Browsing by Author "Ramasubramonian, P R"

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Effect of top dressing with complex fertilizer on the yield of rice
(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 1990) Sam Mathew; Ramasubramonian, P R
A field experiment was conducted in the wet lands of the College of Agriculture, Vellayani campus during the second crop season of 1988 to study the effect of top dressing paddy with phosphorus in the form of ammophos and superphosphate in addition to a basal application on the yield of grain and straw. The experiment was carried out in a simple randomised block design with thirteen treatments. Factomphos and superphosphate were applied at different times viz., full basal, full top dress at AT, ½ basal + ½ at AT, ½ basal + ½ at AT + ¼ at PI. A control treatment without any phosphorus was also included. The Package recommendation of 90:45:45 kg ha-1 of N:P:K was given uniformly to all plots except in the control which received N and K only. The variety used was Jyothi. A destructive row for collection of plant samples was also maintained. Soil and plant samples were withdrawn from each plot at different stages viz. prior to and 15 days after top dressing at AT, 10 days after top dressing at PI and at harvest and analysed for available P in the soil and the phosphorus content of the plant. The growth, yield and yield characters were also studied. Increased plant height and tiller count could be observed during the active tillering and maximum tillering stages when factomphos was applied half as basal and half top dressesd at AT. The two-split treatments of factomphos recorded highest tiller count at harvest. Among the yield characters, increase in the productive tiller count alone was significant under the influence of split application of P either as superphosphate or factomphos. The application of P in two splits of half basal and half top dress at AT resulted in increased grain yield which was significant over the control, three splits and the single top dressed treatments. The two-split treatments and the full basal treatment were similar in their influence. Between superphosphate and factomphos used for top dressing, no significant differences could be noticed. In general, the full top dressed P and the three – split treatments were similar and both were inferior. With regard to straw yield, the phosphorus applied in two splits showed better performance when compared to the others. However, among the different treatments, there was no significant difference. Control was significantly inferior. Between superphosphate and factomphos used in the two – split treatments, the latter was found better. The full top dressed and the three – split treatments were similar and gave lower straw yield. Studies on the phosphorus absorption by rice plant made during three sampling stages indicated that increased absorption of phosphorus was during the period between the first and second sampling stages, which nearly coincided with the active tillering and maximum tillering stages respectively of the crop, with peak absorption at the second stage and thereafter it decreased gradually. In this regard the two - split P treatments recorded higher values among which factomphos application resulted in the highest plant P content of the harvest stage which was significant. The uptake of phosphorus studied in the various stages was also found to be higher in the two – split P treatments of factomphos. Maximum available phosphorus in the soil could be noticed in the treatments where P application was made in two – splits, which was however on par with full basal P treatments. In general the nitrogen content of grain and straw were higher in the two – split P treatments with a maximum content in the factomphos top dressed treatment. However, no treatmental difference could be seen in the case of potassium content of grain or straw. Correlation studies revealed that the available P in the soil and the phosphorus content of the plant estimated at various stages were positively and significantly correlated with yield. The result indicated that peak phosphorus absorption by rice occurs at maximum tillering stage and that the phosphate application at or after PI is not likely to be helpful in bringing about the desired yield increase in rice.
Effect of varying levels and methods of application of zinc on the yield of rice
(Kerala Agricultural University, 1982) Krishnan Nampoodiri, K; Ramasubramonian, P R
A field experiment was laid out in a zinc deficient soil in Kuttanad area, Alleppey district, Kerala to study the effect of different levels and methods of zinc application with and without lime, on the growth and yield of rice. Foliar application of Q.5% and soil application of 20 kg/ha zinc sulphate resulted in significantly higher yield of grain. Root dip treatment with zinc oxide suspension recorded an increase in grain yield over control. The effect of application of lime alone and in combination with zinc, however, could not result in a significant increase in the yield of grain or straw. The study revealed the importance of zinc application to rice grown in the water-logged acid soils of Kuttanad.
