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  • ThesisItemOpen Access
    Response of cucumber (Cucumis melo L.) to drip irrigation under varying levels of nitrogen and potash
    (Department of Agronomy, College of Agriculture, Vellayani, 1997) Lakshmi, S; KAU; Sasidhar, V K
    Two field experiments and one observational trial were conducted in the Instructional Farm, College of Agriculture, Vellayani during 1992 and 1993 to study the effect of drip irrigation and application of N and K fertilizers on the growth and yield of cucumber. In the preliminary observation trial (Experiment I a) three levels of drip irrigation, (2, 3 and 4 I plant-1 day-1) four timings of irrigation (1, 2, 3 and 4 hours) and two number of drippers per plant (1 and 2 dripper plant-1) were evaluated and based on the results of this experiment, the number of drippers per plant and duration of drip irrigation was standardised. Experiment 1 b was conducted to standardise the method of application of fertilizers in Experiment 2 and 3 for which cucumber plants raised under different levels of drip irrigation (2, 3 and 4 I plant-1 day-1). This was conducted during April 1992. The results of these experiments indicated the duration for drip irrigation as 3 hours per day and one number of dripper per plant to be the best. The spread and depth of root system of cucumber plants raised under drip irrigation pointed out that the fertilizers as a ring around the base of the plant at a distance of 20 cm will be within the root zone of the plant. The experiments 2 and 3 were laid out in the field with three levels of drip irrigation (2, 3, and 4 I plant-1 day-1), three levels of nitrogen (35, 70 and 105 kg ha-1) with three levels of potassium (25, 50 and 75 kg ha-1) with three drip irrigation controls (2, 3 and 4 I plant-1 day-1) and farmer's practice. The yield of cucumber was highest at the drip irrigation level of 31 planr-1 day-1. Irrigation at this level favourably influenced the vegetative characters, yield attributes and yield. But root dry matter was not influenced by the different drip irrigation level while the root spread and root depth were highest at the drip irrigation level of 41 plant-1 day-1. When different levels of nitrogen applied were observed, the vegetative characters yield attributes and yield were found to be favourably influenced at 70 kg N ha-1. The root spread of cucumber was highest at the highest level of N applied (l05 kg ha-1). Potassium at 50 kg ha-1 produced the highest yield due to its favourable influence on the vegetative and yield characters. There was no influence of potassium on my of the root characters studied. The soil moisture status was highest up to 30 cm depth in all drip irrigated treatments while in pot watered plots, the soil moisture was higher in the lower layers below 30 cm. The field water use efficiency was highest at the drip irrigation level of 3 I plant-1 day-1, 70 kg nitrogen ha-1 and 50 kg potassium ha-1. The nitrogen, phosphorus and potassium uptake by the plants and fruits were highest at the drip irrigation level of 31 plant day I, 70 kg N ha-I and 50 kg K ha-I. The physical optium levels of drip irrigation was 31 plant -1 day -1, 93 kg N ha-1 and 65 kg K ha-1 in the first season. When another crop is repeatedly grown in the same field, the Nand K levels can be reduced to 75 kg ha-1 and 60. kg ha-1 but drip irrigation is required at the rate of 31 plant-1 day-1. This resulted in higher benefit cost ratio of 2.83 and internal rate of returns of 23%. The payback period of this project worked out to 1.13 years.
