Soil carbon and related soil properties along a soil type and land‐use intensity gradient,New South Wales,Australia

The aim of this study was to systematically quantify differences in soil carbon and key related soil properties along a replicated land‐use intensity gradient on three soil landscapes in northwest New South Wales, Australia. Our results demonstrate consistent land‐use effects across all soil types where C, N and C:N ratio were in the order woodland > unimproved pasture = improved pasture > cultivation while bulk density broadly showed the reverse pattern. These land‐use effects were largely restricted to the near surface soil layers. Improved pasture was associated with a significant soil acidification, indicating that strategies to increase soil carbon through pasture improvement in these environments might also have associated soil degradation issues. Total soil carbon stocks were significantly larger in woodland soils, across all soil types, compared with the other land‐uses studied. Non‐wooded systems, however, had statistically similar carbon stocks and this pattern persisted whether or not carbon quantity was corrected for equivalent mass. Our results suggest that conversion from cultivation to pasture in this environment would yield between 0.06 and 0.15 t C/ha/yr which is at the lower end of predicted ranges in Australia and well below values measured in other cooler, wetter environments. We estimate that a 10% conversion rate (cultivation to pasture) across NSW would yield around 0.36 Mt CO₂‐e/yr which would contribute little to emission reductions in NSW. We conclude that carbon accumulation in agricultural soils in this environment might be more modest than current predictions suggest and that systematically collected, regionally specific data are required for the vegetation communities and full range of land‐uses before accurate and reliable predictions of soil carbon change can be made across these extensive landscapes.     

Effects of grass vegetation strips on soil conservation and crop yield under rainfed conditions in the Indian sub‐Himalayas

Vegetation strips (VS) along with conservation tillage, application of organic amendments and weed mulching improve crop yields by reducing run‐off and topsoil erosion. To investigate these issues, an experiment was conducted under rainfed conditions using grass VS for four and a half years (June 2007 to October 2011) at Dehradun, Uttarakhand, in the Indian Himalayan region. VS were incorporated in the experimental plots (Entisols) in a randomized complete block design in permanent 100 × 20 m (2000 m²) plots with a 2% slope to evaluate the effects of vegetation strips on run‐off, soil loss and crop yield. Three treatments were evaluated: (i) without VS with recommended NPK under conventional tillage, (ii) panicum as VS with recommended NPK under conventional tillage and (iii) palmarosa+ that consists of palmarosa as VS along with organic amendments (farmyard manure, vermicompost and poultry manure) and weed mulch under minimum tillage. The results show that soil loss and run‐off were significantly lower (P < 0.05) in plots under palmarosa+ than without VS treatment. Mean soil loss of 3.4, 5.2 and 7.1 t/ha was recorded from palmarosa+, panicum and without VS treated plots, respectively. Mean run‐off was 234, 356 and 428 mm from plots under palmarosa+, panicum and without VS, respectively. Maize yield was lower on the plots under palmarosa+ compared with panicum, but significantly higher (P < 0.05) than without a strip. The succeeding rainfed wheat yield was significantly greater in plots under palmarosa+ than in the initial years. The wheat yield equivalent was significantly higher in plots under palmarosa+ followed by panicum and without VS. Thus, vegetation strips are recommended for wider adoption to reduce run‐off and soil loss and to increase crop yield. The long‐term goal is to achieve a palmarosa+ system (palmarosa as a vegetation strip along with organic amendments, farmyard manure, vermicompost and poultry manure) and weed mulch under minimum tillage.     

Patterns of Nitrogen Mineralization under Two Water Regimes in an Acidic Entisol as Influenced by Chemical Composition of Plant Residues

A 12-week laboratory incubation experiment was conducted to determine the effect of chemical composition of residues of nine plant species on their cumulative net nitrogen (N) mineralization in soil under submergence (SUB) and field capacity (FC) water conditions. The influence of residues and of water regimes on residue-N released over time was significant. Net mineralization was higher in FC than SUB especially in later periods, although differences either among soil water levels or among species were not significant in all the periods sampled. Net N release had significant correlations with initial N and ratios of carbon, lignin or polyphenol or the (lignin + polyphenol) to N concentration of residues under two water conditions. (Lignin + polyphenol):N ratio in SUB and carbon/nitrogen (C:N) ratio in FC showed highest correlations with N mineralization in all periods and explained 64.1% variation in N mineralization from residues under SUB and 64.5% under FC after 2 and 8 weeks, respectively.     

