Effects of irrigation and fertilization on the emission factors and emission intensities of nitrous oxide in alkaline soil

Environmental damage attributed to nitrous oxide (N2O) emissions have received widespread attention. Agricultural sources release substantial amounts of N2O into the atmosphere. However, comparative studies on the effects of different irrigation and fertilization methods, namely, drip fertigation (a combination of fertilizing and irrigation), sprinkler fertigation, and traditional furrow irrigation with chemical fertilizer spraying, on N2O emissions in alkaline soil have been limited. Therefore, three-year in situ field observations were conducted to investigate the effect of these three irrigation and fertilization modes on N2O emissions using the static chamber method over the period 2015–2017. There are significant seasonal variations in soil N2O emission fluxes among alkaline soils under different fertilization and irrigation modes, with emissions peaking in July and August, but no significant difference in yearly variations. The N2O emission intensity of drip fertigation soil was 0.20 kg N t−1 year−1, of sprinkler fertigation soil was 0.38 kg N t−1 year−1, respectively, while of furrow irrigation was 0.91 kg N t−1 year−1, respectively. Moisture and temperature of soil were key factors driving the observed nitrous oxide variations. Compared with traditional furrow irrigation, drip and sprinkler fertigation significantly increased potato yield and decreased N2O emissions in alkaline soil, thus satisfying both yield and environmental protection.


Introduction
Environmental pollution caused by elevated atmospheric nitrous oxide (N 2 O) concentrations is a major global challenge (Fowler et al 2015).N 2 O emitted into the atmosphere due to agricultural production activities represents 66.1% of the total N 2 O emitted from human activities (UNEP 2013).Soil N 2 O emissions are among the primary routes of N loss in agricultural production (Shi et al 2022).Soil N 2 O emissions in agriculture field account for approximately 60% of global agriculture N 2 O emissions (Case et al 2015) due to nitrogen fertilizer use (Signor et al 2013), soil type (Singh et al 2010), and irrigation management (Yu et al 2022).
Soil pH and other physico-chemical properties have a profound impact on the migration and transformation of soil nitrogen, thereby affecting soil N 2 O emission.Different soil pH will lead to differences in the N 2 O emissions (Reddy and Crohn 2014).There may be limited data but not that most of the measurements of N 2 O emissions have been only done in acidic soils.However, alkaline soils remain poorly investigated.
Fertilization and irrigation are key management strategy used to support crop growth in agricultural fields.Different fertilization and irrigation patterns could lead to changes of spatial and temporal dynamic distribution on soil moisture content and inorganic nitrogen nutrition, which can in turn have significant effects on soil N 2 O emissions (Hou et al 2012, Liu et al 2012, 2013).Some studies have reported that farmland soils with conventional irrigation had higher N 2 O emissions than those of controlled and reduced irrigation (Guo et al 2012).The research on drip irrigation and sprinkler irrigation mainly focuses on the effects of irrigation system on soil nutrition and crop yield in the farmland with sprayed fertilizer (Kang et al 2004, Liu et al 2013).There is a lack of research on gaseous nitrogen loss in farmland under drip irrigation, sprinkler irrigation.The N 2 O emission of conventional fertilization irrigation is high, while that of sprinkler irrigation is lower than that of furrow irrigation (Sánchez-Martín et al 2008, Kallenbach et al 2010, Taryn et al 2013).However, previous studies have even rarely simultaneously compared N 2 O emissions from drip fertigation (a combination of fertilizing and irrigation), sprinkler fertigation, and conventional furrow irrigation with chemical fertilizer spraying in alkaline soil.
Soil pH had a significant impact on the biological processes of soil nitrogen conversion (especially biological nitrification and denitrification processes), mainly reflected in the influence of soil pH on soil microbial and enzyme activities, and affected the production of soil N 2 O (Taryn et al 2013).However, it remains unclear whether the N 2 O emission factor in alkaline soils under furrow irrigation is similar to that under sprinkler and drip fertigation, since differences in water management and soil properties exist between sprinkler/drip fertigation practices and the furrow irrigation mode.Therefore, in situ observations of N 2 O emissions from alkaline soils of farmland under different fertilization and irrigation modes are essential to better estimate total N 2 O emissions from alkaline soil.
To better understand N 2 O emission fluxes from alkaline soil under different irrigation methods, herein, we conducted a three-year experiment using in situ field observations under three fertilization and irrigation methods (drip fertigation, sprinkler fertigation, and conventional furrow irrigation with chemical fertilizer spraying) to investigate the effect of fertilization and irrigation modes on N 2 O emissions using the static chamber method in the alkaline soil of arid region in northwest China.Our study objectives were to (1) quantify N losses via N 2 O emissions from drip fertigation, sprinkler fertigation, and furrow irrigation in alkaline soil in the same study area under the same climatic conditions and (2) determine the process of soil NO 3 − -N, NH 4 + -N, temperature, and moisture change on soil characteristics related to the process of N 2 O emission under different fertilization and irrigation modes, and (3) assess the data on N 2 O emission factors and intensity under different fertilization and irrigation modes in alkaline soil from potatoes field.

