EFFICACY OF GYPSUM AND MAGNESIUM SULFATE AS SOURCES OF SULFUR TO RAPESEED IN LATERITIC SOILS

A field experiment conducted on rapeseed (Brassica juncea L.) during 2005–2006 in a typical lateritic soil (Alfisol) of West Bengal, India revealed that sources of sulfur viz. gypsum and magnesium sulfate and levels of sulfur (0, 20, 40, 60 kg S ha^?1) have significant influence on grain yield, total biological yield, sulfur concentration in grain and stover, total sulfur uptake, oil content and oil yield and chlorophyll content. The maximum grain yield (18.28 q ha^?1) and oil yield (8.59 q ha^?1) was obtained with magnesium sulfate followed by gypsum yielded the grain yield of 17.99 q ha^?1 and oil yield of 8.22 q ha^?1 at 40 kg S ha^?1. Overall, the best performance was recorded when sulfur was applied at 40 kg S ha^?1 either as magnesium sulfate or gypsum. Results revealed that magnesium sulfate may be considered as the better source of sulfur than gypsum to raise the mustard crop in sulfur deficient acidic red and lateritic soils of West Bengal and if farmers apply either magnesium sulfate or gypsum to soils, the possible deficiency of sulfur and magnesium/calcium in soils and plants can be avoided.     

Soil fertility ‐ crop genotype associations and interactions 1

This paper discusses the opportunities to combine the efforts of plant geneticists and soil scientists to develop crop varieties adapted to the existing soil conditions and techniques used for production. Such research should result in improved varieties for the best as well as poorest of soil and production situations.     

Sensitivity of soft red winter wheat cultivars to chlorate‐induced toxicity

The use of chlorate as a nitrate analogue to screen soft red winter wheat (Triticum aestivum L.) cultivars for differences in nitrate reductase activity (NRA) was studied by adding potassium chlorate to a hydroponic nutrient solution in which wheat seedlings were growing. After 14 days, leaf symptoms indicating chlorate‐induced toxicity were rated. It was hypothesized that wheat plants which were susceptible to chlorate‐induced toxicity reduced chlorate and nitrate more rapidly than did resistant plants. In experiments testing the potential of this assay, wheat and barley (Hordeum vulgare L.) cultivars previously reported to have low NRA were less susceptible to chlorate‐induced toxicity than were cultivars reported to have high NRA. The assay was used to screen 15 soft red winter wheat cultivars for differences in sensitivity to chlorate‐induced toxicity. Variable toxic reactions were observed both among and within the cultivars. To determine whether the within‐cultivar variation was environmental or genetic, single plant selections for contrasting chlorate response were made, and bulked progeny were rescreened. In eight of 15 cultivars, the contrasting selections were different for chlorate‐induced toxic response, indicating heterogeneity for this trait within these eight cultivars. These chlorate‐selected lines may also be near‐isogenic lines for NRA. Seedling screening of wheat for chlorate response may be useful for identification of high NRA breeding lines.     

Use of spectral radiance for correcting nitrogen deficiencies and estimating soil test variability in an established bermudagrass pasture

