1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)

Permanent URI for this communityhttp://localhost:4000/handle/123456789/1

Browse

Subject: search.filters.subject.Electrochemical properties

Search Results

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Relative efficency of rice varieties for absorption and utilization of soil and fertilizer phosphorus
    (Department of soil science and agricultural chemistry, College of Horticulture, Vellanikkara, 1986) Mashar Velapurath; Padmaja, P
    Relative efficiency of rice varieties for absorption and utilization of soil and fertilizer phosphorus An investigation was carried out at the college of Horticulture, Vellanikkara, Trichur, during the year 1984-’85 to study the efficiency of popular modern rice varieties of Kerala for absorption and utilization of soil and fertilizer P as well as for their capacity to P deficiency tolerance. A series of pot culture experiments was conducted using five short duration (Rohini, Jyothi, Annapoorna, Triveni and IR-36) and eleven medium duration (Jaya, IR-8, Sabari, Bharathi, Mashuri, IR-20, M0-4, M0-6, M0-7, H-4 and IR-42) rice varieties in karappadam soil of Kuttanad region of Kerala. The first pot culture trial involves evaluation of the above varieties for their capacity to utilize soil and applied fertilizer P using 32P labeled superphosphate. The experiment was carried out in CRD. The relative performance of all the varieties as well as their root distribution pattern were compared from another pot culture trial under identical fertility conditions. Fertilizers and lime were applied as per the package of practices recommendations of the Kerala Agricultural University. The experiment was designed in CRD. An attempt was also made to study the P requirement of each variety for the expression of maximum grain and straw yield from a solution culture trial. Solution containing all the macro and micronutrients was used for the experiment. The treatments consisted of combinations of different varieties and different levels of P supply. The various levels of P used were 0, 1, 2, 4, 5, and 10 ppm. The experiment was conducted in CRD factorial design. The results indicated that cv, IR-36 was having a very low P requirement for the expression of maximum yield potential among short duration varieties and that it responded well to applied fertilizer P, indicating its fertilizer responsive nature as well as tolerance to P deficiency. Triveni and Rohini were also having low requirements, but they differed in their dependence on the source of P to meet the requirement. Rohini was capable of utilizing native soil P efficiently while a good response to applied P was observed in the cv. Triveni. Jyothi utilized both the sources of P viz. soil and fertilizer; efficiently but was found to have a higher requirement for giving maximum grain yield. Among the medium duration varieties cv. Mashuri has the lowest requirement and majority of its requirement was met from the fertilizer revealing its P deficiency tolerance nature and responsiveness to applied fertilizer P. Cv. IR-42 and Bharathi were found to be tolerant to P deficiency due to their capacity to utilize native soil P efficiently and low requirements of P. Cv. H-4 was also having low requirement and it utilized both the sources efficiently. But this was not very much reflected on the grain yield. Cv. IR-8 and Jaya had comparatively higher requirements and it reflected well on the grain yield. But these varieties yielded poor at lower levels indicating its susceptibility to P deficiency.
  • No Thumbnail Available
    Item
    Effect of submergence on the soil testing parameters of paddy soils
    (Department of soil science and agricultural chemistry, College of Agriculture, Vellayani, 1986) Usha Mathew; Alice Abraham
    Laboratory incubation studies were conducted to quantify the changes in pH, EC, lime requirement and availability of important nutrients such as N, P, K, Ca & Mg due to submergence of alluvial, acid saline acid sulphate and saline rice soils of Kerala, The study has revealed that pH of all the soil types increased Immediately after flooding of the air dried soils, reached a maximum and remained more or less steady throughout the period of three months submergence. Consequent to the increase in pH, a corresponding decrease in lime requirement was observed in all the soils. Maximum reduction in lime requirement was noticed for the saline and acid saline soils. A rise in EC was observed in all the soil types due to submergence during the first four to six weeks. It showed a decreasing tendency afterwards. All the soils showed a progressive increase in available nitrogen content with increase in the period of flooding. The increase was in the range of 75 - 395$ for the various soil types. Maximum increase was recorded by saline soils (395$) and minimum by alluvial soils (75%). The levels of available phosphorus recorded for the four soil types in the air dried state were in The low to medium range for rice. Submerging of these soils has resulted in a manifold increase in the content of available phosphorus. The increase was maximum for acid saline soils (700$) and minimum (55$) for alluvial soils. The availability of exchangeable cations like potassium, calcium and magnesium, however, showed a periodical increase and decrease on flooding in all the four soil types. The results of the study have clearly brought out the magnitude of the changes that result in the status of each nutrient upon flooding of soils for wetland paddy cultivation. The manifold increase in the status of major nutrients like N and P upon flooding of soils indicates that addition of fertilizer N and P under such conditions is not likely to produce any significant effect on rice unless the rice varieties are highly responsive to these nutrients. The feasibility of reducing The quantity of fertilizers to be applied or even skipping of fertilizers for one or two seasons may be considered taking into account the responsiveness of the rice variety as well as other economic factors.