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ThesisItem Open Access Availability indices for stressed nutrients for coconut (Cocos nucifera L) in an ultisol(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 2003) Priya, P; KAU; Sureshkumar, PThe present study was conducted with an objective to analyse the soil-plant system, the levels and interactions of nutrient ions in soil, soil solution and plant thereby / finding out the contributing factors to yield. The importance of the term relative intensity lies in the fact that the contribution of mineral elements to growth and yield of plants depend much on the relative amount of one element with respect to the others rather than the absolute content of individual elements. To study the ionic interactions and to unravel the role of Net Ionic Equilibrium based on Ratio Law on soil plant system, a sample of fifty phenotypically identical palms varying in yield from 14.4 to 84.4 nuts palm" year"! grown under an Ultisol were selected. Index leaf samples were collected during pre and post monsoon seasons from 25 palms each from high yielding and low yielding groups. Soil samples were also collected from the basins of these palms during the same seasons at 30 cm (surface) arid 60 cm (subsurface) depths. Soil solutions at saturation point were extracted from the surface samples by centrifugation technique. These leaf, soil and solution samples were analysed / . for different nutrient ions, and the NIE ratios in these three phases were worked out with respect to K and Na. The soil samples were acidic in nature and the variation in rhizosphere pH must have definitely influenced the solubility as well as absorption of different nutrient ions. In the case of available nutrients, the micro nutrients showed significant direct relation with yield both for high and low yielding populations. This might be due to their restricted availability due to aerobic oxidised condition where Fe and Mn might have been precipitated and got into unavailable forms. The BaCh exchangeable ions and the CEC derived from summing up of these exchangeable ions influenced yield directly. Exchangeable K had got a significant dominance in deciding the NIE ratio in soil, solution and in index leaves. Exchangeable K controlled the soil solution concentration of K which in turn controlled the NIE ratio in solution and the ratios in plant. Exchangeable K directly controlled the plant K content and plant K was positively and significantly correlated with the NIE ratios in plant and these ratios were positively and significantly correlated with yield. The negative significant correlation of exchangeable K with plant Mn and Zn revealed the antagonistic effect of exchangeable K in restricting the absorption of Mn and Zn by plants. Among the ionic concentrations in soil solution, Fe was positively and significantly correlated with yield in both the seasons. Soil solution concentrations of Ca and Mg were antagonistically and significantly related with plant Mn content. Potassium content and the NIE ratio in index leaves were found to have a significant direct relation with yield in the pre-monsoon season. Potassium, Ca and Mg were the dominant cations in plant deciding the total cation concentration in index leaves. The NIE ratios between the exchangeable ions, the ions in soil solution and the ions in index leaf samples were mutually, .positively and significantly correlated among themselves. This lead to the conclusion that there exists a constancy in the relative proportion of nutrient ions in the entire soil-plant system which followed Ratio Law. The study lead to the conclusion that the soil test values of the individual ions alone or the plant content of individual ions alone can't give a clear picture of optimum nutrient requirements for the plant. The relative concentration of K in soil through the ~ concentration in soil solution was found to govern the relative concentration in plant which in turn influenced the yield.ThesisItem Open Access Soil test crop response studies on coleus (Solenostemon rotundifolius Poir J.K Morton) in the laterite soils of Kerala(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 2003) Nagarajan, M; KAU; Hassan, M AInvestigation entitled" Soil Test crop response studies on coleus in laterite soil of Kerala" consisting of two experiments namely fertility gradient experiment and STCR experiment was conducted during 2002 in the farm attached to