Overview of the study area
The study area is located in a farm in Yuquan District, Hohhot, at the south foot of Yinshan Mountain, Inner Mongolia Autonomous Region (40°45′34″ N, 111°41′56″ E).The area is located on the Tumochuan Plain in the north, with diluvial and alluvial piedmont inclined plains, and the Daheihe Plain, an alluvial plain, in the south.
The study area has a typical continental monsoon climate of the Mongolian Plateau, with an alkaline soil (table 1).Substantial climate changes occur throughout the four seasons, with drastic changes in cold and hot seasons.The area has low rainfall and high evaporation, dry climate, and short frost-free period.Evaporation is 5-6 times greater than precipitation, with an annual average evaporation of 1851.7 mm.The air temperature had a largely consistent trend, starting to gradually increase in April and peaking in July-August.Precipitation was more frequent in 2016 than in 2015 and 2017.There was no significant difference (P > 0.05) in total annual precipitation during 2015, 2016, and 2017 (219.5, 196.7, and 201.8 mm, respectively).

Experimental treatments and field management
The experiment was conducted over 2015-2017 in a potato field (figure 1).The potato variety was 'Favorite', and a randomized experiments was applied in the farmland.The experiments were set up to compare drip irrigation and sprinkler irrigation with traditional furrow-irrigated potato fields.Each of these treatments were divided into fertilization treatment and control treatment without fertilization, resulting in a total of six treatments with three replicates, totaling 18 plots.'Double-row ridge cultivation' was used in the drip fertigation mode (figure 2(a)) with 110 cm spacing between ridges, 50 cm ridge shoulder width, and 20 cm ridge height.A drip irrigation belt (diameter 16 mm * dripper discharge 1.38 l h −1 * thickness 0.6 mm * drippers spacing 300 mm) was placed in the center of each ridge shoulder, with 30 cm spacing between drip emitters.Double rows were alternately planted on the shoulder of the ridges, with 30 cm spacing between rows and 30 cm spacing between plants on the shoulder of the ridges through the full ridge length of 11.2 m.Each experimental plot had a drip fertigation control system.At the inlet  of the control system, a copper valve, water meter, water and fertilizer control valve, filter, pressure control meter, and water and fertilizer tanks were installed.Each plot was set up with five ridges separated by 110 cm spacing and two protection strips on the left and right side, extending 9.9 m in width.The experimental plot was also lined with two protection strips of 4.8 m at the front and rear sides.The control plot area was 61.6 m 2 .
'Single-row ridge cultivation' was adopted in the sprinkler fertigation mode (figure 2(b)), with 90 cm spacing between ridges, 30 cm ridge shoulder width, and 30 cm ridge height.A sprinkler belt was set up above the center of the shoulder of each ridge, with each belt equipped with four low energy precision application (LEPA) nozzles.Nozzle spacing was 2.8 m, sprinkler belt length was 11.2 m, and the nozzles were placed at the height of 1.3 m above the ridge.A single row was planted on the shoulder of a ridge, with plant spacing of 20 cm.The length of the ridge was also 11.2 m.The sprinklers were automatically controlled.Each experimental plot was equipped with a sprinkler control unit containing water meters, filters, solenoid valves, differential pressure fertilizer tanks, and copper valves assembled at the inlet of the unit.Four ridges were arranged in each experimental plot, with ridge spacing of 90 cm.Two protection strips were placed on the left and right sides of each plot, resulting in a total width of 7.2 m.Protection strips of 4.8 m were also placed in the front and rear side of each plot.The control plot area was 40.32 m 2 .Each experimental plot had 16 LEPA nozzles.
