Browsing by Author "Usha Mathew"
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ThesisItem Open Access Assessment of soil health and status of heavy metals in the certified organic farms of Kerala(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2019) Greeshma, P R; KAU; Usha MathewThe study entitled “Assessment of soil health and status of heavy metals in the certified organic farms of Kerala” was conducted from 2017 to 2019. The objective of the study was to assess and compare the soil health parameters and heavy metal status of the inputs and produce of certified organic farms and conventional farms of Kerala. Samples of soil, inputs and plant produce were collected from different locations of Kerala representing Northern, Hill, Central and Southern zones. The organic farms selected for study were under NPOP certification for more than 10 years. The rate of application of manures in organic and conventional farms were 30 t ha-1 and 2 t ha-1 respectively. The first part of investigation was conducted to comparatively evaluate the effect of organic and conventional farming on soil health, for which composite soil samples from 2 depths (0-15 cm and 15-30 cm) were collected from 10 numbers each of certified organic farms and conventional farms. The collected soil samples were analysed for physical, chemical and biological properties from which soil quality index was calculated for each sample and an in situ enumeration of earthworms and arthropods was conducted by excavating 1 m3 soil in all the farms from where soil samples were collected. Among the physical and chemical properties analysed, available N, K, Ca, Zn and Cu at 0-15 cm depth were significantly higher in soils from organic farms than conventional farms. Bulk density was found to be lower in soils of organic farms which is a good soil quality attribute. pH was significantly lower in soils of organic farms at 0-15 cm depth. Total as well as available content of heavy metals were (Ni, Cd and Pb) were not significantly different among the organic and conventional soil samples. Unlike physical and chemical properties, all biological properties were significantly higher in soils of organic farms than conventional farms. Bacterial, fungal, actinomycetes count, earthworms, soil arthropods and dehydrogenase activity were found to be significantly higher in soils of organic farms than in conventional farms at both depths and respiratory activity was found to be significantly higher in organic farms at 0-15 cm depth. Soil quality index was calculated from various physical, chemical and biological soil properties and the highest index (61.1 per cent) was obtained in the surface soils of hill zone under both management. However the highest soil quality index was observed only in soils of organic farms in Northern and Southern zones. The second part of investigation was input analysis in which inputs used in organic and conventional farms, available at the time of sampling were analysed for Zn, Cu, Cd, Ni and Pb. The results revealed that except for the content of Cu in manures and fertilizers, other heavy metals were not observed to be significantly different in manures and fertilizers. The third part of investigation was plant study, in which edible parts of 10 crops were collected from both organic and conventional farms and analysed for Zn, Cu, Cd, Ni and Pb. Except for Zn, other heavy metals were found to be very much within the limit of food safety standards. Zn was found to be high in amaranthus from both organic (96 mg kg-1) and conventional (105.6 mg kg-1) farms. Content of Zn in yard long bean, salad cucumber and curry leaf from organic farms (60-64 mg kg-1) and was found to be just exceeding the safe limit (60 mg kg-1). Zn in plants was found to be significantly affected by management practices also. A significant positive correlation have been observed between the content of Zn in plants and available Zn in soil in both conventional and organically managed soils. From the study it may be concluded that soil quality was found to be generally high in hill zone soils compared to other zones irrespective of the management practice and in all other regions, organic farming was found to be increasing the soil quality. Heavy metals in inputs and plant produce analysed were very much within safety standards. Zn content of amaranthus in organic and conventional farms exceeded the food safety limit. A significantly higher biological properties of soils in organic farms clearly manifests the long term sustainability of organic farming in Kerala’s climatic condition.ArticleItem Open Access Effect of application of zinc and copper on the yield of rice(Kerala Agricultural University, 2000) Usha Mathew; Beena, C; Balachandran, P V; KAUThesisItem Open Access Effect of submergence on the soil testing parameters of paddy soils(Department of Soil Science and Agricultural Chemistry,College of Agriculture, Vellayani, 1986) Usha Mathew; KAU; Alice AbrahamLaboratory Incubation atudiea were conducted to quantify the changes in