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Open Access
Behaviour of phosphorus in selected soil types of Kerala
(Department of soil science and agricultural chemistry, College of horticulture,Vellanikara, 1993) Vijayan, A P; KAU; Sumam Susan, Varghese
In order to study the distribution of inorganic P-fractions finding suitable chemical extractant for phosphorus, to study Q/1 relationship as a method of estimating available P and for studying adsorption- desorption characteristics of the soil types of Kerala, 100 surface soil samples were collected. These soil types were selected from different parts of the state belonging to five soil types viz., laterite, coastal alluvium, brown hydromorphic, Kuttanad alluvium and black soil. It is observed that all the soil types except black soil were acidic, clay content was comparable in case of black soil, Kuttanad alluvium, brown hydromorphic and lateritic but it was very low in coastal alluvium. Maximum content of sesquioxide and total phosphorus recorded in laterite soils and minimum in coastal alluvium. Dominant inorganic fraction in laterite and black soil was Ca- P while in coastal alluvium, brown hydromorphic, and Kuttanad alluvium dominant fraction was Fe- P. Coastal alluvium recorded maximum content of saloid- P, Al- P and Fe- P content were maximum in Kuttanad alluvium. Maximum content of Ca- P was recorded in black soil. Studies in black soil showed that total P is correlated to free carbonates significantly and positively. The different extractants studied in different soils showed that extractants should be selected according to soil types. Mathew’s triacid proved as a better extractant for available P in laterite and coastal alluvium. In case of Kuttanad alluvium soil Bray No.1 is better. Mathew’s P correlated significantly to uptake in laterite, coastal alluvium and Kuttanad alluvium. Olsen’s P correlated to uptake in laterite and Kuttanad soils. Phosphate potential negatively correlated to uptake in Kuttanad alluvium, coastal alluvium and brown hydromorphic soil. Where as equilibrium phosphate potential negatively correlated to uptake in coastal alluvium alone. DPBC values are not found as a suitable method for the estimation of available P. The P desorption adsorption studies showed that adsorption studies was not correlated to P uptake. While the desorbed P correlated significantly and positively to P uptake in laterite soil alone.
Open Access
Quality and fatty acid composition of coconut oil in relation to varietal variation and mineral nutrition
(Department of soil science and agricultural chemistry, College of Agriculture, Vellayani, 1994) Geetha Kumari, V S; KAU; Ranjendran, P
Coconut is a perennial oil seed crop with a large number of cultivars having widely varying growth and yield characteristics. It is both an agricultural and industrial crop with immense economic importance. A variety of edible oils are available in the market today with wide variations in quality parameters and nutritional characteristics. Although product quality is influenced by many factors associated with production, harvesting, curing and processing; quality is influenced to a greater extent by the genetic parameters and chemical composition. Assessment of quality parameters and fixing standards for the nutritional aspects are to be considered with top priority for the development of new varieties/cultivars along with the yield attributes. Considering the afore mentioned facts in view, it was felt essential to study the effect of varietal variation and mineral nutrition on the oil content, quality and fatty acid composition of coconut oil. Nuts collected from different varieties/cultivars from RARS, Pilicode, Instructional farm, Vellayani and palms of an ongoing fertilizer trial of the CRS, Balaramapuram, were subjected to chemical analysis to study the above aspects. The results of the analysis were summarised and appropriate conclusions drawn. The effect of varietal variation on the oil content and quality parameters like acid value, saponification value and iodine value were found to be significant. Minor quality parameters like Reichert – Meissel and Polenske value also showed considerable differences among the varieties. The fatty acid composition of oil from selected varieties also had shown considerable variation. The effect of mineral nutrition on the oil quality and fatty acid composition of coconut oil were found to be insignificant. The oil content was not influenced by nitrogen and phosphorus while potassium had a significant but negative effect on oil content. The influence of N, P and K fertilizers on the quality parameters like acid value, saponification value and iodine value was not significant in general. Minor quality parameters like Reichert – Meissel and Polenske value showed variation due to fertilizer treatments. The fatty acid composition of oil from selected treatments. The fatty acid composition of oil from selected treatments were also influenced by mineral nutrition. From the results of the study it can be concluded that quality parameters of coconut are much influenced by varietal differences than by mineral nutrition. Thus it is evident from the study that the genetic variability has got a greater role to play in modifying quantity parameters and chemical composition of the most important tropical adible oil namely coconut oil. Selection and breeding should be directed towards tailoring new varieties with higher oil content, quality indices and fatty acid composition.
