Abstract
Irrigation water is limiting for crop production in arid areas and application rates of fertilizers often exceed crop requirements, resulting in high accumulation of nitrate nitrogen (NO3−-N) in the soil. Management practices play a significant role in the leaching of NO3−-N. This experiment compares the effects of traditional furrow irrigation and sprinkler fertigation on the soil NO3−-N concentration trend throughout the cropping season in potato fields in China. Two irrigation systems that were fertilized, namely by furrow (NF-FI) and sprinkler fertigation (NF-SI), and two controlling without any fertilizer (C-FI and C-SI) were tested in the same experimental site for three consecutive years. Both the NF-FI soils and NF-SI soils with three replications and fertilizer applications of 273 kg N ha−1 exhibited a different trend of NO3−-N accumulation at different depths of soil profile. However, the magnitude of NO3−-N accumulation was low in the NF-SI soil profile. In NF-SI treatments, higher NO3−-N was observed at 20–40 cm soil layer. In the NF-FI, the concentration of the highest nitrate was observed at the 40–120 cm soil layer. The concentrations of NO3−-N in the fertilized soil were higher than those of the control soil for each irrigation system. Residual levels of NO3−-N in the soil depth of 40–120 cm from NF-FI were 1.54, 3.45 and 5.28 times higher than NF-SI after harvesting potatoes from 2015 to 2017. In NF-FI treatments, apparent nitrogen loss was 234.7, 237.5 and 276.7 kg ha−1 after harvesting potatoes in 2015, 2016 and 2017. Meanwhile, apparent nitrogen loss from NF-SI treatments was only 161.9, 132.1 and 148.9 kg ha−1, which was 31.0%, 44.4% and 46.2% lower than that of NF-FI in 2015, 2016 and 2017, respectively. The risk of NO3−-N leaching below the root zone from NF-FI was higher than that from NF-SI. It has been demonstrated that sprinkler fertigation can also be used as a tool for mitigating NO3−-N accumulation and apparent nitrogen loss.
Highlights
Nitrogen (N) is both an essential nutrient and a major pollutant in agricultural ecosystems [1].Nitrogen input worldwide mainly comes from the application of chemical nitrogen fertilizer
In sprinkler fertigation and furrow irrigation, Apparent nitrogen loss is an important indicator for evaluating nitrogen use status, which is fertilizers first broadcast on thereactive ridges by handthrough and irrigated. and Fertilizer applications always were associated with substantial
Estimated as the difference between nitrogen output and nitrogen input in soil of a depth from 0 to 120 cm in the control without any fertilizer [25]; NF is nitrogen fertilizer, where the unit is kg N ha−1; NR is from rainfall, where the unit is kg N ha−1; NI is from irrigation water, where the unit is kg N ha−1; NA is nitrogen absorbed by crops after harvest, where the unit is kg N ha−1; The first irrigation began on 19 May 2015, 25
Summary
Nitrogen input worldwide mainly comes from the application of chemical nitrogen fertilizer. The low efficiency of nitrogen fertilizer is mainly attributed to the loss of soil nitrogen caused by unreasonable use of water and fertilizer [2,3]. NO3 − -N in the soil is rapidly solubilized and moves with water, causing N losses due. NO3 − -N leaching is mainly affected by irrigation measures, nitrogen fertilizer management, crop system, soil management and soil type [6,7]. Irrigated agriculture has been identified as a significant source of NO3 − -N pollution [8]. Changes in irrigation systems mainly affect the mineralization and leaching of nitrogen by changing the soil water movement and affecting the distribution of available nitrogen in soil [9]
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