Design method to control runoff from high intensity sprinkler irrigation     

M. G. Kay  H. Abo Ghobar 《Irrigation and Drainage Systems》1990,4(2):109-116

A design method for sprinkler irrigation is presented which takes account of current trends towards the use of low pressure-high intensity sprinkler applications and the need to design cultivation practices which can control the subsequent potential runoff.  相似文献   

Subject Area ´Sediments´: The Subject Editors and Advisors: Challenges and relevant literature in JSS and ESPR (the presentation of the Editors is not complete yet and will be continued)     

Fritz Frimmel  Jan Schwarzbauer  Marc Babut  Henner Hollert  Philip Owens  Kay Hamer 《Journal of Soils and Sediments》2007,7(1):2-8

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Physical assessment of a soil with respect to rooting potential   总被引：1，自引：0，他引：1  

P.H. Groenevelt  B.D. Kay  C.D. Grant 《Geoderma》1984,34(2):101-114

The potential suitability of a soil to accommodate growing roots was assessed on the basis of: (1) the existing pore space available for unobstructed root growth; and (2) the obstruction offered to a growing root by the soil matrix. The former was evaluated by measuring the air permeability of undisturbed soil cores, equilibrated at a chosen water tension. The latter was evaluated by measuring the spectrum of the tip resistance encountered by a slowly penetrating fine probe.The influence of cropping history on this potential suitability was examined by comparing the same soil with two different cropping sequences (corn grown continuously for five years and forages grown for three years followed by two years of corn). Measurements were started shortly before the forages were plowed under.Air permeabilities were higher for the plots on which forages had been grown, indicating greater potential suitability for unobstructed root growth. The penetration experiments showed that the average resistance to deformation of root-sized pores was equal for the two cropping patterns. The average bulk density was higher in the continuous corn plots than in the plots on which forages had been grown. After analysis of our data we postulated that the effect of the higher bulk density was offset by lower aggregate strength in the continuous corn plots. Implications of this hypothesis are discussed.  相似文献   

Chemometric discrimination among wild and cultured age-0 largemouth bass, black crappies, and white crappies based on fatty acid composition   总被引：1，自引：0，他引：1  

Tritt KL  O'Bara CJ  Wells MJ 《Journal of agricultural and food chemistry》2005,53(13):5304-5312

The potential to distinguish juvenile wild from cultured fishes and to discriminate among juvenile fishes by species based on fatty acid composition was demonstrated. Statistical approaches to data evaluation included analysis of variance, correlation analysis, principal component analysis (PCA), and quadratic discriminant analysis (QDA). Differences were determined between wild and cultured fishes both within and between species and between hatcheries. Fatty acid compositions were compared among individual (not composited) specimens of wild and cultured, age-0, freshwater species: largemouth bass Micropterus salmoides, black crappies Pomoxis nigromaculatus, white crappies P. annularis, and black-nose crappies. Four fatty acids were investigated: linoleic acid (18:2n-6), linolenic acid (18:3n-3), arachidonic acid (20:4n-6), and docosahexaenoic acid (22:6n-3). Linoleic acid was the primary fatty acid used to differentiate juvenile wild from cultured fishes. Concentrations of linoleic acid were significantly different (p < 0.05) in cultured largemouth bass and black crappies from the wild counterparts. Linolenic acid concentrations were not significantly different (p < 0.05) between wild and cultured largemouth bass but were significantly different between wild and cultured black crappies. Wild largemouth bass contained higher concentrations of arachidonic acid than the cultured bass, and concentrations of docosahexaenoic acid were twice as high in wild black crappies than cultured black crappies. On the basis of four signature fatty acids, 90 of 91 juvenile fishes were correctly classified as wild or cultured; 32 of 37 wild juvenile fishes originating from the same reservoir were differentiated by species. Data from the training set were used to classify a test set of fishes as to species, source, or origin with 100% accuracy.  相似文献   

Factors contributing to temporal stability in spatial patterns of water content in the tillage zone   总被引：4，自引：0，他引：4  

Alvaro Pires da Silva  Arie Nadler  B. D. Kay   《Soil & Tillage Research》2001,58(3-4):207-218

The rates of many biological processes vary across an agricultural landscape in response to the spatial patterns of water content in the tillage zone. Although, water content varies temporally through the growing season, the combined effects of soil properties, landscape attributes, tillage or position relative to the crop row on the temporal variation in the spatial pattern in soil water content are not well understood. We measured the soil water content (0–0.20 m) regularly through three growing seasons at 32 positions along each of two transects in a side-by-side comparison of corn under conventional tillage (plowing and secondary tillage) and no till in order to identify factors with the strongest influence on the spatial patterns in water content. The tillage comparison traversed a landscape in which the clay content (cl) varied from 5.8 to 37.4% and the organic carbon content (OC) varied from 0.9 to 3.9%. The spatial pattern in water contents during wetting and drying events were temporally stable, as reflected in R²>0.7 of correlation analysis of water contents on successive measurement dates. Multiple regression analyses indicated that the water contents, averaged over all measurement dates, were positively correlated with cl and ln(OC) and were smaller in the row than the inter-row position. The reduction in water content due to conventional tillage was diminished with increasing OC. However, application of multiple regression analyses to each set of water contents measured on a given day for each year indicated that the impact of soil properties, tillage and position relative to the row varied within and among seasons.  相似文献   

Optimum versus non-limiting water contents for root growth, biomass accumulation, gas exchange and the rate of development of maize (Zea mays L.)     