Open Access
Soil temperature and moisture characteristics as influenced by inter-cropping of fodder crops in coconut garden
(Department of soil science and agricultural chemistry, College of Agriculture, Vellayani, 1993) Asok, P I; KAU; Pushkala, S
An investigation was undertaken to study the effect of fodder grasses grown as inter crop in coconut garden on the soil characteristics. The observations were carried out from the already laid out experimental plot in the farm area of college of Agriculture. The layout was in randomised block design with six treatments and four replications. The treatments included guinea grass, congo, signal grass, setaria grass, molassess grass, hybrid napier and contrest. Soil samples were collected from two depths namely 15 cm and 30 cm from the surface. The samples were collected during March-April, July-August and December-January. The soil analysis was done for moisture, porosity, bulkdensity, particle density and water holding capacity. The infiltration rate and hydraulic conductivity were carried out at the close of the experiment. Chemical analysis was done for nitrogen, phosphorous, potassium, calcium and magnesium. The effect of growing fodder crops on soil moisture content was not significant. The thick canopy of guinea and congosignal grass could retain moisture in the field. The water holding capacity in the control plot was less than the fodder plot. So the competition for water would be minimum for coconut and fodder crops. The soil moisture was negatively correlated with soil temperature. Setaria and molasses grass could conserve moisture on the surface while other grasses could retain moisture on the subsurface layer. Fodder grass roots improved the structure of the soil. Bulk density values were reduced. The changes on particle density and porosity values were negligible. The hydraulic conductivity value observed for setaria grass was highest and the lowest value was recorded by guinea grass. Infiltration rate showed no significant difference among treatments. Soil temperature values were brought down by fodder grass cultivation during daytime, insulated the soil when it was cooled. There was no significant effect on the chemical properties of the soil namely, soil reaction , available nitrogen, available potassium, exchangeable calcium and exchangeable magnesium. Soil phosphorous level shown by the setaria grass was high, which was positively correlated with the soil temperature. Inter-cultivation with fodder grass in coconut garden, is not deteriorating the physical properties, but it can improve the hydraulic characteristics and thermal properties thereby leading to an increase in the coconut yield.
Open Access
Classification of the upland soils of Kerala
(Department of soil science and agricultural chemistry, College of Agriculture, Vellayani, 1993) Bindu Kumari, A; KAU; Subramonia iyer, M
Soil taxonomy is one of the well accepted popular system of soil classification through which soil information can be communicated globaly. Inorder to have the soil Taxonomy information of the uplands of Agricultural Rsearch Station and Centres under Kerala Agricultural University and CWRDM, Calicut one representative profiles were examined described analysed for physical chemical and mineralogical properties and with the available site and climatic parameters and from the results of the present study the soil were classified as per Soil taxonomy (1975). All the soils are gravelly, clay loam to clayey texture with kaolinitic to mixed mineralogy with expanding 2:1 minerals at Pampadumpara, Ambalavayal and Kannara. At Calicut the clay fraction is more than non clay fraction. Irrespective of the profiles, the profiles are with ustic moisture regime and isohyperthermic temperature regime. The temperature regime at Pampadumpara and Ambalavayal is hyperthermic. Based on the degree of weathering revealed by silt/clay ratio the profiles can be arranged with a decreasing degree of weathering Calicut > Kottarakara > Balaramapuram > Vellayani > Pampadumpara > Ambalavayal > Thiruvalla > Pillcode > Vellayani II > Tavanur > Odakkali > Vellanikkara > Kannara Based on the available information and results of the present study, keys the profile in to the following taxa as per soil Taxonomy (1975). 1. Balaramapuram Fine loamy kaolinitic isohyperthermic family of kandic Haplustalf. 2. Vellayani Fine loamy kaolinitic isohyperthermic family of Typic Kandiustults. 3. Thiruvalla Fine loamy mixed isohyperthermic 4. Odakkali family of Tropustults. 5. Kottarakara Clayey skeletal kaolinitic 6. Vellanikkara isohyperthermic family of Typic 7. Pilicode Kandiustults 8. Pampadumpara Fine loamy mixed isohyperthermic family Haplustalf. 9. Kannara Fine loamy mixed isohyperthermic 10. Ambalavayal family of Haplustalf. 11. Calicut Clayey skeletal kaolinitic isohyperthermic family of kandiudlts 12. Tavanur Fine clayey kaolinitic isohyperthermic family of petroferric Dystropepts. The family charactors reveal that thesee soils are with less availables water capacity, low cation exchange capacity. Soil temperature is not a problem in these soils. The typic subgroup indicates lesser problems of water logging. The argillic and kandic endopedon indicates low nutrient holding capacity and presence of low active clays (LAC) warranting special soil management measures for increase crop production like split application of fertilizers. Ustic moisture regime is indicative of prevalent water stress in these profiles sites. The order Ultisol , Alfisol and even inceptisol is indicative of highly weathered soil of varied horizon development and less fertility because of lower percentage bases saturation (PBS) The present study gives a “soil basis” for the global communication and appreciation of the valuable research results of these research institutions. The research results, the crop performance from all these research institution are to be gathered and critically analysed with the “soil basis” as a future line of work.