Influence of form of organic matter on the mineralisation of applied phosphorus in submerged rice soils
(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 1989) Nageeb, P H; Ramasubramonian, P R
A field experiment to study the effect of incorporation of different forms of organic matter on the transformation of native and applied phosphorous in submerged rice soils and their effects on the growth and yield of rice (Var. Triveni) was conducted in the Instructional Farm of the College of Agriculture, Vellayani during second crop season in 1986. The treatments included the application of three different form of organic materials (farm yard manure,greenleaves and composted salvinia) and two phosphate fortilizers (super phosphate and Mussooria phosphate). Practionation of soil inorganic phosphorous at fortnightly intervals for a period of 90 days and estimation of available P, exchangeable iron and soil reaction were carried out. Observations on the growth characters were made at active tillering, maximum tillering and flowering and yield of straw and grain were recorded. The chemical analysis of the grain and straw for N, P, K, Ca and Mg was also carried out. It was found that in general submergence of soil increased the transformation of both native and added P in to Fe-P, Al-P, Ca-P and saloid – P. Reductant-P and occluded-P fractions decreased with progressive submergence. Submergence of the soil markedly increased the available P status of soil. Phosphorous applied as super phosphate and Mussooria phosphate was recovered in different inorganic fractions in the order Fe-P > Al-P > Red-P > Occluded-P Ca-P >saloid-P. Organic matter addition suppressed the transformation of native and added inorganic phosphorous into different inorganic P fractions (Fe-P, Al-P, Red-P, Occluded-P and Ca-P) and maintained higher amount of added P in the soil in available form during the initial 75 days of submergence. A marked increase in exchangeable iron was also observed with continuous submergence. The process was accelerated by the addition of organic matter. Phosphate application significantly decreased exchangeable iron content in the soil. Submergence of soil resulted in a significant increase in soil pH upto 45 days beyond which it remained more or less constant. Organic matter treatment significantly decreased soil pH whereas addition of P in the form of Mussoorie phosphate increased the soil pH. The growth parameters (tiller count and plant height) recorded a significant increase due to the application of organic matter and phosphorous. The grain and straw yield increased significantly with the application of P fertilizers and organic matter. Application of Mussoorie phosphate plus green leaves recorded the highest grain and straw yield. There was a significant increase in the mineral contents in the plant by phosphorous and organic matter application. The study highlights the importance of organic matter in producing a better response to phosphatic fertilizers by rice in the submerged paddy fields.
Influence of Iron toxicity on growth yield and plant composition of major rice varieties cultivated in Kerala
(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 1993) Sheela, R; Ramasubramonian, P R
A study was made to identify rice cultivars tolerant to iron toxicity situation culture using Hoagland solution. Thirty cultivars popular among the Kerala farmers were screened under the toxic level of 500 ppm iron and toxicity symptom displayed was scored on 1 - 9 scale. The varieties included high yielding and local ones. The varieties viz., Asha, Annapoorna, Aruna, Aswathi, Jaya, Jyothi, Karthika, Neeraja, Onam, Ptb – 2, Ptb – 10, Ptb – 20, Pavizham, Sabari and Santhosh exhibited severe toxicity symptoms with high scores, exceeding five. The plant iron content of these varieties at AT stage was found relatively higher than that of the remaining ones. Asha, Jaya and Jyothi were seriously affected with scores more than 8 and was therefore treated as highly susceptible. In varieties Bhagya, Bhadra, Bharathy, IR – 36, Kanakam, Makam, Rasi, Red Triveni, Remya and white Triveni, the intensity of visible symptom was lesser with scores ranging between 3 and 5. The iron content of the varieties was lower than in the susceptible varieties. These varieties were classified as moderately tolerant since they had the capacity to resist iron toxicity to a reasonable extent. Display of the least symptoms of iron toxicity and scoring were noticed in five varieties viz., H4, Mahsuri, Cherady, Kochuvithu and Keerthy. Plant analysis of these varieties at the At stage indicated the least iron content. In view of the comparatively better performance, these varieties were further examind to find out the comparative effect of increased iron levels at 400, 500 and 600 ppm on their growth and yield. The study indicated that, in general, growth and yield attributing characters as well as the yield decreased with progressive increase in iron level. H4 and Mahsuri recorded relatively higher grain and straw yields as compared to Cherady, Kochuvithu and keerthy. In all the varieties, the nitrogen content increased with increase in levels of iron whereas the uptake decreased. Keerthy recorded the highest content of nitrogen while H4 recorded the highest uptake of nitrogen. The content and uptake of P, K, Ca and Mg decreased in all the varieties as the level of iron was progressively increased. H4 and Mahsuri recorded significantly higher content and uptake of these elements in grain and straw while Keerthy recorded the lowest. The content of iron in all the varieties increased with increase in levels of levels of iron in growth medium. Relatively lower content of iron was recorded in the aerial parts of H4, Mahsuri and Cherady compared to other varieties, whereas roots of these varieties had higher iron content. The uptake of iron increased upto 500 ppm level and thereafter decreased in all the varieties. The study revealed that the varieties H4, Mahsuri, Cherady Kochuvithu and keerthy exhibited better performance even with toxic concentrations of iron. Among these varieties H4, Mahsuri and Cherady performed reasonably well and H4 performed better with regard to tolerance to iron toxicity. These varieties contained higher P, K, Ca and Mg and lesser iron as revealed by plant analysis. Better performance can be attributed to their genetic superiority such as better root development, improved root oxidation capacity and higher nutrient absorbing ability.
