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Open Access
Recycling of cashew (Anacardium occidentale L.) leaf litter and cashew apple through vermitechnology
(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 2016) Indu, V K; KAU; Jayasree Sankar, S
The present study entitled “Recycling of cashew (Anacardium occidentale L.) leaf litter and cashew apple through vermitechnology was undertaken in the Department of Soil Science and Agricultural Chemistry and at Cashew Research Station,Madakkathara during 2012-2014.The objectives were to study the efficacy of different enrichners on the manorial value of vermicompost prepared from cashew leaf litter and cashew apple using compost worm Eisenia foetida, to identify the role of introduced microbes in decreasing compost maturity time and to evaluate enriched vermicompost as a manurial source in the potting mixture for raising cashew grafts. The objectives were achieved through two experiments viz., (1) preparation of enriched vermicompost and (2) adjudging suitability of enriched vermicompost as a component in potting mixture for cashew grafts. Ferro cement tanks of 1m3 dimension, 300 Kg capacity and lined with jute bags were used for producing vermicompost. All the tanks were initially added with basic feed mixture (cashew leaf litter, cashew apple, sawdust and cowdung in 3:3:2:6 ratio on weight basis. Along with the basic feed mixture, different substrates were added according to the treatments. The experiment was carried out in a Completely Randomized Design with three replications with five tanks per replication. Nutrient status of substrates and that of matured compost was recorded initially and after compost maturity. In addition, pH was also recorded before and after composting, pH ranged from 4.5 in cashew leaf litter to 7.6 in cow dungand poultry manure respectively. Organic carbon content varied from 23% in poultry manure to 49% in coconut leaf. C:N ratio was found between 402.5 in sawdust to 22.62 in poultry manure. The biochemical constituents viz, cellulose, phenol, tannin and lignin were highest in cashew leaf litter (45.9, 1.62, 0.62 and 13.4 mg/100 g respectively) as compared to cashew apple. The compost obtained from T9(T1+ glyricidia leaf+ coconut leaf+ poultry manure+ Trichoderma viride + Pleurotus sajarcaju@ 500 mg kg-1 each of substrate+ Bacillus sp @ 2 kg m-3of substrate) on maturity (120 days), recorded a pH of 7.4, OC (28.6%), N (2.9%), C:N ratio (11), P (0.90%), K (2.0%), total Ca and Mg (1834 & 1185 mg kg-1 respectively) which was highest among other treatments. Earthworm population increased from the initial 200 numbers to1935 numbers in T9 as against 972 in T2which contained Eudrilus euginiaeas the facilitating worms. Xv Daily observations on temperature, weekly observations on pH, total microbial count (initial and final stages), days for compost maturity and earth worm count at maturitywere theother important observations studied in the first experiment. Different treatments was found to have significant effect on temperature. It increased in all the treatments with the composting process, reached a peak and then decreased coinciding with maturity or cooling phase. Highest peak was attained for T9 with 32.5OC. pH of compost mixture were also influenced by the treatments. pH value increased in all the treatments with progress in composting and shifted towards a neutral condition. Maximum pH was associated with T9 (7.3). Number of days required for compost maturity was minimum in T9(120Days) whereas it was maximum in T1(135Days) and the count of earthwormpopulation was nearly nine fold in T9whereas it was only six fold in T1. The lowest multiplication level was observed with T2 which contained Eudrilus eugineae as the compost worms. Based on manurial value assessed by high content of major nutrients (2.4%,0.90% and 2.06% NPKrespectively), compost from T9 of