Browsing by Author "Wahid, P A"

Now showing 1 - 9 of 9

Chemistry of coconut rhizosphere
(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 1987) Anilkumar, K S; Wahid, P A
Effect of variety, spacing and support material on nutrition and yield of blackpepper (Piper Nigrum L.)
(Kerala Agricultural University, 1992) Abi Cheeran; Wahid, P A; Kamalam, N V; Sajan Kurien; Lyla Mathew
A field experiment was conducted with two varieties of black pepper to study the influence of spacing and type of support (standard) on nutrition and yield. During a six year period since planting, soil chemical characteristics were not influenced by variety, spacing and type of standard. The variety Karimunda accumulated more K, Ca and Mn in the leaf compared to Panniyur-1. A depressing effect on foliar Ca level was noticed in vines trailed on Garuga pinnata. Closer spacing down to 2 m x 2 m did not affect the vine yield adversely. Three to four-fold increases in yield were obtained by trailing the vines on teak pole instead of on trees. The decrease in yield of the vine trailed on Erythrina indica and Garufa pinnata as compared to that on teak pole (non-living standard) was discussed in the light of probable competitive interactions between the crop vine and support tree as in mixed cropping system.
Fate of carbofuran applied to the soil basin of black pepper
(Department of Soil science and Agricultural chemistry, College of Horticulture, Vellanikkara, 1996) Betty Bastin; Wahid, P A
An investigation on the fate of carbofuran applied to the soil basin of black pepper (Piper nigrum L.) was conducted during 1992-1995 at the College of Horticulture, Vellanikkara. Laterite soils collected from the predominant pepper growing tracts of Kannur and Wayanad of Kerala state were used for the study. A field study was also conducted at the KADP farm attached to the College of Horticulture, Vellanikkara. The sorption of carbofuran in laterite soils and its persistence, influence of organic matter on the bio-availability of carbofuran, mobility of the insecticide in soil under field conditions and the effect of carbofuran on the growth of black pepper were assessed. The main findings of the study are given below. The sorption of insecticide in soil was found to be explained by Freundlich adsorption equation. The rates of sorption of carbofuran was not influenced by the organic matter contents . . An initial lag period was observed prior to carbofuran degradation in soil under laboratory conditions. Only one metabolite (3-hydroxycarbofuran) was detected as the product of degradation. The total content of 14C derived radioactivity was high in plants grown in soils with lowest organic matter content and vice versa. Hence, bioavailability of the insecticide is less in soils with high organic matter contents. So a discriminatory application of carbofuran is required depending on organic matter content of the soil. Thus for effective control of the pest in a soil with high organic matter content more quantity or carbofuran has to he applied than a soil with low content of organic matter. The residues of 14C-carbofuran absorbed plants left after HCl extraction, retained significant amounts of radioactivity which could be recovered following combustion. This indicated that determination of extraction efficiency by spiking or fortification of the samples with known quantities of insecticides would lead to overestimation of the recovery. The main metabolite of the carbofuran in the leaves was 3-hydroxy- carbofuran. Autoradiography of the bush pepper plants which was allowed to absorb 14C-carbofuran for 6 h showed that carbofuran was absorbed and translocated to the leaves and berry. Both carbofuran and hydroxycarbofuran were leached to the lower layers of soil (0-60 cm) during SW and NE monsoons. The content of hydroxycarbofuran was less than carbofuran in soils. In the foliage and berries carbofuran and the metabolite, 3-hydroxy- carbofuran accumulated. The content of hydroxycarbofuran was greater than that of carbofuran. As the harvesting time was delayed the content of residues also decreased. The early harvesting and use of immature berries may lead to more concentration of pesticide in the produce. This will lead to chances of more residue build-up in the human system.
Growth and nutrition of black pepper as influenced by decaying litter materials in soil
(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 1992) Sivakumar, C; Wahid, P A
An investigation on the growth and nutrition of black pepper (Piper nigrum L.) as influenced by decaying litter materials in soil was conducted at the College of Horticulture, Vellanikkara. The black pepper variety Panniyur – 1 was invariably used for the study. Biomass production in black pepper was significantly increased following the incorporation of organic materials into the soil compared to the control vines. When the different levels of organic sources were compared, total biomass production of the vine decreased at highest level (3 per cent) of application of coffee and black pepper leaves. This was attributed to allelopathic effect of the decaying material. There was a steady increase in biomass production with increasing level of garuga leaf application. Significant increase were noticed in the N ,P and K concentrations of leaf and stem, Mg concentration of leaf, S concentration of leaf and stem, Fe content of stem and foliar Mn content of the vine following the organic matter treatments as compared to control vines. The vine removed significantly higher quantities of N, p, K, Ca, Mg, S, Fe and Mn following the soil application of leaf materials as compared to the control vines. The average nutrient removal by a six – month – old black pepper vine to produce 11.19 g of shoot dry matter was 200.19 mg N, 18.92 mg P, 432.53 mg K, 155.89 mg Ca, 19.44 mg Mg, 12.33 mg S, 1517 µg Fe and 3546 µg Mn. The contribution of leaf to the total nutrient removal was more compared to that of stem. Significant increases in major and micronutrient availability in soil were noticed following the incorporation of leaf materials. On an average, the rate of organic carbon loss in laboratory incubation was the slowest in soil with coffee or silver oak leaves as the organic source and was fastest when the garuga was the organic source. The half – life values for organic carbon was the organic source. The half – life values for organic carbon loss varied from 91 – 193 days. The half – life values obtained for coffee, erythrina and black pepper leaves in field decomposition study were 40, 44 and 53 days respectively.
