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  • ThesisItemOpen Access
    Availability indices of potassium in an ultisol under coleus cultivation
    (Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 2007) Santhosh, C; KAU; Mariyam, K A
    A field experiment was carried out in the main campus of College of Horticulture, Kerala Agricultural University, Vellanikkara to study the availability indices of potassium in an Ultisol under the coleus cultivation. The experiment was laid out in a randomized block design with eight treatments and three replications. The treatments consisted of eight different levels of potassium. All other crop management practices were done uniformly in all plots as per the recommendation of KAU. Observations on biometric parameters as well as yield attributes were recorded during the cropping period. The soil, shoot and tuber were analysed for the various nutrients. The quantity of potassium extractable by various reagents was also estimated at these three stages. The Q/I parameters were estimated for the soil under study and the thermodynamic parameters related to K supplying power of soil were worked out. Tuber number and tuber yield were significantly influenced by the potassium application up to 60 kg K2O ha-1. The size of the tuber was not significantly affected with potassium application. Available potassium status that increased linearly with the levels of K did not affect the availability of P where as availability of N increased during the active growth stage of the coleus. Available potassium increased significantly with the levels of K application. Availability of exchangeable Al and Mn in soil got reduced with the increased levels of K. Even though the nitrogen and potassium content in shoot increased with the levels of K application at active stages of crop growth it had not reflected in the final yield. Calcium and aluminium absorption were found to reduce with increase in available K. Nitrogen and phosphorous content in the tuber reduced towards the harvest of crop. Calcium and magnesium content in tuber was influenced by K application where as K content in tuber was not increased with the levels of K. At all stages of analysis the quantity of K extracted with all reagents increased with the levels of potassium application in the soil. The water soluble, exchangeable and non-exchangeable potassium were reduced from initial stages towards harvest indicating the crop utilization and the presence of dynamic equilibrium between the various forms of potassium. Correlation studies conducted between yield attributes and quantity of K extracted revealed positive correlation between tuber yields and tuber number with water soluble and exchangeable K. The quantity-intensity parameters estimated at temperatures viz. 25°C and 40°C showed that the desorption of potassium is more at higher temperature indicating the higher availability of K in summer season. The potassium adsorption of soil under study followed the Freundlich adsorption isotherm both at 25°C and 40°C.
  • ThesisItemOpen Access
    Rock dust as a nutrient source for coleus (solenostemon rotundifolius (POIR) morton)
    (Department Of Soil Science And Agricultural Chemistry,College of Agriculture, Vellayani, 2008) Divya, S S Rose; KAU; Shehana, R S
    The effect of application of rock dust at different rates alone as well as in combination with FYM and chemical fertilizers and the resultant effect on growth and yield of Coleus (Solenostemon rotundifolius) var. Sreedhara was evaluated by conducting a laboratory incubation study and field experiment at College of Agriculture , Vellayani during 2006- 2007. The results of the incubation study revealed that increasing the rate of application of rock dust resulted in an increase in the available nutrient contents of soil. Application of rock dust in conjunction with an equal quantity of FYM also enhanced the availability of all the major as well as minor nutrients. The pattern of release of available N was found maximum during 30th day of incubation and for P, the highest value was recorded during 120th day of incubation. The release of K was found to increase over time reaching the maximum during the later part of the study. The pattern of solubilisation of micronutrients viz. Fe, Mn and Zn revealed that there was a gradual increase in their concentration from the start of experiment, reaching the highest values during the later stages of incubation. Application of rock dust at a higher rate i.e.12 t ha -1 along with an equal quantity of FYM resulted in the maximum release of almost all the nutrients viz. N, P, K, Fe, Mn, and Zn through out the incubation period. Addition of rock dust along with an equal quantity of FYM resulted the percentage increases from 7 to 17.5, 19.50 to 29.22, 22.95 to 45.38, 10.47 to 14.14 15.58 to 26.36 and 1.3 to 8.6 respectively for available N, P, K, Fe, Mn and Zn when compared to the application of rock dust alone. The results from the field experiment conducted to evaluate the efficiency of rock dust revealed that the plant growth characters like number of