experiment I was selected as the best and designated as enriched vermicompost. Its suitability as a component in potting mixture of cashew grafts was assessed in another experiment. The study consisted of four treatments in four replication with five poly bags (25 x 15cm and 300 gauge) per replication in a CRD Design. The scion for grafting was collected from variety ‘Dhana’. Performance of the grafted seedlings was evaluated for a period of three months. Observations included chemical analysis with and without applying vermicompost for OC, available N, P, K,Ca, Mg, Fe, Mn, Zn and Cu.In addition pH was also recorded. Among the four treatments studied,T4 (sand, soil and enriched vermicompost in 1:1:3 ratio) recorded highest nutrient status (2.75, 0.34 and 0.72 g kg-1 of NPK respectively).The number of days for seed germination was minimum in T4 (15) as against 20 days recorded for seed germination for T1. Other biometric observations like plant height (40.37cm), number of leaves (35) and collar girth (5.3cm) were observed maximum in plants grown in T4. Phytotoxicity was not seen in any of the treatments during the three months of evaluation. By employing the epigeic earthworms Eisenia foetida, the enormously available but untreated lignocellulotic solid organic resource, cashew leaf litter and cashew apple, could be effectively converted to nutrient rich vermifertilizer by suitably admering with various organic enrichners. The vermifertilizer thus produced could be efficiently used as a component in the potting mixture for raising cashew plants. Crop performance was the best when the vermifertilizer was mixed at three parts on volume basis with one part each of xvi sand and soil. Based on results vermicomposting could be established as a ecofriendly and ecologically sound method for manure from cashew leaf litter and cashew apple
Open Access
Enzyme Characterization of the acid sulphate soils of Kuttanad
(Department of Soil Science and Agricultural Chemistry, college of Agriculture, Vellayani, 2016) Arya Nath V; KAU; Aparna, B
Regarding the enzyme status of the acid sulphate soils, the activity of urease was the highest in Thakazhi (L4-75.78 ppm of urea hydrolyzed g-1 soil h-1) in the surface layer. Acid and alkaline phosphatase activities were found to be the highest in Purakkad (L3-57.58 μg pnp released g-1 soil h-1) and Thakazhi series (L4-46.41 μg pnp released g-1 soil h-1) respectively in the surface layers. The highest activity of dehydrogenase was noticed in Thuravur series (L6-115.74 μg of TPF released g-1 soil 24 h-1) in the surface and Kallara series in the subsurface layers (L2-55.39 μg of TPF released g-1 soil 24 h-1). Karappadam and Kayal recorded the values of 145.73 and 114.80 μg of TPF released g-1 soil 24 h-1 for dehydrogenase activity respectively at surface layers. With regard to the microbial population, Thottappalli (L5) recorded the highest total bacterial count and fungal population in both surface and subsurface layers. Thiobacillus spp. recorded the highest population of 9.08 log cfu g-1 of soil at Kallara series (L2) while P solubilizers recorded the highest count at Ambalapuzha series (L1). Thuravur series recorded the highest actinomycetes population in subsurface soils. Micahelis – Menten constant, Km and the maximum velocity Vmax for different enzymes were determined and it was observed that for dehydrogenase Vmax value was found to be the highest in 6th week and for phosphatase only after 12th week of incubation. Thematic maps were prepared based on themes like microflora and enzyme status using GIS (ARC VIEW). Hence the study conclude that, with respect to biological fertility status of the study area, Purakkad recorded the highest enzyme activity number (23.69) at 0-15 cm, while Kallara series recorded the highest enzyme activity number in the subsurface layer and are observed to be biologically sustainable.
