The uptake of different tillage practices in England

Reduced tillage systems have been argued to provide several potential benefits to soil, environment and to farm incomes. In England, while many farms have partially adopted such practices, a large proportion of arable farmers do not undertake reduced tillage in any form. This paper analyses the rationale for and uptake of different cultivation techniques, including analysis of the barriers to adoption of reduced tillage, aiming to benefit policy makers and researchers and increase the spread of smart agricultural practices. Based on a postal questionnaire, we estimated that 47.6% of English arable land is cultivated using minimum‐tillage and 7% under no‐tillage. As farm size increased, so did the probability of reduced tillage uptake. Furthermore, farms growing combinable crops were more likely to utilise reduced tillage approaches than other farm types. Soil type, weed control and weather conditions were noted as the main drivers for ‘strategic' and ‘rotational' ploughing, constraining continuous reduced tillage use. To effect greater reduced tillage uptake, greater communication between researchers and farmers is needed to facilitate the implementation of sustainable soil management solutions, supported by current legislation permitting responsible herbicide use in arable production. Financial support to access reduced tillage machinery may also be required for farmers operating smaller holdings. Adopting reduced tillage is a continuous learning process requiring ongoing training and information‐gathering; supporting a network of reduced tillage ‘farmer champions' would facilitate practical knowledge exchange, allow farmers to observe soil improvements, understand transition phase barriers, and ultimately encourage increased reduced tillage uptake

) Maceil, C. E.; In The Encyclopedia of Nuclear Magnetic Resonance

Evanescent-wave cavity ring-down spectroscopy has been applied to a planar fused-silica surface covered with crystal violet (CV + ) cations to characterize the silanol groups indirectly. A radiation-polarization dependence of the adsorption isotherm of CV + at the CH 3 CN/silica interface is measured and fit to a two-site Langmuir equation to determine the relative populations of two different types of isolated silanol groups. CV + binding at type I sites yields a free energy of adsorption of -29.9 ( 0.2 kJ/mol and a saturation surface density of (7.4 ( 0.5) × 10 12 cm -2 , whereas the values of -17.9 ( 0.4 kJ/mol and (3.1 ( 0.4) × 10 13 cm -2 are obtained for the type II sites. The CV + cations, each with a planar area of ∼120 Å 2 , seem to be aligned randomly while lying over the SiOtype I sites, thereby suggesting that this type of site may be surrounded by a large empty surface area (>480 Å 2 ). In contrast, the CV + cations on a type II sites are restricted with an average angle of ∼40°tilted off the surface normal, suggesting that the CV + cations on these sites are grouped closely together. The average tilt angle increases with increasing concentration of crystal violet so that CV + cations may be separated from each other to minimize the repulsion of nearby CV + and SiOH sites. Adsorption behavior of organic molecules on silica surfaces has been the major theme of interface studies for improving the efficiency of chromatographic separations. When cationic molecules are involved, the strong electrostatic interaction with the negatively charged silanol (SiOH) groups on the surface of the stationary-phase silica may cause unwanted peak broadening and tailing, mainly from a slow kinetic response of the electrostatic adsorption. [1][2][3][4][5][6] The surface charge density is one of the primary factors influencing the strength of electrostatics. Accordingly, insight into how the cationic molecules interact with the local silanol groups of the silica surface should aid in the improvement of the design of surface modifications. Silanol groups play the main role in influencing the interfacial adsorption behavior, possessing an average surface density of ∼4.9 × 10 14 cm -2 on the silica surface 7-9 or an average surface area of 20.4 Å 2 per silanol group. As compared to silica sol particles, which have higher surface areas of (0.1-5) × 10 22 Å 2 /g, 7-9 only a few studies focus on characterization of silanol groups on a planar silica surface. 10-12 Ong et al. 10 first reported that isolated and vicinal silanol groups both exist at the water/silica interface possessing different pK a values of 4.9 and 8.5, with corresponding surface populations of 19 and 81%, respectively. These results were confirmed by means of cross-polarization magic angle spinning NMR 13 and fluorescence microscopy. 14 The isolated silanol groups with pK a ) 4.9 are anticipated to be separated far from each other (>5.5 Å), permitting proton dissociation. The vicinal silanol groups are located so closely as to form hydrogen bonds directly with their neighbors (<3.3 Å), which share 46% of the surface population, or through a water-molecule bridge (3.5-5.5 Å), which covers ∼35% of the surface population. 12,[15][16][17] By using second harmonic generation (SHG) with a cationic crystal violet (CV + ) molecular probe to investigate the local density distribution of the isolated silanols (pK a ) 4.9) on the planar fusedsilica surface, Xu and co-workers 12 classified them into two types. The first type of silanol group is anticipated to be surrounded by a large empty surface area (g120 Å 2 ) with a surface density o

The Role of Canine Distemper Virus and Persistent Organic Pollutants in Mortality Patterns of Caspian Seals (Pusa caspica)

Persistent organic pollutants are a concern for species occupying high trophic levels since they can cause immunosuppression and impair reproduction. Mass mortalities due to canine distemper virus (CDV) occurred in Caspian seals (Pusa caspica), in spring of 1997, 2000 and 2001, but the potential role of organochlorine exposure in these epizootics remains undetermined. Here we integrate Caspian seal mortality data spanning 1971-2008, with data on age, body condition, pathology and blubber organochlorine concentration for carcases stranded between 1997 and 2002. We test the hypothesis that summed PCB and DDT concentrations contributed to CDV associated mortality during epizootics. We show that age is the primary factor explaining variation in blubber organochlorine concentrations, and that organochlorine burden, age, sex, and body condition do not account for CDV infection status (positive/negative) of animals dying in epizootics. Most animals (57%, n = 67) had PCB concentrations below proposed thresholds for toxic effects in marine mammals (17 μg/g lipid weight), and only 3 of 67 animals had predicted TEQ values exceeding levels seen to be associated with immune suppression in harbour seals (200 pg/g lipid weight). Mean organonchlorine levels were higher in CDV-negative animals indicating that organochlorines did not contribute significantly to CDV mortality in epizootics. Mortality monitoring in Azerbaijan 1971-2008 revealed bi-annual stranding peaks in late spring, following the annual moult and during autumn migrations northwards. Mortality peaks comparable to epizootic years were also recorded in the 1970s-1980s, consistent with previous undocumented CDV outbreaks. Gompertz growth curves show that Caspian seals achieve an asymptotic standard body length of 126-129 cm (n = 111). Males may continue to grow slowly throughout life. Mortality during epizootics may exceed the potential biological removal level (PBR) for the population, but the low frequency of epizootics suggest they are of secondary importance compared to anthropogenic sources of mortality such as fishing by-catch