Effects of Different Irrigation Water Types, N Fertilizer Types, and Soil Moisture Contents on N2O Emissions and N Fertilizer Transformations in Soils

Abstract

The use of reclaimed water (RW) for irrigation alleviates agricultural water shortages. However, N 2 O emissions and N fertilizer transformations in soils irrigated with RW under different N fertilizer types and soil moisture contents are poorly understood. A 216-h laboratory incubation experiment was conducted to evaluate the effects of irrigation water types (RW and fresh water, FW), N fertilizer types ( 15 N-labeled KNO 3 and (NH 4 ) 2 SO 4 ), and soil moisture contents at 40, 60, and 90 % water-filled pore space (WFPS) on N 2 O emissions and N fertilizer transformations in intact soil cores. The results showed that cumulative N 2 O emissions ranged from 3.78 to 36.30 mg N m −2 , and fertilizer-derived N 2 O losses accounted for 0.14-2.44 % of N fertilizers, while fertilizer-derived N residues (NO 3 − -N + NH 4 + -N) accounted for 10.16-26.95 % of N fertilizers. The N 2 O emissions at 40 % WFPS and fertilizer-derived N residues at 60 % WFPS in soils irrigated with RW were significantly (10.98 and 20.95 %, respectively) higher than those irrigated with FW, while fertilizer-derived N 2 O losses at 60 % WFPS in soils irrigated with RW were 10.26 % higher than those irrigated with FW. The N 2 O emissions and fertilizer-derived N 2 O losses in soils amended with (NH 4 ) 2 SO 4 at 40 and 60 % WFPS were significantly (26.61-178.84 %) larger than those amended with KNO 3 , while fertilizer-derived N residues in soils amended with KNO 3 were significantly (41.47 %) higher than those amended with (NH 4 ) 2 SO 4 . The N 2 O emissions significantly increased with increasing soil moisture content. Our results indicate that N fertilizer types and soil moisture contents are the two important factors regulating N 2 O emissions and N fertilizer transformations. When RW irrigation is used, controlling soil moisture contents within 41 and 60 % WFPS (the optimum is 46 % WFPS) and application of KNO 3 can reduce N 2 O emissions and fertilizer-derived N 2 O losses, and correspondingly increase fertilizer-derived N residues, which can contribute to climate change mitigation.

Nitrogen Related Diffuse Pollution from Horticulture Production—Mitigation Practices and Assessment Strategies

“…A meta-analysis of several strategies to control nitrate leaching led to the conclusion that the group of strategies based on improving water irrigation management had the largest effect [88]. Irrigation water management has a significant impact on N losses not only because it controls the nutrient delivery to the water bodies (transport type method), but also as a mitigation method at the source, since moisture content controls most of the biochemical reactions leading to N transformations [95]. Irrigation water management can be improved at different levels, as described next.…”

Effects of three types of soil amendments on yield and soil nitrogen balance of maize-wheat rotation system in the Hetao Irrigation Area, China

“…However, over use of N fertilizer that is a common practice in agriculture can result in significant N losses. Moreover, over use of N fertilizer is responsible for air pollution, eutrophication and groundwater pollution (Jussy et al, 2004;Sutton et al, 2011;Yang et al, 2015;Shang et al, 2016). Therefore, effective measures to reduce N losses in agriculture have received considerable attentions in various areas, especially in irrigated area (Cameron et al, 2013;Geng et al, 2015).…”