1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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Item 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; Harikrishnan Nair, KThough 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.Item Suitability of Tunisia rock phosphate for direct application in acid rice soils of Kerala(Department of Soil Science and Agricultural Chemistry, College of Horticulture,Vellanikara, 1997) SanthoshKumar, V C; Mariam, K AA study was conducted at College of Horticulture during the period 1993-95 so as to assess the suitability of Tunisia rockphosphate for direct application in acid rice soils of Kerala as a source of P compared with single superphosphate (SSP) diammonium phosphate (DAP) and Mussoorie rockphosphate (MRP). In addition to above sources a control treatment (with no P fertilizer) and another treatment with SSP of the rate of 45 kg P2O5 ha-1) given twice (conventional practice) were also included. The P release from all the sources was monitored with an incubation experiment. In order to evaluate the residual effect of fertilizers two continuous pot culture experiments were undertaken using Triveni variety of rice. The acids soils of Kerala namely Kuttanad alluvium and laterites were used for the study. The soils showed variation in pH with submergence irrespective of the treatments. The different nutrients like N, K, Ca, Mg were higher in Kuttanad soil compared to laterite soil and was found to decrease with period of incubation. The available phosphorus content gradually increased with period of incubation and reached a peak .fit 60 to 90 days for water soluble phosphates and 90th to 120th day for rockphosphates. Comparing the two extractants, Mathew's triacid extracted more available P than that of Bray solution in both soil types. In general, Kuttanad alluvium recorded higher content of available nutrient as compared to laterite. The extent of fixation of P was higher in Kuttanad soil with Fe-P as dominant fraction while in laterite soil it was Al-P which was dominated. While evaluating pot culture experiment the different nutrients showed a decrease in soil and increase in uptake with the advancement of crop. Of the different soils Kuttanad alluvium registered a higher yield compared to laterite soil. It was found that TRP registered a comparable uptake of phosphorus and gave a comparable yield of grain and straw with other sources in laterite and Kuttanad alluvium. The residual effectiveness of rockphosphate was found to be higher than that of water soluble sources and TRP gave the highest. Of the two different type of soils Kuttanad soil showed a higher residual effectivenes and resulted in higher yield for 2nd crop while laterite soil registered a lower yield.Item Efficiency of rock phosphate in the acid rice soils of Kerala(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 1992) Visakha, L; Sundaresan Nair, CInvestigations were conducted to assess the suitability of Rajasthan rock phosphate for rice in two acid rice soils viz. Vellayani kayal soil and Moncompu soil respectively. The study also included a study on fractionation of the soil P collected at periodical intervals from these two locations for the different forms of P. The results are summarized below: 1. At both the locations a significant increase in height of plants, number of tillers, panicle length, thousand grain weight etc. was obtained by the application of phosphatic fertilizers over control. But between the different phosphatic forms no significant difference could not be observed. 2. In both the locations application of rock phosphate both Rajasthan rock phosphate as well as Mussoorie rock phosphate has been found to be as good as super phosphate in enhancing the yield of rice grain. 3. In both the locations the treatments with different forms of P increased the P content of grain and straw. This indicates that, the rock phosphate applied in acid soils while increasing the yield significantly increase the P content in plants also. In general, the treatments with phosphate fertilizers increase both the Ca and Mg content of grain and straw. The increase is much more marked in the case of calcium. 4. At both the locations the total P content of the soil is found to be significantly enhanced by the phosphatic fertilizer treatments. The highest total P content was recorded 20 days after transplanting and there is a progressive decrease in total P with time. 5. At Vellayani, super phosphate is found to be significantly superior to the other two rock phosphate in enhancing the available P status of the soil. But there is no significant difference between the two forms of rock phosphate in enhancing the available P. At Moncompu all the phosphatic treatments ie. super phosphate, mussoorie rock phosphate and Rajasthan rock phosphate were found to be equally good in enhancing the available P. The difference in response might be due to the difference in pH of the two soils. The highest available P content was recorded at 40th day at Vellayani and on 60th day at Moncompu.Thus there is variation in the period of submergence required for the attainment of peak value in available P in the two soils. Soil to soil variation is partly responsible for this. 6. Fe- P fraction of the soils treated with phosphatic fertilizers increase with period. Maximum Fe- P was recorded by super phosphate. However between the two rock phosphate there is no significant difference. Maximum Fe- P was recorded at 40th day of water logging. At Moncompu all the phosphatic fertilizer treatments significantly enhance the Fe- P content. All the phosphatic fertilizer forms significantly increase the Al- P fraction over control. But there is considerable variation in the behaviour at the two locations. The treatments significantly enhance the Al- P level at Moncompu than at Vellayani. The peak Al- P was recorded at 40th day at both the locations. There is progressive decrease in reductant soluble P and occluded P as the period progresses. The pattern was followed irrespective of soil types. The progressive decrease in reductant soluble P is accelerated by phosphatic fertilizer treatment in kayal and Moncompu soils. Same is the case with occluded P. The treatments with phosphatic fertilizers increase the Calcium P fractions in all the soils. Application of Mussoorie rock phosphate and Rajasthan rock phosphate as well as super phosphate enhance the Ca- P fraction. There is not much difference between the locations in enhancing the Ca-P fraction with respect to the treatments. Saloid fraction reach a peak value by 60 days of water logging. The results of the present study indicate that Rajasthan rock phosphate compares very well with super phosphate and Mussoorie rock phosphate under water logged situations. Its lower cost will substantially contribute towards reducing the input cost of phosphates under acid rice soil conditions. The studies on the pattern of dissolution give an indication that its solubilization and conversion to more available forms can be put to greater advantage in the growing of a rice crop by synchronizing the peak period of utilization of phosphate by the rice crop with the peak period of availability by shifting the basal application of rock phosphate by about 10 to 15 days perior to transplanting or sowing, in situations where such a practice is feasible.