The first irrigation amount after sowing was 20 mm for drip irrigated potatoes and 40 mm for sprinkler irrigated potatoes.A tensiometer was used to facilitate fertilizer application after the seedlings emerged.Kang et al (2004) and Wang et al (2007) found that potato yield and water use efficiency were the highest when the average soil matrix potential (SMP) was −25 kPa at the depth of 20 cm directly under the dripper or −20 kPa at the depth of 20 cm directly under the sprinkler nozzles.Thus, in our experiment, drip irrigation was initiated once the average SMP reached −25 kPa at a soil depth of 20 cm directly below the dripper, sprinkler irrigation was started when the average soil matrix potential reached −20 kPa at a soil depth of 20 cm directly below the sprinkler nozzles, and was controlled automatically.Soil matrix potential was maintained at −15.0 to −10.0 kPa.The tensiometer readings were taken twice daily at 8:00 and 15:00.
The furrow irrigation mode also used 'single-row ridge cultivation' (figure 2(c)), with a ridge spacing of 90 cm, ridge shoulder width of 30 cm, and ridge height of 30 cm.Potatoes were planted in a single row on the shoulder of the ridge, with a plant spacing of 20 cm throughout the 11.2 m length of the ridge.Each plot hosted four ridges, separated by 90 cm spacing and lined with a protection strip on both sides, extending the total width to 7.2 m.A protection strip of 4.8 m was placed at both the front and rear of the experimental area.The control plot area was 40.32 m 2 .Irrigation time and amount of irrigation for potatoes followed the traditional local planting practice.Each irrigation lasted until water reached the end of the furrow, and irrigation volume was based on water meter readings.The irrigation water used in the present study was groundwater.

Fertilization application
The total amount of fertilizer (base fertilizer, urea, potassium nitrate added up) was 273 kg N ha −1 , and was determined according to the nutrient amount of soil and fertilization requirements of potato in the study site (Feng et al 2018).The base fertilizer was potato specific fertilizer of K 2 SO 4 type with the N-P-K ratio of 12-19-16 (produced by Sino-Arab Chemical Fertilizer Co., Ltd) during planting.The amounts of base fertilizer were 92.36 kg N ha −1 in the treatment of these three fertigation methods.
The fertigation technology was applied to the topdressing of drip and sprinkler irrigation.Fertilizer type and amount of topdressing as follows: N fertilizer-urea (46% N content) with the amounts of 94.67 kg N ha −1 ; K fertilizer-potassium nitrate (13.9% N content, 46.5% K 2 O content) with the amounts of 85.97 kg N ha −1 .
The fertilizers were dissolved in the fertilizer tank and applied together with water during irrigation.Urea and potassium nitrate were applied in split doses once a day under the drip and sprinkler fertigation system.Urea was applied for 25 days as a topdressing fertilizer from the emergence of potatoes.Potassium nitrate was applied for 70 days from potato emergence to 20 days before potato harvest.If no water was required for three consecutive days owing to rainy weather, the fertilizer for the first 3 days would then be applied together with the fertilizer for day 4 when irrigation commenced.Fertilization was terminated 20 days before the potato harvesting, after which the field was irrigated for 10 days without fertilization.Irrigation was stopped 10 days before the harvesting.
Top dressing for the traditional furrow irrigation followed the traditional local supplementary fertilization method, which were sprayed to the surface of soil near the potato plant by hand.All topdressing amounts were applied at one time during tuber setting stage of potato.Other management measures were the same for all experimental treatments, including two turns of inter-till hilling, weeding, and pesticide spraying under the three irrigation modes.