the College of Horticulture, Vellan ikkara. Objective of the study was to develop soil test based balanced fertilizer recommendation for specific yield targets of coleus in laterite soils of kerala and provide a basis for fertilizer recommendation for maximum and economic tuber yield at varying soil test values. The fertility gradient experiment was conducted to create desired gradient in soil fertility in one and the same field by applying graded doses ofN, P, and K fertilizers and raising fodder maize var.Co.l. After development of fertility gradient, the STCR experiment was conducted in the same field with the test crop, coleus variety Nidhi.The treatment structure consisted of four levels of N (0,20,40, and 80 kg ha'), three levels of P20S (0,45 and 90 kg ha-I) and five levels of K (0, 25, 50, 100, 200 kg ha-I) along with three levels of FYM (0, 7.5 and 15 t ha-I) The nutrient requirement of coleus, variety Nidhi were estimated to be 9.15,1.38 and16.38 kg ha-I N, P20S and K20 respectively to produce one tonne of tuber. The soil efficiencies worked out as 21,46.85 and 40.85 per cent for N, . , P205 and K20 respectively for coleus in laterite soil. The contribution of nutrients from the fertilizers for coleus was calculated as 61.6,9.57 and 56.60 per cent for N, P205 and K20 respectively. From the above basic data, fertilizer prescription equation for specific yield targets of coleus variety Nidhi in the laterite soil were derived as follows, Without rVM FN =14.85T-0.34SN FP205 =14.42T-l J.21SP FK20 =28.98T-0.87SK FN, F P20S, F K20 - Fertilizer N, P20S and K20 respectively T - Target yield of tuber in t ha-I SN, SP, SK - Soil available N, P and K in' kg ha-I respectively . WithFYM FN 14.85 T - 0.34 SN - 0.34 ON 14.42 T - 11.21 SP - 3.25 OP F K20 = 28.93 T - 0.87 SK - 1.22 OK Where, ON, OP and OK are quantities ofN, P and K supplied through organic manure in kg ha" Multiple regression models calibrated with yield as dependent variable and STVs for available N, P and K and applied nutrients as independent variables had 67.4 per cent predictability. Among the three fertilizer nutrients, FN only showed the normal type (+, -, -) of response. The fertilizer adjustment equation fur v,!rying levels of soil available N for maximum tuber yield (t ha") of coleus in laterite soil was derived as FN= 168 SN, where FN is fertilizer N (kg ha"): SN is available N (kg ha-I) is soil. The behavior of applied p and K was found to produce responses other than normal and hence optimization coula not be done for fertilizer P and K at varying soil test values. Simple correlations coefficient was worked out for Nutrient uptake, soil available nutrients, applied nutrients with yield of coleus. Available nutrients -! showed higher positive correlation" than that of allied nutrients. The uptake of nutrients (N, P and K) also significantly correlated with yield of coleus. This study is useful to adjust fertilizer doses based on the specific objective and available resources of coleus farmers of the state.ThesisItem Open Access Effect of sulphur on yield, quality and uptake of nutrients by Cowpea (vigna unguiculata L. Walp) in a Rhodig Haplustox(Department Of Soil Science And Agricultural Chemistry,College Of Agriculture, Vellayani, 2000) Beena, V I; KAU; Usha, P BThe proposed piece of research work entitled " Effect of sulphur on yield, quality and uptake of nutrients by cowpea (Vigna unguiculata L Walp) in a Rhodic Haplustox" was conducted at Instructional farm,College of Agriculture, Vellayani. The study WHS undertaken to evaluate the effect of different levels and sources of sulphur application on yield, quality and uptake of nutrients by cowpea using the var Kanakamoni. The experiment was laid out in RBD with three replications. Combination of three factors, organic manures (FYM), NPK fertilizers and sulphur constituted the ten treatments. Sulphur was applied through two sources viz gypsum and factamphos. Different levels of S application were I) no sulphur 2) S @ 15 kg ha,l and 3) S @ 30 kg ha,l. All treatments included normal NPK applied through urea,mussooriephos and MOP at the rates of 20:30: 1 0 kg ha". FYM application was also done at two levels i.e.treatrnents with FYM and without rYM. Growth characters like height of the plants, number of branches per plant, number and weight of effective nodules, chlorophyll content and NRA were significantly enhanced as a result of S fertilization.The treatment combination