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71.
Marco Erni Pay Drechsel Hans-Peter Bader Ruth Scheidegger Christian Zurbruegg Rolf Kipfer 《Irrigation and Drainage Systems》2010,24(1-2):113-125
Due to poor urban sanitation farmers in and around most cities in developing countries face highly polluted surface water. While the sanitation challenge has obvious implications for environmental pollution and food safety it can also provide ‘free’ nutrients for irrigating farmers. To understand the related dimensions, a box-flow model was used to identify the most important water and nutrient flows for the Ghanaian city of Kumasi, a rapidly growing African city with significant irrigation in its direct vicinity. The analysis focused on nitrogen and phosphorus and was supplemented by a farm based nutrient balance assessment. Results show that the city constitutes a vast nutrient sink that releases considerable nutrients loads in its passing streams, contributing to the eutrophication of downstream waters. However, farmers have for various practical reasons little means and motivation in using this resource of nutrients. This might change under increasing fertilizer prices as the nutrient load will continue to increase by 40% till 2015 assuming a widening gap between population growth and investments in water supply on one side and investments in sanitation on the other. However, even a strong investment into flushing toilets would not reduce environmental pollution due to the dominance of on-site sanitation systems, but instead strongly increase water competition. Key options to reduce the nutrient load would be via optimized waste collection and investment in dry or low-flush toilets. The latter seems also appropriate for the city to meet the water and sanitation Millennium Development Goals (MDGs) without increasing water shortages in toilet connected households. 相似文献
72.
Hans-Peter Piepho Emlyn R. Williams Volker Michel 《Journal of Agricultural, Biological & Environmental Statistics》2016,21(2):227-242
When generating experimental designs for field trials laid out on a rectangular grid of plots, it is useful to allow for blocking in both rows and columns. When the design is nonresolvable, randomized classical row–column designs may occasionally involve clustered placement of several replications of a treatment. In our experience, this feature prevents the more frequent use of these useful designs in practice. Practitioners often prefer a more even distribution of treatment replications. In this paper we illustrate how spatial variance–covariance structures can be used to achieve a more even distribution of treatment replications across the field and how such designs compare with classical row–column designs in terms of efficiency factors. We consider both equally and unequally replicated designs, including partially replicated designs. Supplementary materials accompanying this paper appear online. 相似文献
73.
74.
Ilatsia ED Roessler R Kahi AK Piepho HP Zárate V 《Tropical animal health and production》2012,44(3):519-530
The Sahiwal breed has been used for upgrading the East African Zebu (EAZ) for improved milk production and growth performance
in the southern rangelands of Kenya. Main users of this breed are Maasai pastoralists. Until now, there has been no deliberate
effort to understand why these pastoralists specifically prefer to keep Sahiwal genetic resources as well as which traits
are considered important by them and what is the underlying reason for this. However, this information is regarded vital for
further development of the breed. A survey was conducted between May and October 2009 among Maasai pastoralists in Kajiado
and Narok counties in the Southern part of Kenya, and private ranches and government farms to identify production objectives
and breeding goals of Sahiwal cattle producers. Sahiwal genetic resources were mainly kept for domestic milk production and
for revenue generation through milk sales and live animals. To a limited extent, they were kept for breeding and also for
multiple objectives that included insurance against risks and social functions. Production aims were influenced to varying
extents by various household and farmer characteristics. Sahiwal cattle and their crosses were generally perceived to be better
with respect to productive traits and fertility traits when compared to the EAZ. However, the EAZ was rated higher with respect
to adaptation traits. The breeding objective traits of primary importance were high milk yield and big body size, good reproductive
efficiency and relatively good adaptation to local production conditions. Performance and functional traits are important
breeding goals that play a major role in fulfilling the multiple production objectives. This forms the basis for the optimisation
of a breeding programme for sustainable utilisation to meet the needs of Sahiwal cattle producers. 相似文献
75.