Long–term effect of crop rotation and nutrient management on soil–plant nutrient cycling and nutrient budgeting in Indo–Gangetic plains of India

In the present investigation, the long-term effect of pulse crop inclusion in the maize-wheat rotation was assessed for the nutrient availability and soil-plant nutrient cycling under different nutrient management practices. Including pulses in the maize-wheat rotation improved soil organic carbon (SOC) and plant available macronutrients being higher in maize-wheat-mungbean rotation. Inclusion of mungbean to maize-wheat rotation enhanced the nitrogen (33.9%), phosphorus (46.4%), potassium (36.3%), and sulphur (55.5%) uptake in maize crop; likewise, alternate-year chickpea inclusion increased the uptake of these nutrients by 18.2, 19.1, 21.7, 32.1%, respectively. Inorganic fertilization maintained the positive annual balance of nitrogen, phosphorus, and zinc. By contrast, the nutrient balance under organic nutrient management was mostly negative. The magnitude of negative balance of potassium and sulphur was higher in inorganic than that of organic nutrient management. The low nutrient supply (particularly nitrogen) in organic fertilization largely inhibited the yield of cereal crops but not that of pulses. In view of this, the inclusion of pulses in the cereal-cereal systems could cause substantial improvement in soil fertility and sustainability in Indo-Gangetic plains. We infer that supply of nutrients like nitrogen and phosphorus in organic, and potassium and sulphur in recommended inorganic fertilization merit special attention.     

Oxygen doping modifies near-infrared band gaps in fluorescent single-walled carbon nanotubes

Controlled chemical modifications of single-walled carbon nanotubes (SWCNTs) that tune their useful properties have been sought for multiple applications. We found that beneficial optical changes in SWCNTs resulted from introducing low concentrations of oxygen atoms. Stable covalently oxygen-doped nanotubes were prepared by exposure to ozone and then light. Treated samples showed distinct, structure-specific near-infrared fluorescence at wavelengths 10 to 15% longer than displayed by pristine semiconducting SWCNTs. Dopant sites harvest light energy absorbed in undoped nanotube regions by trapping mobile excitons. The oxygen-doped SWCNTs are much easier to detect and image than pristine SWCNTs because they give stronger near-infrared emission and do not absorb at the shifted emission wavelength.     

27 kDa Fasciola gigantica Glycoprotein for the Diagnosis of Prepatent Fasciolosis in Cattle

An indirect enzyme-linked immunosorbent assay (ELISA) using 27 kDa glycoprotein of Fasciola gigantica has been evaluated for its potential use in the diagnosis of bovine fasciolosis. Following experimental infection of rabbits, F. gigantica infection-induced antibodies were isolated and later used as ligands in affinity chromatography for isolation of infection-induced antibody-specific proteins. Among the five infection-specific proteins isolated, a glycoprotein of 27 kDa was later isolated by second-step purification using concanavalin A matrix. In crossbred cattle receiving different doses of infection (100, 200 and 400 metacercariae), the anti-27 kDa antibodies were detected as early as the 2nd week post infection. No direct correlation between initial dose, antibody response and fluke establishment was recorded. No cross-reaction was noted with the sera of goats experimentally infected with Paramphistomum epiclitum. ELISA with the 27 kDa glycoprotein could be a feasible diagnostic tool for the early detection of bovine fasciolosis.     

Polymorphism in 5′ untranslated region of heat‐shock protein 70 gene as marker of post‐partum anoestrus in Murrah buffaloes

