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91.
Flexible delivery schedules to improve farm irrigation and reduce pressure on groundwater: a case study in southern Italy 总被引:1,自引:1,他引:0
Daniele Zaccaria Ines Oueslati Christopher M. U. Neale Nicola Lamaddalena Michele Vurro Luis S. Pereira 《Irrigation Science》2010,28(3):257-270
This study was conducted on an irrigated area of southern Italy to analyze the current operation of a large-scale irrigation
delivery system and the effects of the operation procedures on crop irrigation management and aquifer salinity increase. The
area is characterized by relatively high levels of groundwater salinity in the summer that are probably due to intensive groundwater
pumping by farmers during periods of peak irrigation demand, with the resulting seawater intrusion. Two alternative delivery
schedules, namely the rotation delivery schedule and the flexible delivery schedule, referred to as RDS and FDS, respectively,
were simulated using a soil-water balance model under different combinations of crop, soil and climatic conditions. The first
set of simulations concerned the farm irrigation management constrained by the rotational delivery used by the local water
management organization. The second scenario simulated the farm irrigation schedule most commonly used by growers in the area
for maximizing crop yields. Based on crop irrigation management under RDS and FDS, two alternative operational scenarios were
also developed at the scheme level and then compared for evaluation. Winter and summer salinity maps of the aquifer were developed
by interpolating salinity measurements of the groundwater samples collected during the 2006 irrigation season. From these
maps, a close relationship can be inferred among delivery schedule, aquifer exploitation and salinity increase, which justifies
the need for implementing FDS that might reduce the groundwater demand for irrigation. 相似文献
92.
Sujittra Charoenhirunyingyos Kiyoshi HondaDaroonwan Kamthonkiat Amor V.M. Ines 《Computers and Electronics in Agriculture》2011,75(2):278-287
Soil hydraulic parameters are essential inputs to agricultural and hydrologic models for simulating soil moisture. These parameters however are difficult to obtain especially when the application is aimed at the regional scale. Laboratory and field methods have been used for quantifying soil hydraulic parameters but they are proved to be laborious and expensive. An emerging alternative of estimating soil hydraulic parameters is soil moisture model inversion using remote sensing (RS) data. Although soil hydraulic parameters could not be derived directly from remote sensing, they could be quantified by the inverse modeling of RS data. In this study, we conducted a multi-criteria inverse modeling approach to estimate the rootzone soil hydraulic parameters in a rainfed rice field at depths 3, 12, 28 and 60 cm, respectively. The conditioning data used in the inverse modeling are leaf area index (LAI) and actual evapotranspiration (ETa) from satellite imageries, and soil moisture (SM) data from in situ measurements. The performances of all the model inversion experiments were evaluated against observed soil moisture in the field, and measured LAI during the growing season. The results showed that using remotely sensed LAI and ETa in the inverse modeling provided a good matching between observed and simulated soil moisture down to 28 cm depth from the soil surface. With the addition of soil moisture information from the site, the model inversion significantly improved the soil moisture simulation up to a depth of 60 cm. 相似文献
93.
94.
Purpose
Peatlands have an important role in methane cycling in the natural environment. Methane emissions as a result of methanogenesis and methanotrophy in soil are affected by several environmental factors such as temperature, oxygen and groundwater level. The objective of this study was to analyse methane cycling as a function of soil depth.Materials and methods
In this study, methane cycling and soil organic matter mineralization were investigated in a drained fen grassland area of Ljubljana marsh, Slovenia that has been subjected to reclamation strategies for several centuries. Potential mineralization, methane production and methane oxidation rates were measured in slurry incubation experiments with soil samples from 10 sampling depths of a 1-m profile. In addition, the extent of iron reduction in the soil was determined.Results and discussion
The potential for methane production was low in the investigated soil profile, even in constantly flooded layers below the water table fluctuations. During anaerobic incubations, the highest accumulated concentrations and production rates of methane were observed in the upper 10-cm layer and the lowest in deeper soil layers, indicating that plant exudates are the main source of energy for heterotrophic soil microbes and that methanogenesis in deeper layers is limited by the availability of appropriate organic substrates. Methane oxidation was on the other hand active throughout the soil profile, suggesting that the potentially active methane oxidizing community is present despite low methane production. The highest abundance and activity of methanotrophs was detected in the water table fluctuation layers.Conclusions
Together, these findings have implications for understanding the biogeochemical function of drained peat soils and emphasize the influence of drainage on quality of soil organic matter and consequently on methane production even in flooded soils.95.
Rodriguez I Choromanski L Rodgers SJ Weinstock D 《Veterinary therapeutics : research in applied veterinary medicine》2002,3(4):396-401
Serum samples from 4,907 cows from 93 dairy and five beef herds were analyzed for antibodies to Neospora caninum by commercially available ELISA. The herds were recruited from 20 states and the territory of Puerto Rico. A questionnaire assessed the herd's abortion history and exposure risks to N. caninum. Results showed that 788 (16%) cows tested positive for antibodies to N. caninum. At least one positive animal was detected in 90% of the herds tested. The prevalence of cows seropositive to N. caninum varied from 2% to 65% among herds. Abortion rates ranging from 2% to 19% were reported. The epidemiologic data collected from the questionnaire suggested that the presence of farm dogs does not increase the risk of exposure of cows to N. caninum. 相似文献
96.