  • ThesisItemOpen Access
    Soil test crop response studies in cassava in laterite soils of Kerala
    (Department of Agronomy, College of Agriculture, Vellayani, 1997) Kumari Swadija, O; KAU; Sreedharan, C
    An investigation was undertaken at the College of Agriculture, Vellayani to establish soil test crop response correlation for soil test based balanced fertilizer prescription for cassava var. M-4 in laterite soils of Kerala. The field investigation consisted of fertility gradient experiment, STCR experiment and technology verification trial. The fertility gradient experiment was conducted during April- May 1994 in the Instructional farm, Vellayani. The desired gradient in soil fertility was created in one and the same field by applying graded doses of N, P and K fertilizers and raising fodder maize var. African Tall. The STCR experiment was conducted in the same field during June '94-March '95 using the test crop, cassava var. M-4. The treatments consisted of factorial combinations of four levels of N (0, 50, 100 and 150 kg ha-1), three levels of P (0, 50 and 100 kg P2O5 ha-1) and five levels of K (0, 50, 100, 150 and 200 kg K20 ha-1) along with three levels of farmyard manure (0, 6.25 and 12.50 t ha-1) fitted in a response surface design. Using multiple regression model, the fertilizer adjustment equation for N at varying soil test values for available N for maximum tuber yield (t ha-1) of cassava in laterite soil was derived as FN = 136.6 - 0.2 SN where FN is fertilizer N (kg ha-1) and SN is soil available N (kg ha-1). The equation becomes FN = 136.6 - 0.2 SN - R for economic tuber production where R is the ratio of cost of one kg of fertilizer N to price of one kg of tuber. At varying soil test values for organic carbon% (OC) the above equations become FN = 226.13 - 378.13 OC for maximum tuber yield and FN = 226.13 - 378.13 OC - 1.25 R for economic tuber yield. The behaviour of fertilizer P and K was found to produce responses other than 'normal' and hence optimisation could not be done for fertilizer P and K for maximum and economic tuber yield at varying soil test values. The nutrient requirements of cassava var. M-4 were estimated to be 6.58, 2.37 and 6.28 kg N, P2O5 and K2O respectively to produce one ton of tuber. In the laterite soil, the efficiencies of contribution of nutrients from the soil for cassava were calculated as 40.17, 41. 3 3 and 48.60% N, P2O5 and K2O respectively. The fertilizer efficiencies were worked out as 54.38, 47 and 52.650% N, P2O5 and K2O respectively. The efficiencies of contribution of nutrients from farmyard manure were calculated as 78.24, 57.33 and 69.66%) N, P2O5 and K2O respectively. From the above basic data, fertilizer prescription equations for specific yield targets of cassava var. M-4 in the laterite soil were derived as given below. Without FYM FN = 12.10 T - 0.74 SN FP2O5 - 5.04 T - 2.02 SP FK2O = 11.93 T - 1.10 SK With FYM FN = 12.10 T - 0.74 SN - 1.44 ON F P2O5 - 5.04 T - 2.02 SP - 2.79 OP FK2O = 11.93 T - 1.10 SK - 1.58 OK where FN, F P2O5 and FK2O are fertilizer N, P2O5 and K2O respectively in kg ha-1, T is the target of tuber yield in t ha-1, SN, SP and SK are soil available N, P and K in kg ha-1 respectively and ON, OP and OK are quantities of N, P and K supplied through organic manure in kg ha-1 The technology verification trial was undertaken during June '96-March. '97 in the laterite soil in three farmers' fields in Thiruvananthapuram district and also in the Instructional Farm, Vellayani. The treatments consisted of Package of Practices recommendation for fertilizer, fertilizer recommendation by the Soil Testing Laboratory and fertilizer doses for the yield targets of 15, 20 and 25 t ha-1 along with a uniform dose of 6.25 t ha-1 of farmyard manure for all treatments. The fertilizer doses based on targeted yield equations recorded higher tuber yield and net income, benefit cost ratio and net returns per rupee invested over the fertilizer recommendation by the Soil Testing Laboratory and Package of Practices recommendation emphasising the need for site specific recommendation based on soil tests. The yield targets of 15 and 20 t ha-1 recorded more than cent per cent achievement and the yield target of 25 t ha-1 recorded about 90% achievement. Higher tuber yield, benefit cost ratio and net returns per rupee invested could be achieved for the yield target of 20 t ha-1. The fertilizer dose for the yield target of 15 t ha-1 recorded the highest returns per rupee invested on fertilizers. The study has revealed the superiority of fertilizer application based on targeted yield approach over the semi-quantitative approach employed in the soil testing laboratories and generalised state level Package of Practices recommendation for the crop. In this approach, the fertilizer dose can be adjusted in accordance with the specific objective and available resources of the farmer.