Collection and determination of N 2 O in soil
Three fixed sampling points were set within each replicate sub-plot of each study plot.Atmospheric air samples were collected in an open-bottomed cylindrical chamber (figure 3).While taking gas samples, the chamber was placed over the vegetation with the rim of the chamber fitted into the groove of the pot.The chamber was placed on the ground when samples were taken.The chamber measured 0.5 m × 0.5 m × 0.5 m.Gas samples were collected between 07:00 and 10:00 once every 7 days from June to September.Approximately 100 ml of gas was drawn through a 100-mL injector connected to three sampling ports that passed through the chamber.The sampling time was 20 min per chamber.Samples were taken over 0, 5, 10, 15, and 20 min, with 5 samples per chamber and 3 replicates per sampling.The collected gas samples, in cap-lock syringes, were taken back to the laboratory and analyzed using gas chromatograph (Agilent 6820D, Agilent Technologies, Santa Clara, CA, USA).A linear regression was performed by comparing the slope of N 2 O mixing ratio change in the five samples, taken at 0, 5, 10, 15, or 20 min.The soil N 2 O emissions rate was estimated based on this regression.The N 2 O emissions flux per unit area was calculated from the atmospheric pressure, temperature, universal gas constant, the effective height of the sample chamber, and N 2 O molecular weight (Yang et al 2018).

Calculation of N 2 O emission
N 2 O emission was calculated as follows: H is the height of the static dark chamber in cm; Mc is the molar mass of GHG in g mol -1 ; V 0 is the molar volume of N 2 O in the standard state in L; P 0 and T 0 are the atmospheric pressure and temperature in the standard state in Pa and °C, respectively; P and T are the actual atmospheric pressure and temperature at the sampling site in Pa and °C, respectively; dc/dt is the slope of the N 2 O gas content with time during sampling, with c in ppm and t in h.

Collection and measurement of soil
Samples were obtained from 10 sampling sites from each experiment site chosen using the 'S' shaped sampling method (Yang et al 2018), evenly mixed, divided into two portions, and placed into sealed bags separately.One portion was placed into a 4 °C refrigerator for the determination of soil organic carbon, total nitrogen (TN), NH 4 + -N, and NO 3 − -N (Yu et al 2022).Soil temperature was determined using a thermometer; gravimetric soil water content was determined via weighing; volumetric soil water content was determined via Time-Domain Reflectometry (TDR); soil organic carbon (SOC) was measured via the potassium dichromate volumetric method; soil TN was determined via the concentrated sulfuric acid digestion-semi-micro Kjeldahl method; soil pH was measured using a potentiometer; electrical conductivity was determined via the composite electrode method; soil density (ρb) was measured via the ring method, and soil texture was analyzed using a hydrometer.

Meteorological observation
Meteorological observation of the experimental plots was carried out using an automatic weather station installed at the test site, which automatically recorded the local meteorological conditions, including solar radiation, precipitation, wind speed, air temperature, and humidity.Rain gauges were installed near the weather station to observe rainfall, while evaporating dishes were used to measure evaporation.

Data processing and statistical analysis
Excel 2013 was used for classification, recording, processing, and linear regression of the experimental data.
One-way analysis of variance (ANOVA) used for significance testing of sample mean differences, and was performed using SPSS 22.0.Multiple comparison analysis was performed using Duncan's method.Plots were prepared using SigmaPlot 12.5 and Origin Pro 2017.

