Role of Some Agricultural and Industrial By-products in Modifying Soil Physical Properties

In a pot culture study, saw dust, vermiculite, lignite, magnesium oxide, wheat straw, paddy shell, ground nut shell and farm yard manure (FYM) were incorporated in to wet sandy loam and clay soils at the rate of 30 g/kg. Relative changes in soil structure and moisture retention were evaluated at the end of 160 day incubation period. All the amendments except vermiculite, ground nut shell and FYM in sandy loam soil and except vermiculite, lignite, magnesium oxide in clay soil significantly increased MWD and aggregates > 1 mm. Structural index was significantly improved by all the amendments except vermiculite and FYM in sandy loam and vermiculite and magnesium oxide in clay soil. Moisture retention and release in clay soil in the wet range (0 to 0.33 bar) were considerably increased by soil amendments except magnesium oxide, vermiculite and lignite. Almost all the amendments significantly increased moisture retention in the wet range in sandy loam soil. However, moisture release at 50 mbar was reduced only by wheat straw in sandy loam soil.     

Carbon sequestration and relationship between carbon addition and storage under rainfed soybean–wheat rotation in a sandy loam soil of the Indian Himalayas

Soil organic matter (SOM) contributes to the productivity and physical properties of soils. Although crop productivity is sustained mainly through the application of organic manure in the Indian Himalayas, no information is available on the effects of long-term manure addition along with mineral fertilizers on C sequestration and the contribution of total C input towards soil organic C (SOC) storage. We analyzed results of a long-term experiment, initiated in 1973 on a sandy loam soil under rainfed conditions to determine the influence of different combinations of NPK fertilizer and fertilizer + farmyard manure (FYM) at 10 Mg ha⁻¹ on SOC content and its changes in the 0–45 cm soil depth. Concentration of SOC increased 40 and 70% in the NPK + FYM-treated plots as compared to NPK (43.1 Mg C ha⁻¹) and unfertilized control plots (35.5 Mg C ha⁻¹), respectively. Average annual contribution of C input from soybean (Glycine max (L.) Merr.) was 29% and that from wheat (Triticum aestivum L. Emend. Flori and Paol) was 24% of the harvestable above-ground biomass yield. Annual gross C input and annual rate of total SOC enrichment were 4852 and 900 kg C ha⁻¹, respectively, for the plots under NPK + FYM. It was estimated that 19% of the gross C input contributed towards the increase in SOC content. C loss from native SOM during 30 years averaged 61 kg C ha⁻¹ yr⁻¹. The estimated quantity of biomass C required to maintain equilibrium SOM content was 321 kg ha⁻¹ yr⁻¹. The total annual C input by the soybean–wheat rotation in the plots under unfertilized control was 890 kg ha⁻¹ yr⁻¹. Thus, increase in SOC concentration under long-term (30 years) rainfed soybean–wheat cropping was due to the fact that annual C input by the system was higher than the required amount to maintaining equilibrium SOM content.     

A modified nitrogen oxide-ozone photolytic cycle

Nitrogen Oxide-0₃ photolytic cycle is dependent upon the presence of NO in ambient air. From our air monitoring observations we have found that the NO concentration in the atmosphere is often zero (0 to 5 ppb). This suggests a need to modify/change the photolytic cycle. Linear regression analyses on the O₃ and NO₂ concentrations in ambient air, measured in real time were carried out. The predicted values of O₃ and NO₂ from these regression equations were close to the observed values. On the basis of these two observations a modified photolytic cycle, including some other components (such as HONO₂) is discussed.     

Potential of Eisenia foetida for Sustainable and Efficient Vermicomposting of Fly Ash