  • ThesisItemOpen Access
    Effect of different inputs on productivity and quality relations in njavara (Oryza sativa)
    (Department of Agronomy, College of Horticulture, Vellanikkara, 1996) Meera Menon, V; Kau; Potty, N N
    Productivity characteristics of Njavara (Oryza sativa), a medicinal rice variety were investigated based on the results of four separate experiments conducted at the Regional Agricultural Research Station, Pilicode, during 1994-96. The experiments were to study (i) growth and development characteristics (ii) crop weather relations (iii) response to nitrogen, phosphorus and potassic fertilizers and (iv) the effect of integrated nutrient management. Two biotypes of Njavara, the black glumed and golden yellow glumed, were tested in the first two experiments. The black glumed biotype alone was studed in the third and fourth experiments. The first experiment, consisting of the two biotypes as treatments, was conducted in wetland, open upland, heavily shaded upland and partially shaded upland, and pooled analyses of the data were conducted. Treatments of the second experiment which studied the effect of date of sowing on productivity of Njavara included 10 dates of sowing at fortnightly intervals starting from the 15th of May. Combinations of three levels of nitrogen, phosphorus and potassium, each at levels of 15, 30 and 45 kg ha-1 along with a standard and absolute control constituted the treatments of Experiment III. The last trial consisted of two treatments, one exclusively with farmyard manure and another with fertilizer alone, both at 30 kg nitrogen equivalent, two treatments with organic and inorganic manure in different ratios and three combinations of Azospirillum with 25, 50 and 75 per cent of the full farmyard manure dose. The second experiment was conducted in open upland and the third and fourth experiment in heavily shaded coconut gardens. Biometric, nutritional and quality criteria estimated through accepted methodology were used for the evaluation of treatments. An abstract of the results obtained has been presented in the following paragraphs. The results showed that three phases could be distinguished in the growth and development of Njavara. They are a primary phase of absorption and accumulation of nutrients, a grand growth phase of rapid accumulation of dry matter and a diversion phase when the seed and quality develop. Continued growth till harvest gave high yield and dry matter decline in the final phase led to superior quality characteristics. Golden yellow glumed biotype exhibited continuous growth and higher yield of grain. Black glumed biotype manifested dry matter decline in the final phase, leading to lower yield of grain and higher free amino acid content in the grain. Profound influence of cropping situation on yield and quality of grain was observed. Lowest yield of 684 kg ha-1 and highest amino acid content of 0.492 mg g-1 were observed in the uplands and highest yield of 2401 kg ha-1 and lowest amino acid content of 0.203 mg g-1 were observed when Njavara was sown in the wetlands. Viewed on the basis of variation in nutrition in the different situations, the results showed that yield limiting influences were not the deficiency of any element but the excess contents of Mg and Mn at maximum tillering and of P, K, S, Zn and Cu at panicle initiation stages in the plant. This appeared to be a highly significant result in the context of stagnant productivity of crops like rice. Content of free amino acids in the grain appeared to be unique characteristic of Njavara rice. Among the amino acids, sulphur containing amino acids, methionine and cysteine were also present. Possibly, these amino acids are related to the medicinal value of Njavara in the treatment of rheumatic complaints, the symptoms of which resemble thiamin deficiency. Inherently high yield potential of Njavara was expressed in the date of sowing trial. Both the biotypes recorded grain yields of 6000 kg ha-1 when sown on most favourable dates. Weather influence contributed to be highest yield through two ways, firstly, by increasing the total dry matter yield and secondly, by improving the grain-straw ratio. The golden yellow glumed biotype produced higher grain yield than the black glumed biotype. Application of N, P and K fertilizers increased the uptake of all the elements studied. Positive interaction of fertilizer elements on content and uptake of elements was also evident. However, application of fertilizers could influence only the straw yield significantly. One possible reason for the absence of significant improvement of grain yield by fertilizer application appeared to be due to the high levels of application. Even 15 kg ha-1 of N, P and K were found to be excess in shaded situations. Results of the integrated nutrient management studies showed that level of application was more important than the source in affecting the ultimate yield. Farmyard manaure application led to a more balanced development of the components of yield whereas fertilizer source improved only the floret number per panicle. Nutritional management at levels below 15 kg ha-1 N equivalent significantly reduced the yield. Azospirillum did not have any effect in increasing the yield of Njavara. The results of the different experiment brought out the role of soil and atmosphere environment as well as the biotype influence on the yield and contributed to the development of the concept of soil-plant-atmospheric continuum on the technical side. On the pracical side they showed that Njavara is an ideal crop for growing in the first crop season in the uplands in North Malabar when no other crop can be grown and that growing in heavily shaded uplands will give high quality grain. Advantageously, the crop will not require intense management.
