Nitrogen availability and economic returns of various crop rotations with forage and annual crops

Non-Peer Reviewe

Nitrogen availability and economic returns of various crop rotations with forage and annual crops

Non-Peer Reviewe

Adoption of rice varieties. 2. Accelerating uptake

SUMMARYPlant breeding makes genetic gains over years, so growing newer varieties generally provides greater benefits than growing older ones. However, in low-altitude districts of Nepal, a few rice varieties covered 75% of the rice area and were more than 20 years old (first paper in this series). We test here if this slow rate of adoption of new varieties could be accelerated using a participatory method, Informal Research and Development (IRD), where packets of seeds of new rice varieties are widely distributed to many farmers. From 2008 to 2011, over 117 000 IRD packets were distributed in 18 districts of the Nepal Terai, including over 70 000 of three released varieties from a client-oriented breeding (COB) programme in Nepal. The IRD significantly increased the adoption of the three COB varieties. The benefits obtained by farmers in a single growing season equal the costs of IRD, if for every 75 kits distributed an additional 1 ha is grown. This assumes that the new varieties produce a 10% increase in yield (lower than that evidenced in their release proposals). On an average, fewer than three IRD kits were distributed for each hectare of a new variety grown by farmers in 2011. Furthermore, the effectiveness of IRD could be increased 1.2 to 2.7 fold (depending on the COB variety) if the IRD distribution were to be restricted to the region where the variety was most accepted. The best comparison of IRD with extension by the conventional system was their popularity compared with similar-aged varieties that had been promoted in the two systems. The adoption of three COB varieties was about twicethat of three varieties from the National Rice Research Programme (NRRP) that were closest in release date to the COB varieties. Unlike cost effectiveness assessed by hectares grown per IRD kit distributed, this comparison can only indicate efficacy because, as well as extension method, many factors influenced the adoption rates of the COB and NRRP varieties. The costs of IRD are small, both relative to the cost of breeding new varieties and to the benefits gained; so it is one of the simplest and most cost-effective interventions to increase agricultural productivity.</jats:p

Adoption of rice varieties - I. Age of varieties and patterns of variability

SUMMARYFarmers who continue to grow old and obsolete varieties do not gain the benefits they could get from growing newer ones. Given the potential large scale of these foregone benefits, relatively few studies have examined the age of varieties that farmers grow. In three surveys, members of over 3300 households were interviewed to find the rice varieties they grew in 2008 and 2011 in 18 districts in the Terai, the low-altitude region of Nepal. This provided the first description of detailed geographical patterns of adoption of rice varieties and their ages that were repeated over time. There were large differences between district and individual varieties that showed specific geographical patterns of adoption. Such detailed knowledge on spatial diversity of varieties is invaluable for planning extension activities and developing breeding programmes, and cheaper ways than household surveys of collecting this information are discussed. Some of the factors considered important in determining this complex pattern of adoption were seed availability, growing environments that differed from east to west and the continued popularity of varieties once they had established markets. Rice diversity was low because a small number of rice varieties occupied large areas. In 2011, nine varieties covered at least 75% of the total rice area in western districts, just four in central districts and eight in eastern districts. Of these, most were released before 1995 resulting in a high average age of the predominant varieties – they always had an average age of over 20 years no matter which region or year was considered. Even though there were some large changes in varietal composition from 2008 to 2011, the average age of the predominant varieties remained almost the same. In a second paper in this series, we examine how these very low varietal replacement rates, that reduce yields and increase risk to farmers, can be accelerated using a participatory research for development approach called Informal Research and Development (IRD) (Joshi et al., 2012).</jats:p

Unsteady aerodynamics analysis and modelling of a Slingsby Firefly aircraft:Detached-Eddy Simulation model and flight test validation

