Optimizing water management for increasing production while conserving water and nutrients within agricultural lands

点击翻译按钮获取中文摘要

Irrigated high-value crop production is expanding in Southern Manitoba, where salinization from poor quality groundwater has been a significant concern. Wherever irrigation water is applied to crops, they take up the water for evapotranspiration and leave behind the salts which accumulate within the root zone over time and alter the physical properties. Generally, clay particles tend to disperse in the presence of sodium ions in the salts, leading to the destruction of the soil structure, which renders the soil unproductive. Drainage systems are needed to remove the excess water applied to leach the salts below the root zone. However, conventional drainage systems may also over-drain the field, removing valuable nutrients and water. The exported nutrients from the field can affect the water quality of rivers and lakes downstream. Controlled drainage has been used to overcome this shortcoming. My NSERC-funded research conducted in well-designed and replicated large-scale field experiments in Winkler, MB, helped introduce controlled drainage/subirrigation as a practice for the first time in Manitoba. This research indicated that irrigation and drainage systems significantly improved yield by 30% in potatoes and 15% in corn, contributing to a boom in drainage installations. However, significant nutrient outflows were observed during the spring snowmelt period as well as during high-intensity rainfall. Controlled drainage was shown to decrease the nutrient outflow by 80 to 90% compared to conventional drainage. Therefore, holding the water back within the root zone during the spring snowmelt period and after high-intensity rainfall was a best management practice (BMP) to minimize nutrient export from the field. However, this practice may negatively impact soil trafficability due to high water tables during the spring. The proposed research will allow us to collect field data and create computer models that can assess the impact of different water management strategies. This research will help develop protocols for managing controlled drainage to optimize water management in the field. In the short term, soil physical properties will be measured in several farms planning to install tile drains with inline drainage control structures providing the ability to subirrigate. This data will be used to create computer models of individual farms and calibrate and validate the models. The validated models will develop an optimized operational plan to manage the water and nutrients within the field. The long-term objective of this research program is to establish protocols to optimize farm water management through controlled drainage and irrigation to conserve water and nutrients within the field and protect the soil and water resources for the long term. Developing a web-based water and nutrient management tool will significantly assist farmers in managing the water and nutrients to get a better return while protecting the environment.