B.D. Kay  M.A. Hajabbasi  J. Ying  M. Tollenaar 《Soil & Tillage Research》2006,88(1-2):42-54

Many biological processes vary in a curvilinear manner, reaching a maximum rate at an optimum water content. Optimum conditions commonly extend across a range in water contents, and providing there are no soil-related limitations to biological processes, this range can be referred to as the non-limiting water range (NLWR) of a soil. The rate of a biological process would be expected to be similar in soils with different structure when the water content is in the NLWR and soils are under similar environmental conditions. This range potentially is a useful characteristic to describe the quality of soil structures with respect to a biological process—the larger the range the higher the quality. The distinction between optimum and NLWR has received little attention. The objective of this study was to determine if gas exchange rates, biomass accumulation in shoots and roots, root morphology and rate of development of maize (Zea mays L.) vary among soils under optimum soil water contents. Plants were grown to the 12-leaf stage under controlled environment conditions in four soils of different texture, packed to two levels of compaction with two rates of N addition and maintained at three different water contents. The optimum water content, for processes involving both shoots and roots, bracketed an air content of 0.15 for the different soils. The magnitude of the plant responses at optimum water content varied among soils and with relative compaction. Plant responses were largest in the Conestogo (loam soil) and smallest in soils with the highest clay contents. The magnitude of several responses decreased with increasing compaction. In the process of determining the NLWR, it is not appropriate to assume that either shoot or root characteristics are similar in soils of different structure when the water content of each soil is within a range that is optimum for that soil. The largest root and shoot growth that can be achieved at optimum water content across a range of soil conditions must be determined and NLWR determined on soils exhibiting these growth rates. Soils at their optimum water content with root and shoot growth that are less than the largest values imply the existence of soil-related limitations and therefore, by definition, have a value of zero for NLWR.  相似文献   

Localisation and combination of resistance genes against soil-borne viruses of barley (BaMMV,BaYMV) using doubled haploids and molecular markers     

Kay Werner  Wolfgang Friedt  Frank Ordon 《Euphytica》2007,158(3):323-329

Barley yellow mosaic virus disease caused by different strains of BaYMV and BaMMV is a major threat to winter barley cultivation in Europe. Different resistance genes against these viruses have been mapped and suitable PCR-based markers have been developed. In this respect doubled haploid (DH) populations proved to be advantageous as they facilitate a repeated test for resistance against all agents of the barley yellow mosaic virus complex and besides this, dominant marker systems are as informative as co-dominant ones in DHs due to the lack of heterozygous genotypes. Using DH populations resistance genes rym4, rym5, rym11, rym13, rym15 and the BaYMV/BaYMV-2 resistance of the barley cultivar ‘Chikurin Ibaraki 1’ have been mapped. DHs are also well suited to pyramiding resistance genes against BaMMV and BaYMV. Since homozygous recessive genotypes are more frequent in DHs than in segregating F₂ populations, DHs can be efficiently used to create broad-spectrum resistance and to extend the usability of partly overcome resistance genes. Results from employing two different strategies for pyramiding, based on one and two DH-steps, respectively, combining three recessive resistance genes, i.e. rym4/rym5, rym9 and rym11, are presented. The faster strategy based on one haploidy step resulted in the identification of all three and two-way combinations of the respective resistance genes.  相似文献   

Three Farmers of Singapore     

Ng Kay Fong  Tan Chee Lian  R. Wikkramatileke 《Asia Pacific viewpoint》1966,7(2):169-197

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Locally invasive melanoma in the internal laminae of the hoof of a bay mule     

G. Kay  P. McNeil  D. Knottenbelt  N. Tligui 《Equine Veterinary Education》2020,32(2):66-70

An 8-year-old bay mule was presented with moderate right forelimb lameness and dark discolouration of the white line. Histopathology of the dark material indicated a melanoma. Extensive resection and debridement were not curative and the mule was subjected to euthanasia 70 days after presentation.  相似文献   

Linking process capability analysis and least limiting water range for assessing soil physical quality     

Alvaro Pires da Silva  B.D. Kay 《Soil & Tillage Research》2004,79(2):167

In the process of evaluating the physical quality of soil for crop production, measurable sources of stress that the soil imposes on growing crops must be identified. Approaches for monitoring or evaluating soil physical quality should then be based on properties or processes that relate to these stresses and must be measured against definable standards. We hypothesized that process capability analysis applied to measurements of soil water content and the least limiting water range (LLWR) would meet these requirements and could be used to evaluate the physical quality of soils for crop growth. Previously published data obtained over 3 years in a field with a variable landscape planted to corn under no-till were used to test the hypothesis. The temporal variability of soil water content was regarded as a process which aims to generate individual values for soil water content inside the limits specified by the LLWR. Process capability analysis successfully linked the temporal variability of soil water content in relation to the LLWR. The main process capability parameter, i.e. distance to nearest specification (DNS) varied by a factor of three across the landscape and was related to clay and organic carbon contents. Values of DNS were strongly correlated with shoot growth (R² = 0.97) suggesting that DNS effectively characterized the spatial variability in stresses imposed on plant growth by soil and described changes in the soil physical quality for crop growth across the site. The results supported our hypothesis.  相似文献