The use of variable rate technology has become increasingly popular for applying plant nutrient elements. The most widely used method for determining variable fertilizer rates is presently based on soil testing and yield mapping. Three field studies (Bumeyville 1995, Burneyville 1996, and Ardmore 1996) were initiated in established Midland bermudagrass [Cynodon dacrylon (L) Pers.] pastures to determine the relationship between spectral radiance at specific wavelengths with forage nitrogen (N) removal and biomass, and to determine field variability of soil test parameters. Variable N (applied to 1.5 × 2.4 m subplots within 2.4 × 45.7 m main plots), fixed N and check treatments were evaluated at each location. Spectral radiance readings were taken in the red (671±6 nm), green (570±6 nm), and near infrared (NIR) (780±6 nm) wavelengths. The normalized difference vegetation index (NDVI) was calculated as NIR‐red/NIR+red. Variable N rates were applied based on NDVI. The highest fixed variable N rate was set at 224, 336, and 672 kg N ha^‐1 for Burneyville, 1995, 1996, and Ardmore, 1996, respectively. At Bumeyville, soil samples were collected in all variable rate plots (1.5 × 2.4 m) and analyzed for various soil test characteristics. NDVI, red, green, and NIR spectral radiance readings were correlated with bermudagrass forage N removal and yield. Correlation of forage yield and N removal with red, NIR, and NDVI were best with maximum forage production, however, when forage production levels were low correlation decreased dramatically for the red wavelength compared with NIR and NDVI. Forage yield and forage N removal in variable rate treatments increased when compared to the check while being equal to the half‐fixed and fixed rates where higher N rates were applied. Also, variability about the mean in variable rate plots was significantly lower than half‐fixed and fixed rates which supports adjusting N rates based on indirect NDVI measurements. Variable N rate plots reduced fertilizer inputs by 60% and produced the same yield as fixed rate plots, while fixed and half‐fixed rates did not increase N content in the forage over that of the variable rate treatment. Soil sample data collected from small consecutive plots (<4 m²) was extremely variable indicating that intense sampling would be needed if variable fertilizer application were to be based on soil test results.     

Influence of salinity in irrigation water on forage sorghum and soil chemical properties

Abstract

Soluble salts found in wastewater can be toxic when used for irrigation of forages. Thus, two greenhouse experiments were conducted to investigate effects of saline [CaCl₂NaCl (3:1, w:w)] treatments on soil chemical properties and ‘Dekalb FS‐5’ forage sorghum [Sorghum bicolor(L.) Moench]. Treatments for the first experiment consisted of a nonsaline control or 500 mL of a solution with an electrical conductivity (EC) of 10 dS m^?1 applied once. In the second experiment, treatments were salinity levels of 1.7,3.5,5.2,8.5, and 12.2 dS m^?1, applied in non‐nitrogenous Hoagland's solution as the sole source of irrigation. Both experiments were replicated four times. For both experiments forage sorghum was seeded in pots containing 7 kg of air‐dried Amarillo fine sandy loam soil. Sorghum survivability and plant height were measured. In the second experiment, water use by sorghum was also measured. Plants were harvested 7 wk after seeding, weighed, dried at 55°C, weighed, and ground for subsequent mineral analysis. After harvest, soil salinity, pH, and in the second experiment, extractable soil elements were determined. Soil salinity increased, while soil pH decreased, with the salinity treatments. Extracted soil calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), manganese (Mn), and cadmium (Cd) increased while sulfur (S), iron (Fe), and copper (Cu) decreased, and aluminum (Al) and zinc (Zn) exhibited no change with increasing salinity. Sorghum aerial plant and root production decreased with increasing salinity. Plant Ca, strontium (Sr), Mn, and Cd levels increased with increasing salinity. In contrast, sorghum K, P, and S levels declined with increasing salinity.     

Effect of biofertilizers on the nutrient availability in soil in relation to growth,yield and yield attributes of Stevia rebaudiana

A field experiment was conducted at Rani Chandramma Agricultural University (Arabhavi, Belgaum), Karnataka, India, in basic soil to study the nutrient availability in soil, yield and yield attributes of the medicinal plant stevia (Stevia rebaudiana). The results showed that the availability of nutrients such as nitrogen (N), phosphorus (P) and potassium (K) in the soil increased up to the fifth month; and thereafter, decreased by the same amount with the progress of the plant growth up to the sixth month, irrespective of treatments. Results also showed that the fresh and dry biomass yields significantly increased up to the sixth month with different treatments, but the yield attributes like plant height and the number of branches were observed to be varied with various treatments, being highest in the combined application of biofertilizers over that of their corresponding sole applications.     