Implications of changes in soil pH on the Al, Fe and Mn status of the major coconut growing soils of Kerala
(Kerala Agricultural University, 1974) Kamala Devi, C B; Wahid, P A; Pillai, N G
Reductive transformations of iron and sulphate in anaerobic soils
(Department of Soil science and Agricultural chemistry, College of Horticulture, Vellanikkara, 1988) Padmini Amma, K P; Wahid, P A
An investigation on the physico-chemical characteristics, reductive transformation of iron and sulphate in kari and karappadam soils of Kuttanad and pokkali soils of Ernakulam District was conducted under flooded conditions during 1986-88 at Radiotracer Laboratory, College of Horticulture, Vellanikkara. Particular emphasis was given to evaluate the changes in soil properties and their influence on the transformation of Fe3+ in anaerobic soils, to examine whether there was preferential reduction of amorphous Fe oxides, to determine the relative extent of chemical versus microbiological reduction of Fe3+ and also to develop a methodology for studying sulphate reduction in anaerobic soils using 35S. For chemical analysis, spectrophotometric, flame- photometric and atomic absorption spectrophotometric methods were adopted. Radioassays of 35S were done using liquid scintillation counting technique. The salient findings from these studies are summarized below: Changes in soil characteristics were monitored at different intervals upto 150 days after flooding the soils. Following flooding, the pH of the soils generally increased in pokkali, karappadam and kari soils but the extent of rise in pH was much less in kari soils. Redox potential (Eh) decreased in all the soils and the decrease was seen evenafter 3 to 5 months. The redox potential of kari soils remained much higher at all intervals upto 5 months than in other soils. Among the three soils, pokkali (4-35 mmho cm-1) and kari (2-10.5 mmho cm-1) were found to be more saline as compared to karappadam soils (less than 3 mmho cm-1) and a slight increase in EC was observed from 5th day of flooding onwards. Analysis of free Fe oxide content indicated that kari soils contained the highest quantities of free Fe followed by karappadam. In all the three soil types the amorphous Fe content was generally higher than crystalline Fe. Transformation of Fe3+ in submerged soils was studied by monitoring NaOAc-extractable Fe2+ concentration. High concentrations of Fe2+ were observed in pokkali (19375ppm) and kari (31250 ppm) soils compared to karappadam (13125 ppm) soils. In pokkali soils Fe2+ concentrations reached peak values within 15 to 30 days where as in karappadam and kari soils highest concentrations were obtained 2 months and in about 1 to 2 months after flooding respectively. Studies on the preferential reduction of amorphous and crystalline forms of Fe in flooded soils revealed that with time there was a more or less linear increase on the concentration of Fe2+ where as a reverse trend was noticed in total free Fe, amorphous Fe and crystalline Fe forms with a decrease in Eh and an increase in pH. The preferential reduction of crystalline Fe (III) oxides over amorphous forms is observed in the present study and the reduction of these Fe (III) forms was more marked below an Eh of 200mV. The phenomenon was attributed to the reductases responsible for the transformation of amorphous and crystalline Fe (III) oxides, which require attainment of certain critical redox levels in flooded soils for their induction as well as for their function. The extent of chemical and microbial reduction of Fe in flooded soils was studied with and without sterilization by gamma irradiation. The results indicated a less pronounced decline in the redox potential and more or less a constant pH as well as Fe2+ content in the irradiated soils as against substantial increase in pH as well as Fe2+ content and a drop in redox potential observed in the unirradiated soils suggesting the participation of microorganisms in the reduction of Fe. The data relating to the changes in the concentration of soil sulphate following flooding revealed that in general there was an increase in sulphate concentrations in all the three types of soils as a result of flooding. Extractable sulphate content showed highest concentrations in kari soils (63,750 ppm) followed by pokkali (33,333 ppm) and karappadam (6666ppm). Peak concentrations were attained within 25-30 days of flooding in pokkali, where as in karappadam and kari soils it attained maxima within 15 days. A method was developed to study the reduction of sulphate in flooded soil to its end product H2S using 35S. The evolution of H235S was detected from 91.5 h onwards. Evolution of H235S steadily increased upto 211.5 h of incubation beyond which there was a slight decrease in the rate of evolution. The total quantity of H235S evolved during 312.5 h of experiment was 1589 cpm. It was also observed that Eh of the flooded soil system decreased very rapidly with a concomitant increase in pH. It was found that reduction of 35SO42- to H235S commenced when the Eh of the flooded soil system dropped to -5mV whereas the transformation of Fe3+ to Fe2+ started at a still higher Eh much earlier to the reduction of 35SO42-.
