Bano Mehdi

Estimation of Future Crop Water Requirements for 2020 and 2050, Using CROPWAT

The objective of this study was to determine the impacts of potential climate change on daily and total crop water requirements (CWR) of peaches in Southern Ontario using CROPWAT in conjunction with the climate scenarios derived from SDSM. Baseline climate is based on the 30 year-period, 1971-2000 of the mean monthly normals, and two time periods in the future centered on the decades of 2020s (2010-2039) and 2050s (2040-2069). The climate parameters of temperature, precipitation, relative humidity, sunshine duration and wind speed were downscaled using the SDSM (version 3.1) method. To determine the future crop water requirements (CWR), the CROPWAT model (FAO, 1992) was used to simulate the daily and the season total CWR and irrigation requirements for the present and the future decades. Results compared to the base climate show an increase in crop water requirements of 6.0 % (39 mm) per season using the SDSM-CGCM1 model for 2020s and 3.0% (20 mm) per season using both the SDSM-HADCM3 A2 & B2 models for 2020s. About 8 % (56 mm) increase in using the SDSM-CGCM1 and HADMC3 A2 models for 2050s, and 7.0 % (43 mm) per season. However, the irrigation requirements decreased, compared to the current situation, by 6.0 % (18 mm) (assuming 90% irrigation efficiency) using the SDSM-CGCM1 for 2020s and by 27% (81 mm) for both SDSM-HADCM3 A2 & B2 models for 2020s. While in 2050s, a decrease of 2.71% (8 mm), 21% (64 mm) and 6% (59 mm) using the SDSM-CGCM1, SDSM-HADCM3 A2 and SDSM-HADCM3 B2, respectively for 2050s.

Evaluation of Winter Freeze Damage Risk to Apple Trees in Global Warming Projections

Winter freeze damage affects fruit production regularly in the northern part of North America. This situation, which is related to climatic conditions, financially affects fruit producers and limits the affected areas to the use of cultivars that are freeze-resistant but do not always yield a sufficient market return. The purpose of this study is to conduct an experiment with a newly developed numerical model (W5L+) and its associated snow cover module to evaluate the effects of the projected climatic change on the risk of winter freeze damage to apple trees. The model W5L+ quantifies the risk of freeze damage occurrence at defined locations based on local meteorological records or projections. Risk quantification is achieved by screening daily meteorological time series with pre-identified parameters that are known to be proxies for conditions that result in freeze-damage. The model was parameterized using historical meteorological records from apple orchards in Farnham, southern Quebec, and descriptions of regional winter freeze damaging events that were recorded between 1920 and 2005. In 82% of the years studied, the model was able to identify correctly the order of magnitude of the recorded freeze events. During the same period, results suggest that extremely low temperatures and prolonged periods of low temperatures were responsible for the majority of damaging events. When used with climatic projections downscaled from a global climate model (GCM), the model predicted a decrease in freeze risk for apple trees at the Farnham orchards in the next 60 years. This trend is due to a decrease in extreme cold events as well as in prolonged periods of low temperature. The present study demonstrates the potential of the W5L+ modeling approach in studying the impact of climate change on the occurrence of damaging freezes. However, the predictions need to be verified by using the model with a large range of agro-climatic conditions and climate projections.

Assessing on-farm irrigation water use efficiency in Southern Ontario.

For high-value horticultural crop production in southern Ontario, irrigation is an essential ingredient in overcoming insufficient rainfall and achieving stabilized crop production. In a context where competition for limited water resources intensifies due to the expansion of the agricultural sector, increasing urban development and tourism, and potential climate change impacts, conserving water through efficient irrigation has become a key solution in addressing this growing challenge. The implementation of advanced soil water monitoring technologies and water budgeting methods for improved irrigation scheduling is examined with regard to water conservation and thus as a means to cope with competing demands for limited water supplies. During the 2007 growing season, soil moisture was measured using two sensors at four field sites (comprising a total of six irrigated zones as two sites include two different irrigation/production systems) in southern Ontario. Irrigation water consumption was measured by flow meters at three sites. In addition, a survey was administered to collect information on growers’ current irrigation scheduling practices. On-farm irrigation performance was assessed by comparing calculated tomato, green bell pepper, strawberry and peach water requirements (using the water budget method) with growers’ estimates of irrigation water use and with soil moisture measurements taken during the growing season. Four out of the six irrigated zones were excessively irrigated, while in one zone, water was insufficiently applied. The crop water requirements were met efficiently exclusively in one zone where tomatoes were grown. Overall, the results of this research show that by implementing advanced soil moisture monitoring technologies, growers can increase precision in water application and reduce the uncertainty in their current irrigation scheduling practices.

