USCID fourth international conference

Presented at the Role of irrigation and drainage in a sustainable future: USCID fourth international conference on irrigation and drainage on October 3-6, 2007 in Sacramento, California.Includes bibliographical references.One of the most efficient techniques used to protect the buds, flowers, and fruits of apple trees against potentially damaging spring frosts, is by spraying irrigation water on the fruit trees via a sprinkler irrigation system. The purpose of this study was to evaluate the impacts of global warming on frost occurrences for the fruit growing conditions in Québec, with the long-term objective being to evaluate how this will alter amounts of water used for frost protection. Frost injury risk is characterized by using a phenological model coupled with a risk index generator. The phenological model was selected amongst a group of models for its ability to maintain a satisfactory level of accuracy when tested under different climatic conditions. Based on meteorological and phenological observations on apple trees in the Monteregie region of Québec, the model calibration and validations provided evidence of the ability of the selected model to reproduce and predict frost injury risk trends. Local climatic conditions downscaled from a GCM were used to assess the effects of future climate scenarios on the risk of frost injuries. Under the tested scenario, the risk index increases significantly, suggesting that the number and / or the severity of spring frost injuries would increase in the future. This would imply that the use of a sprinkler system as a protection method against frost injuries has to be taken into consideration for the assessment of climate change impacts on overall water demands for crop water requirements

Nitrous oxide and carbon dioxide emissions from surface and subsurface drip irrigated tomato fields

Irrigation practices change the soil moisture in agricultural fields and influence emissions of greenhouse gases (GHG). A 2 yr field study was conducted to assess carbon dioxide (CO2) and nitrous oxide (N2O) emissions from surface and subsurface drip irrigated tomato (Solanum lycopersicum L.) fields on a loamy sand in southern Ontario. Surface and subsurface drip irrigation are common irrigation practices used by tomato growers in southern Ontario. The N2O fluxes were generally ≤50 μg N2O-N m⁻² h⁻¹, with mean cumulative emissions ranging between 352 ± 83 and 486 ± 138 mg N2O-N m⁻². No significant difference in N2O emissions between the two drip irrigation practices was found in either study year. Mean CO2 fluxes ranged from 22 to 160 mg CO2-C m² h⁻¹ with cumulative fluxes between 188 ± 42 and 306 ± 31 g CO2-C m⁻². Seasonal CO2 emissions from surface drip irrigation were significantly greater than subsurface drip irrigation in both years, likely attributed to sampling time temperature differences. We conclude that these irrigation methods did not have a direct effect on the GHG emissions from tomato fields in this study. Therefore, both irrigation methods are expected to have similar environmental impacts and are recommended to growers

Independent principal component analysis for simulation of soil water content and bulk density in a Canadian Watershed

Accurate characterization of soil properties such as soil water content (SWC) and bulk density (BD) is vital for hydrologic processes and thus, it is importance to estimate θ (water content) and ρ (soil bulk density) among other soil surface parameters involved in water retention and infiltration, runoff generation and water erosion, etc. The spatial estimation of these soil properties are important in guiding agricultural management decisions. These soil properties vary both in space and time and are correlated. Therefore, it is important to find an efficient and robust technique to simulate spatially correlated variables. Methods such as principal component analysis (PCA) and independent component analysis (ICA) can be used for the joint simulations of spatially correlated variables, but they are not without their flaws. This study applied a variant of PCA called independent principal component analysis (IPCA) that combines the strengths of both PCA and ICA for spatial simulation of SWC and BD using the soil data set from an 11 km2 Castor watershed in southern Quebec, Canada. Diagnostic checks using the histograms and cumulative distribution function (cdf) both raw and back transformed simulations show good agreement. Therefore, the results from this study has potential in characterization of water content variability and bulk density variation for precision agriculture

Carbon availability limits the denitrification potential of sandy loam soil from corn agroecosystems with long-term tillage and residue management

Conservation tillage and crop residues should increase the soluble organic carbon and nitrate concentration in agricultural soil, which increases the denitrification potential. Basal denitrification (72 h laboratory incubation) was 2.1–2.7 times higher in a sandy loam soil under 15 yr of conservation tillage than conventional tillage and 1.8–2.0 times higher with high-residue (additional input 8.6–9.4 Mg dry matter·ha−1·yr−1) than low-residue inputs. Adding glucose and nitrate increased the soil denitrification potential 3- to 14-fold. Denitrification was limited by carbon availability, even in soil with 15 yr of conservation tillage and high-residue inputs.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Enhancing environmental sustainability in eastern Canada's corn agroecosystem with controlled drainage and subsurface irrigation

Water table management through controlled tile drainage and subsurface irrigation (CDSI), retrofitting to conventional tile drainage, has been developed to abate the environmental impacts of irrigation and drainage meanwhile supporting agroecosystems and crop productivity. Since the environmental profile of new technologies is a prerequisite to understanding their socio-economic benefits, a life cycle assessment was conducted to assess the environmental impacts of CDSI on corn production for the 2014 and 2015 growing seasons at St-Emmanuel, south-western Quebec in eastern Canada, compared to the free drainage (FD). Inventory flows of corn production with CDSI and FD were developed using biophysical data from field experiments and public databases. Then, environmental impacts were compared for corn production with CDSI and FD, including climate change, eutrophication potential, acidification potential, and toxicity. The assessment results show the environmental benefits of implementing CDSI, particularly in improving water quality. However, potential synergy and trade-offs of climate change, eutrophication, and acidification impacts from the implementation of CDSI, especially under different climatic conditions, should be further monitored to improve the performance of the technology. Nevertheless, CDSI and associated practices can be adopted as adaptation measures in agricultural water management to support agroecosystems and address the challenges posed by environmental impacts. HIGHLIGHTS This study compares environmental impacts of controlled drainage with sub-irrigation (CDSI) and free drainage (FD) for corn agroecosystems in eastern Canada.; GHG fluxes data from the field were integrated into the life cycle inventory.; CDSI has positive impacts in reducing environmental impacts of corn production on climate change and eutrophication compared to FD.; Trade-offs between climate change, eutrophication and acidification may affect CDSI's environmental performance.