Soil fertility of coconut rootzone as influenced by long term inorganic fertilization
(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellanikkara, 1993) Jomon Joseph; Wahid, P A
An investigation on soil fertility of coconut rootzone as influenced by long term inorganic fertilization was conducted at the College of Horticulture, Vellanikkara. Soil samples from coconut basins of NPK factorial experiment at the Coconut Research Station, Balaramapuram, which had been receiving inorganic fertilizers for the past 22 years were used for the present study. It was found that both exchange acidity and exchangeable AI were increased following the application of ammonium sulphate. Ammonium sulphate x superphosphate and ammonium sulphate x muriate of potash interactions were found significant. Application of superphosphate in combination with ammonium sulphate was found to decrease exchangeable AI. Muriate of potash decreased the exchangeable AI content in the absence of ammonium sulphate. Considerable build-up of P reserve in the soil following superphosphate application was observed. Soil k content was increased by muriate of potash application. Calcium reserve was improved as a result of superphosphate application while ammonium sulphate application reduced it. A decrease IN Mg content was noticed in plots which did not receive ammonium sulphate. Both ammonium sulphate and superphosphate application improved S status considerably whereas muriate of potash application was found to reduce total S. Ammonium sulphate application decreased total Mn and total Zn. A reverse trend was noticed in the case of Cu, while total Fe content remained unaffected. Generally exchange acidity, exchangeable AI, total K, total S and total Fe increased with depth while total P, total Ca and total Mn decreased with depth. Application of ammonium sulphate increased exchange acidity and exchangeable AI in different soil layers and the increase was more conspicuous in the deeper layers. Application of muriate of potash decreased the exchange acidity and exchangeable AI down to a depth of 75 cm. Continuous superphosphate application increased the Ca reserve upto a depth of 50 cm while total P content increased significantly to a depth of 75 cm, showing leaching of P to deeper layers as a result of superphosphate application. Application of muriate of potash resulted in large increase in K reserve to a depth of 100 cm and accumulation of K was more beyond 50 cm depth. There were increases in all the P fractions in plots receiving superphosphate whereas in muriate of potash – fertilized plots, increase was seen only in insoluble P. All the fractions tended to decrease in plots which did not receive superphosphate. Depth – wise distribution of soil P forms showed concentration gradients decreasing with depth. Among the five fractions the build – up of AI – P, especially in the upper layers was considerable. The various P forms decreased in the order of insoluble P> AI – P> Fe – P> Ca – P> saloid – bound P. Significant positive correlations were obtained between AI – P, Fe – P, Ca – P saloid – P and available P. Step – wise regression and path coefficient analyses indicated that AI – P and saloid bound P were more important in explanting the variations in available P. Easily reducible Mn and exchangeable Mn were found to be affected by the regular application of ammonium sulphate alone. Both these Mn forms gave significantly low values in ammonium sulphate applied plots. Depth – wise distribution showed concentration gradients decreasing with depth. The comparison of the chemical characteristics of the uncropped and unfertilized area with cropped but unfertilized area revealed that chemical characteristics of the soil remained more or less same throughout the root zone upto a depth of 100 cm irrespective of whether the land is cropped to coconut or not. Depth – wise comparison of soil P as well as soil Mn fractions between the two situations mentioned above showed no significant difference in both soil P and soil Mn forms studied.