Evaluating the Importance of Non-Unique Behavioural Parameter Sets on Surface Water Quality Variables under Climate Change Conditions in a Mesoscale Agricultural Watershed

The parameter uncertainty in the eco-hydrological model Soil and Water Assessment Tool (SWAT) was estimated using non-unique parameter sets for the Altmühl watershed (Bavaria, Germany). The Sequential Uncertainty Fitting Algorithm (SUFI-2) was used to calibrate SWAT. The non-unique parameter sets found were subsequently applied to SWAT concurrently with climate change simulations to determine the variables of streamflow, nitrate nitrogen (NO3−-N) and total phosphorus (TP). A suite of seven bias corrected climate change simulations provided reference (1970–2000) and future (2041–2070) climate data. The non-unique behavioural parameter sets that met an objective function of NSE >0.6 during calibration were applied to SWAT with the reference climate and with the future climate simulations. The best parameter set was also propagated through SWAT with each reference and future climate simulation in turn. Combining the non-unique behavioural parameter sets for estimating uncertainty bounds with an ensemble of climate change simulations led to a wider mean monthly spread (difference between maximum and minimum) of simulated NO3−-N and TP than using the best run with the future climate simulations. More monthly data was considered using the non-unique approach, resulting in statistical significances for more months of the year and overall lower interquartile ranges. The study quantifies the non-unique behavioural parameter set contributions to the modelling prediction, which assists in making more informed decisions based on available knowledge, with its limitations, of the future simulations. We outline a simple approach that can easily be replicated for similar hydrological modelling studies.

Simulated future changes of extreme nutrient loads in a mesoscale agricultural watershed in Bavaria / Simulierte zukünftige Änderungen der Extremwerte für Nährstofffrachten in einem mesoskaligen landwirtschaftlichen Einzugsgebiet in Bayern

Summary The hydrological model SWAT was applied to the upper Altmühl watershed to examine the simulated 10th and 90th percentiles of streamflow, nitrate nitrogen (NO3--N), and total phosphorus loads (TP), using an ensemble of reference climate (1975–2000) and future climate (2046–2070) simulations. A comparison between the two periods showed that in the future, the 90th percentiles of the NO3--N loads increase in all seasons which indicates a trend to increasing diffuse pollution in the mid-term future. Conversely, the 90th percentile TP loads diminished in winter and otherwise remained similar to the reference period. The 10th and 90th percentile changes in the future streamflow followed changes in precipitation, and did not have any apparent influence on extreme nutrient transport events. Zusammenfassung Das hydrologische Modell SWAT wurde im Altmühl-Einzugsgebiet angewendet, um die 10. und 90. Perzentile der Abfluss, NitratStickstoff (NO3--N) und Gesamtphosphor (TP) für Ensembles von Referenz- (1975-2000) und zukünftige (2046-2070) Klimabedingungen zu simulieren. Der Vergleich zwischen den Ensemble-Simulationen in beiden Zeiträumen zeigt, dass die 90. Perzentile der NO3--N Frachten in allen Jahrzeiten in der Zukunft signifikant erhöht waren. Dies deutet darauf hin, dass Stickstoff einen größeren Einfluss auf Frachttransporte in der mittelfristigen Zukunft in dem Altmühl Einzugsgebiet haben könnte. Umgekehrt waren die 90. Perzentile der TP Frachten im Winter verringert und ansonsten ähnlich wie im Referenzzeitraum. Die Veränderungen der 10. und 90. Perzentile für den Abfluss unter zukünftige Klimabedingungen folgten den Niederschlagsänderungen und hatten keinen eindeutigen Einfluss auf die extrem Nährstofftransportereignisse.

A Comparison of Soil Moisture Monitoring Technologies for Irrigation Scheduling

Currently, there is a range of sophisticated and user-friendly soil moisture monitoring equipment on the market which varies in cost, ease of installation/maintenance, as well the information output. However, for the most part, growers are still using antiquated methods (e.g. “feel method”) for determining when to apply water. A variety of soil moisture sensors were installed on southern Ontario farms for use in irrigation scheduling for selected horticultural crops. With the help of growers, the project assessed several of the available units for use in timely determination of irrigation need.

Growth analysis and land equivalent ratio of fenugreek-buckwheat intercrops at different fertilizer types

Summary Intercropping can increase crop growth and yield due to improved resource use efficiency. A two-year field experiment was performed in Shahrekord (Iran) to determine the effect of crop stand composition and fertilizer type on the productions of aboveground dry matter and growth parameters of fenugreek-buckwheat intercrops. Sole crops of fenugreek (F) and buckwheat (B) were compared to the three substitutive intercropping ratios (F:B = 2:1, 1:1 and 1:2). Crop stands were fertilized with chemical fertilizer or broiler litter. Fenugreek could produce in intercrops a similar amount of above-ground dry matter compared to its corresponding share on the sowing ratio. Contrary to that, buckwheat could produce in intercrops more above-ground dry matter than its share on the sowing ratio, especially with a low to medium share of buckwheat. Consequently, the intercrops with F:B (2:1) and F:B (1:1) had an above-ground dry matter yield advantage compared to the pure crop stands of both crops. Broiler litter was more effective in increasing the growth rates and thus the above-ground dry matter production compared to the chemical fertilizer. Thus, growing fenugreek and buckwheat in intercrops fertilized with broiler litter can be beneficial for increasing the biomass production in semiarid environments.