Open Access
Sequestration of carbon as influenced by nutrient management practices under long term fertilizer experiments
(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 2017) Sumayya Sulaiman; KAU; Thulasi, V
The present study entitled “Sequestration of carbon as influenced by nutrient management practices under long term fertilizer experiments” was undertaken at RARS, Pattambi and College of Horticulture, Vellanikkara. The soil samples were collected from the plots of Permanent Manurial Trial (PMT) and AICRP on long term fertilizer experiments (LTFE) at Pattambi after the harvest of rice (Virippu crop), 2016. New Permanent Manurial Trial with dwarf indica rice variety, was started in Virippu, 1973. The AICRP on Long term fertilizer experiment was initiated in Mundakan 1997. The two field experiments where being conducted continuously in the same fields, the present Virippu crops of these experiments being in their, 89th and 39th season respectively. The objectives were set out to study the effect of long term application of fertilizers and manures on soil carbon pools, thermal stability of stored carbon and growth characteristics of plant. The PMT consists of 8 treatments viz.,T1: 90 kg N ha-1 as cattle manure, T2: 90 kg N ha-1 as green leaf manure, T3: 45 kg N ha-1 as cattle manure + 45 kg N ha-1 as green leaf manure, T4: 90 kg N ha-1 as ammonium sulphate, T5: 45 kg N ha-1 as cattle manure + N:P2O5:K2O 45:45:45 kg ha -1, T6: 45 kg N ha-1 as green leaf manure + N:P2O5:K2O 45:45:45 kg ha -1, T7: 22.5 kg N ha-1 as green leaf manure + 22.5 kg N ha-1 as cattle manure + N:P2O5:K2O 45:45:45 kg ha -1 and T8: N:P2O5:K2O 90:45:45kg ha -1. The LTFE consists of 12 treatments viz.,T1: 50 per cent NPK (as per KAU POP recommendation), T2 : 100 per cent NPK, T3 : 150 per cent NPK, T4 : 100 per cent NPK + 600 kg ha -1 CaCO3, T5 : 100 per cent NPK, T6 : 100 per cent NP, T7 : 100 per cent N, T8: 100 per cent NPK + FYM @ 5 t ha -1to the virippu crop only, T9: 50 per cent NPK + FYM @ 5 t ha -1,T10 : 100 per cent NPK + in situ growing of Sesbania aculeata (for Virippu crop only), T11 : 50 per cent NPK + in situ growing of Sesbania aculeata (for Virippu crop only) and T12 : Absolute control (No fertilizers or manures). In PMT, the organic nutrient management (T1) and Integrated Nutrient Management (INM) practice (T5) were equally superior in growth and productivity of the crop. However the dehydrogenase activity and microbial biomass carbon was significantly influenced by the INM practice. The physiological properties of the plant like stomatal conductance and photosynthetic rate, yield attributes such as panicle length, number of panicles per plant and number of filled grains corroborated the trend in yield. The available primary nutrient status of the post harvest soil was higher in T8 (N: P2O5: K2O 90:45:45kg ha -1). However the substitution of 50 per cent mineral N by organic manures under INM treatments improved the available nutrient status suggesting the synergistic role of organic manures. In LTFE, the integrated nutrient package (T8) had significantly higher dehydrogenase activity and microbial biomass carbon in post harvest soil which was positively reflected on yield and yield attributes. Application of FYM had beneficial role over green manures towards organic carbon build up in soil. In LTFE with 20 years history, it was seen that all the carbon pools (active, slow and passive) contributed towards yield whereas in PMT, with 44 years history, it was the slow pool of carbon that showed higher correlation with crop yield. Data on analysis of different carbon pools revealed that slow pool is the most predominant yield determining pool in the long run. The percentage contribution of carbon pool towards total soil organic carbon in paddy soil of the present work can be rated as passive (54%) > slow (36%) > active (10%). An incubation study was conducted at four different temperature regimes (15, 25, 35 and 450C) using the soil collected from the plots of LTFE as well as PMT. The activation energy and the rate constants provided a good insight on decomposability of organic matter. In general, all the treatments in PMT, except T5 (25°C), T6 (15°C) and T8 (35 and 45°C) had comparable amounts of carbon decomposition. Thermal stability studies indicated that the rate of reaction decreased with increase in temperature due to the faster exhaustion of the substrates in initial days of decomposition at higher temperatures. Q10 values were also less than one in both the experiments due to the exhaustion of labile pool available for microbial decomposition. Treatments with inorganics recorded lowest activation energies indicating the instability of even recalcitrant or passive pools. It could be summarized from the results that, the carbon build up in soil was significantly higher under organic nutrient management. But the per cent share of slow carbon pool (Mean Residence Time: 20-40 years) to total carbon was higher under INM. Moreover, the thermal stability of carbon was found to be remarkably higher under INM than sole application of organic manures or inorganic fertilizers. The study fortifies INM as a stable practice to sustain soil organic carbon and crop productivity in the context of rising temperatures. Chemical and physical stability of carbon and its threshold carbon concept in soils of Kerala need to be explored.