Vermicomposting of fly ash has been attempted, using red earthworm, Eisenia foetida. Fly ash, which was obtained from thermal power station, was mixed with cowdung in different proportions (20, 40, 60 and 80%). These mixtures were used as feed for earthworms, and after 30 days, vermicast recovery, worm zoomass and numbers of juveniles produced were recorded. A total of six runs each of 30 days were conducted during the whole study. Concentrations of heavy metals in different mixtures of fly ash–cowdung, before and after vermicomposting and in the earthworms used in the study were also estimated. Results show maximum output of vermicasts and maximum number of juveniles produced was in reactors with 40% fly ash while maximum weight gain by earthworm was in 20% fly ash vermireactors. Performance of vermireactors up to 60% fly ash was more or less similar but at 80% fly ash, there is a marked reduction in overall performance of the reactors. Chemical analysis of different samples of fly ash–cowdung mixtures prior to vermicomposting revealed high concentrations of zinc, chromium, lead, nickel and copper. Chemical analysis of vermicomposted samples showed 30–50% reduction in heavy metals up to 60% fly ash and 10–30% reduction in 80% fly ash. Metal analysis of earthworms revealed considerable bioaccumulation of heavy metals in their body. The Present study indicates the feasibility of E. foetida for mitigating the toxicity of metals and up to 60% fly ash–cowdung mixtures can be used for sustainable and efficient vermicomposting.     

阿灭净在菠萝与土壤中的残留及消解动态研究

采用气相色谱(GC-NPD)分析技术测定除草剂阿灭净在菠萝与土壤中的残留及消解动态结果表明,GC-NPD方法的最小检出量为0.0232ng,菠萝及土壤的最小检出浓度分别为0.002mg/kg和0.005mg/kg,GC-NPD方法回收率分别为87.23%~92.10%和88.80%~93.77%。喷施阿灭净80%WP4800g(a.i/)hm2,处理检测出菠萝与土壤中原始沉积量分别为0.1448~0.1646mg/kg和3.3318~3.5536mg/kg,消解半衰期分别为29.17~29.45d和25.75~30.68d,按阿灭净用量4800g(a.i/)hm2施药菠萝1次,间隔期为10d,菠萝果实残留量2年分别为0.1646mg/kg和0.1448mg/kg,参照欧共体的MRL值0.2mg/kg,按上述阿灭净剂量方法施用菠萝是安全的。     

Heavy metal accumulation by three species of mosses in Shillong,North-Eastern India

Comparisons were made of the accumulation of cadmium, copper, manganese, lead, and zinc in Plagiothecium denticulatum, Bryum argenteum and Sphagnum sp. in Shillong, Meghalaya State, Northeastern India. Samples of P. denticulatum and B. argenteum were collected inside Shillong city (urban) and its immediately adjacent outskirts (suburban), while Sphagnum sp. was collected from a suburban site only. Lead and copper levels were higher in P. denticulatum, while Sphagnum sp. accumulated higher amounts of zinc, manganese, and cadmium. An urban-suburban gradient was evident for lead and zinc in P. denticulatum, and for cadmium in B. argenteum, while a reverse trend could be discerned for manganese in P. denticulatum. Besides vehicles and minor industries, quarry dust was likely to be an important source of manganese, copper, and zinc.     

Stress distribution over a triangular tillage tool

To simplify the analysis of stress over a cultivator shovel moving at a certain depth, it was represented by an isosceles triangular plate of uniform thickness. To simulate the boundary conditions to which a cultivator shovel is subjected, the triangular plate was assumed as clamped along one of the edges while the other two edges were assumed as free. These assumptions made it possible to apply the theory of bending of laterally loaded plates for the computation of stresses set up in the tillage tool. This theory involves fundamental equations of elasticity, namely the equations of equilibrium, equations of continuity and surface conditions. The theoretically calculated values of stresses were fairly close to experimentally observed values.     

Study of resistance against some ionophores in Eimeria tenella field isolates.

Three Eimeria tenella field isolates from Gurgaon district of Haryana (north India) were studied in a battery test for evaluating drug resistance against two currently used ionophores; maduramicin (5ppm) and salinomycin (60ppm). Broiler birds (Ross strain) were infected with 10(5) sporulated oocysts each at the age of 2 weeks and prophylactic medication commenced 2 days prior to infection. Drug resistance was assessed by calculating the global index for individual ionophore compounds based on weight gain, feed conversion ratio, oocyst index, lesion score and mortality. Present studies revealed no resistance of the ionophores in any of the field isolates. Both the drugs showed varying degree of efficacy, e.g. maduramicin exhibited limited efficacy against all the three field isolates, whereas salinomycin showed limited efficacy against Gurgaon isolate (GrI)-I, good efficacy against GrI-II and partial resistance against GrI-III.