content. The heavy metal load of the commonly used P fertilizers in Kerala is found to be highly variable. Zn is the highest contaminant followed by Pb, Ni, Cd and Cu. With respect to manures commonly used in Kerala, Zn is the most abundant among the five elements studied followed by Cu. Retention of heavy metals was found to be more in the roots of all plants compared to the above ground portions except Zn in amaranthus. The grain, straw and root of rice plants collected from PME plots which were receiving organic manures and inorganic fertilizers continuously for several years had a distinctly higher content of all heavy metals compared to the samples obtained from absolute control plots. The content of Cu in rice samples and that of Zn and Cu in the fodder samples from sewage farm exceeded the critical level to express phytotoxicity. In some of the samples of amaranthus and cowpea, content of Zn, Pb and Cd exceeded the food safety standards prescribed in Germany. Studies on the pattern of retention of applied Cd and Ni in undisturbed soil columns of important soil types of Kerala showed that retention of Cd and Ni was more in the top than in the bottom layers. Higher retention and lower leaching loss of applied Cd and Ni was observed in the columns not treated with FYM. Pot culture studies have shown a significant reduction in yield of rice, sesame and cowpea at various levels of Cd and Ni with and without FYM. Nutrient content of seed, shoot and root showed variations but did not reveal any specific pattern in various crops. In cowpea, low levels of Cd and Ni in the absence of FYM stimulated nodulation and nitrogen content. Intake of Cd and Ni in various plant parts of rice, sesame and cowpea was in the order root> shoot> seed. It was more in the presence of FYM than in its absence. The toxic effects of Ni on growth and yield parameters were of lesser magnitude compared to Cd especially in rice and cowpea. Maximum accumulation of Cd in edible portions was recorded by sesame with no ill effect on germination. However a moqerate accumulation of Cd in rice seeds resulted in significant reduction in germination. An alarming observation obtained from the study was that almost all samples of rice grains exceeded the food safety standard of 1 mg Cd kg-1 indicating that rice, the staple food of the people of Kerala is contaminated with Cd, the most hazardous heavy metal for human health. This pioneer study on the heavy metal status of selected soils and crop plants of Kerala has brought out the need for conducting detailed studies on these aspects.
Open Access
Forms, availability and transformation of potassium in laterite soils as influenced by crop uptake
(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 1998) Nicy Thomas; KAU; Gopi, C S
An investigation was taken up to study the fate of applied and native potassium in a laterite soil as influenced by other major nutrients and organic matter and uptake by an annual crop, banana. The experiment was laid out at Banana Research Station, Kannara, Kerala Agricultural University during the period 1996- 1997. The result of the study revealed the necessity of fertilization of the field/soil for better yield. The maximum content and uptake of nutrients N, P and K occurred during the early and late vegetative stages of banana. Hence fertilizers should be applied for the crop from 2 months after planting onwards and continued up to six months after planting. Correlation studies revealed the significant relationship of total K in the soil with yield at different stages. Also poistive correlation between the exchangeable K content in the soil and yield was established. Path coefficient analysis revealed that the direct effect of total K content in the soil on yield was highest at P4 (6 MAP). The indirect effect was maximum at P4 (6 MAP) through P3 (4 MAP). The exchangeable K also was found to have positive direct effect on yield. The indirect effects were not significant. Water soluble K at different stages showed a direct effect of comparable magnitude on yield.

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