Impacts of soil erosion on organic carbon and nutrient dynamics in an alpine grassland soil

The impact of soil erosion on the nutrient dynamics in alpine grassland soils is still an essential problem. Selecting a grass-covered hillslope in eastern Tibet Plateau, the cesium-137 (¹³⁷Cs) technique was used to determine the impacts of soil erosion on soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), and total potassium (TK). The ¹³⁷Cs data revealed that there were distinct soil redistribution patterns in different hillslope positions because of the influences of slope runoff, plant coverage and grazing activity. For the upper slope, soil erosion first decreased downward, followed by soil deposition in its lower part. In contrast, for middle and toe slopes, there was an increasing soil erosion along a downslope transect. Across the lower slope, soil erosion showed an irregular variation. Influenced by the selective transport of water erosion, SOC, TN and TP storage decreased with increasing soil erosion in upper, middle and toe slopes. In contrast, SOC, TN and TP storage varied little with soil erosion in the lower slope. On the whole hillslope, TK storage also varied little with soil erosion due to the large amount of potassium elements derived from soil parent materials. Particularly noteworthy was the greatest storage of SOC, TN and TP in the lower slope where most obvious net soil erosion occurred, which is closely related to the humus accumulation combined with gravel separation as well as weathering and pedogenesis of parent rocks induced by soil freeze-thaw.     

Promising approaches to the purification of soils and groundwater from hydrocarbons (A Review)

Soils and waters are affected by oil spills in the course of oil production and hydrocarbon leakages because of the corrosion of underground reservoirs, as well as the filtration of hydrocarbons from the tailing ponds formed during the extraction of oil from oil sands. The conventional technology for the withdrawal of contaminated water and its purification on the surface is low-efficient and expensive. New approaches are proposed for the in situ purification of soils and groundwater. To accelerate the oxidation, active substances atypical for the supergenesis zone are used: peroxides of metals and hydrogen. The efficiency of hydrogen peroxide significantly increases when the oxidation is catalyzed by Fe²⁺ or Fe³⁺ (Fenton reaction). The effects of Fe(III), sulfates, and carbon dioxide as electron acceptors are studied under anaerobic conditions (with oxygen deficit).     

Morphology and properties of the soils of permafrost peatlands in the southeast of the Bol’shezemel’skaya tundra

The morphology and properties of the soils of permafrost peatlands in the southeast of the Bol’shezemel’skaya tundra are characterized. The soils developing in the areas of barren peat circles differ from oligotrophic permafrost-affected peat soils (Cryic Histosols) of vegetated peat mounds in a number of morphological and physicochemical parameters. The soils of barren circles are characterized by the wellstructured surface horizons, relatively low exchangeable acidity, and higher rates of decomposition and humification of organic matter. It is shown that the development of barren peat circles on tops of peat mounds is favored by the activation of erosional and cryogenic processes in the topsoil. The role of winter wind erosion in the destruction of the upper peat and litter horizons is demonstrated. A comparative analysis of the temperature regime of soils of vegetated peat mounds and barren peat circles is presented. The soil–geocryological complex of peat mounds is a system consisting of three major layers: seasonally thawing layer–upper permafrost–underlying permafrost. The upper permafrost horizons of peat mounds at the depth of 50–90 cm are morphologically similar to the underlying permafrost. However, these layers differ in their physicochemical properties, especially in the composition and properties of their organic matter.     

Effect of NPK Fertilizers and Co-inoculation with Phosphate-Solubilizing Arbuscular Mycorrhizal Fungus and Potassium-Mobilizing Bacteria on Growth,Yield, Nutrient Acquisition,and Quality of Tobacco (Nicotiana tabacum L.)

In the present study, the effects of inoculation of biofertilizers (phosphorus-solubilizing arbuscular mycorrhizal (AM) fungi (AMF), Glomus intraradices, and potassium-mobilizing bacterium (KMB), Frateuria aurantia) in combination with chemical fertilizers nitrogen, phosphorus, and potassium (NPK) on growth, yield, nutrient acquisition, and quality of tobacco were observed in pot culture. Factorial combinations of biofertilizers (AMF and KMB) and chemical fertilizer (NPK) alone and in combination were applied to see the effects on growth, biomass, nutrient acquisition, and leaf quality in tobacco. Results showed that bioinocula applied either singly or in combination did not significantly enhance soil availability of P and K, indicating their unsuitability for direct application. Application of chemical fertilizer in combination with both AMF and KMB strains consistently increased availability of P and K in the soil, improved leaf quality parameters, and enhanced plant growth and vigor, suggesting the potential use of AMF and KMB as biofertilizers in sustainable tobacco crop production.