  • ThesisItemOpen Access
    Ecophysiology and management of Isachne in rice fields of Onattukara
    (Department of Agronomy, College of Horticulture, Vellanikkara, 1996) Abraham, Varughese; KAU; Tajuddin, E
    Isachne miliacea Roth is the most dominant weed in the 28,000 ha of low land rice fields of the coastal sandy Onattukara region, situated in Kollam and Alapuzha districts of Kerala. A serious of investigations were undertaken at Rice Research Station, Kayamkulam, during 1991 to 1994 with the objective to identify the major weeds in the rice ecosystem and to bring out the ecophysiology of 1. Miliacea and to find out a suitable weed management strategy for the rice based cropping system of Onattukara. Isachne miliacea was found to be the dominant weed in rice during Kharif and Rabi seasons. The weed seeds germinate in April – May, attains its peak vegetative growth in July and flowers in October. The seeds mature in November and the plants dry off in January with the onset of summer. The weed is propagated by seeds and stem cuttings. Germination of seeds can be prevented by submerging the seeds in the area in water even to a depth of one centimetre. The forcing of the stem cuttings of 1. Miliacea to a depth of five centimetre below the soil surface or maintaining a submergence for more than five centimetre can effectively check the vegetative multiplication of the weed. Seeds attained physiological maturity in November and remained dormant upto March. Seeds of the season that remain on the surface germinate fully in April – May with the pre – monsoon showers while the buried seeds remain dormant. Burying the seeds to more than five centimetre depth and water stagnation in July to November induced secondary dormancy. Viability of the seeds was lost faster at shallow depth of burial. Crop weed competition studies were conducted in Kharif and Rabi for two years with different densities of 1. Miliacea. Weed competition was severe in dry dibbled Kharif compared to wet transplanted Rabi. Even a small density of five 1. Miliacea plants per square metre produced appreciable biomass and reduced the DMP of rice substantially. Integrated weed management study was conducted in Kharif and Rabi for two years in a split – plot design in three randomised blocks. Kharif season treatments formed the main plots for Rabi trial. In Kharif five pre – emergence herbicides were compared with local practice. Local practice of hoeing on 15 DAS and HW twice on 25 and 40 DAS gave maximum grain yield. Application of oxyfluorfen 0.1 kg ha-1 followed by HW on 30 DAS was on par with local practice and ranked second. The performance of other herbicides anilofos 0.40 kg, butachlor 1.25 kg and thiobencarb 1.25 kg per hectare were also satisfactory when followed by one HW on 30 DAS. Pretilachlor 0.50 kg ha-1 was phytotoxic to rice. The tested herbicides effectively controlled 1. miliacea upto harvest of rice compared to local practice. During Rabi the effect of pre-plant spray of glyphosate and hand weedings were compared. Among the treatments a pre – plant spray of glyphosate after harvest of Kharif controlled 1. miliacea best and gave maximum rice yield in Rabi season. Kharif treatments did not show any significant influence on yield of rice during Rabi. From the study it could be concluded that pre – emergence spray of oxyfluorfen 0.1 kg ha-1 followed by one HW on DAS in Kharif and pre – plant application of glyphosate 0.75 kg ha-1 on residual weeds immediately after the harvest of the Kharif crop gave efficient weed control and economic yield of rice in the rice based cropping system involving rice – rice – fallow of Onattukara region.
  • ThesisItemOpen Access
    Standradisation of organic and inorganic fertiliser comnbinations for maximising productivity in bitter gourd (Momordica Charantia L.)
    (Department of Agronomy, College of Agriculture, Vellayani, 1999) Rajasree, G; KAU; Raghavan Pillai, G
    An investigation was carried out during 1995-96 and 1996-97 at the Instructional Farm attached to College of Agriculture, Vellayani to study the efficacy of different levels of N applications (200, 250 and 300 kg N ha") in different ratios of organic - chemical N substitutions (l : 1, 1:2 or 2: 1) at different frequencies (F I - full quantity of organic source as basal, F2 - organic source at basal and at 40th and 70th DAS, F3 - organic source as basal + fortnightly equal splits and chemical N source as basal + fortnightly intervals in equal splits in all the frequencies) of application. Two different organic sources ie. farm yard manure and poultry manure were used in two simultaneous experiments viz. Experiment I and 11. The experiments were separately and simultaneously laid out as confounded 33 design in 9 plot blocks with 2 replications, confounding LR2F in RI and LRF2 in R 11. Higher levels ofN nutrition was found to reduce days taken to flower in farm yard manure applied trial