Impact of overhead irrigation on nitrogen dynamics and marketable yield of potato
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Date
2015-04-01
Authors
Abbas, Haider
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Abstract
In Southern Manitoba, potato producers are experiencing wetter and drier conditions within the soil profile during the growing season leading to poor quality and inconsistent yields. Russet Burbank Potato cultivar was grown in Southern Manitoba on fine sandy loam soil in a two year (2013-2014) study using two water management treatments: (i) overhead irrigation and (ii) no-irrigation. The main objectives of the study were (i) to assess the impact of overhead irrigation on water table depth and potato yield (ii) to estimate the shallow groundwater contribution to potato water requirement through upward flux (iii) to track the nitrogen dynamics within the potato root-zone under overhead irrigation and no-irrigation scenarios (iv) to examine the effects of no-irrigation and overhead irrigation system at critical growth stages on marketable yield and quality of potatoes. In 2013, water was applied using a linear move irrigation system and in 2014 a rain gun irrigation system was used for the irrigated treatment. Volumetric soil water content, precipitation, irrigation depth, water table depth, nitrate concentration and electrical conductivity in potato root-zone, groundwater electrical conductivity, weather variables, total potato yield, marketable yield, and quality parameters were measured. The total yield was not significantly different between the two treatments in both years. The marketable yield of the irrigated treatment (36.89 MT/ha) was 20% higher (p = 0.017) compared to the non-irrigated treatment (30.74 MT/ha) in 2013. However, no significant difference was found between the irrigated (39.0 MT/ha) and non-irrigated (43.7 MT/ha) treatments in 2014. Potato yields from both treatments were significantly correlated with the average groundwater depth. Water balance analysis within the root-zone during rainy and rain-free periods showed that nitrate rich groundwater may have contributed to some of the crop water demand. The lack of rainfall and high temperature during tuber initiation and tuber bulking stages resulted in the accumulation of high concentration of nitrates within the root-zone by the late release of nitrates from the polymer-coated urea and the upward migration of groundwater containing 55 ppm and 70 ppm of nitrates in the 2013 and 2014 growing seasons, respectively. Overhead irrigation was found to be economically advantageous to produce better quality potatoes with higher marketable yields.
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Keywords
Overhead irrigation, Marketable yield, Nitrogen dynamics, Potato, Groundwater level, Soil water content, Upward flux