pH, EC, lime requirement and availability of important nutrients such as N, P, K, Ca & Mg due to submergence of alluvial, acid saline acid sulphate and saline rice soils of Kerala The study has revealed that pH of all the soil types increased immediately after flooding of the. air dried soils, reached a maximum and remained more or less steady throughout the period of three months submergence. Consequent to the increase in pH, a corresponding decrease in lime requirement was observed In all the soils. Maximum reduction in lime requirement was noticed for the saline and acid saline soils. A rise in EC was observed in all the soil typos due to submergence during the first four to six weeks. It showed a decreasing tendency afterwards All the soils showed a progressive increase in available nitrogen content with increase in the period of flooding. The increase was in the range of 75 - 393% for the various soil types. Maximum increase was,recorded by saline soils (395%) and minimum by alluvial soils (75%). The levels of available phosphorus recorded for the four soil types in the air dried state were in the low to medium range for rice. Submerging of these soils has resulted in a manifold increase in the content of available phosphorus. The increase was maximum for acid saline soils (700%) and minimum (55%) for alluvial soils. The availability of exchangeable cations like potassium calcium and magnesium, however, showed a periodical increase and decrease on flooding in all the four soil types. The results of the study have clearly brought out the magnitude of the changes that result in the status of each nutrient upon flooding of soils for wetland paddy cultivation. The manifold increase in the statue of major nutrients like ft and P upon flooding of soils indicates that addition of fertilizer ft and P under such conditions is not likely to produce any significant effect on rice unless the rice varieties are highly responsive to these nutrients. The feasibility of reducing the quantity of fertilizers to be applied or even skipping of fertilizers for one or two seasons may be considered taking into account the responsiveness of the rice variety as well as other economic factors.ThesisItem Open Access Evaluation of fortified humic acids from grow bag mixtures as phytotonic in okra [Abelmoschus esculentus (L.) Moench.](Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2017) Dhanesh Kumar, T V; KAU; Usha MathewThe research entitled “Evaluation of fortified humic acids from growbag mixtures as phytotonic in Okra [Abelmoschus esculentus (L.) Moench]” was undertaken with an objective to study the physicochemical characteristics and microbial enumeration of different growbag mixtures and the effect of their humic acids fortified with multinutrient mixture on growth, yield and quality of okra. The study consisted of two parts, an incubation study and a crop study in grow bags. Incubation study was carried out for a period of three months maintaining 60% of water holding capacity. Conventional composition of growbag media, soil + sand + FYM. The third component FYM was replaced by various composts to form 6 treatments. T1- soil + sand + FYM, T2 -soil + sand + coirpith compost, T3- soil + sand + vermicompost, T4- soil + sand + desi cowdung with assorted farm waste soil, T5- sand + soil+ desi cowdung mixed with straw and Gliricidia, T6- soil + sand + composted kitchen waste using composting inoculum. Incubated mixtures were sampled 6 times and analysed for physicochemical properties and microbial load at fortnightly intervals. Humic acids were extracted from incubation mixtures and were characterised and fortified with multinutrient mixture. The effect of multinutrient fortified humic acids were assessed in the growbag containing routine potting mixture using okra variety Varsha Uphar as the test crop during January 2017- April 2017 as per POP recommendations. The study consisted of eight treatments in which HA1 to HA6, were humic acids extracted from the incubated growbag media of different composition and fortified with multinutrient mixture as T1 to T6 respectively, T7- water spray and T8- extractant spray (0.5 N NaOH). Foliar application of treatments at 0.5 % concentration were given at fortnightly intervals throughout the crop period. The plant samples were analysed at fifty percent flowering and at final harvest. Incubation study recorded neutral to alkaline pH in all media except coirpith medium (5.49 - 7.5) and kitchen waste inoculum compost (8.75-10.4). EC of the growing media was non saline in all media except kitchen waste inoculum compost (7.15 - 8.50 d Sm-1). Available N content was highest in kitchen waste inoculum compost (703.0 kg ha-1) and all other media were in low to medium range. Available P content was highest in vermicompost medium (93.9 kg ha-1). Available K was high in all media except coirpith medium where it was low to medium and the highest K content was recorded in kitchen waste inoculum compost (9893 kg ha-1). Ca content was sufficient throughout the incubation