Nitrogen balance studies in the rice soils of Kerala
(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 1986) Meera, K; Ramasubramonian, P R
Nitrogen 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.
Studies on the detection of adulteration of bone-meal during routine analysis
(Kerala Agricultural University, Vellanikara, 1968) Ramasubramonian, P R; Money, N S
Studies on the dynamics of forms of soil iron in the acid soils of Kerala during submergence
(Department of Soil Science & Agricultural Chemistry, College of Agriculture, Vellayani, 1989) Harikumar, K P; Ramasubramonian, P R
The main objective of the study were to understand the pattern of distribution of water soluble, exchangeable, active free oxide, total amorphous, amorphous organic, amorphous inorganic and crystalline forms of iron and their variation under the influence of submergence, the effect of management practices on the variations in the available forms of iron under submergence and the relationship between soil reaction and the forms of iron in the major acid rice soils of Kerala. Viz., lateritic alluvium. Kari, kayal, karappadom, kole and pokkali. The pattern of distribution of different forms of iron studied, varied significantly among the six soils. The water soluble, exchangeable, active, free oxide, total amorphous and amorphous organic forms of iron were maximum in the kari soil, while crystalline iron was maximum in the lateritic alluvium. Kari and kole soils had the highest content of amorphous inorganic form of iron. The minimum content of water soluble iron was recorded in the kole and the lateritic alluvium, exchangeable and crystalline iron in karappadom soil, active, free oxide, total amorphous and amorphous inorganic forms of iron in pokkali soil and the amorphous organic iron in the lateritic alluvium. The total iron was highest in the kole and the lowest in the karappadom soils. Correlation studies indicated that pH had a significant negative correlation with water soluble and exchangeable forms of iron, while electrical conductivity, CEC, organic matter and clay content had positive correlation. Electrical conductivity and organic matter were positively correlated with active iron. Submergence significantly increased the pH and the contents of some of the forms of soil iron. Crystalline iron however, decreased with submergence. Active and free oxide forms of iron had no significant effect. The pH attained peak values on the 20th day of submergence in the lateritic alluvium, 30th day in the karappadom soil and 60th day in kayal, kole and pokkali soils. However, kari soil showed steady slow increases throughout the period of submergence. The addition of organic matter @ 5 t/ha and 2.5 t/ha decreased the pH slightly up to 5th day and then increased and equalled that of the control on the 90th day in all the soils. The decrease in pH was significantly more in the higher level of treatment then in the lower level. Water soluble iron increased significantly due to the treatments in all the soils. The maximum increase was observed in kari soil and the minimum in kayal and karappadom soils. However, the release of water soluble iron due to the higher level treatment was more than that of the lower level. The exchangeable iron also increased due to the organic matter treatment. The maximum increase was observed in the lateritic alluvium and the minimum in karappadom soils. The increase in the content of exchangeable iron due to higher level of organic matter was significantly higher than that due to the lower level. The lime application at full LR and half LR levels substantially increased the pH upto the 5th day in all the soils except in the kari soil, after which it decreased with further periods of submergence. However, in the kari soil, a peak value could be noticed on the 20th day. Water soluble and exchangeable iron decreased significantly due to the lime treatment. The decrease due to full LR treatment was significantly more than that due to the lower level. The active iron neither increased nor decreased significantly due to the organic matter and the lime treatments.
Studies on the effect of varying levels of zinc on the growth and yield of rice
(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 1980) Krishnan Namboodiri, K; Ramasubramonian, P R
A field experiment was conducted in a cultivators field at Edathua (Kuttanad) to study the effect of different levels and methods of zinc application on the growth and yield of rice (var. Jaya). Soil application of 0, 10, 20 and 30 kg zinc sulphate per hectare: foliar application of 0.25per cent and 0.5 per cent zinc sulphate, root dip in 2 per cent zinc oxide suspension , lime at 150, 300 and 600 kg CaO per hectare and their combinations were included in the treatments. The field was selected on the basis of a low content of available zinc (EDTA extractable). Observations were recorded on the growth parameters and yield characters . The chemical analysis of the plant material for N, P, K, Ca, Mg and Zn at harvest were also carried out . The different growth parameters studied, recorded a significant increase in the grain yield could be obtained by zinc application . Foliar application of 0.5 per cent zinc sulphate and soil application of 20 kg zinc sulphate per hectare recorded the maximum yield of grain. These treatment yielded more than 20 per cent grain over control and were statistically on per. There was no significant increase in the mineral contents in the plant by zinc application, except zinc and phosphorus.