branches per plant at 90 DAP and plant spread at 60 DAP showed significant variation due to the application of rock dust @ 10 t ha -1 mixed with equal quantity of FYM and kept for 15 days before the field application. Leaf chlorophyll concentration was increased by 47.36 per cent due to the application of rock dust when compared to POP recommendation. Yield component like number of tubers per plant was also increased by 14.81 per cent due to the application of rock dust. Application of rock dust @ 10 t ha -1 along with equal quantity of FYM and 50 per cent of the chemical fertilizers NPK @ 30:30:50 kg ha -1 also produced yield (17.26 t ha -1, B. C ratio 2.63) equivalent to POP (19.55 t ha -1, B. C ratio 2.39). This treatment also produced the highest number of tubers per plant, dry matter content of plant parts and total dry matter production. The highest yield of 19.55 t ha -1 was obtained for POP recommendation. But application of rock dust along with half the recommended dose of NPK and FYM also produced the similar yield as (17.26 t ha -1) that of POP recommendation. This shows that partial substitution (50 per cent) of chemical fertilizers with rock dust can be recommended to the farmers where ever it is locally available. The starch content and cooking quality of the tubers were also favoured by the application of rock dust @ 10 t ha -1. Starch content increased by 35.02 per cent due to the application of rock dust. Priming rock dust with FYM two weeks prior to field application resulted in the maximum release of P, K, Ca, Mg, Fe, Mn and Zn from rock dust. Rock dust application resulted in the percentage increases of 34.55 to 43.12, 47.96 to 58.49, 20, 17.55 to 55.00, 74.50 to 78.69 and 20 for P, K, Mg, Fe, Mn and Zn respectively when compared to the application of inorganic fertilizers for coleus. Rock dust @ 10 t ha-1 along with equal quantity of FYM resulted in the highest returns per rupee invested (B.C ratio 2.89). It can be concluded from the results of the study that the present recommended dose of in organic fertilizers for coleus can be reduced to half provided it is applied along with rock dust @ 10 t ha -1 . 100 per cent substitution of chemical fertilizers with rock dust 10 t ha -1 and FYM 10 t ha -1 can be recommended for coleus wherever rock dust is locally available.
  • ThesisItemOpen Access
    Yield maximisation in rice (Oryza sativa L) in the acid sulphate soils of Kuttanad through systematic approach in fertilizer use
    (Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2007) Annie, Koruth; KAU; Venugopal, V K
    Cereals are the world’s major source of food for human nutrition. Among these, rice is very important and represents the staple diet for more than two-fifths (2.4 billion) of the world’s population, making it the most important food crop of the developing world. Rice is the staple food of Kerala and is the only cereal crop of significance to the food basket of the State. Kuttanad is the rice bowl of Kerala producing nearly 30% of the State’s rice output. The entire area is now planted with high yielding rice varieties adopting all improved agricultural practices including higher doses of fertilizers and pesticides. The problems associated with the application of heavy doses of fertilizers, leading to nutrient imbalance and economic loss to the farmer is a major constraint. Therefore improvement in soil health through balanced fertilization, leading to productivity increase and economic benefit to the farmer, will have a measurable impact on rice production in the state. With a view to realize the maximum economic yield in rice by optimizing the nutritional status of the soil, a series of experiments were undertaken under the present study entitled “Yield maximisation in rice (Oryza sativa L.) in the acid sulphate soils of Kuttanad through ‘systematic approach’ in fertilizer use”. This involved preliminary soil analysis, nutrient fixation study and green house nutrient survey to demarcate the nutrient constraints and also to optimize the soil nutrient status. The critical level of P & K for the soils of Kuttanad were also done since the basic concept of systematic approach is based on the critical level of nutrients in soil. Pot culture studies were undertaken to find out the critical level of P & K using maize as indicator crop. The soil test values of P & K were correlated with the per cent yield and a significant correlation was obtained only for P with yield. A quadratic relationship was observed with per cent yield and soil test P values. This relationship gave a critical level value of 11.17 mg I' 1 for P. But in the case of K, no such relationship was obtained. Fixation study conducted for P, K, Cu, Zn, Mn, S & B to find out if any of the applied plant nutrients, fixed or complexed abnormally with the soil indicated P, K, Zn, S & B as the limiting nutrients, and the optimum quantities of these limiting nutrients were determined as 224 mg f 1 P, 122 mg l"1 K, 5.8 mg f 1 Zn, 2 mg I' 1 S & 1.52 mg I' 1 B. The green house nutrient survey conducted to arrive at the optimum treatment revealed that, for