N 2 O emission factors under various fertilizer and irrigation modes
N 2 O emission factors (EF-N 2 O) of drip fertigation soil was 0.09%-0.15%,sprinkler fertigation was 0.15%-0.20%,and furrow irrigation was 0.32%-0.76%(table 2).EF-N 2 O of drip fertigation was 72%-81% lower on average compared with that of furrow irrigation, and the EF-N 2 O of sprinkler fertigation was 53%-74% lower than that of furrow irrigation.Therefore, compared with the furrow irrigation, drip and sprinkler fertigation can significantly reduce EF-N 2 O.

N 2 O emission intensity of alkaline soils under various fertilizer and irrigation modes
Emission intensity (EI-N 2 O) refers to the annual N 2 O-N emission of per ton of harvested product.Compared with furrow irrigation, EI-N 2 O of drip and sprinkler fertigation treatment was significantly reduced (table 2).The potato had the highest yield of drip and sprinkler irrigation, and EI-N 2 O was the lowest.From 2015 to 2017, EI-N 2 O of drip fertigation soil was 0.09, 0.17, and 0.34 kg N t −1 year −1 , and sprinkler fertigation soil was 0.14, 0.37, and 0.64 kg N t −1 year −1 , respectively, while EI-N 2 O of furrow irrigation soil was 0.31, 1.18, and 1.24 kg N t −1 year −1, respectively.Compared with furrow irrigation, the drip and sprinkler fertigation can reduce EI-N 2 O and had an obvious effect of N 2 O reduction.

Effects of physical and chemical properties of alkaline soil on N 2 O emissions
For the entire crop growing season, the correlation analysis between accumulative N 2 O emissions and the corresponding seasonal average moisture and temperature showed that accumulative N 2 O emissions had a linear and significantly positive correlation with temperature and moisture of soil under different fertilization and irrigation modes (figure 5).The pH of alkaline soil was 8.3 under furrow irrigation, 7.6 under sprinkler fertigation, and 7.3 under drip fertigation.There was a non-linear relationship between pH with soil N 2 O emissions.However, during the crop growing season, the correlation analysis between accumulative N 2 O emissions and the corresponding seasonal average NH 4 + -N or NO 3 − -N showed that there was no correlation between NH 4 + -N or NO 3 − -N and N 2 O emissions in the soils under different fertilization and irrigation modes.

Potato yield under different fertilizer and irrigation modes
Potato yield was determined in the mature season.Potato tubers of 10 m 2 were randomly selected and weighed to calculate the yield per hectare (ha) from each experimental plot (table 2).Among the yields of potato under different fertigation and irrigation methods, that under drip fertigation was the highest, while under the furrow irrigation was the lowest.The yield of potato between sprinkler fertigation or drip fertigation and furrow irrigation was significantly different (p < 0.05).temporal N 2 O emissions (Sánchez-Martín et al 2008).In this study, the drip and sprinkler fertigation mode used a tensiometer to control the irrigation.In sprinkler and drip fertigation treatment, when the soil matrix potential reaches −20.0 kPa in sprinkler fertigation or −25.0 kPa in drip fertigation treatment at the soil depth of 20 cm, the fertigation was initiated (Kang et al 2004, Wang et al 2007).When the water supply of every irrigation is 10 mm under sprinkler fertigation or 5 mm under drip fertigation, fertigation will stop.With less irrigation amount per time, the soil of potato root layer is loose under sprinkler fertigation and drip fertigation.Drip and sprinkler fertigation is conducive to regulating soil water content and ensuring that soil moisture is maintained at the most appropriate level for crop fertilizer requirements.Compared with drip and sprinkler fertigation, furrow irrigation with massive and rapid flooding results in soil compaction and weakened ventilation.The physical and chemical properties of drip, sprinkler, and traditional furrow irrigations soil have changed (Yang et al 2020).In this study, comparing between drip or sprinkler fertigation and furrow irrigation, soil bulk density was reduced, and permeability was good under drip and sprinkler fertigation (table 3).From 2015 to 2017, the soil bulk density of sprinkler fertigation was 1.17-1.28g cm −3 , drip fertigation was 1.18-1.23 g cm −3 , while traditional furrow irrigation was 1.29-1.61g cm −3 .There was no significant difference in soil bulk density between drip and sprinkler fertigation (p > 0.05).Soil porosity was 46.28%-50.42%under furrow irrigation,

Figure 3 .
Figure 3.A device for collecting nitrous oxide in situ.