while sex ratio was narrowed at 90 DAS in poultry manure applied experiment. Higher jassid population was noticed at 60 DAS when higher levels ofN was supplied predominantly through organic source as farm yard manure. Fungal leaf spot infestation was higher with the application of200 kg N at 90 DAS and was also more with split applications of both farm yard manure and chemical N source at early stages of growth. Full basal application of poultry manure was found to promote the per hectare yield of fruits, fruit yield planr I and number of fruits planr I compared to its split applications. When highest level ofN (300 kg) was supplied through 2: 1 ratio of organic - chemical N substitution using poultry manure as organic source, it effectively increased the fruit yield and number of fruits plant". 2 Shelf life of fruits at room temperature was more when nutrient N was supplied through 2: 1 ratio of organic - chemical N substitution using farm yard manure or poultry manure as an organic source. When N level was increased beyond 200 kg, shelf life of fruits at room temperature slightly decreased even when it was predominantly supplied through organic source of farm yard manure or poultry manure. Similar trend was noticed at refiigeratory condition too. Nitrogen nutrition showed depressing effect on ascorbic acid or vitamin-C content of fruits in Experiment I. Iron content in fruits was more with the application of 200 or 300 kg N level in Experiment ll. When 300 kg N was applied through a major source of poultry manure (2: 1 ratio) it produced higher iron content in fruits. Higher nitrogen levels or nitrogen nutrition through 2: 1 ratio of substitution promoted the soil bacterial population in both Experiment I and II. Full basal application of farm yard manure or poultry manure favourably influenced the soil bacterial population. Nitrogen nutrition showed depressing effect on fungal population of soil in Experiment I while it stimulated the fungal growth in Experiment 11. Soil actinomycetes population was higher with 2: 1 substitution ratio using farm yard manure as organic source ofN. When farm yard manure or poultry manure as organic source was used in equal or higher proportion with chemical N source, it showed moderating effect on the soil acidity. Full basal application of farm yard manure also enhanced the soil pH from the acidic range and the organic carbon content. Application of higher levels ofN increased the net loss ofN, P and K of soil in both the Experiment I and H. Net loss ofN was higher with 1:2 ratio ofN substitution or few or more split applications of organic source (farm yard manure) in Experiment 1. Net loss of nutrients was moderated during the second year of field experimentation. Nitrogen 3 nutrition in 1:2 ratio of substitution enhanced the net loss ofN in Experiment H. Nitrogen nutrition through 2: 1 ratio ofN substitution or basal + 2 split doses of farm yard manure increased the net loss of P in soil. The net loss of K in soil was more when farm yard manure and chemical N sources were applied in 2: 1 or 1: 1 ratio of substitution. Net gain of K was observed in Experiment H, when chemical N source was substituted in higher proportion compared to poultry manure or when full dose of poultry manure was applied as basal dressing. Higher levels ofN application have resulted in negative net energy returns or energy loss in both the experiments. The 1: 1 or 1 :2 ratio ofN substitution caused higher net energy losses in Experiment I while split applications of poultry manure resulted in more energy loss in Experiment H. Total energy output was higher with full basal application of poultry manure in Experiment I. Energy ratios registered a negative value and was higher with low level ofN application in Experiment I and II. Higher gross returns were obtained when full quantity of poultry manure was applied as basal dose in Experiment 11. Application of300 kg N through 2: 1 ratio of organic- chemical N substitution registered higher gross returns in Experiment II. Net returns was higher when 200 kg N ha! was applied. Increasing N level beyond 200 kg was not economic in Experiment I using farm yard manure as organic source. When full quantity of poultry manure was applied completely as basal dose, higher net returns was obtained in Experiment H. Benefit-cost ratio decreased when N level was enhanced beyond 200 kg ha' in Experiment I. Higher benefit - cost ratio was recorded when poultry manure was applied in full dose as basal dressing. Study revealed the favourable influence of organic sources; farm yard manure and poultry manure on fruit quality, shelf life and soil properties. The suitability of poultry manure as organic source for vegetable cultivation was also established by this study.
  • ThesisItemOpen Access
    Inter-relationship of applied nutrients on growth, productivity and latex flow characteristics of havea brasiliensis muell. arg.