Elcio L. Balota Ines F. Yada Higo Amaral Andre S. Nakatani Richard P. Dick Mark S. Coyne 《Land Degradation \u0026amp; Development》2014,25(4):397-406
Land use choices differentially affect soil physical and biological properties. Tillage choices in particular affect soil erosion, the retention of soil organic matter, and the biological activity that organic matter supports. The present study evaluated the consequences of different cropping and tillage systems (undisturbed forest, coffee plantation, conventional, and no‐tillage row cropping) for soil microbial indicators and sulfur mineralization after 24 years of cropping on an Oxisol (Typic Haplorthox) in an experimental area at Londrina, Brazil. Soil samples were taken at 0–5, 5–10, and 10–20 cm depths and evaluated for microbial biomass P and S, S mineralization, and phosphatase and arylsulfatase activities. Land use affected microbial biomass P and S, and enzyme activity at all depths studied. The cultivated sites had lower values of microbial activity than the undisturbed forested site. Although the coffee site was not tilled and had high organic carbon content, there was low microbial activity, probably due to higher soil acidity and Al content. The estimates of pool stock for microbial P and annual P flux through the soil microbial biomass suggest that these pools are large enough to significantly affect plant nutrient availability. The greater microbial biomass and activity under forested and no‐tillage sites may be attributed, at least partially, to higher organic matter content. The soil microbial variables examined proved to be strong indicators of soil sustainability. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
97.
Lederer I Schulzki G Gross J Steffen JP 《Journal of agricultural and food chemistry》2006,54(6):1970-1974
In this study, a methodological approach for an effective and reliable quality control of Chinese star anise (Illicium verum Hook. F.) is developed and validated. A combined method of TLC and HPLC-MS/MS was used for differentiation of various Illicium species, especially Chinese and Japanese star anise. Species can be distinguished by their TLC flavonoid pattern. A sensitive and selective HPLC/ESI-MS/MS method was developed for the detection and quantification of lower admixtures of I. anisatum and of further toxic Illicium species at a low concentration range using the sesquiterpene lactone anisatin as a marker. The proposed assay includes a solid-phase extraction cleanup procedure with a high recovery (>90%). Chromatographic separation of anisatin was carried out on a C18 column, followed by MS detection using ESI in negative mode. The precursor/product ion transitions m/z 327 --> 127 (quantifier) and m/z 327 --> 297 (qualifier) were monitored. Statistical evaluation of this multireaction-monitoring procedure reveals good linearity and intra- and interday precision. The limits of detection and quantification are 1.2 and 3.9 microg/kg, respectively. 相似文献
98.
Fernando J. Peña Cristina Ortega Ferrusola Jose A. Tapia Ines M. Aparicio 《Journal of Equine Veterinary Science》2012
Recent findings on the molecular damage occurring in the stallion spermatozoa are reviewed. Mechanisms leading to cell death or survival are briefly overviewed, and recent discoveries on molecular pathways leading to sperm death and sublethal damage are discussed. Increasing the understanding of this particular area may disclose clues to develop new strategies to improve current sperm conservation methods. 相似文献
99.
100.
Diversity and seasonal variations of mycorrhiza and rhizosphere bacteria in three common plant species at the Slovenian Ljubljana Marsh 总被引:1,自引:0,他引:1
Matevž Likar Marjana Regvar Ines Mandic-Mulec Blaž Stres Hermann Bothe 《Biology and Fertility of Soils》2009,45(6):573-583
Interactions between plants and microorganisms can significantly affect plant health and productivity as well as ecosystem
functioning. Detailed knowledge of the tripartite relationships between plants, fungi, and bacteria, and their environment
is still limited. In the present study, the soils adjacent to three plant species (Cruciata laevipes, Mentha piperita, Equisetum arvense) in the Ljubljana Marsh and the bulk, plant-free soil were analyzed for their bacterial community structure in June and October
2006. The terminal restriction fragment length polymorphism analysis indicated a different bacterial community structure in
the rhizosphere and in bulk soil, however, with almost no seasonal changes between late spring and autumn samples and no apparent
impact of the three plant species. In addition, root colonization of the three plant species by arbuscular mycorrhizal fungi
(AMF) and dark septate endophytes (DSE) was microscopically assessed monthly from May until October 2006. A presumably accidental
correlation between monthly precipitation and the degree of arbuscule formation, with the latter lagging 1 month, was noted
for M. piperita, the most heavily colonized of the three plant species. With all three plants, the phosphorus content in roots correlated
positively with most AMF structures. Microsclerotia of DSE were mainly abundant in autumn samples. Fungal diversity in roots
was estimated using temporal temperature gradient gel electrophoresis separation of the fungal polymerase chain reaction products
obtained for both 18S-rDNA and the 5.8S-ITS2-28S rDNA segments. No specific effects of either plant species or seasonal changes
on mycorrhizal community structure were discernible. 相似文献