3. 1 .
Difference of N 2 O emission fluxes in alkaline soil under various fertilization and irrigation modes During the crop growing season, with the progress of potato growth, the N 2 O emission fluxes exhibited noticeable seasonal variations in the fields under different fertilization and irrigation modes and in their control treatments (figure 4).The soil N 2 O emission flux of potato fields under drip, sprinkler fertigation, traditional furrow irrigation mode showed a similar change trend.During the 2015-2017 crop growth season, the N 2 O emissions peaked in July-August.From 2015 to 2017, the peak N 2 O emission flux of drip fertigation soil (NF-DI) was 50.9-173.9μg m −2 h−1 , sprinkler fertigation soil (NF-SI) was 98.0-129.7 μg m −2 h−1 , and traditional furrow irrigation (NF-FI) was 192.4-744.2μg m −2 h −1

Figure 4 .
Figure 4. (a) N 2 O emission fluxes and the soil moisture or soil temperature in alkaline fertilited soil under conventional furrow irrigation, sprinkler fertigation, and drip fertigation in 2017.The detailed results in 2015 and 2016 were presented as a supplementary material.Note: Vertical bars indicate standard error.The y-axes in graphs are on different scales.(b) N 2 O emission fluxes and the soil moisture or soil temperature in alkaline controlled soil under conventional furrow irrigation, sprinkler fertigation, and drip fertigation in 2017.The detailed results in 2015 and 2016 were presented as a supplementary material.Note: Vertical bars indicate standard error.The y-axes in graphs are on different scales.
Effect of different fertilization and irrigation modes on N 2 O emissions in the alkaline soil Fertilization and irrigation mode affected N 2 O emission of alkaline soil.Compared with the furrow irrigation, sprinkler and drip fertigation significantly reduced the N 2 O emission (figure4).In 2015-2017, the accumulative N 2 O emissions in furrow irrigation mode was 173.01, 373.03, and 425.12 mg m −2 , and were 1.89, 2.48, and 1.68 times those of sprinkler fertigation, respectively, and 2.45, 2.89, and 2.01 times those of drip fertigation.Soil moisture in the root area of drip and sprinkler fertigation crops was different from furrow irrigation soil, forming obvious drying and wet areas (Yang et al 2020).Different irrigation water infiltration and redistribution lead to differences in water distribution in time and soil profiles, which has an important impact on spatial and

Figure 5 .
Figure 5. Correlation analysis between soil moisture or soil temperature and accumulative emission of N 2 O.

Fertilization
and irrigation practices significantly affect N 2 O emissions in the alkaline soil.N 2 O emission fluxes exhibited significant seasonal variations under various fertilization and irrigation modes, with uniformly emissions peaking in July-August.Drip and sprinkler fertigation modes decreased the accumulative emission, EF, EI of N 2 O, and significantly increased potato yield, compared with the traditional furrow irrigation.The main factors driving the differences in N 2 O emissions between different fertilization and irrigation production methods are soil moisture content and soil temperature.N 2 O emission rate was high under high moisture and temperature of soil.Drip fertigation and sprinkler fertigation method significantly increased potato yield and reduced N 2 O emissions, compared with furrow irrigation.

Table 1 .
Physical and chemical properties for potato fields in the study area.