The enormous production potential of buffaloes has never been accomplished due to various reproductive insufficiencies. Among them, post‐partum anoestrus, a multifactorial disorder, is predominant but any genetic association is yet to be established. This study focused to identify novel polymorphisms in heat‐shock protein 70 (HSP70) gene and its possible association with post‐partum anoestrus in Murrah buffaloes. A 579‐bp fragment from 5′ untranslated region of HSP70 gene was amplified by polymerase chain reaction from blood genomic DNA of 614 animals maintained under similar management conditions. In phase‐I experiment, custom sequencing and restriction enzyme (RE) digestion of the amplified fragment were performed in 40 buffaloes with similar post‐partum oestrous conditions over previous consecutive three or more gestations—20 animals each showing post‐partum anoestrus (>120 days after parturition) and normal cyclicity (<65 days after parturition). While in phase‐II experiment, herd screening by RE analysis was performed in remaining 574 animals. Four transversions at T‐75G, C+31G, T+38G and C+97A and three transition mutations at T‐153C, T+33C and A+44G positions were observed. Polymorphism at T+38G site revealed significant (p < .05) variation, where homozygous G was present only in post‐partum anoestrous animals while nucleotide T was present randomly in both groups of phase‐I animals whereas phase‐II experiments revealed homozygous G in 55 animals. Regression analysis in relation to average post‐partum interval against genotypic frequencies at T+38G also depicted significant association. HSP70 gene polymorphism at T+38G position can therefore be used as genetic marker for excluding probable post‐partum anoestrous buffaloes from herd for breeding programmes.     

PCR-based segregation of one hybrid variety of Labeo rohita and Catla catla from their wild-types

High consumer preference together with its polyculture potential has undoubtedly driven Rohu (Labeo rohita) and Catla (Catla catla) to top the list of the most preferred fishes among the Indian major carps. Commonly found in these fishes are hybrids that can be natural or man-made. Increasing emphasis on biodiversity issues has necessitated proper stock management of these through molecular genetics techniques. Also with few morphological differences that can be used to differentiate wild types and hybrids properly, the problem demands a straightforward molecular approach. Here, we report a simple PCR-based technique that can differentiate the hybrid variety from wild types easily using three different microsatellite markers. Three sets of primers were used to amplify three different microsatellite markers from the genomic DNA isolated from pectoral fins. When the PCR products using all three primer sets were analyzed, ‘hybrid–Rohu’ could be distinguished from wild types. Whereas the hybrid–Rohu DNA yielded specific PCR products with all three primer pairs, only two PCR products were obtained either from wild-type Catla DNA (by primer sets 1 and 2) or from wild-type Rohu DNA (by primer sets 1 and 3). This study clearly demonstrates that a simple PCR-based technique will help the fish breeders and hatcheries to identify and differentiate suspected hybrid–Rohu carp from the wild types within a few hours.     

Weather-based prediction of anthracnose severity using artificial neural network models

Data were collected and analysed from seven field sites in Australia, Brazil and Colombia on weather conditions and the severity of anthracnose disease of the tropical pasture legume Stylosanthes scabra caused by Colletotrichum gloeosporioides . Disease severity and weather data were analysed using artificial neural network (ANN) models developed using data from some or all field sites in Australia and/or South America to predict severity at other sites. Three series of models were developed using different weather summaries. Of these, ANN models with weather for the day of disease assessment and the previous 24 h period had the highest prediction success, and models trained on data from all sites within one continent correctly predicted disease severity in the other continent on more than 75% of days; the overall prediction error was 21·9% for the Australian and 22·1% for the South American model. Of the six cross-continent ANN models trained on pooled data for five sites from two continents to predict severity for the remaining sixth site, the model developed without data from Planaltina in Brazil was the most accurate, with >85% prediction success, and the model without Carimagua in Colombia was the least accurate, with only 54% success. In common with multiple regression models, moisture-related variables such as rain, leaf surface wetness and variables that influence moisture availability such as radiation and wind on the day of disease severity assessment or the day before assessment were the most important weather variables in all ANN models. A set of weights from the ANN models was used to calculate the overall risk of anthracnose for the various sites. Sites with high and low anthracnose risk are present in both continents, and weather conditions at centres of diversity in Brazil and Colombia do not appear to be more conducive than conditions in Australia to serious anthracnose development.     

Solarization for the control of Pueraria montana (kudzu)

The effects of translucent polyethylene sheeting as a thermal covering to eradicate Pueraria montana (kudzu) were investigated at Clemson, South Carolina on a clay loam. In 2005, the highest reduction of live root crowns was observed where P. montana was covered for the entire growing season (May–October) with a reduction of 42% of live root crowns compared with the control plots. Where P. montana was covered for alternate weeks throughout the growing season live root crowns were reduced by 35%. Covering P. montana for one week and then uncovering for four weeks repeatedly through the season killed 24% of root crowns. In 2006, the second year of treatment to the same plots, the three solarization treatments had similar efficacy of about 97%. The use of polyethylene sheeting appears not to be cost‐effective for general control of large P. montana infestations, but may be useful for small patches.