Browsing by Author "Prema, D"

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Assessment of 'blue carbon' in sediment of Indian mangrove (Avicennia officinalis) in selected locations of Vembanad lake ecosystem in Kerala
(Academy of Climate Change Education and Research, Vellanikkara, 2018) Aarathy, G S; Prema, D
The present investigation, focused on the estimation of the sediment pool of the blue carbon stocks of the mangrove species Avicennia officinalis (Indian Mangrove) in selected locations of Vembanad lake. Sediment core samples were collected in post monsoon (October – November 2017) and pre monsoon (February – March 2018). The treatments included ‘aged’, ‘recent’, ‘healthy’ and ‘degraded’ mangroves of the selected species and ‘control’ without mangroves. Sediment core samples up to 30 cm depth with 10 cm interval were subjected to standard laboratory and statistical analytical procedures. The cumulative stock of blue carbon in sediment ranged from 6.00 to 139.96 Mg ha -1 in post monsoon and 2.00 to 84.58 Mg ha -1 in pre monsoon. The treatments differed significantly in the cumulative stock of blue carbon in sedimen (p < 0.05), highest seen in ‘healthy’ at 0-30 cm depth in both seasons. Highly significant difference was observed between ‘healthy’ and ‘degraded’, ‘healthy’ having more stock in both seasons. These two treatments differed significantly for layer wise blue carbon in sediment also in both seasons, higher content being seen in ‘healthy’ and there was no significant variation among depths. The range of layer wise blue carbon in sediment, considering all treatments was 0.06 to 0.56 g cm-3 in post monsoon and 0.02 to 0.35 g cm-3 in pre monsoon. Significant difference among treatments was observed at 0-10 cm depth for layer wise blue carbon in two seasons together, and no significant variation was found in sub surface (10-20 cm and 20-30 cm) depth. Spatial maps were prepared for the cumulative stock of blue carbon and layer wise blue carbon in sediment during post monsoon and pre monsoon seasons. The cumulative stock and layer wise blue carbon were higher in post monsoon. Depth wise increase was seen in layer wise blue carbon in post monsoon, though they were not statistically significant. Layer wise blue carbon was significantly correlated with total organic carbon and organic matter (p < 0.01) positively and with C/N ratio in the sediment (p < 0.05). The study suggests total organic carbon and C/N ratio as possible predictive indicators of blue carbon in sediment, with further investigation.
Effect of potassium chloride and sodium chloride on the performance of coconut in a laterite soil
(Kerala Agricultural University, 1992) Prema, D; Jose, A I; Narayanan Nambiar, P K
A field experiment was conducted to study the effect of Nad on the performance of young coconut palms grown in a laterite soil at the Regional Agricultural Research Station, Pilicode. The treatments were the substitution of K2O (applied as KC1) by Na2O (applied as Nad) to the extent of 100, 75, 50, 25 and 0 per cent. The palms receiving 50 per cent substitution of toO by Na2O retained maximum number of functioning leaves. The treatments differed significantly in their influence on nutrient uptake of the palms in the case of K, Na and Cl. Palms receiving higher amount of K or Na retained higher amount of these elements. Palms receiving neither KG nor Nad registered significantly lower uptake of Cl than palms receiving other treatments. The available K and available Na increased with increased application of K and Na respectively while the other characteristics of the soil were not affected.
Effect of sodium chloride on growth and yield of coconut palms in a laterite soil
(Kerala Agricultural University, 1987) Prema, D; Jose, A I; Narayanan nambiar, P K
An investigation was carried out drawing soil and leaf samples from coconut palms of a sodium chloride trial conducted at the Regional Agricultural Research Station, Pilicode, Kasaragod, Kerala, in order to evaluate the effect of sodium chloride on growth, yield and uptake of nutrients by coconut palms grown in laterite soil. The treatments were superimposed on 24 year old palms in 1976 and samples for the study were drawn in 1986. The palms were receiving substitution of KCI by NaCI in various proportions for the last 10 years. The study revealed that there was no significant difference in yield of nuts by substitution of KCI by NaCI. However, treatments receiving 100% recommended dose of K20 and that receiving 50% substitution of K20 by Na20 appeared superior to other treatments- There was no significant difference between treatments in the case of other growth characteristics, and the nutrient uptake by the palms except K and Na. Palms receiving higher amount of K or Na retained higher amount of these elements. The available nutrient status of the soil except available K and basic chemical properties of the soil like, pH, EC and CEC remained the same. The available K content in soil increased with increased application of K to the soil.
Effect of sodium chloride on soil characteristics, yield and quallity of coconut grown in a laterite Soil
(1987) Prema, D; Jose A I
Evaluation of laboratory indices of magnesium availability
(Kerala Agricultural University, 1995) Prema, D; Jose, A I
A study was conducted to evolve a suitable extractant of available Mg in soil. Twenty soils were selected for the study assuring wide variation in their properties in relation to Mg availability. The various extractants in the final screening showed the following decreasing order in their efficiency for extracting Mg; 0.005 M DTPA + 0.005 M CaCI2 .Mathew's triacid > 0.1 M acetic acid + 0.04 M Ca lactate > Keith's reagent > 0.0125 M CaCI,, 1 N NH4OAc > 0.05 M HCI > 0.005 M DTPA. The amount of Mg extracted by various extractants failed to correlate significantly with the Mg uptake of test crop (rice) as well as the per cent of Mg in the crop. The performance of 0.05 M HCI was promising with respect to the pattern of release, degree of variability due to varying periods of equilibration ami the magnitude of Mg extracted at the optimum period of equilibration.
Magnesium status of soils
(Kerala Agricultural University, 1994) Prema, D; Jose, A I
The magnesium status of the soils of Kerala was studied. In general, they were deficient in total Mg reserves (61 per cent of the soils studied). Altogether, 17 per cent of the soils were deficient in available Mg and 25 per cent deficient in exchangeable Mg. Black soils were rather rich in total Mg, available Mg and exchangeable Mg. The most deficient were the sandy loam soils of coastal alluvium. The laterite group was in between. The inter-relati onships among total, available and exchangeable Mg were found to be significant and positive. Exchangeable Mg correlated positively with other exchangeable cations. About 24 per cent of the total Mg reserve in the soils under study is considered available and 11 per cent exchangeable. The total Mg reserves in Kerala soils are found to be poor and Mg can be considered as a critical element in these acid soils
Quality of copra and oil of coconut as influenced by sodium chloride nutrition
(Kerala Agricultural University, 1987) Prema, D; Jose, A I; Narayanan Nambiar, P K
Status, availability and transformation of magnesium in acid soils of Kerala
(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 1992) Prema, D; Jose, A I
The investigation consisted of four parts, namely (1) magnesium status of soils in Kerala (2) evaluation of laboratory indices of Mg availability (3) transformation of applied Mg in soil and (4) pattern of Mg uptake by banana from different sources at different levels. In Part I, one hundred and fifty surface samples were collected from all over the State of Kerala, to study the status of Mg as well as properties in relation to the behaviour of Mg in these soils. In part 2, some selected chemical agents were tried in twenty selected soils in order to evolve a suitable extractant for available Mg. In Part 3, two acid rice soils of Kerala namely, Karappadam and laterite were incubated at field capacity for a period of 180 days with and without the addition of magnesium sulphate, magnesite and dolomite at the rate of 1250, 2500 and 3750 kg MgO ha-1, to monitor the pattern of release of Mg from applied sources . Soil samples were drawn regularly at 15 days interval for the determination of available Mq and at 60 days interval for the determination of other important chemical properties. In Part 4, a field experiment of banana was conducted to study the response to applied Mg.