Open Access
Behaviour of potassium in selected soil series of Thiruvananthapuram district
(Department of soil science and agricultural chemistry, College of Agriculture, Vellayani, 1993) George, Joseph; KAU; Saifudeen, N
An experiment was conducted at the Department of Soil Science and agricultural Chemistry, College of Agriculture, Vellayani with 50 surface soil samples each from Trivandrum, Kazhakuttom and Kottor series to assess the behaviour of soil potassium. Water soluble, available, exchangeable, nitric acid soluble and non – exchangeable potassium in these soils were determined. Sample observations on total potassium from soils with low, medium and high available potassium were also undertaken. In addition, the physical and chemical properties of all the samples were studied through observations on soil separates, pH, electrical conductivity, organic carbon, cation exchange capacity, base saturation and exchangeable forms of calcium, magnesium and sodium. Neutral ammonium acetate (1.0 N) extractable potassium (available form) was found to be positively influenced by water soluble, exchangeable and nitric acid extractable forms of potassium. The organic carbon content positively influenced the available potassium where the soil organic carbon was low viz., Trivandrum and Kazhakuttom series. Cation exchange capacity also had a positive influence on available potassium. Percentage base saturation influenced available potassium positively, except in forest soils. In Trivandrum series 71 percent of nitric acid potassium was available to crops; while the corresponding values were 46 and 51 percent in Kazhakuttom and Kotoor series respectively. The total potassium content was also relatively high in Trivandrum series. The relationship between various forms of soil potassium and also between potassium fractions and other soil components expressed varying trends in soils falling under different fertility classes. This aspect needs further investigation. Quantification of the contribution of different fractions of soil potassium towards crop uptake is suggested as a future line of work. Basic studies on the ionic equilibria in soil solutions which affect potassium exchange and availability in these soils also warrants attention.
Open Access
Toxic hazards of the industrial atmospheric pollutant, SO2,on tree crops
(Department of soil science and agricultural chemistry, College of Agriculture, Vellayani, 1993) Rani, B; KAU; Babukutty, K
A study was conducted to assess the effects of the industrial atmospheric pollutant, sulphur dioxide, on tree crops. The Veli area in Thiruvananthapuram district, Kerala which has been established as a polluted zone, due to the working of the Travancore Titanium products, was selected as the experimental site. Since coconut dominates the tree crops in the area, and due to its added importance as an oilseed, the study was conducted on coconut palms near the factory. Influence of sulphur dioxide pollution on plant parameters like sulphur content of foliage, pigment concentration, macro and micro nutrients, plant metabolites like glucose and ascorbic acid, catalase activity and the copra and oil contents of nuts were studied. Leaf and nut samples were taken at distances of 250, 500, 1000, 1500, 2000 and 5000 m, with the samples at 5000m taken as control. Visual observations, detailed chemical analysis of leaf samples and study of nut characters were conducted on the sampled palms. Visual observations revealed a high degree of chlorosis and necrosis of palms near the factory. As distance from the pollution source increased, the intensity of damage decreased, with the control palms at 5000 m showing no signs of visible injury. Data from Chemical analyses showed significantly higher concentration of total sulphur and sulphate sulphur in palms near the Titanium factory (1.731 and 0.364 per cent respectively). A drastic reduction was noticed in the plant nutrients like nitrogen, phosphorus, potassium and calcium in palms exposed to higher sulphur dioxide concentrations. Magnesium content was not affected significantly though in palms near the factory, there was a decrease in concentration. Among the micronutrients analysed, iron, copper and boron were affected, with the contents of iron and copper increasing with increased sulphur dioxide pollution and boron showing a decrease. Sulphur dioxide had no effect on the zinc, molybdenum and manganese contents while sodium and chlorine contents was reduced. The contents of aluminium was increased significantly in palms near the pollution source. Plant metabolites like ascorbic acid and glucose were decreased but the activity of catalase enzyme in leaf remained unaffected. The plant pigments like chlorophyll and carotenoids were also reduced in quantity, which may either be due to their degradation or decreased production. Among the nut characters studied, the contents of copra and oil were drastically reduced. The adverse effects of increased sulphur dioxide content in the atmosphere was high upto 1 km from the source and gradually decreased with the effect not felt at 5 km. These findings reveal that concentrations of sulphur dioxide higher than normal in the atmosphere can lead to plant injury in the surrounding area, in addition to the effects on human beings. The establishment of new industries and thermal power stations pose a new treat to the cultivated and native plants in that area. Since industrialization is the forerunner of development, the contribution of industries to toxic gases should be reduced by the adoption of suitable pollution control measures, if plant life in nature should proceed unhindered.