with 30 kg S ha,l along with POP recommendation recorded the maximum value in all these cases. Gypsum was found to be superior in all these cases execpt ip the case of number of branches per plant. Treatment with 30 kg S ha,l as gypsum along with POP recommendation recorded significantly minimum value for days to maximum flowering and N:S ratio. A 42 per cent increaese in yield over control was recorded by 30 kg ha" as gypsum along with POP recommendations. A significant increase in yield attributes and protein content (25.39%) was also noticed through S fertilization. Uptake of N,r, K, Ca, Mg and S was increased due to S fertilization indicating a synergistic effect. All the growth characters and yield attributes were best correlated with yield. Uptake of nutrients showed positive and significant correlation with yield, the best correlation being obtained at MFS. Yield is decided by the uptake of nutrients at MFS. N:S ratio and days to maximum flowering showed significantly negative correlation with yield. Field experiment revealed that S as well as combination of S with organic manures exerted significant effect on most of growth and yield attributing charecters of cowpea. The treatment combination with normal level ofNPK and FYM along with S @ 30 kg ha-I was found significantly superior to other treatments. Gypsum as the source was found to be superior to factamphos,ThesisItem Open Access Biotic enrichment of organic wastes from ayurvedic preparations(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 2003) Preetha, D; KAU; Sushama, K PThe study on the 'Biotic Enrichment of Organic Wastes from Ayurvedic Preparations' was conducted at College of Horticulture, Vellanikkara, during the period 2001-2003 using ayurvedic wastes from' Oushadhi, the Pharmaceutical Corporation (Indian Medicines), a Government of Kerala undertaking. The investigations were undertaken to standardise the substrate controlled' micro-environment as well as to identify the promising bioagents for the cornposting of Oushadhi wastes and to determine the effect of the best selected enriched compost on soil and plant. The standardisation of the best substrate and enrichment techniques were based on the principle of aerobic composting. The collected wastes were grouped into three different size categories such as unsieved, 4 mm sieved and 2 mm sieved. The enrichers used were cowdung, quail manure and their 1: 1 mixtures, each at 5, 10 and 15 percent levels respectively. As the introduced biotic agents, two types of earthworms (Eudrilus eugeniae and Eisenia foetida) and two fungal inoculi (Schizophyllus communae and Pleurotus platypus) were tried. They were compared with native macrofauna and micro flora so as to monitor their respective role in the composting process. Analysis of the alkaloid rich Oushadhi wastes with aromatic odour revealed that it contains the nutrients N, P and K as 2.03, 0.33 and 0.85 percent respectively, Biochemical composition of the same, included crude protein (12.67%), crude fibre (3c,.4%), crude lipid (6.3%), cellulose (35.7%) and lignin (37.9%). The temperature within the tre~tme~ts of compost was recorded daily and the fluctuations of pH were noted at fortnightly intervals. Based on these parameters, three distinct stages of ~omposting as mesophilic (upto 10 days), thermophilic (10-30 days) and maturity (30-60 days) were identified. Dehydrogenase activity was maximum (3119.3 ug TPF s" soil h-I) at thermophilic stage, followed by maturity and mesophilic stages. After the thermophilic stage, the earthworms were introduced and the counts with respect to Eudrilus eugeniae were more than that of Eisenia foetida at the two stages of sampling. Based on the C:N rati~ (11.4) and the least time take (48 days) for maturity the " best treatment was selected, 'which registered manurial contents ofN (3.62%), P (0.85%) and K (0.89%). In the same material, the biochemical constituents of crude fibre (13.9%), crude lipid (0.7%), crude protein (12.68%), lignin (28.2%) and cellulose (18.8%) were determined. The best means of composting involves the use of the unsieved substrate which must be enriched with 5 per cent mixture of cowdung and quail manure (1: 1 ratio) and later vermicomposted with Eisenia foetida. So as to evaluate the effect of the selected enriched compost, the much responsive crop amaranthus was field tested for a period of two months. The selected enriched compost was tested at two rates (5 