43 research outputs found
EFFECT OF SOWING DATES OF THREE COWPEA CULTIVARS ON THEIR INFESTATION RATE WITH COWPEA POD BORER ETIELLA ZINCKENELLA
Field trials were conducted during 2005 and 2006 seasons at Minofia governorate to evaluate the effect of planting date of three cowpea cultivars on their infestation rate with cowpea pod borer, Etiella zienckenella. For each cowpea cultivar planted at each tested date, the numbers of bores and larvae were counted in green and dry pods as well as in dry seeds and the means were obtained to estimate the degree of insect infestations. Results indicated that, regardless the planting date in both seasons, Kream7 was the highest resistant cultivar to insect infestation followed by Kaha1 and then Kafr El Shikh1. On the other hand, regardless the cowpea cultivar, the rate of insect infestation was greatly reduced at the early plantation. Thus, selection of Kream7 cultivar and early plantation could be involved in reducing E. zinckenella infestation and subsequently increase the cowpea yield. These studies clearly demonstrated that several non-insecticidal approaches have great potential for cowpea pod borer Etiella zinckenella management. These approaches include some of integrated pest management strategies which can effectively prevent or reduce infestatio
Apparent timing and duration of the Matuyama-Brunhes geomagnetic reversal in Chinese loess
The Matuyama-Brunhes (MB) geomagnetic reversal in Chinese loess has been studied extensively as an important boundary for land-ocean stratigraphic and paleoclimatic correlations. However, the apparent timing and duration of the MB boundary remain controversial in Chinese loess deposits due to its inconsistent stratigraphic position and the uncertain chronologies. Here we synthesized high-resolution paleomagnetic records from four loess sequences in the central Chinese Loess Plateau and synchronized the loess-paleosol chronology by matching the grain-size variations to orbitally tuned grain-size time series. The synthesized paleomagnetic results reveal consistent features of the MB transition in Chinese loess, including the stratigraphic position (L8/S8 transition), timing (∼808–826 ka), duration (∼14–16 ka), and rapid directional oscillations. Compared with the MB transition in marine records (770–775 ka), the timing of the MB transition is relatively older and longer in Chinese loess, due to a complex interplay between different remanence acquisition mechanisms which occurred during the course of postdepositional physical and chemical processes.</p
Miljö och vatten i fysisk planering : Detaljplanering av Norra Älvstranden i Göteborg
Många kustnära svenska städer riskerar att drabbas av framtida klimatförändringar, men framförallt stigande havsnivåer, något som ska beaktas och tas hänsyn till i den fysiska planeringen. Men hur? Parallellt med detta pågår stadsomvandlingar, med bland annat nybyggnation i kust- och vattennära områden, för att skapa en attraktiv kommun där folk vill bosätta sig och bo kvar. Den fysiska planeringen präglas , å andra sidan, av en osäkerhet kring hur anpassning till ett förändrat klimat, och särskilt stigande havsnivåer, ska gå till fastän det på den lokala nivån finns medvetenhet om detta. Denna uppsats syftar till att öka kunskapen kring hur klimatfrågor, i synnerhet risker med stigande havsnivåer, hanteras i den fysiska planeringen, genom att undersöka hur detta har behandlats i detaljplanering av tre planområden i Norra Älvstranden i Göteborg. För att undersöka syftet har en fallstudie gjorts över tre planområden i Norra Älvstranden, med en kvalitativ dokumentstudie som metod. Detaljplan, med tillhörande plankarta och planbeskrivning för respektive planområde, har ingått i fallstudien. Vidare har Plan- och bygglagen, Boverket och Länsstyrelsen studerats i enighet med uppsatsens syfte. Dessa har undersökts enligt följande analysfrågor som lyder: Hur hanterar lagar och regler samt riktlinjer på nationell nivå klimatfrågor i den fysiska planeringen, mer specifikt i detaljplanering? Var och i vilken utsträckning behandlar detaljplanerna klimatfrågor, framförallt stigande havsnivåer? Hur beskriver detaljplanerna synen på vattnet? Hur hanteras bebyggelsen när det gäller: a) lägsta golvnivå för färdigt golv? b) avstånd till vattnet? Diskussionen i uppsatsen görs utifrån teoretiska utgångspunkter som har sin grund i hur den fysiska planeringen hanterar risker med klimatfrågor i dagens samhälle med den ökade globaliseringen och den tekniska utvecklingen, också kallad för ett risksamhälle. Begrepp som robusthet, ett robust samhälle, experternas roll och expertkunskap diskuteras. Att dagens klimatförändringar är orsakade av mänskliga aktiviteter är något många forskare diskuterar idag. Det innebär att vi ska möta dess konsekvenser, inte minst inom den fysiska planeringen. Risker med stigande havsnivåer är något som