Open Access
Surface charge characteristics and phosphorus availability in selected oxisoils and ultisoils of Kerala
(Department of soil science and agricultural chemistry, College of Agriculture, Vellayani, 1993) Sreekala, S; KAU; Rajendran, P
To meet the goal of increased food production in areas dominated by LAC soils, it is essential to alleviate specific physical and chemical soil related constraints. A major constraint identified in the Oxisols and Ultisols is the widespread deficiency of phosphorus and moderate to high P – fixation coupled with low nutrient holding capacity. The use of low grade silicates and lime suggested as a low input strategy for sound phosphorus management in these soils is tested in the present study. In addition to this objective the by – product effect of the application of phosphate and silicate in excercising cation protection by enhancement of CEC is also tested in these selected soils. The results of the studies are summarised and appropriate conclusions drawn. The electro – chemical properties of the two soils studied clearly showed that the inorganic components of the soils are of variable charge type. The results of the incubation experiment proved the beneficial effect of silicate application in enhancing the available ‘P’ status. Adsorption studies of phosphate and silicate showed that the Kandiustult of Kottarakkara exhibited extremely high adsorption capacity for ‘P’ indicating a higher ‘P’ fixing capacity than the Haplustox of Pachalloor. The column study conducted revealed that it is possible to increase the retention of cations by applying phosphate and silicate as soil amendments. Neubauer’s experiment conducted to determine the effect of silicate lime and phosphate application on ‘P’ availability, did not show any significant result. However, the trend was indicative of the beneficial effect of silicate application in increasing the phosphate release from the soil. This aspect of the study needs further elaboration through field experiments.
Open Access
Comparative efficiency of different phosphatic fertilizers in rainfed Nendran Banana
(Department of Soil Science and Agricultural Chemistry, College of Agriculture,Vellanikara, 1990) Sheeja, V G; KAU; Harikrishnan, Nair; K
Though phosphorus is one of the key nutrients for plant growth, the consumption rate of phosphatic fertilizers in India is found to be comparatively low. The escalating cost of the imported raw material used for the manufacture of P fertilizers may be one of the possible reasons for the low intake. In this regard, the direct application of cheap native ground rockphosphate as a P source is a fruitful attempt especially in acid soils. The present investigation was conducted to compare the efficiency of different phosphatic fertilizers including rockphosphates in upland soils with ‘Nendran’ variety of banana as the test crop. The present study comprises of two aspects, field experiment and laboratory incubation study. The field experiment was conducted at two locations, viz. at the Instructional Farm attached to College of Agriculture, Vellayani and at Kattakada, in the cultivator’s field. The experiment was laid out in randomised block design with four treatments and five replications. The laboratory study was carried out in the soil, treated with different phosphatic fertilizers after incubation with organic matter under moist conditions to assess the influence of organic matter on the release of P from different P sources. The growth characters of banana plant such as height and girth of pseudostem, number of photosynthetically active leaves, leaf area and period taken for flowering were recorded and analysed upto shooting stages of the crop. The bunch characters like weight of bunch, length of bunch, number of fingers and hands bunch-1, and length and girth of finger were also recorded and analysed. Phosphorus application significantly influenced biometric characters of the crop while the differences between the various P sources were not statistically significant. In most of the growth and yield characters, comparatively higher efficiency was shown by plants treated with superphosphate, eventhough, it was statistically on par with the other sources in both locations. Thus, it indicates the possibility of using cheaper rockphosphates for meeting the phosphorus requirement of banana in upland soils of Kerala, rather than going in for the costly superphosphate. The effect of treatments on the drymatter production was significant at both locations. Phosphorus application significantly increased the P uptake. However the different P sources could not produce significant variation in the uptake of phosphorus in both locations. The phosphorus content in the leaf was found to be maximum from the late vegetative phase to shooting period of the plant growth. With respect to available and total P2o5 content in the soil, the differences between the various sources were not statistically significant though, addition of phosphorus increased the available as well as total P2o5 content of soil significantly over no P treatment. A significant positive correlation existed between the leaf P content and total P uptake. Similarly a significant positive correlation between yield as well as total drymatter content with P uptake was observed. The incubation study revealed that organic matter produced significant effect on the release of phosphorus from different P sources added to the soil under moist conditions. Upto 90 days of incubation, increased availability of phosphorus was recorded in all treatments, and the trend continued till 135 days. A gradual decline in the concentration of available P was noticed thereafter. However, a favourable influence of organic matter on the release of P from different sources has been brought out from this study. When the mean values of available P over all the periods were compared, maximum availability was recorded by soils incubated with organic matter and superphosphate. In general, various sources of P behaved similarly and were on par with respect to the release of phosphorus due to organic matter incubation.