Interactions between flavonoids and proteins: effect on the total antioxidant capacity 总被引:7,自引:0,他引:7
Arts MJ Haenen GR Wilms LC Beetstra SA Heijnen CG Voss HP Bast A 《Journal of agricultural and food chemistry》2002,50(5):1184-1187
Flavonoids are potent antioxidants. It is also known that flavonoids bind to proteins. The effect of the interaction between tea flavonoids and proteins on the antioxidant capacity was examined. Their separate and combined antioxidant capacities were measured with the Trolox equivalent antioxidant capacity (TEAC) assay. It was observed that the antioxidant capacity of several components of green and black tea with alpha-, beta-, and kappa-casein or albumin is not additive; that is, a part of the total antioxidant capacity is masked by the interaction. This masking depends on both the protein and the flavonoid used. Components in green and black tea, which show the highest masking in combination with beta-casein, are epigallocatechin gallate and gallic acid. The results demonstrate that the matrix influences the efficacy of an antioxidant. 相似文献
76.
Karin Hartung Hans-Peter Piepho Helmut Knüpffer 《Genetic Resources and Crop Evolution》2006,53(4):737-751
Genebanks often characterize accessions based on evaluation trials. This paper evaluates geostatistical methods as a tool
to increase the utility of evaluation data. These methods were selected to overcome limitations resulting from a relative
lack of replication and the scarcity of standards or check varieties. The data employed in the present study comprise nine
characteristics of spring and winter barley, evaluated mostly as ratings. Ratings with quasi-metric scales were transformed
by using the folded exponential transformation. To estimate the genetic component of the total effect, we compared two methods:
Method 1 whereby a variogram is fitted by non-linear regression, and subsequently the implied spatial correlation is embedded
into a mixed model analysis, which estimates the genetic effect by Best Linear Unbiased Prediction (BLUP); and Method 2 where
each data value is re-estimated by kriging to correct for spatial effects and then the corrected data are submitted to a mixed
model analysis. For practical application we propose Method 1 (though occasionally we met convergence problems): Fit the short
range of the empirical variogram, visually choose the suitable covariance model. Use this and the initial values from non-linear
regression fit with the mixed model, fixing the spatial parts at their starting values from non-linear regression, and estimate
genetic effects by BLUP by using the fitted mixed model. To improve performance, we recommend that more standard or check
varieties be used and, wherever possible, replace rating scales with metric scales or free-percentage scales (without categories). 相似文献
77.
Water erosion causes the accumulation of soil material, especially at the bottom slope and in landscape depressions. According to FAO-UNESCO (1990) colluvial soils can be classified as Cumuli-Aric Anthrosols if the minimum thickness of the altered topsoil is 5 dm or more. These soils are characterized by addition of small amounts of soil material that has been incorporated into the underlying material by tillage and/or turbation. As a result of geological factors and land-use intensities, Cumuli-Aric Anthrosols differ markedly in their ecological properties. In the study area ‘Bornhoeved Lake District (Schleswig-Holstein, North-Germany)’ soil patterns have been investigated showing the interdependence of soil landscapes and their soil units by water erosion and accumulation. Examples of various colluvial soils in catenary sequences in the study area are presented. Colluvial soils in the study area are characterized by a layer thickness between 5 and 14 dm and show significantly higher quantities of organic matter, nitrogen and plant-available water in comparison with eroded soils. 相似文献
78.
Soil lipid content is an important characteristic of the soil organic matter. One of the commonly used extractants for the determination of soil lipid is benzene/ethanol 1:1(v/v). In this study the toxic solvent mixture benzene/ethanol was substituted with the less harmful one toluene/ethanol 1:2.3 (v/v). Both solvent mixtures give a comparably high recovery of soil lipid and the composition of both lipid fractions are very similar according to their thin layer chromatography (TLC). Further investigations with NMR-spectroscopy confirmed that the extracted lipid fraction consists mainly (7gt;90%) of structure elements of aliphatic hydrocarbons. 相似文献
79.
Felix Spindler Benoit Pugin Hanspeter Buser Hans-Peter Jalett Ulrich Pittelkow Hans-Ulrich Blaser 《Pest management science》1998,54(3):302-304
The application of enantioselective catalytic methods for the technical preparation of chiral agrochemicals is illustrated for three active ingredients of the acylanilide type. The key step for the technical synthesis of the herbicide (S)-metolachlor is the enantioselective hydrogenation of an imine intermediate using a novel iridium ferrocenyldiphosphine catalyst with an unprecedented high activity and 80% ee. (R)-metalaxyl and (αS,3R)-clozylacon were synthesized via the enantioselective hydrogenation of corre-sponding enamide precursors with Rh and Ru/binap catalysts with >95% and 99% enantiomeric purity, respectively. © 1998 Society of Chemical Industry 相似文献
80.