Open Access
Response of tomato to calcium and boron in the onattukara tract of alappuzha district
(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2017) Aswathy Mohan; KAU; Indira, M
The experiment entitled “Response of tomato to calcium and boron in the Onattukara tract of Alappuzha district” was conducted at the ORARS, Kayamkulam during the period from September to December 2016. The objective of the study was to find out the effect of calcium and boron on yield and quality of tomato and to develop a recommendation for these nutrients to optimize the productivity. The experiment was laid out as factorial RBD (42 + 1) with two replications. The treatments included two factors viz. calcium levels and boron levels. The calcium levels were- no calcium (Ca-0), full dose of calcium as basal (Ca-1), half dose of calcium as basal (Ca-2) and one fourth dose of calcium as basal (Ca-3). Calcium was supplied through CaO and the dose of calcium was worked out from lime requirement by SMP (Buffer method by Shoemaker et al.) method. Levels of boron were – no boron (B-0), foliar spray 0.1% (B-1), foliar spray 0.2% (B-2) and foliar spray 0.3% (B-3). Boron was supplied through borax at 50% flowering stage. The Package of Practices Recommendations of KAU (20 t ha-1 FYM and 75:40:25 kg ha-1 NPK) was uniformly followed in all treatments. The control treatment was soil test based application of N, P, K, recommended dose of lime and B. Results of the study revealed that the application of calcium had a significant effect on biometric characters, per cent incidence of physiological disorders, soil pH and plant uptake of nutrients. Application of full dose of calcium as basal (Ca-1) recorded the highest yield. The lowest incidence of blossom end rot and fruit cracking was observed in Ca-1. The highest B : C ratio was also observed in Ca-1. Calcium application did not have any significant effect on available nutrients except calcium. Ca-1 recorded a significant effect on the plant content of calcium. It also contributed to a significant effect on the uptake of nutrients such as N, P, K, Ca, Mg, S, B, Fe, Cu, Mn and Zn. Boron application produced significant effect on biometric characters, per cent incidence of physiological disorders and plant uptake of nutrients. Among various levels, foliar spray of 0.3% boron (B-3) was found to be the best treatment. B-3 has recorded the highest yield and B: C ratio. It also produced the lowest incidence of fruit cracking. Boron application did not have any significant effect on soil available nutrients, soil pH and plant content of nutrients except plant boron. B-3 has also contributed to a significant effect on the uptake of nutrients such as N, P, K, Ca, Mg, S, B, Fe, Cu, Mn and Zn. Among various interactions, application of full dose of calcium as basal along with foliar spray of 0.3% boron (Ca1B3) has contributed to the maximum yield, B: C ratio and the lowest incidence of fruit cracking. Ca1B3 recorded the highest uptake of nutrients such as N, P, K, Ca, Mg, S, Fe, Cu and Mn. None of the interactions were observed to be significant for soil pH, soil available nutrients and plant nutrient content. But the application of Ca and B produced no significant effect on the quality characters such as TSS, lycopene content and ascorbic acid contents. From the results of the study, it can be concluded that higher yield of tomato in Onattukara tract of Alappuzha district can be obtained by the combined application of full dose of calcium as per lime requirement of the soil along with 0.3% foliar spray of boron (Ca1B3) in addition to the blanket recommendations of KAU (20 t ha-1 FYM and 75:40:25 kg ha-1 NPK).
Open Access
Flux and dynamics of iron and aluminium in wetlands of Kuttanad and its management for rice (Oryza sativa L.)