in all media except coirpith during the first fortnight (103.3 mg kg-1). Available Mg was found to be deficient in coirpith, vermicompost and kitchen waste during the first fortnight. Available B was highest in kitchen waste compost (6.71 – 3.50 mg kg-1). Generally, the availability of other micronutrients (Fe, Mn, Cu and Zn) were not significantly influenced by the composition of the growth media. Microbial enumeration of incubated samples showed highest bacterial count from vermicompost (8.88 log cfu /g soil). Fungal population was found to be maximum in coirpith compost (5.39 log cfu/g soil) and highest count of actinomycetes was noted in medium with desi cowdung and farm waste. Humic acids extracted from the vermicompost growth media showed a higher total acidity of 12 meq g-1 of humic material. Content of humic acids was the highest in vermicompost media. Time taken for pH stabilization of humic acids was highest for desi cowdung + farm waste medium. Crop study in growbag revealed that different humic acids fortified with multinutrient mixture have significant effect on growth and yield of bhindi. Application of vermicompost HA (T3) recorded best biometric characters and yield characters viz., days to flowering (36 days), number of fruits per plant (24 no.), average fruit weight (17.1 g) and a highest yield of (573.15 g plant-1). T3 also showed maximum keeping quality (9 days) and highest crude protein content (15.40 %) in fruit. B: C ratio (1.76) was also highest in T3. The results of plant nutrient analysis indicated that T3 (vermicompost HA) has the highest content of total N (2.80%) and K (2.52 %), while T6 recorded highest content of P (0.66%) which was on par with T3. The N, P, K status of T3 was found to be positively correlated with yield. Content of secondary nutrients was also the highest in T3. Hence it may be concluded that composition of growth media has significantly influenced quantity and quality of humic acids. In the incubation study T6 (kitchen waste compost) recorded the highest nutrient content followed by T3 (Vermicompost). However, the highest humic acids content was noted in the medium containing vermicompost comparing the effects of fortified humic acids, best results in crop study were shown by the vermicompost HA (T3), followed by the treatment which received HA extracted from medium containing desi cowdung + assorted farm waste (T4). Hence humic acids extracted from growing media containing vermicompost, fortified with multinutrient mixture can be recommended as a phytotonic.ThesisItem Open Access Status and impact of heavy metals in selected soils and crops of Kerala(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 1999) Usha Mathew; KAU; Alice AbrahamStatus of Cu, Zn, Ni, Pb and Cd in samples of selected soils, fertilizers, manures and crops were estimated. A critical analysis of the total content of these heavy metals in the soils studied here revealed that Cu arid Cd are existing beyond the critical level in the some of the samples. In the wetland soils, content of all heavy metals was lowest for phytotoxicity and food safety in samples from absolute control plots of rice PME at Pattambi, Moncompu and Kayamkulam and highest in samples from plots receiving maximum quantity of organic manures and inorganic fertilizers. The DTPA extractable form is only a very minor part of their total content. The heavy metal load of the commonly used P fertilizers in Kerala is found to be highly variable. Zn is the highest contaminant followed by Pb, Ni, Cd and Cu. With respect to manures commonly used in Kerala, Zn is the most abundant among the five elements studied followed by Cu. Retention of heavy metals was found to be more in the roots of all plants compared to the above ground portions except Zn in amaranthus. The grain, straw and root of rice plants collected from PME plots which were receiving organic manures and inorganic fertilizers continuously for several years had a distinctly higher content of all heavy metals compared to the samples obtained from absolute control plots. The content of Cu in rice samples and that of Zn and Cu in the fodder samples from sewage farm exceeded the critical level to express phytotoxicity. In some of the samples of amaranthus and cowpea, content of Zn, Pb and Cd exceeded the food safety standards prescribed in Germany. Studies on the pattern of retention of applied Cd and Ni in undisturbed soil columns of important soil types of Kerala showed that retention of Cd and Ni was more in the top than in the bottom layers. Higher retention and lower leaching loss of applied Cd and Ni was observed in the columns not treated with FYM. Pot culture studies have shown a significant reduction in yield of rice, sesame and cowpea at various levels of Cd and Ni with and without FYM. Nutrient content of seed, shoot and root showed variations but did not reveal any specific pattern in various crops. In cowpea, low levels of Cd and Ni in the absence of FYM stimulated nodulation and nitrogen content. Intake of Cd and Ni in various