Studies on the Solubilisation of iron in submerged soils and methods to minimise its solubility and toxic concentration to paddy
(Department of soil science and agricultural chemistry, College of Agriculture, Vellayani, 1989) Ramasubramonian, P R; Koshy, M M (Guide)
A study has been made of the extent of solubilisation of iron in the submerged acid rice soils of Kerala State where iron toxicity is likely to be a serious field problem during rice cultivation. The kayal, kari and karapadom soils of Kuttanad, brown hydromorphic soils of the midland lateric zone and the sandy soils of Onattukara were included in the study. Chemical characterisation of the soils and soil profiles in relation to forms of iron were investigated with a view to obtain a better understanding of the dynamic aspects of iron in these soils. The nature, and extent of periodical variations in soluble iron as influenced by levels of sea water, organic matter (farm yard manure) and ammonium sulphate added to kayal, kari, karapadom and brown hydromorphic soils under submerged conditions were also studied along with the influence of levels of applied lime on the amelioration of iron toxicity. Among the Kuttanad soils, kari soil was most acidic with a mean pH of 3.77, high organic carbon content and CEC compared to others. The water soluble iron ranged from 79 – 165 ppm in the Kuttanad soils. This form of iron and pH were negatively correlated. Electrical conductivity and water soluble iron were significantly and positively correlated. The exchangeable iron varied between 144 – 310 ppm and was positively correlated with CEC. Active iron ranged between 1460 and 5200 ppm. Active iron had a significant positive correlation with organic carbon and electrical conductivity. Kuttanad soils contained high contents of water soluble and exchangeable iron, together known to contribute towards the development of iron toxicity to transplanted rice in these soils. High contents of water soluble, exchangeable and active iron were noticed in the profiles of Kuttanad soils as well. Compared to these, the brown hydromorphic and sandy (Onattukara) soils had much lower contents of soluble iron. Total iron content decreased with depth in most of the profiles while water soluble, exchangeable and active iron, increased with depth studied upto 100cm. In brown hydromorphic soil the water soluble and exchangeable iron were found to decrease with depth. Incubation studies under laboratory conditions indicated that submergence of soils resulted in an increase in the soluble iron with time, reached a peak value on the 10th day in kari soil and 25th day in the other soils, after which the soluble Fe2+ decreased to lower values. Sea water submergence resulted in enhanced releases of Fe2+ with time to reach peak value around the 25th day followed by decrease. Kayal soil alone, however, needed 40 days for peak release of Fe2+. The release of Fe2+ was influenced by the dilution of sea water used. Kayal, kari and karapadom soils released significantly higher amounts of Fe2+ compared to brown hydromorphic soils. However, at the lowest level of 25 per cent sea water all soils behaved similarly. Presence of organic matter under the submerged conditions enhanced the Fe2+ release considerably depending on the content of organic matter in the soil. Kari soil on the 25th day and kayal soil on the 40th day of submergence released significantly higher amounts of Fe2+. Addition of ammonium sulphate to soils under submerged conditions resulted in increased releases of Fe2+ in the soil solution with time. Peak releases of Fe2+ were noticed on the 25th day in all the soils. Maximum release by kari soil was influenced by ammonium sulphate applied at 100 kg N/ha, in the karapadom and brown hydromorphic soils by 200 kg N/ha. The beneficial effect of lime on the suppression of iron release was clearly evident in the soils though to varying extents. In kayal soil 600 kg lime/ha suppressed iron release upto 10 days and 1000 kg/ha could suppress more soluble iron for 25 days. However, after the 40th day, soluble iron exceeded that of the control. In kari soil the iron suppressing effect of both the levels of lime was evident only up to the 10th day after which the release of soluble iron exceeded that of the control. In karapadom and brown hydromorphic soils, lime at 600 kg/ha was helpful in suppressing the release of Fe2+ till the 40th day. Lime at 1000 kg/ha, however, could suppress more of the soluble Fe2+ throughout the period of submergence. In kayal and kari soils, levels of lime upto 1000 kg/ha appear to be inadequate in controlling iron toxicity. Flooding the field for 25 days and leaching out the released Fe2+ just before planting of rice is suggested as an alternate solution to minimise iron toxicity to rice in Kuttanad soils.
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; Ramasubramonian, P R
An 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.