t ha"1 and 2.5 t ha"I), with and without full and half levels of recommended package of NPK fertilizers, along with FYM and absolute control. Recording of growth and yield parameters, nutrient uptake studies and determination of nutrient removal were undertaken during the period of study, April-May 2003. The results indicated that with higher doses (5 t ha"l) of the selected enriched compost along with 50:50:50 NPK gave the maximum yield followed by the treatment in which 2.5 t ha"1 of selected enriched compost along with 50:50:50 NPK was applied.ThesisItem Open Access Aerobic composting and enrichment of ayurvedic waste(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 2003) Lekshmisree, C S; KAU; Betty BastinThe study on "Aerobic Composting of Ayurvedic Waste" was conducted at College of Horticulture, Vellanikkara during the period 2001-2003, to investigate the basic physico-chemical properties of Oushadhi waste material, standardize formulations of enriched compost from the waste material and also to determine the effect of compost on plant and soil. . The waste material for the .study was collected from the manufacturing unit of Oushadhi pharmaceuticals l6c~d at Kuttanelloor, 8 km east of Thrissur. The factory produced nearly 1 tonne of waste per day during the manufacture of various products like Lehyam, Arishtam, Choomam, Kalkam etc. Hence the safe disposal of these wastes was a serious problem. A preliminary study was conducted to confirm the basic physico-chemical properties of the waste material for a period of 6 months by taking composite samples from the factory at an interval of 10 days. Temperature, pH, microbial count, colour, odour and consistency as well as the major nutrient contents of the waste material were analysed during the time period. Then the waste material were categorised into three substrates namely unsieved (01), 4 mm sieved (02) and 2 mm sieved (03) fractions. Then each substrate was enriched with organic and inorganic enrichers at different levels. The organic enrichers used were cowdung, poultry manure and neemcake each at 5, 10 and 15 per cent of substrate and also their mixtures. The study involved aerobic composting of enriched treatment combinations in pots of size 30 x 32 cm2. Temperature was measured daily and other parameters like pH, dehydrogenase activity and C: N ratio were monitored at 10 days interval throughout the composting process. The end phase of the bioprocessing was arrived at through indications on stabilisation of temperature, pH and the quality of material. Nutrient quality of the composted waste material was arrived at by analysing the content of N, P and K at initial and [mal stages of comp 0 sting. The best selected enriched compost was used to study the effect on plant and soil. It was field tested using amaranthus (var. Arun) near the vegetable farm of Department of Olericulture. The selected enriched compost was tried at three levels - 5, 2.5 and 1 t ha". A combination of the selected enriched compost at these three levels along with full doze and half doze of recommended NPK was also tried. For comparing the efficiency of the compost over FYM, FYM @ 5 t ha-I and FYM 5 t ha-I along with full dose of recommended NPK was also tried. An absolute control was also tried in field. The pot experiments on composting revealed that the selected enriched compost was superior in nutrient contents compared to ordinary composts. This enriched compost contained 3.25, 0.36 and 0.68 per cent N, P and K respectively. Apart from its nutrient value compost observed was odourless and fme textured near neutral pH of 6.37. The compost matured within 50 days resulting in a favourable C:N ratio of 12 at maturity. With respect to organic and inorganic enrichers, eventhough the nutrient content was' high in inorganic enrichment the time taken for attaining maturity was low in organic enricher' treatment combinations due to the high temperature registered by these treatment combinations during all periods of composting. . From the field study, it was inferred that with higher doses of selected compost, there was corresponding increase in growth and yield in test crop. However the selected compost at the highest level i.e. 5 t ha-I with full dose of recommended NPK emerged as the best treatment for economic yield return. This treatment also witnessed the increased build of available nutrient status of soil. This treatment could bring down expenditure for raising the crop without affecting the yield. The SEC application also resulted in increased nutrient availability by increasing the CEC and water holding capacity of soil.ThesisItem Open Access Effect of major nutrients on the yield and quality of nuts in graft-raised cashew (Anacardium occidentale Linn.)