(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Padannakkad, 2017) Ebimol, N L; KAU; Suresh, P R
The investigation entitled “Flux and dynamics of iron and aluminium in wetlands of Kuttanad and its management for rice (Oryza sativa L.)” was carried out at College of Agriculture, Padannakkad during 2015-2017. The objective of the study was to evaluate the performance of two popular rice varieties viz. Uma and Prathyasa to varying levels of iron and aluminium concentrations at different growth stages and to examine suitable amelioration strategies. The entire experiment was conducted in three parts, which included collection and analysis of soil sample from Kuttanad, solution culture with graded levels of Fe and Al and a pot culture experiment using the Kuttanad soil. As a preparatory to pot culture study, an incubation experiment was also conducted using the bulk soil collected from Kuttanad so that nutrient release pattern under submergence could be obtained. Soil samples at GPS coordinates (latitude: 9°:18ˈ:56ˈˈ.99, longitude: 76°:24ˈ:30ˈˈ.68) were collected from the ‘Kari’ lands of Kuttanad and brought to College of Agriculture, Padannakkad and analysed for various physical and chemical properties. It was observed that the soil has extremely low pH, very low available P and toxic levels of Fe and Al. This soil was used for incubation study and pot culture experiment. The incubation study was conducted with four treatments at two levels of submergence (5 cm and 10 cm) in factorial CRD. The treatments were designed based on the recommendations of KAU POP 2011 viz. lime @ 600 kg ha-1 (T1); phosphogypsum + 1⁄2 lime @ 300 kg ha-1 (T2); magnesium carbonate @ 50 kg ha-1 + 1⁄2 lime @ 300 kg ha-1 (T3) and control (T4). During the submergence period among the various parameters monitored, a steady increase was observed for pH, Ca and Mg of the soil. Application of phosphogypsum + 1⁄2 lime showed the highest increase in soil pH and available calcium content and was highly effective in lowering the toxic concentration of Fe and Al in the acid sulphate soils of Kuttanad. The solution culture experiment was carried out using Hoagland’s nutrient solution as nutrient medium in which four levels of Fe (200, 400, 800 and 1200 mg L- 1 ) and two levels of Al (50 and 100 mg L-1) were added in factorial combination and experiment was designed in CRD. The treatment with 1200 mg L-1 Fe and 100 mg L-1 Al suppressed the plant height, root length, root dry weight and recorded maximum concentration of Fe and Al in the root and displayed thick iron coating (iron plaque) around the root as observed in the root sections. The third part of the investigation, pot culture experiment was conducted with seven treatments as amendments and two varieties Uma and Prathyasa in factorial CRD. The leachate was collected and analysed by placing a perforated pipe at the centre of the pot. The treatments were designed based on the recommendations of KAU POP 2011. The treatment combinations were: lime @ 600 kg ha-1 (T1); magnesium carbonate @ 50 kg ha-1 + 1⁄2 lime @ 300 kg ha-1 (T2); phosphogypsum + 1⁄2 lime @ 300 kg ha-1 (T3); lime @ 600 kg ha-1 + potassium silicate 0.25% + 0.25% boron (T4); magnesium carbonate @ 50 kg ha-1 + 1⁄2 lime @ 300 kg ha-1 + potassium silicate 0.25% + 0.25% Boron (T5); phosphogypsum + 1⁄2 lime @ 300 kg ha-1 + potassium silicate 0.25% + 0.25% boron (T6) and control (T7). The application of amendments significantly improved the biometric characters. The treatment T4 showed higher plant height and grain yield per pot whereas T6 showed more number of tillers and maximum number of grains per panicle. The treatment T6 considerably reduced the Fe, Al and Mn content in soil and leachate, which also recorded significantly higher of P, Ca, B and Si content in soil and leachate. The treatment T6 also recorded highest plant nutrient concentrations of N, P, K, Ca, S and B while significantly reduced the concentration of Fe and Al whereas the treatment T4 reduced the Mn content, increased the Si content and maximum increase in value of soil pH. The highest soil available N, K and Mg was recorded in treatment T5 which also showed highest plant content of Mg, Zn and Cu. The acid sulphate soils of Kuttanad region are having constraints of extreme acidic soil pH and pronounced toxicity of Fe and Al. This can be ameliorated using amendments and can be made more productive. The results of the investigation clearly indicate that application of phosphogypsum along with lime and foliar application of B and Si enhances the grain and straw yield of rice. This treatment also enhanced the available nutrient status of soil and plant nutrient content. It was very effective in alleviating toxicity of Fe and Al.
