Browsing by Author "Mathew Jacob, K"

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Evaluation of available phosphate reserve of soil by chemical methodes
(Department of soil science and agricultural chemistry, College of Horticulture, Vellanikkara, 1979) Mathew Jacob, K; Jose, A I
A laboratory study including a pot culture experiment was carried out using 18 lateritic soil to evolve a suitable laboratory chemical method as an index for the estimation of available phosphate reserve (Ra-value). The total plant removable phosphorus of the soils was determined growing rice (variety IR-8) continuously in soils taken in pots, till the content of phosphorus in plants became below the critical level. The pot culture experiment was designed in completely randomized design with 18 treatments (soils) and 3 replications. To evolve a suitable extractant for the estimation of “Ra-value” H2SO4 and HCI at different concentrations and combinations were tried. Out of the 29 extractants employed, 17 were selected based on their consistence in the pattern of phosphorus release and the amount of phosphorous extracted. From a pilot study, in which different organic acids at different concentrations were screened, oxalic acid at the strength of 0.05 N was selected as the best chelating agent to be employed with the 17 mineral acid combinations. The results showed that compared to Bray No.1, the performance of HCI was very poor and had only a little pronounced influence on the extraction of phosphorus. Sulphuric acid at analogous concentrations extracted higher quantities of phosphorus and obtained better correlations with phosphorus uptake values at the end of 6th crop. Combinations of mineral acids extracted higher quantities of phosphorus from soil than the individual acids, with a pronounced influence at lower concentrations. The pattern of release of phosphorus fluctuated widely when the mineral acids were used individually, but the degree of fluctuation was considerably less when employed in combination. In all the above cases the major part of phosphorus was extracted within 30 minutes and thereafter the release was very slow. The pilot study employed in the selection of organic acids for chelated system, to prevent the resorption of phosphorus into the soil from the solution, revealed that resorption of phosphorus from the solution can be effectively prevented by employing organic acids; the amount of phosphorus extracted by the mineral acids can be increased by the presence of organic acids notably oxalic acid and acids at the strengths of 0.05 N were as good as 0.10 N in their effects on the extraction of soil phosphorus. A period of equilibration not less than 30 minutes was considered critical and optimum. The extractant No.10 (0.06 N H2SO4 & 0.06 N HCI in 0.05 N oxalic acid) was found to be superior to the remaining combinations and gave better correlation with “Ra-value” of the soil. Phosphorus extracted by Bray No.1 failed to correlate significantly with phosphorus uptake by crops in soil groups in which the percentage phosphorus content of plants were below 0.025, 0.05 and 0.2 showing that Bray No.1 is not an efficient extractant for the estimation of “Ra-value” of the soil. Thus the present study recommend the extractant 0.06 N H2SO4 and 0.06 N HCI in 0.05 N oxalic acid with an equilibration period of 30 minutes and soil solution ratio 1 : 10 as a better method for estimating the “Ra-value”. Regression equation between phosphorus extracted by this method and “Ra-value” of the soils selected was rather narrow, the application of this equation in predicting the possibility of skipping phosphorus application in soils appeared very much limited.
Keeping quality of sugarcane setts of the popular varieties of Kerala
(Kerala Agricultural University, 1983) Sukumaran Nair, S; Mathew Jacob, K; Nair, P K C
In order to estimate the loss in weight of seed cane, viability of buds during storage and germination of viable buds, a study was taken up at the Sugarcane Research Station, Thiru valla during 1980-81 planting season, with four popular varieties of the tract. The maximum loss in weight was recorded in the variety Co-997 during storage upto 30 days and the loss in weight was rapid after 25 days of storage in the varieties Co 997 and Co. 785. This loss in weight is important when the seed materials are supplied to the cane growers in weight basis. The buds in the four varieties studied remained viable to a fair degree upto 1 5 days after the collection of the setts and thereafter the vaibility was reduced drastically. This loss was maximum in the variety Co 449 and minimum in Co-62175. Co 62175 showed the maximum tendency for pre-germination of buds in storage and such behaviour was minimum in Co 449. Considering the loss in weight of the seed cane, loss in viability and germination of the buds during varying periods of storages, the safe margin was found to be 15 days- It is desirable that the setts are planted as early as possible after harvest of the canes.
Lodging of sugarcane and its influence on yield and quality of certain cultivars
(Kerala Agricultural University, 1982) Sukumaran Nair, S; Mathew Jacob, K; Chellappan Nair, P K
In order to estimate the loss in weight and recovery of sugar in the lodged crop of sugarcane a study was conducted at the Sugarcane Research Station, Thiru valla, Kerala during 1980-81. The length of canes, number of mi liable canes, weight and recovery of sugar were found to be reduced as the canes lodge. The loss in weight ranged from 10.16% to 18.95% for half lodged canes and 30-81% to 38.71% in full lodged canes. The loss in cane sugar varied from 33.84$ to 43,48# when the cane lodged completely. This phenomenon was more in fully lodged canes when compared with half lodged canes. It is therefore evident that lodging of sugarcane is one of the factors which decrease the production of cane and sugar.