(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 2002) Nair Rajiv, R K; KAU; Sam, T KurumthotticalAn experiment was conducted to study the "Effect of major nutrients on the yield and quality of nuts in graft raised cashew" at Cashew Research Station Madakkathara Kerala. The treatments consisted of three levels each of N, P and K on eight year old cashew trees. The salient findings are abstracted below. The study revealed that increasing levels of nitrogen significantly increased the height and spread of cashew trees, while the girth was significantly increased by the interaction effects of nitrogen and potassium. The yield parameters such as number of flushes, number of leaves per flush, number of panicles and the number of nuts per panicle were significantly enhanced by the application of nitrogen at increasing levels, while the application of phosphorus at increasing levels also significantly increased the number of nuts per panicle. The yield of cashew nuts and apples were significantly increased due to the highest level of nitrogen applications. Application of potassium at the highest level also significantly increased the apple yield per tree. Weight and volume of cashew apples was significantly increased by the application of increasing levels of potassium but nitrogen application was found to significantly decrease the weight of fruits. The juice percentage was positively and significantly influenced by the application of nitrogen and potassium. Potassium applications were found to significantly increase the nut length and weight while nitrogen applications were found to reduce the nut weight. Shelling percentage of cashew nuts was enhanced by the application of nitrogen and potassium at increasing levels. The kernel weight was increased due to the application of potassium. Ascorbic acid content of cashew apples was positively influenced due to the application of increasing levels ofNPK. The Total Soluble Solids of the apple was significantly enhanced by the application of nitrogen. Applications of nitrogen alone and in combination with phosphorus were found to increase the protein content of kernels. The carbohydrate, Non-reducing sugars and reducing sugars content of kernels were significantly enhanced by the application of different levels of nitrogen. Increase in the soil major nutrient content due to the individual effects of nitrogen, phosphorus and potassium applications were also observed. The leaf phosphorus and potassium content was enhanced specifically due to the application of increasing levels of phosphorus and potassium respectively, while the nitrogen content of leaves was positively influenced by the application of nitrogen and phosphorus. The average nutrient off-take through nuts and apples was computed to be 279.43, 4l.58 and I 86.40g of nitrogen, phosphorus and potassium respectively. The average nutrient off take per tree through nuts from an average yield of 2.89 kg tree" was found to be 93.56, 2.89 and 48.85g of nitrogen, phosphorus and potassium respectively and through apples was found to be 185.87, 38.69 and 137.54g of nitrogen, phosphorus and potassium respectively from an average yield of 18.20 kg tree". In 'general, among the major nutrients applied at different levels only nitrogen had shown exceedingly high effects in sustaining the growth, yield and quality parameters. The yield and quality parameters were also seen to be affected to a certain extent by potassium applications but the response of the crop to phosphorus was seen to be exceedingly limited.ThesisItem Open Access Substitution of muriate of potash by common salt in banana Musa (AAA group CAVENDISH subgroup) ‘Robusta’(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2001) Sunu, S; KAU; Sudharminidevi, C RA field experiment was conducted III the College of Agriculture, Vellayani during August 1999 to June 2000 to study the extent of substitution of K of muriate of potash by Na of common salt in banana cv. Robusta. Four treatments involving four levels of K at 25, 50, 75 and 100 per cent of recommended dose and four treatments substituting K with N a at 25, 50, 75 and 100 per cent