Abstract
The purpose of this study was to evaluate the effects of furrow fertigation on nitrate deep leaching, nitrate runoff losses, and plant nitrogen supply in various growth stages of maize (Zea mays L.). Furrow fertigation experiment was conducted in 120 (W1), 100 (W2), 80 (W3), and 60% (W4) levels of required water (560 mm) and 100 (N1), 80 (N2), 60 (N3), and 0% (N4) levels of required nitrogen fertilizer (184 kg N ha−1). N-fertilizer was applied in four split applications (before planting, at the seven-leaf, shooting, and flowering). In the farmers’ conventional fertilization (FCF) method, 120% level of required water and 100% level of the required N-fertilizer were used in two split applications (before planting and at the seven-leaf stage). Results showed that the highest maize aboveground nitrogen content was 3.11% for FCF treatments at the seven-leaf stage. The maximum nitrogen content in the sensitive flowering stage and the maximum grain yield were also observed in W2N1 treatment with 2.27% and 12.93 ton ha−1, respectively. While, there were no significant differences in aboveground nitrogen content and grain yield between W2N1 and W3N1, W2N2, and W3N2. The highest amounts of nitrate leaching out of the 80-cm soil layer and nitrate runoff losses, were also recorded in FCF treatment, followed by W1N1, W2N1, and W3N1. Based on plant nitrogen content, nitrate losses and maize yield, 80% levels of the required N-fertilizer and required irrigation water could be recommended as the optimal levels to reduce nitrate losses and improve maize yield.
Highlights
Water and nitrogen are the two key factors in agriculture production
Nitrate deep leaching was only observed in furrow fertigation treatments (FF), which consisted of 100% (N1) level of required N-fertilizer and 120 (W1), 100 (W2), and 80% (W3) levels of required irrigation water, and farmers’ conventional fertilization treatment (FCF)
Unlike W1N1, W2N1 treatments, in which nitrate deep leaching gradually decreased, nitrate leaching in W3N1 treatment decreased sharply, which may be explained by a greater influence of 60% level of
Summary
Water and nitrogen are the two key factors in agriculture production. The relationship between nitrogen and water supply for crop production has been proved [1]. The excessive application of water and nitrogen in the conventional method which fertilizer is spread on soil surface, are the main cause of nitrate leaching [5]; that can cause the water surface and groundwater contamination [6]. Fertigation methods through reduction of applied fertilizer amount and enhanced fertilizer uptake efficiency reduce fertilizer inputs and mitigate potential environmental contamination [7]. This method increases nutrient uptake through preserving optimal level of nutrients in the plant root zone during the growing period, and enhanced timing of nutrient applications simultaneously declined N leaching compared to farmers’ conventional fertilization where a large portion of the nitrogen is applied before planting [8].
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