de flesta av kustnära svenska städer möts av redan idag. Norra Älvstranden i Göteborg ligger vid Göta Älv och dessutom i en låglänt terräng. Området, som tidigare har varit ett hamnområde, har successivt omvandlats till ett attraktivt bostadsområde med blandade aktiviteter. Av de granskade detaljplanerna går det att se en medvetenhet om klimatriskerna i detaljplaneringen. Planerna föreslår åtgärder för att anpassa bebyggelsen inför kommande klimatförändringar, exempelvis höjs den lägsta grundläggningsnivån. Å andra sidan går det läsa hur synen på vatten kvarblir som ett viktigt element i planeringen. Sammanfattningsvis kan det konstateras att det finns en ganska oföränderlig syn på hur klimatfrågorna i detaljplaneringen ska behandlas
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Assessment of Irrigation and Rainfall Effects on Soil Salinity in Selected Drip-Irrigated Orchards in San Joaquin Valley, CA
Preventing an accumulation of harmful salts in the root zone (RZ) of crops is necessary for sustaining irrigated agriculture in arid and semi-arid regions. Climate change may impact future maintenance of the RZ salt balance due to changing temperatures and evapotranspiration, altered precipitation patterns, and related shifts to alternative, lower quality irrigation waters. In this study, experimental field data, including soil water contents, electrical conductivities, spatial root distributions, and soil physical and chemical properties, were collected to assess salinity trends under different environmental and management conditions in almond and pistachio orchards at five locations in San Joaquin Valley (SJV), California, in 2017-2019. Diverse seasonal soil salinity trends were obtained for the eastern and western geo-hydrological regions of SJV and almond and pistachio orchards. The experimental data were then used to carry out numerical analyses with the one-dimensional HYDRUS-1D model to quantify water and solute transport in almond and pistachio trees' RZs. The model was successfully calibrated and validated using soil water content and electrical conductivity measurements at two experimental sites during 2017-2018 and 2019. Simulated soil water contents and evapotranspiration at these two sites showed good agreement with the measured data. Salinity patterns in the RZ were also described successfully by the HYDRUS-1D simulations. There were uncertainties in simulated trends at the other locations due to, for example, the presence of a duripan, solution chemistry effects on soil hydraulic properties, or functional errors with the GS3 soil sensors in some depths. Finally, additional simulations were carried out to predict future soil salinity accumulation and leaching trends for selected future climate (rainfall) and irrigation (the use of surface (less saline) and ground (more saline) waters) scenarios. Future rainfall trends were predicted using two climate models (CSM4_mid-range precipitations and CNRM_CM5_wetter precipitations) (CalAdapt, 2018). The simulated results of future salinity trends under different regional, geological, irrigation, and climate conditions in SJV can be used to design different salinity management options in the future
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Assessment of Irrigation and Rainfall Effects on Soil Salinity in Selected Drip-Irrigated Orchards in San Joaquin Valley, CA
Preventing an accumulation of harmful salts in the root zone (RZ) of crops is necessary for sustaining irrigated agriculture in arid and semi-arid regions. Climate change may impact future maintenance of the RZ salt balance due to changing temperatures and evapotranspiration, altered precipitation patterns, and related shifts to alternative, lower quality irrigation waters. In this study, experimental field data, including soil water contents, electrical conductivities, spatial root distributions, and soil physical and chemical properties, were collected to assess salinity trends under different environmental and management conditions in almond and pistachio orchards at five locations in San Joaquin Valley (SJV), California, in 2017-2019. Diverse seasonal soil salinity trends were obtained for the eastern and western geo-hydrological regions of SJV and almond and pistachio orchards. The experimental data were then used to carry out numerical analyses with the one-dimensional HYDRUS-1D model to quantify water and solute transport in almond and pistachio trees' RZs. The model was successfully calibrated and validated using soil water content and electrical conductivity measurements at two experimental sites during 2017-2018 and 2019. Simulated soil water contents and evapotranspiration at these two sites showed good agreement with the measured data. Salinity patterns in the RZ were also described successfully by the HYDRUS-1D simulations. There were uncertainties in simulated trends at