formulating the optimum treatment, lime @ 0.07 g CaCC>3 100 ml' 1 soil, Ca @ 822.4 mg I'1, Mg @ 349 mg f 1, P, K, Zn, S & B at the above concentrations, Mo @ 2 mg I' 1 & N @ 100 mg I' 1 has to be added. There were 16 treatments. This experiment was conducted with Sorghum as indicator crop and the relative yield calculated from the biomass yield, recorded on the 45th day of planting revealed P only as the limiting nutrient for this particular soil. The quantity of P to be added to the optimum treatment was 224 mg I'1, which is 602 kg P ha'1. Since this is a very high and uneconomic dose for farmers to adopt, the Package of Practices Recommendations: Crops (POP) for medium duration rice variety, 45 kg P2O5 ha’1 was opted as the base and since P is the limiting nutrient, two higher doses, 60 & 75 kg P2O5 ha' 1 were tested as the three levels of P application. As balanced fertilization is a must for the rice crop, three levels of K were also included. Since K was not limiting, the POP recommended dose and two lower levels were tested, i.e., 15, 30 & 45 kg K2O ha'1. Thus the design for the field experiment was 3x3 Factorial RBD with an absolute control. Total 9+1 treatments. N @ 90 kg ha' 1 was applied to all treatment plots. The main effect of P & K and their interactions were studied. The field experiment was laid out for two consecutive seasons, Puncha (Rabi) 2004-05 (Nov. ’04 - March ’05) and Additional Crop (,Khan/) 2005 (May ’05 to Oct. ’05) in the experimental field of Rice Research Station (RRS), Moncompu, Kuttanad, Kerala. The medium duration rice variety, Uma (MO. 16) released from RRS, Moncompu with an average grain yield of 4.5 - 5.0 t ha' 1 was used for the experiment. The effect of these treatments on dry matter yield of shoot & root, soil & plant nutrient content and nutrient uptake of N, P & K at the critical stages of rice growth were studied. Biometric observations, yield and yield components were also recorded. For P, the limiting nutrient, significant differences in the phosphorus content of plant were observed when different doses of P were applied. The P content and uptake of grain and straw were not influenced during the Puncha season, while during the Additional Crop season it was significantly influenced by the varying doses of P. All the control plots recorded a significantly lower P content and uptake & low P soil status compared to treated plots on an average during both seasons. An increase in the application of K doses, resulted in a significant increase in the K status of soil during Puncha season, while during the Additional Crop season, this was not noticed and the treated plots were on par with control. With an increase in applied K, there was a significantly corresponding increase in K content in plant during the Puncha season, while during the Additional Crop season this was not so. The K content and uptake of grain and straw was not influenced during both seasons by the different doses of K but the treated plots recorded a significantly higher uptake
  • ThesisItemOpen Access
    Quantity - intensity relations of phosphorus with reference to its bioavailability in lateritic soils
    (College of Horticulture, Vellanikkara, 2008) Geetha, P; KAU; SureshKumar, P
    Five benchmark soils of lateritic origin were collected and used for the present study of Q-I relations, dynamics and transformations of P. Samples of these soils were collected from Kunnamangalam (Calicut), Angadippuram (Malappuram), Vellanikkara (Thrissur), Pattambi and Thirumittakkodu(Palakkad) . The soils were characterized with respect to pH, EC, CEC and exchangeable cations, AEC, available nutrient status ( Organic carbon, available P, K, Fe, Mn, Cu and Zn) and P fixing capacity The inorganic P fractions viz. soluble P, Al bound P Fe bound P, sesquioxide occluded P, and Ca bound P as well as organic P was estimated. The equilibrium phosphate potential and buffer power of these soils were estimated from the Q/I curve. Among the five soils, Vellanikkara soil series recorded the lowest available P and soluble P fraction, the highest P fixing capacity and highest adsorption maximum as per Langmuir equation Based on the above characteristics this soil was selected for pot culture experiments to grow cowpea as a test crop using three different amendments (Pongamia, Cleistanthus, and lime) three levels of labeled phosphatic fertilizer and two methods applications. Available P and fractions of phosphorus in the soil was estimated at three stages. P content as well as 32P counts in the plants were also estimated. A and L values were computed at 15 and 30 days after sowing. It can be concluded from the present study that application of different amendments dictated the transformation of P in soil. The available P, soluble P and %Pdff could be improved significantly. A different trend in radioactive phosphorus activity in available P as well as in A and L values indicated that the applied P though contributing to the available pool in amended soils, this might be routed through the inorganic fraction Ca-P and not directly coming to the soluble/labile pool.