were tried in RBD with three replications. The plant growth parameters like plant height, pseudostem girth, number of functional leaves and LAI varied significantly due to treatments at all growth stages. These parameters in the 100 per cent K and 50 per cent K plus 50 per cent Na treatments were on par at all growth stages. Chlorophyll content and RLWC showed an increase with the addition of Na along with K. Highest bunch yield was recorded in the 50 per cent K plus 50 per cent N a treatment followed by the yield in the lOO per cent K treatment. The yield attributes like length of bunch, number of hands per bunch, number of fingers per bunch, length and girth of fingers reflected similar trends. The quality of fruits as reflected in the total soluble solid content, total sugar content and acidity was as good in 50 per cent K plus 50 per cent N a treatment as in 100 per cent K treatment. With increase in the levels of substitution above 50 per cent there was reduction in total soluble solids and sugar content. Shelf life of fruits did not vary significantly due to treatments. Pulp/peel ratio in the 100 per cent K and 50 per cent K plus 50 per cent N a treatments were on par. Pulp/peel ratio decreased significantly with increase 10 substitution of K by Na above 50 per cent level. The uptake of nutrients except N a was higher at the 50 per cent K plus 50 per cent N a treatment and decreased with increase in substitution of K by Na above this level. Na uptake increased upto 75 per cent substitution of K by N a and decreased at 100 per cent substitution. The treatments did not have any influence on the soil physical and chemical p-roperties. Bunch yield was positively and significantly correlated to plant girth (2MAP), chlorophyll content and LA!. It can thus be concluded that upto fifty per cent of the K requirement of Robusta banana, grown in soils of low K status, can be replaced by Na of common salt.ThesisItem Open Access Persistence of selective herbicides in rice -rice system(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 2003) Muthu Kannan, M; KAU; Durga Devi, K MThe study entitled "Persistence of selective herbicides in rice-rice system" was the part of 'permanent herbicide trial' of All India Coordinated Research Programme on Weed Control conducted during the years 2001 and 2002 with the objective of determining the persistence of butachlor, pretilachlor and 2,4-D in the rice-rice cropping system. The effect of herbicides on soil microflora, weed growth and nutrient content were also studied. The field experiments were conducted during 2001 to 2002 at Agricultural Research Station, Mannuthy. Residue studies related to field experiments were conducted at Herbicide Residue Laboratory of All India Coordinated Research Programme on Weed Control, Thrissur Centre, located at Radio Tracer Laboratory, College of Horticulture, Vel1anikkara. Microbiological studies and physico chemical analysis of the soil samples were conducted at College of Horticulture, Vellanikkara. The technical programme consisted of six treatments namely (i) hand weeding twice (25 and 40 DAS); (ii) butachlor fb 2,4-D (with 100% NPK as inorganic fertilizer) in the first and second crop seasons of 2001 and 2002; (iii) butachlor fb 2,4-D (with 100% NPK as inorganic fertilizer) in the first crop season of 2001 and 2002, pretilachlor fb 2,4- D (with 100% NPK as inorganic fertilizer) in the second crop season of 2001 and 2002; (iv) butachlor fb 2,4-D (with 75% NPK as inorganic fertilizer and 25% through FYM) in first crop of2001 and 2002, pretilachlor fb 2,4-D (with 100% NPK as inorganic fertilizer) in second crop of 2001 and 2002; (v) butachlor fb 2,4-D (with 100% NPK as inorganic fertilizer) in the first and second crop of 2001, pretilachlor fb 2,4- D (with 100% NPK as inorganic fertilizer) in the first and second crop of2002 and (vi) butachlor fb 2,4- D in the first and second crop of 2001 (with 75% NPK as inorganic fertilizer and 25% through FYM in the first crop and 100% NPK as inorganic fertilizer in the second crop), pretilachlor fb 2,4-D in the first and second crop of 2002 (with 75% NPK as inorganic fertilizer and 25% through FYM in the first crop and 100% NPK as inorganic fertilizer in the second crop). The pre-emergence herbicides butachlor @ 1.25 kg a.i ha-1 and pretilachlor @ 0.75 kg a.i ha-1 were applied at 8 days after sowing for the control of grassy weeds. 