    (Department of Agronomy, College of Agriculture, Vellayani, 1993) Punnoose, K I; KAU; Sreedharan, C
    Three field experiments were conducted in three locations representing the major rubber growing regions in South India to study the response to nutrient applications on growth characters, yield and latex flow characteristics and to study the inter-relationship between soil and plant nutrients on yield. It was also envisaged to assess the relative response in the different locations and to make economic analysis of the benefit of manuring. Three levels of 0, 40 and 80 N ha-1, 0, 30 and 60 kg P2O5 ha-1 and 0, 40 and 80 kg k2O ha-1 and two levels of 0 and 10 kg MgO ha-1 were used. A 33 x 2 partially confounded factorial split plot experiment in randomised block design with two replications was followed. The 80 kg level of N and 30 and 40 kg levels respectively of P and K were optimum for girth increment in all the locations. Application of Mg was also beneficial. For virgin bark thickness the 40, 30 and 40 kg levels of N, P and K respectively were sufficient in all the locations and application of Mg was not beneficial. For bark renewal 80 kg N was optimum at Thodupuzha whereas the 40 kg level was sufficient in the other locations. The 60 kg level of P was useful at Kulasekharam and Thodupuzha while 30 kg was sufficient at Balussery. The 40 kg level of K was optimum in all the locations and application of Mg was not beneficial. The 80 kg level of N gave the maximum weight of leaf litter in all places while for P and K the 30 and 40 kg levels respectively were sufficient. Magnesium was beneficial only at Balussery in one year. The 40, 30 and 40 kg levels respectively of N, P and K gave the highest total volume of latex in all the locations except at Balussery where 80 kg K was superior to 40 kg. Application of Mg was beneficial at Balussery while it had a reducing effect at Kulasekharam and no effect at Thodupuzha. Application of N and K reduced the plugging index and that of P and Mg increased it in all the locations. For dry rubber content, the 80 kg level of N was optimum at Kulasekharam while the 40 kg level was sufficient in the other locations. With regard to P and K the 30 and 40 kg levels respectively were sufficient. Application of Mg was beneficial only at Thodupuzha. In the case of yield of rubber 40 kg N and 30 kg P2O5 were found to be optimum in all locations. The 40 kg level of K2O was sufficient at Kulasekharam and Thodupuzha while the 80 kg gave the highest yield at Balussery. At Thodupuzha and Balussery application of Mg was beneficial while at kulasekharam it reduced the yield. Application of N increased the organic carbon content of soil. The available P, K and Mg contents of soil were increased by the application of the respective nutrients. The N, P, K and Mg contents of leaf and latex were increased by application of the respective nutrients. Application of P as rock phosphorus also increased the available Ca content of soil and Ca contents of leaf and latex. The yield of rubber was positively correlated with girth increment, rate of bark renewal, initial flow rate, total volume and dry rubber content of latex and negatively with plugging index. Yield was also positively correlated with the available N, P, K and Ca contents of soil N, K and Ca contents of leaf and P and K contents of latex and negatively correlated with Mg contents of soil and leaf. The strongest correlations with yield were given by soil N, latex P and K and leaf Ca. Total volume of latex was positively correlated with the available N, P, K and Ca contents of soil, N, K and Ca contents of leaf and P and K contents of latex. The dry rubber content of latex was positively correlated with the available N, P and Ca contents of soil, N, K and Ca contents of leaf and N, P, K and Ca contents of latex. The plugging index was positively correlated with the P and Ca contents and negatively with the N and K contents of soil, leaf and latex. Positive correlations, were obtained between soil and leaf nutrients, soil and latex nutrients and leaf and latex nutrients in the case of N, P, K and Ca. In the case of yield of rubber 40 kg N and 30 kg P were found to be optimum in all the locations. The 40 kg level of K was sufficient at Kulasekharam and Thodupuzha while the 80 kg level gave the highest yield at Balussery. Application of Mg was beneficial at Thodupuzha and Balussery while at Kulasekharam it reduced the yield. An overall evaluation of the economic analysis indicated that 40 kg N, 30 kg P2O5 and 40 kg K2O were the optimum doses in all the three locations. Application of Mg was profitable only at Thodupuzha.
  • ThesisItemOpen Access
    Rice based cropping system analysis in kerala
    (Department of Agronomy, College of Agriculture, Vellayani, 1993) Chidananda Pillai, M R; KAU; Sreedharan, C
    With the objectives of identifying the most economic crop combination for the double crop wet rice fields of Kerala and to assess soil fertility changes due to rice based cropping systems and also to find out the residual effects of the summer crops on the succeeding rice crops an investigation was conducted at the R.A.R.S. Pattambi in a split – split plot design, for a period of two years. The salient findings of the investigation are as follows. In the Cassava-rice-rice system 25 per cent saving was recorded for P and K for maximum grain yield of kharif rice than the recommended doses. A saving of 50 per cent each of P and K was recorded for the maximum straw yield than the recommended doses. In cowpea–rice-rice system for maximum grain yield of kharif rice there was a saving of 25 per cent of P and K than recommended doses. The same trend followed