Table 2 .
(Kang et al 2012)2014)06)to, accumulative soil N 2 O emissions, soil N 2 O emission factor (EF), and soil N 2 O emission intensity (EI) from six treatment (NF-FI, NF-SI, NF-DI, C-FI, C-SI, and C-DI) in 2015, 2016, and 2017.Annual N 2 O-N emission per ton of harvested product.For each of the six treatments, means followed by a different letter are significantly different at p < 0.05.The same letters within same column denote no significant difference among treatments (p > 0.05).51.75%-52.58%undersprinklerfertigation,and50.85%-57.81%underdripfertigation.The production mode of sprinkler fertigation and drip fertigation increased the soil porosity and improved soil permeability compared with furrow irrigation.High porosity in soil is conducive to nitrification and reduces N 2 O emissions (Yang et al 2019).Under drip fertigation conditions, due to limited water supply, and good ventilation in the alkaline soil, the N 2 O occurrence process of soil denitrification process would be limited, while N 2 O emission was reduced., and the EF of N 2 O emissions in the soil is 0.51%.Compared with the north China farmland soil, EF of N 2 O emissions in our study under furrow irrigation increased by 21.57%, drip fertigation decreased by 62.75%, and sprinkler fertigation decreased by 70.59%.In our study, the EF of N 2 O emissions in alkaline soil was significantly lower than that of IPCC(Eggleston and IPCC 2006), which was 1.0% in the acidic and nearly neutral soil (soil pH = 6.76).The EF of N 2 O emissions under furrow irrigation was 38.0% lower, 81.0% lower under drip fertigation, and 85.0% lower under sprinkler fertigation than that of IPCC(Eggleston and IPCC 2006).Compared with non alkaline soils, soil alkalinity strongly inhibits N 2 O reductase, leading to an increase in N 2 O emissions from alkaline soils(Reddy and Crohn 2014).Our study used drip irrigation and sprinkler irrigation to maintain soil matrix potential at −15.0 to −10.0 kPa.Alkali in the soil was effectively leached, and there was no problem of alkali accumulation, reducing soil pH(Kang et al 2012).Our study suggests that application of large-area drip fertigation and sprinkler fertigation can significantly reduce the pH of alkaline soil and the N 2 O emissions.
a Emission factor of N 2 O. b

Table 3 .
Physical and chemical properties in 0-30 cm soil under the different modes of production with irrigation systems in 2015, 2016 and 2017.+ -N, Bulk density and porosity of 0-30 cm are the means values at the end of the growing season.For each treatment factor, means within a column followed by a different letter are significantly different at p < 0.05. 10 Environ.Res.Commun.6 (2024) 025017 Y Wenzhu et al Singh B P, Hatton B J, Singh B, Cowie A L and Kathuria A 2010 Influence of biochars on nitrous oxide emission and nitrogen leaching from two contrasting soils J. Environ.Qual.39 1224-35 Taryn L K, Emma C S and Johan S 2013 Reduced nitrous oxide emissions and increased yields in California tomato cropping systems under drip irrigation and fertigation Agr.Ecosyst.Environ.170 16-27 United Nations Environment Programme (UNEP) 2013 Drawing down N 2 O to Protect Climate and the Ozone Layer: A UNEP Synthesis Report (Kenya, Nairobi) pp 1-57 Wang F X, Kang Y H, Liu S P and Hou X Y 2007 Effects of soil matric potential on potato growth under drip irrigation in the north china plain Agr.Water Manage.88 34-42 Yang W Z, Jiao Y, Yang M D and Wen H Y 2018 Methane uptake by saline-alkaline soils with varying electrical conductivity in the Hetao Irrigation District of Inner Mongolia, China Nutr.Cycl.Agroecosys.112 265-76 Yang W Z, Jiao Y, Yang M D, Wen H Y, Gu P, Yang J, Liu L J and Yu J X 2020 Minimizing soil nitrogen leaching by changing furrow irrigation into sprinkler fertigation in potato fields in the northwestern china plain Water 12 1-15 Yang W Z, Kang Y H, Feng Z W, Gu P, Wen H Y and Liu L J 2019 Potential for nitrous oxide emission mitigation from sprinkling irrigation applications of chemical fertilizer compared to furrow irrigation in arid region agriculture Appl.Ecol.Env.Res. 17 10963-76 Yu Y Z, Jiao Y, Yang W Z, Song C N, Zhang J and Liu Y B 2022 Mechanisms underlying nitrous oxide emissions and nitrogen leaching from potato fields under drip irrigation and furrow irrigation Agr.Water Manage.260 107270