Improving nitrogen management in lettuce production by predicting nitrate leaching

Lettuce is an important crop in Nova Scotia, with a farm gate value over $2 million annually. With over 100acres of lettuce in production, Vermeulen Farms is the largest commercial producer of lettuce in AtlanticCanada. Lettuce is a short season, shallow-rooted crop that is sensitive to fluctuations in nitrogen (N)availability in the soil, which is often reduced caused by leaching after significant rainfall events. This is aserious problem for Vermeulen Farms, as a deficiency in N will reduce yield (5-10%) and quality of lettuce. Itcan also limit uptake of other essential nutrients like calcium causing tip burn, in addition to crop yellowing,causing crops to yellow and become unmarketable. Additional N fertilizer must be added to compensate for Nloss to leaching to achieve adequate production, yet there is often no indication of the quantity of N lost.Nitrate-N (NO3-N) from agriculture is an environmental contaminant and excessive N application increases theenvironmental risk. The objectives of the study are (i) to quantify amount of nitrate losses after each certainamount of rain fall, (ii) adjust sidedress application of N fertilizer based on nitrate leaching data, and (iii) toimprove N management practices with adjusting the application time (split application) and rates and studyeffect of N management on crop yield and quality, N use efficiency and N losses through leaching. Lettuce willbe grown in greenhouse with fertility treatments consisting of standard treatment used by Vermeulen Farms,and an improved fertility program recommended by the Ontario Ministry of Agriculture. The anticipatedoutcomes of this research will be to reduce Vermeulen Farms crop losses due to lack of soil N by developingfertility management tools to predict N losses following significant rainfall events.