for the maximum yield of strew also. In groundnut –rice-rice system, for maximum grain yield of kharif rice there was a saving of 25 per cent of P and K than recommended doses. For the production of maximum straw yield full dose of recommended nutrients were required. In bhindi– rice-rice system for maximum grain yield of kharif rice there was a saving of 50 per cent of P and K than recommended doses. For the production of maximum straw yield full dose of recommended nutrients were essential. In rice-rice-rice system for maximum grain yield a saving of 25 per cent of P and K was recorded than recommended doses. For the production of maximum straw yield full dose of recommended nutrients were required. In fallow-rice-rice system for maximum grain yield full dose of recommended nutrients were essential, whereas for the production of maximum straw yield a saving of 25 per cent of P and K than the full dose was recorded. In cassava, rice and fallow systems for the manifestation of residual effect to the rabi rice, balanced nutrients at high doses are to be applied to the preceding kharif crop where as in the cowpea, groundnut and bhindi systems, residual effects of nutrients are seen manifested to the rabi rice crop even when the kharif rice crop is applied with medium doses of nutrients. There was a trend of slight decrease in the organic carbon content of the soil under all the cropping systems. The status of available nitrogen and potash after one and two year crop sequences also followed the above trend. Regarding the status of phosphorus in the soil, there was a slight increase after one and two year crop sequences. Cassava system produced maximum yield in terms of energy value followed by groundnut. From the economic point of view bhindi system gave the maximum net return. Maximum dry matter production (biomass production potential) was recorded in the cassava system followed by groundnut system. A vegetable crop like bhindi or a tuber crop like cassava seem to be more profitable than growing rice in summer season in the double crop wet rice fields of Kerala, rice being least economic. Among the cropping systems rice-rice-rice system generates maximum employment opportunities for the farm labourers with maximum job opportunities for women labourers as well.
  • ThesisItemOpen Access
    Effect of cover crops on nutrient dynamics in the rubber plantations
    (Department of Agronomy, College of Agriculture, Vellayani, 1995) Prathapan, K; KAU; Sreedharan, C
    Three field experiments were conducted at Bethany Estate, Mukkampala, Kanyakumari District from February 1991 to October 1993 to study the effect of cover crops on the nutrient dynamics in immature, mature rubber plantation and an open area. In Experiment I there were two cover crops viz. Pueraria phaseoloides and Mucuna braceata and five levels of NPK viz. 0:0:0, 0:30:30, 10:30:30, 0:60:60 with one year old RRII-105, replicated thrice and statistically laid in RBD. In Experiment II there was one cover crop Mucuna sp alone with five levels of NPK as above with 8 years old RRII-105 replicated 4 times and statistically laid in RBD. In Expt. III there were 10 microplots, with both cover crops. N, P, K, Ca, Mg content of both Hevea and cover crops were increasing as the crops growth progressed. Fertilizer application to cover crops improved the Hevea leaf nutrient content than the absolute control. Among the levels 10:30:30 was found optimum. Mucuna was found better than Pueraria in increasing the Hevea leaf nutrient content. Girth increment was better with 10:30:30. This was found to be optimum under both experiments. More height increment was observed in this level, as well as in cover cropped treatments when compared to absolute control. Biomass production of cover crops were maximum at 10:60:60 followed by 10:30:30 under both experiments. Biomass production, root weight and length were higher in Mucuna and it was found increasing as the crop growth progressed. Nodule count was higher in Pueraria and the fresh weight of nodule per plant was higher in Mucuna as the size of its nodule was found bigger. Soil Moisture retention capacity was found higher under cover cropped plots at both shallow (0-30cm) and deeper (30-60cm) soil depths at-0.033 and -1.5 Mpa pressures than control. Pore space and aggregation percentage were improved whereas bulk density decreased. Among the levels of NPK 10:30:30 was found optimum in improving the soil physical properties. The percentage of improvement was found greater at shallow depth of soil than deeper. Soil moisture content during summer months were improved in the cover cropped area. The soil moisture in than the top soil (0-30cm) was lesser than the bottom soil (30-60cm) in Pueraria grown plots. This trend was reverse in the case of Mucuna. Growing of cover crops improved the microbial population of bacteria, fungi and phosphate solubilising organisms. The level 10:30:30 was found optimum for the better microbial activity. 10:30:30 was found optimum for better yield and Latex Flow Characteristics. Covercropping has increased the latex yield by 15-20%. 10:30:30 was optimum for better leaf litter production of Hevea. In cover cropped plots the leaf litter production was higher and wintering was delayed by 26-30 days over the control. This has enhanced 10 additional tapping days. Girth is positively correlated with cover crop biomass, nutrient uptake, soil available nutrients, soil moisture contents and Hevea leaf nutrient contents. Strongest correlation for girth was found with Hevea leaf N content, and uptake of N by cover crops, suggesting the importance of foliar diagnosis. Yield was negatively correlated with Mg content of soil.