2,4-D @ 1.00 kg a.i ha" was applied at 20 days after sowing for the control of broad leaved weeds. Persistence of the above three herbicides applied in first and second crop of 2002 was estimated at one and 30 days after spraying and at the time of harvest. Residues of butachlor at one day after spraying ranged from 0.331 to 0.396 ug g-l in first crop of 2002. The highest concentration of 0.396 ug g-l was recorded in the plot where butachlor was applied with 75 per cent NPK as inorganic fertilizer and 25 per cent through FYM. About 95.21 to 97.66% of the applied butachlor dissipated from the soil by 30 days after spraying. Greater dissipation was observed in the FYM applied plots (97.66%). The application of FYM enhanced the microbial degradation which resulted in higher dissipation of butachlor. In the second crop, only one plot received butachlor spraying which recorded residues of 0.343 ug g-l at 1 day after spraying and 0.020 ug g-l at 30 days after spraying. Residues of pretilachlor at one day after spraying ranged from 0.200 to 0.215 ug g-l in the first crop season and 0.199 to 0.250 ug i1 in the second crop season. At 30 days after spraying residues ranged from 0.020 to 0.013 ug g" and 0.010 to 0.030 ug g-l in the first and second crop season respectively. As in case of butachlor higher degree of dissipation was observed in FYM applied plots (97.47 to 98.05%). Residues of 2,4-D at one day after spraying ranged from 0.310 to 0.502 ug g-l in first crop season and 0.395 to 0.480 ug g' in second crop season of 2002. At 30 days after spraying the residues ranged from 0.035 to 0.010 ug g' in first crop and 0.016 to 0.005 ug g-l in second crop season. Up to 97.81 to 99.27 per cent of 2,4-D had been dissipated from the plots which received FYM. In the other plots percent dissipation of 2,4-D from the soil was 94.89 to 97.81 per cent. On comparing the extent dissipation of butachlor, pretilachlor and 2,4-D it was found that 2,4-D had been dissipated to a higher magnitude than butachlor and pretilachlor. At the time of harvest residues were not detected in soil, rice grain and straw. Studies on the effect of herbicides on soil bacterial population showed that the total number of bacteria in the soil had been considerably reduced by spraying herbicides. The extent of reduction was maximum (95.24 to 96.80%) at 7 DAS. The inhibitory effect of pretilachlor on soil bacteria was comparitively less than that of butachlor. The herbicides reduced the population of soil fungi. However, the magnitude of reduction was less than that of soil bacteria. It was also observed that butachlor and pretilachlor inhibited fungal population to the same degree (76.80%). Actinomycetal population in the soil was also inhibited by the application of herbicide and the maximum percent inhibition (77.00 to 85.00%) was at 15 DAS. Effect of butachlor on supression of soil actinomycetes was found to be intermediary to bacteria and fungi. In the plot where FYM was applied, population of bacteria, fungi and actinomycetes were higher than that of other plots, which gave an indication that FYM could reduce the adverse effect of herbicides on soil rnicroflora. The data on weed count and dry matter production of different weed species showed that Echinochloa spp. contributed very much to total weed population and total dry weight. Build up in the population of Echinochloa spp. was observed with continuous use of pre emergence herbicides. The plot where pretilachlor fb 2,4-D was applied with 100 per cent NPK as inorganic fertilizer recorded higher counts of Echinochloa spp. Application of 2,4-D was effective in controlling broad leaved weeds. None of the broad leaved weeds showed build up in the population. The plot which received butachlor fb 2,4-D with 100 per cent NPK as inorganic fertilizer recorded highest grain and straw yield. From the study it could be concluded that at the present recommended rate of application, residues of herbicides butachlor, pretilachlor and 2,4-D do not persist in paddy soil to detectable level beyond 30 days. Residues were not detected in the grain and straw. Application of FYM enhanced microbial degradation of herbicides and reduced the adverse effect of herbicides on soil microflora. 