This paper presents unsteady stall characteristics of a Slingsby T67M260 Fire y light aircraft from both a computational uid dynamics (CFD) half model and ight tests. Initial results from the steady CFD, based on a RANS k . ! SST turbulence model, established the critical angle of attack of the stall to be stall = 16 , with a maximum lift coe cient of CLmax = 1.2. Comparisons with straight and level ight test data were comparable up to = 12 { 14 , with the increasing deviation at higher attributed to the e ect of the propeller slipstream under these ight conditions. The RANS CFD model was then extended to an unsteady Detached-Eddy Simulation (DES) model for three angles of attack at pre-stall and stall condition ( = 14 , 16 , 18 ), with analysis of the vortex shedding frequency. Further comparisons were then made with ight test data taken using on-board accelerometers and wing tuft surface ow visualization, at a stalled condition at equivalent . These unsteady CFD data established a dominant shedding frequency ranging from 11.7 Hz { 8.74 Hz with increasing and a Strouhal number based on wing chord of St = 0.11, which when compared to flight test accelerometer spectra matched within 2.9% of the measured frequenc

The hypergeneralized Heun equation in QFT in curved space-times

In this article we show for the first time the role played by the hypergeneralized Heun equation (HHE) in the context of Quantum Field Theory in curved space-times. More precisely, we find suitable transformations relating the separated radial and angular parts of a massive Dirac equation in the Kerr-Newman-deSitter metric to a HHE.Comment: 8 page

Participatory research approaches rapidly improve household food security in Nepal and identify policy changes required for institutionalisation

The introduction, testing, promotion and release of a rice variety, BG 1442, in Nepal were examined in relation to existing policies governing these procedures and to how more participatory approaches could benefit food security. From 1998 to 2006, participatory varietal selection (PVS) was used to test BG 1442 and other candidate rice varieties in the spring (Chaite) rice-growing season (February to June) and in the main season (June to November). The testing of BG 1442 commenced 11 years after it was first introduced into Nepal in 1987 by the national rice research programme (NRRP). Following its initial acceptance by farmers, it was widely disseminated from 1998 by non-governmental organisations (NGOs) in the low altitude region of Nepal called the terai in projects funded by the Department for International Development (DFID), UK. This dissemination was done using a method termed informal research and development (IRD) where many small packets of seed were distributed without fertiliser or pesticides, the only additional input being a description of varietal characteristics on an enclosed leaflet. From 2001 to 2008, various assessments were made of its extent of adoption and its impact on livelihoods. In a randomised survey of households in 10 districts, BG 1442 increased from not being used at all in 1997 to being grown by about 20% of the surveyed rice farmers by 2008. It was grown both in the Chaite and the main season and was well adapted to the rainfed-upland and medium-land rice ecosystems. The variety was grown from the far west to the far east of low-altitude Nepal by resource-poor farmers. IRD was important in accelerating adoption and improving food security as it was by far the most important external source of seed for farmers. Prior to the adoption of BG 1442, farmers who did not harvest sufficient rice to last their households for 12 months increased rice self sufficiency by over 2 months (25% more). Those households that sold surplus grain and who grew BG 1442 increased grain sales by 600 kg (25% more) in the Chaite season and by 370 kg (24% more) from main season cultivation

Temperature, RF Field, and Frequency Dependence Performance Evaluation of Superconducting Niobium Half-Wave Coaxial Cavity

Recent advancement in superconducting radio frequency cavity processing techniques, with diffusion of impurities within the RF penetration depth, resulted in high quality factor with increase in quality factor with increasing accelerating gradient. The increase in quality factor is the result of a decrease in the surface resistance as a result of nonmagnetic impurities doping and change in electronic density of states. The fundamental understanding of the dependence of surface resistance on frequency and surface preparation is still an active area of research. Here, we present the result of RF measurements of the TEM modes in a coaxial half-wave niobium cavity resonating at frequencies between 0.3 - 1.3 GHz. The temperature dependence of the surface resistance was measured between 4.2 K and 1.6 K. The field dependence of the surface resistance was measured at 2.0 K. The baseline measurements were made after standard surface preparation by buffered chemical polishing