Open Access
Evalulation of soil and water quality in potta watershed of pazhayannur block in Thrissur district
(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 2017) Raghunath, H N; KAU; Betty Bastin
An investigation entitled ‘Evaluation of soil and water quality in Potta watershed of Pazhayannur Block in Thrissur district” was undertaken in the department of Soil Science and Agricultural Chemistry, College of Horticulture, Kerala Agricultural University during the Year 2016-17. An intial survey was carried out in the different reaches of the watershed to identify the water resources, crops. Vegetation, manures, fertilizers and pesticides used. Based on the data generated, thirty Soil samples were samples were collected from each reach. Soil samples were collected only during the pre-monsoon season (April to May, 2016) and post-monsoon November to December, 2016) season. The soil samples were characterized for texture, bulk density, particle density, water holding capacity (WHC), pH, electrical conductivity (EC), organic carbon (OC), cation exchange capacity (CEC), available nutrients (N, P, K, Ca, Mg, S, Fe, Mn, Zn, and Cu) and heavy metals (Pb, Ni, Cr, and Cd) and heavy metals (Pb,Ni,Cr and Cd). Water samples were analyzed for chemical properties like pH, EC, TSS, cations, (Na+ , Ca2+ , K+, Mg2+) anions (CI-1, SO42-, CO32-, HCO3- and NO3- )heavy metals Cd, Pb, Cr, and Ni). The texture of soils in all the three reaches were found to be sandy loam. Soils from all the reaches were acidic and the pH varied from 3.47 to 6.80 with very low electrical conductivity(0.021 to 0.170 dS m-1). Cation exchange capacity of the soil samples varied between 4.15 to 8.97 c mol (p+) Kg-1. in the soil samples of upper reach was deficient in soil OC. Deficiency of available N in all reaches and that of P in upper and lower reaches was observed. The highest deficiency of K was noticed in the soil samples of upper reach. All the reaches were deficient in secondary nutrients (Ca and Mg). The available heavy metals in the soil was found to be below toxic level and their contents decreased in the order of Pb > Ni > Cr > Cd. Micronutrients (Fe, Mn, Zn and Cu) were found to be sufficient and their contents followed the order Mn > Fe>Cu > Zn Significant differences were observed between upper and middle reached in the content of soil available N, P and K. The association of soil properties showed that the soil organic carbon (SOC) was significantly and positively correlated with soil water holding capacity and available nitrogen in all the reaches, whereas it was negatively correlated with the bulk density of soil. During both pre and post – monsoon periods, PH of the water samples ranged between acidic to neutral values (5.62 to 7.47). electrical conductivity of water samples ranged from 0.14 to 0.54 dS m-1 . The content of cations, viz.,Ca and Mg were high in post-monsoon season while Na and K were high in pre-monsoon season. Analysis of anionic composition of water samples showed that the content of anions viz., bicarbonates, chlorides and nitrates were higher in post monsoon compared to pre-monsoon. The heavy metals like lead, chromium and cadmium were found to be below detectable level in all the water samples collected during both pre and post –monsoon seasons. Water samples registered significant differences in the contents of Ca, Mg, HCO3- between pre and post –monsoon seasons . The quality of water from all the reaches can be rated as good and suitable for irrigation. Further studies can be focused on the assessment of the impact of different soil conservation measures on the soil health. Soil test based fertilizer recommendations including various organic resources have to be adopted by the farmers.
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 Mathew
The 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.