  • ThesisItemOpen Access
    Nutrient- moisture interaction under phasic stress irrigation of sweet potato in summer rice fallows
    (Department of Agronomy, College of Agriculture,Vellayani, 1994) Muraleedharan, Nair; G, KAU; Muraleedharan, Nair; v
    A field experiment on sweet potato was laid out in the rice field fallowed during summer season at the Instructional Farm, College of Agriculture, Vellayani. The study was intended to work out of the irrigation schedule and fertilizer practice for sweet potato grown as a catch crop during the summer season of 1990 and 1991. The experiment was designed to economise the use of irrigation water as well as fertilizers by inducing phasic stress at certain phases of plant growth which are considered critical for sweet potato. The field experiment was laid out in a strip plot design replicated thrice with irrigation in horizontal strips and fertility levels in vertical strips. Irrigation water at full CPE was given during tuber initiation phase (10-30 DAP), full CPE at tuber maturity phase (80-100 DAP) and full CPE at tuber initiation and tuber maturity phases. The crop received irrigation at ½ CPE during the rest of the period of plant growth. Nitrogen and potassium were applied @ 25, 50 and 75 kg ha-1 and a uniform dose of P2 O5 @ 50 kg ha-1 and lime @ 500 kg ha-1 were applied. A control plot that received NPK @ 75:50:75 kg ha-1 and FYM @ 10 t ha-1 was maintained for treatment comparison. Growth characters were recorded at an interval of 21 days from planting and it was observed that providing irrigation at full CPE during tuber initiation phase resulted in significant increase in vine length and number of leaves plant-1. Enhanced rate of application of Nitrogen promoted the growth of vines, number of branches plant-1 and number of leaves produced plant-1. Potassium did not exert any influence on these growth characters. Growth analysis studies showed that the LAI was maximum in plots that received irrigation at full CPE during tuber initiation phase. Nitrogen substantially influenced the LAI, higher levels being significantly superior to the lower levels. Higher levels of potassium also influenced the LAI. The NAR and specific leaf weight were the highest in plots that received irrigation at ½ CPE during tuber initiation phase. Both NAR and CGR were high in the early stage of plant growth and decreased towards harvest. Increased rates of nitrogen supply decreased the NAR and specific leaf weight whereas no definite trend could be observed on CGR> Higher levels of potassium had a favourable influence on NAR and CGR. The dry matter of leaves, shoots, fibrous roots and tubers were significantly enhances by providing full CPE during tuber initiation phase. Increasing the level of nitrogen, influenced the dry matter in the aerial parts. The influence of K on dry matter production was not consistent. Tuber bulking rate showed a positive trend under irrigation at full CPE during tuber initiation phase. Nitrogen levels at 50 and 75 kg ha-1 had an overlapping influence on tuber bulking rate and both remained superior to 25 kg ha-1. Scheduling of irrigation did not exert any influence on the length and girth of tuber. However, an increase in the length and a corresponding decrease in the girth were noticed at enhanced rates of nitrogen supply. The number of tubers plant-1 showed a significant improvement by providing irrigation at full CPE during tuber initiation phase. The total number of tubers plant-1 was increased by high rates of N, but did not influence the number of marketable tubers. Application of K at 50 kg ha-1 promoted the production of more tubers. Tuber yield was significantly influenced by irrigation wherein providing full CPE during tuber initiation phase resulted in superior yield of both total and marketable tubers. Tuber yield was maximum at 50 kg ha-1 each of nitrogen and potash. Vine yield was significantly enhanced by higher rates of applied nitrogen. The harvest index and utilization index were enhanced by the application of irrigation water at full CPE during tuber initiation phase. Application of N at 25 kg ha-1 resulted in the production of high starch content whereas the sugar content was increased upto the highest level of 75 kg ha-1. The uptake of nitrogen by vines and tubers showed a progressive increase by applying full CPE during tuber initiation phase. Application of higher levels of nitrogen invariably promoted the uptake of N, P and K by the plant. Application of potash at 50 or 75 kg ha-1 also resulted in higher uptake of potassium. The fertility status of the soil did not show a positive trend by scheduling of irrigation. The plots that received the lowest dose of nitrogen, invariably recorded the highest level of available phosphorus. Available potassium content was also high in plots that received higher rates of potash. Irrigation at full CPE during tuber initiation and/or tuber maturity phase recorded significantly higher water use efficiency and net returns as compared to including stress during tuber initiation phase. Nitrogen and potash both at 50 kg ha-1 recorded the maximum water use efficiency and net returns from sweet potato cultivation.