The purposes of this thesis are to examine experimental results obtained with subsurface irrigation of maize in 1988, and to provide preliminary plans and an economic analysis for the subsurface irrigation of maize in Richelieu County, Quebec. A mean increase in maize yield of 3.7 % was observed in 1988 on experimental plots with subsurface irrigation at the Charbonneau farm. However, a review of results obtained at the same experimental site from 1982 to 1988 indicated that the mean increase in maize yield with subsurface irrigation was 29 %. / Plans for two possible water supply systems designed to provide 180 mm a year of irrigation water for the subsurface irrigation of 1,250 ha in Richelieu County were considered. An economic analysis indicates that subsurface irrigation using groundwater has the greatest net benefits with an internal rate of return of 22.92 % and benefit to cost ratios of 1.90, 1.72 and 1.56 for discount rates of 8 %, 10 % and 12 % respectively. However, much of the groundwater in this region is saline and its use for irrigation may need to be restricted. Subsurface Irrigation using surface water from the Yamaska River was also profitable with an internal rate of return of 17.31 % and benefit to cost ratios of 1.66, 1.46 and 1.30 for the same discount rates.

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During 1995 and 1996, experiments with globe artichoke (Cynara scolymus L.) were conducted in southwestern Quebec (lat. 45° 26 'N long. 73° 56 'W) to determine the optimum nitrogen fertilizer requirements and irrigation levels and to evaluate two widely grown cultivars for their suitability to Quebec regions. In order for flowering to occur plants must undergo a vernalization period. In 1995, plants received 32 chilling hours, an amount sufficient for 89 % Imperial Star plants and 39 % of Green Globe Improved to produce buds. In 1996, plants received 72 chilling hours, an amount sufficient for 94% of Imperial Star and 81 % Green Globe Improved plants to flower. Imperial Star produced 3 marketable lateral buds per plant compared to 2 buds per plant for Green Globe Improved in 1995. Both cultivars in 1996 produced 2 marketable lateral buds per plant. The average bud weight was higher for both cultivars in 1996 compared to 1995. Total yield was significantly higher with regular irrigation compared to variable irrigation. Nitrogen applications above 100 kg N/ha did not significantly increase weight of buds in both years suggesting that that this amount was sufficient for our culture situation. Imperial Star appeared to be a significant improvement over Green Globe Improved plants grown from seed.

Field water table measurements were taken at two sites in Southern Quebec in order to validate DRAINMOD, a field scale water table management model. Two growing seasons of data were collected on a loamy sand soil near Sorel, Quebec and one year of data on a clay soil to the south-west of Montreal. Several water table management schemes were investigated, ranging from conventional subsurface drainage to automated subsurface irrigation. / DRAINMOD was used to simulate the measured water table fluctuations and relative corn crop yields over the growing season. Verification of the model was needed to determine if it could be a useful tool in the design and operation of water table management systems for the Quebec region. / It was found that DRAINMOD output closely simulated the water table fluctuations for conventional drainage and subsurface irrigation plots provided no exceptional circumstances existed. More study is needed in some areas such as bedded fields and in the use of fluctuating water level control structures.

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L’utilisation rationnelle de l’eau est une préoccupation croissante. Il importe d’optimiser la gestion des irrigations du fraisier à jours neutres afin de répondre adéquatement au besoin de la plante tout en diminuant la pression du secteur agricole sur l’eau. Dans les sols de l’île d’Orléans, la fraction des particules de sol supérieure à 2 mm peut varier de 15 à 30%. L’eau s’écoule principalement verticalement sous le tube de goutte-à-goutte et le mouvement vertical rapide de l’eau entraine un assèchement du sol en bordure de l’andain et une perte de nutriments. Diverses techniques combinées à l’utilisation de tensiomètres peuvent être envisagées afin d’améliorer l’efficacité d’utilisation de l’eau d’irrigation (EUEI) dans ce type de sol. L’irrigation fractionnée, l’ajustement du seuil de déclenchement de l’irrigation selon l’ETc prévisionnelle, l’installation de matelas capillaires sous la zone racinaire et un système de production hors-sol sur butte profilée ont été testés. Le projet avait pour objectif de déterminer l’effet des techniques présentées sur le développement des fraisiers à jours neutres, le rendement, la qualité des fruits, l’EUEI et les propriétés physico-chimiques du sol. Un dispositif en bloc aléatoire comportant cinq traitements a été mis en place à Saint-Jean-de-l'Île-d'Orléans durant deux saisons de production. Le fractionnement de l’irrigation et le système de production hors-sol ont engendré une augmentation non significative du rendement vendable de 10% et 12%, respectivement, par rapport au traitement témoin. Le système hors-sol a toutefois permis d’augmenter significativement de 86% le rendement vendable durant le premier mois de production. L’EUEI a été améliorée par tous les traitements. En raison de sa simplicité et de sa tendance à augmenter le rendement, l’irrigation fractionnée est recommandée pour le type de sol à l’étude. / Rational use of water is a growing concern. It is important to optimize the irrigation management of day-neutral strawberry plants in order to adequately meet the plant needs while reducing the pressure of agriculture on water. Some soils in the area of Île d’Orléans (Québec, Canada) present an important proportion of schist fragments (15-30%). Because of the high hydraulic conductivity, water flows mainly vertically under the drip tape with little horizontal movement, causing losses of water and nutrients. Different techniques, combined with the use of tensiometer, may be considered to improve the irrigation water use efficiency (IWUE) in this type of soil. Pulse irrigation, irrigation threshold (IT) adjusted according to ETc, installation of capillary mat under the root zone and a raised bed trough system with peat substrate were tested. The project aimed to determine the effect of irrigation management techniques on day-neutral strawberry plants development, yield, fruit quality, IWUE and soil properties. A randomized block design with five treatment was established in Saint-Jean-de-l’Ile-d’Orléans for two productions seasons. Pulse irrigation and soilless system have induced a non-significant increase of marketable yield by 10 % and 12 %, respectively, compared to the control treatment. Soilless system has, however, significantly increased the marketable yield by 86% in the first months of production. All treatments tested allowed to increase IWUE compared to the control. Because of its simplicity and its yield increase, pulse irrigation is recommended for this type of soil in order to reduce the amount of irrigation water.