Open Access
Evaluation of methods to improve the nitrogen use efficiency of urea in rice
(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 1993) Sapheena, K S; KAU; Chinnamma, N P
An investigation was carried out to evaluate the various methods recommended by different agencies to increase the N use efficiency of urea in rice. The study consisted of an incubation study and a field experiment during two crop seasons, first and second crop seasons in 1991 using rice variety jyothi. The incubation study was conducted at College of Horticulture, Vellanikkara, Trichur. There were five treatments for the incubation study which were control and recommended dose of N as prilled urea, meemcake – coated urea, neemcake-mixed urea and Nimin – coated urea. The experiment was laid out in Completely Randomised Design. The 13 treatments for field experiments consisted of control, recommended dose of N in two types of splits (50 :50 and 75:25) as prilled urea, neemcake – coated urea, neemcake – mixed urea and Nimin – coated urea and 75 per cent of the recommended dose of N in 50:50 split as prilled urea, neemcake – coated urea, neemcake – mixed urea and Nimin – coated urea. The field experiment was conducted at Agricultural Research Station, Mannuthy under Kerala Agricultural University. The soil for the incubation study was collected from the location where field experiment was carried out. The soil was sandy clay loam in texture, acidic and non saline. Ammoniacal nitrogen content of the soil in incubation study, increased upto a period of 20 days in all the treatments. The treatments showed significant difference in the NH4 –N content at most of the later intervals. In the initial period no definite trend due to treatments was observed but from 15th day onwards Nimin – coated urea recorded highest value at all the intervals. Neemcake – coated urea and neemcake – mixed urea have also recorded higher content of NH4-N than prilled urea but the difference was statistically not significant. At all the intervals control recorded lowest value. The proportion of NO3-N formed compared to total nitrogen was quite low. Significant difference in the NO3-N content of soil due to treatment application was noticed from 8th day of incubation. Significant difference due to different treatment application was not obtained for total N content of the soil and pH of soil and soil solution at different periods of incubation. Ammoniacal nitrogen content of the soil solution was high during the initial periods of incubation both for control and treatments, and gradually decreased and reached minimum value by the end of the period of incubation. The control recorded lowest value throughout the period of incubation and there was not much variation between the other treatments. The NO3-N content of the soil solution was found to be high than that of the soil. The control recorded lowest value at most of the intervals and among the four treatments with N application, the lowest value was recorded by Nimin – coated urea at most of the intervals. In the field experiment significant difference was noticed in the NH4-N content of the soil throughout the period of study in first crop season. At all the intervals control recorded lowest value. Nimin – coated urea recorded highest value at most of the intervals for both full and 75 per cent of the recommended dose of N. Neemcake – coated and neemcake – mixed urea were also found to be better than prilled when full dose of N was applied. But such difference was not noticed when 75 per cent of the recommended dose of N was applied. In the second crop season, variation due to treatments was not significant in the initial periods. Nimin – coated urea recorded higher NH4 – N content than prilled urea at most of the intervals from 15th day after transplanting both for full and 75 per cent of the recommended dose of N. Neemcake – coated urea and neemcake-mixed urea were alsostages this treatment recorded comparatively higher values, both for treatments with full and 75 per cent of recommended dose of N. As in the case of Incubation study proportion of NO3-N formed was quite low. Similar trend was obtained during second crop season also. No uniform trend was obtained in the total N content of soil at different intervals due to treatments in both the seasons. Significant difference in soil pH was also not noticed. The difference due to treatment application was not high enough to attain the level of statistical significance for the major biometric characters of the plant during both the crop seasons. Though the difference due to treatments was not significant on grain yield, Nimin – coated urea recorded maximum grain yield both for full and 75 per cent of the recommended dose of N during both the crop seasons. Nitrogen content in plant was increased by N application. Nimin – coated urea showed a favourable influence in increasing the N content of grain during both the crop seasons. In general application of Nimin enhanced the uptake of N by grain and straw during both the seasons. Significant variation was obtained in the content and uptake of P, K, Ca and Mg at various stages of crop growth during both the seasons.

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