2,4-D was highly efficient in controlling broad leaved weeds in the rice-rice system. Both pretilachlor and butachlor controlled grasses except Echinochloa spp. Butachlor had shown its superiority over pretilachlor in the weed management of rice-rice cropping system.ThesisItem Open Access Soil resource inventory of the main campus Kerala Agricultural University Vellanikkara: Part II (WEST)(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 2000) Sajnanth, K; KAU; Saifudeen, NKerala Agricultural University is situated in Madakkathara panchayat in Thrissur district. It is having an area of about 380 ha in its main campus in Vellanikkara. The main campus includes three colleges and the areas of three Research Stations. In this campus, so many research works are going on in different fields. Thus the knowledge about the resource capacity may help in the production scenario of the University itself. In this ~ inventory, the western part of the. main campus, which includes the areas of Research stations and Farms .occupied mostly by perennial crops. For identification of sample sites, a 1 :2000 scale map of the campus was used.' A grid size of 80 m x 80m was used to locate the sites. ThF study area constitutes 12 blocks out of 37 in the campus. The samples were taken ~rom both surface (0-20cm). and subsurface (20-40cm) layer. Altogether 518 soil samples, collected from the 23 phases of the study area, were analysed by standard procedures to record their physical, chemical arid electrochemical properties. The surface and subsurface samples were analysed for available nutrients and other fertility parameters. The soils are gravelly in nature in surface and subsurface samples. Still an increase in amount of fine earth from surface to subsurface level was noted. The particle size analysis of the soil samples revealed that most of the samples were sandy clay loam in nature. In most of the soils, the texture was same for surface and subsurface samples. The data obtained on the soil components were used for their textural classificatio~. The most of the soil samples were acidic in nature. The electrical conductivity of almost all the samples was found to be very low in every phase. Buffer pH and hence the lime I requirement of the sa~ples has a very wide range among the soil phases. The organic carbon contents were medium in most of the soil samples. It is high in surface layer than subsurface in majority of the phases. Available phosphorus was generally low in content in 60 - 90% of samples. About 25% were in medium class. The potassium content was rated as low in 56% of the surface samples and 66% of subsurface samples. Among the secondary nutrients, both available calcium' and magnesium were recorded in a wide range in the soils. In Micronutrients, manganese was the highest content followed by iron. All the soils are above critical range in both cases. In copper 96% of surface and 86% of subsurface contents were in above critical range. But in general, zinc was low in concentration. About 88% of surface and 94% of subsurface samples were in below critical range. The P fixing capacity of all the soils was found to be high. In the exchangeable complex, the order of concentrations of the ions were Ca>Mn>Na>K>Al>Fe. The cation exchange capacity of the soil was low since a good amount of cations were leached off during the rainy season. The percentage base saturation was high. Percentage sodium saturation was higher than 15%. The regression analysis of the data revealed that the relative factor for exchangeable K -and Na with respect to other multivalent ions could be better expressed as K/CCa + Mn)1I2 + CAl)1I3 ions. The generated data were used for the study of nutrient interactions in the study area. Using the potential of Geographic Information System CGIS), the soil fertility map of the study area for the major parameters such as soil texture, organic carbon, available P and K were prepared. The present study outlines the need for significant changes to be made in soil survey and preparation of maps. The properties of soils, in phase wise manner were used for Fertility Capability Classification with its limitations. From the FCC notation, the . problems and limitations of the soils can be estimated. Incorporation of fertility parameters of the already defined soil units will enhance the utility of soil maps. The soil maps with FCC units super imposed will help in the delineating areas with similar limitations and management requirement. The information regarding the properties of soils of the western part of the main campus, can be manipulated for the planning and motivating the cultivating practices and thus attain the maximum output with available resources.