Open Access
Dynamics of iron and aluminium toxicity on rice (Oryza sativa L.) in saline hydromorphic soils of kaipad
(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Padannakkad, 2017) Santhi, G R; KAU; Binitha, N K
An investigation entitled “Dynamics of iron and aluminium toxicity on rice (Oryza sativa L.) in saline hydromorphic soils of Kaipad” was carried out at College of Agriculture, Padannakkad during the academic year 2015 to 2017. The objectives of the study were to investigate the status of iron and aluminium in saline hydromorphic soils of Kaipad, evaluate the performance of popular rice varieties to varying levels of iron and aluminium concentration at different salinity levels, and examine amelioration strategies for iron and aluminium toxicity. The study was carried out in four parts namely collection and soil analysis, incubation study, solution culture and pot culture experiments. As a part of the initial study, representative surface soil samples were collected from 15 selected locations of Kaipad areas comprising of Muttil and Cherukunnu panchayath during the first week of April 2016 to assess the different physical and chemical properties. The GPS data for the sites were also recorded. The pH of the soils varied from ultra-acidic to slightly acidic. The electrical conductivity during the summer months was very high. Among the macro and micro nutrients studied, very high available K and Ca values were observed and extreme toxicity of available Fe and Al were also recorded. An incubation study was conducted with four treatments at two levels of submergence (5 cm and 10 cm) in factorial CRD. The treatments were fixed based on the recommendations of KAU POP, 2011 viz. lime (T1); magnesium sulphate + 1⁄2 lime (T2); phosphogypsum + 1⁄2 lime (T3) and control (T4). The application of treatments showed a positive effect in reducing iron and aluminium toxicity. The toxic levels of available Fe were significantly reduced in T 1 at 30 and 120 DAI whereas, at 60 and 90 DAI, T3 was significantly superior in reducing the iron toxicity. The aluminium toxicity was reduced to minimum level at 30, 60 and 120 DAI in treatment T3. However at 90 DAI, the least aluminium content was recorded in the soil treated with lime alone. The solution culture experiment was conducted by maintaining Hoagland‟s nutrient solution containing 3 levels of iron (400, 800, 1200 mg L-1), 2 levels of aluminium (15 and 30 mg L-1) and 2 levels of salinity (5 and 10 dS m-1) along with one control in factorial combinations using CRD. The two selected varieties, Ezhome-1 and Kuthiru were evaluated for their tolerance to iron and aluminium toxicity coupled with salinity. Maximum iron coating around the roots with respect to the treatments were displayed in T12 (1200 mg L-1 iron, 30 mg L-1 aluminium and 10 dS m-1 salinity) solution. Increase in levels of iron, aluminium and salinity significantly reduced the plant height, root dry weight, root length and root CEC of rice plants. The pot culture experiment was conducted with seven treatments as amendments and two varieties Ezhome-1 and Kuthiru in factorial CRD during July to October 2016. The treatment combinations were: Lime (T1); Magnesium sulphate + 1⁄2 lime (T2); Phosphogypsum + 1⁄2 lime (T3); Lime + potassium silicate 0.25% + 0.25% boron (T4); Magnesium sulphate + 1⁄2 lime + potassium silicate 0.25% + 0.25% boron (T5); Phosphogypsum + 1⁄2 lime + potassium silicate 0.25% + 0.25% boron (T6) and control (T7). The leachate was collected and analysed by inserting a perforated pipe at the centre of each pot. The variety Ezhome-1 recorded maximum significant plant height at 30, 60 and 90 DAT. The number of productive tillers/ number of panicles, grains per panicle, grain yield, straw yield and 1000 grain weight were also significantly superior in Ezhome-1. Among the amendments, T6 recorded significantly superior plant height, grain yield, total Ca, B, Si and lowest Al content in rice. The treatment T 3 recorded maximum significant number of panicles, productive tillers, grains per panicle, straw yield, 1000 grain weight and lowest Na and Fe content in plant tissue. The treatments receiving phosphogypsum + 1⁄2 lime (T 3 and T6) were highly effective in reducing the toxic levels of available Fe and Al whereas, application of lime (T 4) was significantly superior in increasing the soil pH, available P and reducing the EC and exchangeable Na status of Kaipad soil. The saline hydromorphic soils of Kaipad are having severe constraints of acidity, extreme toxicity of iron and aluminium coupled with high salinity. These problems can be ameliorated using combinations of amendments including phosphogypsum, lime and foliar application of boron and silicon to enhance the growth and yield of rice crop. Adoption of aforementioned management strategy could help in improving the soil health and thereby increasing the yield potential of Kaipad rice.