Soil nutrirent dynamics in cocoa
(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 1995) Smitha, B; Wahid, P A
An investigation on the dynamics of soil nutrients in the rootzone of cocoa (Theobroma cacao) was conducted during 1993 – 94 at the College of Horticulture, Vellanikkara. Soil and leaf samples were taken from cocoa trees under the Cadbury – KAU Co – operative Cocoa Research Project, Vellanikkara. Cocoa variety used for the study was forastero. The soil of the site was laterite (Oxisol). The treatments consisted of factorial combinations of N, P and K fertilizers each at two levels (with and without), two levels (with and without) of irrigation and shade and seven age groups namely 1, 3, 4, 5, 6, 9 and 12 years. Soil samples were also collected from an uncropped and unfertilized area nearby. The impact of long – term inorganic fertilization, irrigation and shade and age of the tree on soil chemical characteristics as well as foliar nutrition of cocoa influenced by long – term inorganic fertilization, irrigation and shade were assessed. Continuous application of urea for a period of nine years increased soil acidity and availability of P, S, Fe and Mn. It also increased total soil P and Fe. But it resulted in depletion of available K, Ca, Mg, Zn and Zn and Mn reserves of the soil. Long – term application of superphosphate resulted in the build – up of available and total P in soil. It also improved the status of soil available Ca, S and soil reserves of Ca and S. But it depleted soil available and total K, available and total Zn, available Mg and Cu and total Mn. Muriate of potash application increased the available and total K content of the soil. On the other hand it caused depletion of available P, Ca, S, Mn, Cu and soil Ca and Mg reserves. Interactions among urea, superphosphate and muriate of potash were also significant with regard to the fertility of the cocoa rootzone is concerned. Increasing soil acidity due to urea application, enrichment of S and Ca due to superphosphate application, and decrease in available P and S due to muriate of potash application were highly influenced by depth. Regular irrigation over a period of five years resulted in reducing the availability of P, Ca, Mn and Cu. It also reduced the total P and Mn in soil. But available K, Zn, S and total S tended to increase with irrigation. In the irrigated plots, total and available P were significantly lower in the surface layers compared to that in unirrigated plots. Provision of shade for a period of 13 years resulted in the build – up of soil organic carbon, available P, Fe and soil reserves of P, Ca, S, Fe, Zn and Mn. On the other hand it decreased the concentrations of available and total K, available S, and Zn and total Mg. Irrigation x shade interaction significantly influenced the available P content of soil. Urea application increased the foliar concentrations of N, Fe, Mn and Cu, but it decreased the leaf K content significantly. Long – term superphosphate application reduced Zn content of cocoa leaf. Application of muriate of potash increased leaf K content, but depressed foliar mg content significantly. Leaf N and K contents of cocoa were highly influenced by N x K interactions. N x P interaction significantly affected foliar Zn concentration of cocoa. Foliar Zn recorded higher values in plants receiving no nitrogen and phosphorus. Irrigation resulted in increased foliar concentrations of almost all nutrients except that of Ca and Mg. Foliar Ca content was higher in unirrigated plants. Effects of irrigation on leaf Mg was not significant. Cocoa trees under shade recorded higher concentrations of N, P, Mg, Fe and Mn and Cu in their foliage while K content was higher in open grown plants. Irrigation x shade interaction significantly influenced foliar N content. Shaded and irrigated conditions resulted in highest foliar N content. Nutrient dynamics in rootzone of cocoa over a period of 12 years of crop growth and fertilization could be described by linear or quadratic model. The linear model was found to be a better fit for available and total K, available and total Mg, available Cu and total Zn. In the case of available and total P, available and total Ca, available Zn, total S and total Cu the changes in concentrations with time could be described by a quadratic model. Available Mn content of the soil showed steady increase with age up to nine years followed by a sharp decrease.
Studies on the root activity pattern of black pepper employing radiotracer technique
(Department of soil science and agricultural chemistry, College of Horticulture, Vellanikkara, 1985) Jayasree Sankar, S; Wahid, P A
An investigation on the root activity pattern of black pepper vine and allied aspects was conducted employing phosphorus-32. The results indicated that the active root zone of black pepper vine trailed either on erythrina or on teak pole is in a soil column of 30 cm radius around the vine. It is suggested that fertilizer application to pepper vines may be done in a semicircle of 30 cm radius facing the vine for the most effective utilization of the added nutrients. Growing the vine in association with erythrina as support was found to reduce the uptake of 32p by at least 20 per cent as compared to that grown on teak pole. The active root system of erythrina was found to be more extensive than the vine reaching upto 60 cm from the pepper plant. The absorption of 32p by the climbing roots of the vine was found to be insignificant. A method of leaf sampling for 32p assay in black pepper vine as well as a method of soil injection of 32p solution into root zone of crop plants was developed. Annual exhaust of nutrients by way of harvest of 1.284 kg dry pepper was found to be 38.5g N, 36.7 g K, 14.9 g Ca, 13.7 g Mg, 2.2 g P, 1.37 g S, 218 mg Fe, 155 mg Mn, 28 mg Zn and 47 mg of Cu. From the defoliation of erythrina, an annual recycling of 0.7 kg dry matter containing 25.7 g N, 0.94 g P, 6.5 g K, 20 g each of Ca and Mg, 0.8 g S, 131.4 mg Fe, 1008 mg Mn, 13 mg Zn and 14.2 mg Cu may be expected.