plant parts of rice, sesame and cowpea was in the order root> shoot> seed. It was more in the presence of FYM than in its absence. The toxic effects of Ni on growth and yield parameters were of lesser magnitude compared to Cd especially in rice and cowpea. Maximum accumulation of Cd in edible portions was recorded by sesame with no ill effect on germination. However a moqerate accumulation of Cd in rice seeds resulted in significant reduction in germination. An alarming observation obtained from the study was that almost all samples of rice grains exceeded the food safety standard of 1 mg Cd kg-1 indicating that rice, the staple food of the people of Kerala is contaminated with Cd, the most hazardous heavy metal for human health. This pioneer study on the heavy metal status of selected soils and crop plants of Kerala has brought out the need for conducting detailed studies on these aspects.ThesisItem Open Access Zinc and boron availability in soils and impact of carriers on crop productivity(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2005) Jyolsna, V K; KAU; Usha MathewA study entitled “Zinc and boron availability in soils and impact of carriers on crop productivity” was carried out at College of Agriculture, Vellayani 2003-2005 to monitor the effect of moisture levels with and without FYM on the availability of B and Zn in three types of soil viz., red, laterite and Onattukara sandy and the influence of carriers of Zn and B on tomato. The experiment consisted of two parts viz., incubation study and separate pot culture experiments with B and Zn. The physico-chemical analysis of soils used for incubation study was done using suitable analytical procedures. Incubation study was conducted at the laboratory to monitor the availability of B and Zn in red, laterite and Onattukara sandy soils. Two kg of each type of soil was taken in earthern pots of uniform size and incubated for two months at three moisture levels viz., air dry, field capacity and full saturation with and without FYM. The experiment was laid out in CRD with six treatments. They were, T1 – Air dry, T2 – Field capacity, T3 – Full saturation, T4 – T1 + FYM, T5 – T2 + FYM and T6 – T3 + FYM. Soil samples were drawn at fortnightly intervals and analysed for the available content of boron and zinc following standard analytical procedures. Separate pot culture experiments were conducted to study the influence of B and Zn using laterite soil on growth, yield and quality of tomato. They were laid out in CRD with treatments viz., T1 – fertilizers alone as per POP, T2 – fertilizers and FYM as per POP, T3 - T1 + B/Zn @ 0.5 /2.5 kg ha-1, T4 – T1 + B/Zn @ 1.0/5.0 kg ha-1, T5 – T1 + B/Zn @ 1.5/10 kg ha-1, T6 – T2 + B/Zn @ 0.5/2.5 kg ha-1, T7 – T2 + B/Zn @ 1.0/5.0 kg ha-1 and T8 – T2 + B/Zn @ 1.5/10.0 kg ha-1. Observation on various biometric and yield parameters had been recorded. Soil, plant and fruit analysis were done using standard analytical procedures. From the incubation study, it can be seen that B availability was more at full saturation condition than at air dry and field capacity moisture regimes in all the three soils. It was minimum at air dried state of soil. Available Zn recorded maximum value at air dried state than at field capacity and full saturation moisture regimes. The influence of B and Zn on the growth, yield and quality of tomato can be clearly understood from the pot culture experiments. Plant height and number of primary branches showed significant increase with B and Zn application. Yield, B : C ratio and quality parameters were higher in the treatments which comprise B/Zn along with FYM. Available K in soil after pot culture increased with increase in levels application of boron. The same trend was shown by DTPA-extracted Zn and Cu. Available Fe and Mn decreased by B application. Soil B increased with increase in level of B application. Plant content of these nutrients showed the same trend as that of soil content. Available P, Fe, Mn and Cu decreased with increase in levels of Zn application in the pot culture experiment with Zn. Soil available Zn increased with increase in level of application of Zn. Plant nutrient content showed considerable variations. There was an increasing trend for uptake of nutrients from T1 to T8 as there was an increase in total dry matter production in both the experiments. From the results cited above it can be confirmed that B and Zn fertilization has an important role in improving yield and quality of tomato. The highest yield, quality and B : C ratio were obtained when B was applied @ 1.5 kg ha-1. This indicates that further experiments may be conducted by raising the level of B above 1.5 kg ha-1 to verify its effect on contributing to further increase in yield. In the experiment with Zn, though the yield was the highest in T8, the B : C ratio was higher in T7 than in T8 . This indicates that economic yield was obtained when Zn was at 5 kg ha-1. For the purpose of formulating recommendations on application of B and Zn, more field studies need to be conducted.