Open Access
Mineralization of soil nitrogen, carbon and kinetics of enzymes under coconut based cropping system
(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2017) Usharani, K V; KAU; Aparna, B
A study entitled “Mineralization of soil nitrogen, carbon and kinetics of enzymes under coconut based cropping system” was carried out during 2015-17 in the Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani. The study was envisaged toassess the mineralization potential of soil nitrogen and carbon and to evaluate the kinetic parameters of agriculturally significant soil enzymes of coconut based cropping systems in mid laterite soils of Agro Ecological Unit (AEU) 9. Soil samples were collected from five coconut based cropping systems 1. Coconut + Fodder grass 2. Coconut + Banana, 3.Coconut + Pepper, 4. Coconut + Tuber and 5. Coconut + Vegetable under organic and conventional farming situations. With regard to physical properties, the lowest bulk density of 1.30 Mg m-3 was noticed in Coconut + Vegetable under organic management. Coconut + Tuber under organic system recorded the highest value for water holding capacity (19.86 %). The highest porosity was noticed under Coconut + Pepper (41.60 %) cropping system, while the interaction effects of cropping and farming systems on porosity was non significant. With regard to the electrochemical properties, the highest pH of 5.33 was noticed in Coconut + Vegetable under organic management and the lowest EC value of 0.26 dSm-1 was noticed in Coconut + Pepper and Coconut + Tuber under conventional management system. Analysis of available nutrient status revealed that the N and K status were higher in Coconut + Vegetable cropping system under conventional management viz., 326.14 kg ha-1 and 183.68 kg ha-1, while the highest value of available P (91.87 kg ha-1) was noticed in Coconut + Fodder under organic management. Among the secondary nutrients, calcium was noticed highest in Coconut + Vegetable (310.59 mg kg-1) and magnesium in Coconut + Tuber (143.49 mg kg -1) under organic management. Coconut + Banana under organic management system recorded the highest available micronutrient status of Fe, Zn, Mn and Cu viz., 45.19 mg kg-1, 1.64 mg kg-1, 23.29 mg kg-1 and 5.74 mg kg-1 respectively, while Coconut + Pepper recorded the highest boron content (1.5 mg kg -1) in the conventional management system. Coconut + Banana cropping system under organic management situation recorded the highest activities of major enzymes viz., dehydrogenase, acid phosphatase and catalase i.e., 462.52 μg of TPF released g -1 of soil 24 h-1, 80.35 μg of p-nitrophenol released g -1 of soil 24 h-1 and 3.90 % of H2O2 hydrolysed g-1 of soil h-1 respectively. In general, the enzyme activities were found to be the highest in organic farming situation than the conventional farming situation. In the case of β-glucosidase and amylase, Coconut + Pepper recorded the highest values viz., 4.10 μgpnp D-glucosidase g-1 soil h-1 X 10-4 and 13.82 μΜ of maltose g-1 of soil respectively.The highest values of bacterial count of 8.04 log cfu g -1 and actinomycetes count of 4.30 log cfu g -1 were noticed in Coconut + Banana under organic system of management. Enzyme activity number (EAN) was calculated using the expression EAN = 0.2{TPF+catalase (%)/10 + phenol (μg)/40 + amino-N (μg)/40 + amylase (%)/20}.The highest value for EAN was noticed in Coconut + Banana under organic system (94.01) followed by Coconut + Pepper (74.92). With respect to mineralization of soil carbon, the highest values for organic carbon, water soluble carbon and particulate organic carbon 1.63%, 72.74 mg kg -1and 0.75 % respectively were noticed for Coconut + Tuber under organic management. The highest microbial biomass carbon noticed in Coconut + Banana (15.11 mg of CO 2 g-1) might have contributed to the higher enzyme activity and thus higher enzyme activity number (EAN). In the case of mineralization of soil nitrogen, Coconut + Vegetable (organic) recorded the highest value of 281.80 mg kg -1 for mineralizable nitrogen and 0.31% for total nitrogen thus contributing to14.95 % of mineralizable nitrogen to total nitrogen. From the enzyme kinetics studies, V max was found to be maximum in the 8th week for urease and acid phosphatase and 6th week for dehydrogenase. From the study, it is concluded that Coconut + Tuber and Coconut + Vegetable cropping system under organic farming situation favours the mineralization of carbon and nitrogen respectively. Coconut + Banana under organic situation was found to be the best with respect to the soil biological properties.

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