the other locations due to, for example, the presence of a duripan, solution chemistry effects on soil hydraulic properties, or functional errors with the GS3 soil sensors in some depths. Finally, additional simulations were carried out to predict future soil salinity accumulation and leaching trends for selected future climate (rainfall) and irrigation (the use of surface (less saline) and ground (more saline) waters) scenarios. Future rainfall trends were predicted using two climate models (CSM4_mid-range precipitations and CNRM_CM5_wetter precipitations) (CalAdapt, 2018). The simulated results of future salinity trends under different regional, geological, irrigation, and climate conditions in SJV can be used to design different salinity management options in the future
Effect of Gypsum and Polyacrylamides on Water Turbidity and Infiltration in a Sodic Soil
Water ponded on sodic soils can develop turbidity problems which seriously affect rice crop establishment. A total of 19 polyacrylamide products were tested to assess their effectiveness to control water turbidity in a sodic soil under laboratory conditions. Anionic polyacrylamides were more effective than cationic or non-ionic polyacrylamides. When combined with gypsum, polyacrylamides were found to be more effective than applied alone. A split application strategy was more efficient than continuous application of polyacrylamide treatments. Different rates of polyacrylamides at 2.5, 5 and 10 kg/ha did not show significant difference in controlling water turbidity. Selected polyacrylamides were also tested on soil columns to study their effect on infiltration and percolation of water through the soil. Results have shown that polyacrylamides combined with low rates of gypsum did not modify the infiltration pattern to a greater extent. This study demonstrated that anionic polyacrylamides applied with small quantities of gypsum through a split application strategy would be an appropriate technique to overcome water turbidity problems in sodic soils
Efficiency of fluazifop-p-butyl and Oxyfluorfen herbicides separately and in combinations with selected spray tank additives on weeds in onion field
Two field experiments were carried out at Faculty of Agriculture Farm, Al-Azhar University, Assiut governorate in 2014-2015 and 2015-2016 seasons to evaluate the efficiency of two post-emergence herbicides, i.e. Fusilade forte (fluazifop-p-butyl) and Goal (oxyfluorfen) on onion weed control at 30 and 60 days after treatment. Both herbicides were applied at their recommended and ¾ recommended rates with and without spray tank additives, i.e. sodium lauryl ether sulphate and organosilicone adjuvants. The results showed that the tested adjuvants obviously increased the herbicidal efficiency of fusilade forte against grassy weeds and Goal against broad leave weeds. In most cases the maximum efficiency was achieved when both fusilade forte and Goal were applied at their recommended (187.5 and 180 g a.i/fed.) or ¾ recommended (140.625 and 135 g a.i/feddan) rates, + organosilicone adjuvant at 0.1% v/v concentration without significant adverse effects in onion crop
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The effect of different fertigation strategies and furrow surface treatments on plant water and nitrogen use
Furrow irrigation and fertigation systems should be designed and managed to optimize the availability of water and fertilizer to plants and minimize their losses through evaporation, deep drainage and leaching. We developed a furrow irrigation submodule for HYDRUS (2D/3D) and used it to evaluate the effects of different furrow soil surface treatments and different timings of fertigation on root water and solute uptake, deep drainage and solute leaching in a loamy soil. Numerical simulations showed that more water was available for transpiration in the treatments with plastic placed at the furrow bottom compared to the control treatments. However, more water was lost due to evaporation and less water was drained from the soil profile for these treatments. The highest and lowest root solute uptake was achieved when fertigation was applied in the middle and at the beginning of the irrigation cycle, respectively. The least amount of solute was leached from the soil profile for treatments with the plastic bottom and when fertigation was applied at the end of the irrigation cycle. The scenarios with plastic and irrigation in alternate furrows showed a reduction in transpiration and yield, more water loss due to deep drainage, and less water lost due to evaporation. However, similar crop yields were obtained for this alternate furrow strategy as for the control furrow surface treatments. When only half the water was used for irrigation in this scenario, the reduction in yield was less than 20 % compared to the control treatments, producing higher water-use efficiency