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ISSN : 2287-5824(Print)
ISSN : 2287-5832(Online)
Journal of The Korean Society of Grassland and Forage Science Vol.40 No.4 pp.274-278

The Effects of Zeolite on Ammonia, Nitrous Oxide Emission, and Forage Yield from Pig Slurry Applied to the Forage Corn Cropping

Ah-Reum Choi1, Sang-Hyun Park2, Tae-Hwan Kim2*
1Department of Animal Science, College of Agriculture & Life Science, Chonnam National University, Gwangju, 61186 Korea
2Institute of Environmentally-friendly Agriculture, Chonnam National University, Gwangju 61186 Korea
*Corresponding author: Tae-Hwan Kim, Department of Animal Science, College of Agriculture & Life Science, Chonnam National University,
Gwangju 61186, Korea, Tel: +82-62-530-2126, Fax: +82-62-530-2129, E-mail:
October 8, 2020 November 11, 2020 November 14, 2020


Pig slurry (PS) is the most applicable recycling option as an alternative organic fertilizer. The application of pig slurry has the risk of air pollution via atmospheric ammonia (NH3) and nitrous oxide (N2O) emission. The zeolite has a porous structure that can accommodate a wide variety of cations, thus utilizing for the potential additive of deodorization and gas adsorption. This study aimed to investigate the possible roles of zeolite in mitigating NH3 and N2O emission from the pig slurry applied to the maize cropping. The experiment was composed of three treatments: 1) non-N fertilized control, 2) pig slurry (PS) and 3) pig slurry mixed with natural zeolite (PZ). Both of NH3 and N2O emission from applied pig slurry highly increased by more than 3-fold compared to non-N fertilized control. The NH3 emission from the pig slurry was dominant during early 14 days after application and 20.1% of reduction by zeolite application was estimated in this period. Total NH3 emission through whole period of measurement was 0.31, 1.33, and 1.14 kg ha-1. Nitrous oxide emission in the plot applied with pig slurry was also reduced by zeolite treatment by 16.3%. Significant increases in forage and ear yield, as well as nutrient values were obtained by pig slurry application, while no significant effects of zeolite were observed. These results indicate that the application of zeolite and pig slurry efficiently reduces the emission of ammonia and nitrous oxide without negative effects on maize crop production.


    National Research Foundation of Korea(NRF)


    Animal manures, which is emitted over 48 million tons per year in Korea, is an over-burden to environment. Besides, they are an important organic resource as eco-friendly organic fertilizer containing nitrogen (N), phosphorus (P), potassium (K) and other nutrients. Among these, pig slurry utilization as an alternative organic fertilizer has become the most viable recycling option to improve crop yield and soil quality (Ndayegamiye and Côté, 1989; Bernal et al., 1992)

    However, the application of pig slurry has the risk of the ecological pollution by emitting the greenhouse gas such as nitrous oxide (N2O) and methane (CH4), and nitrogen loss as ammonia (NH3) and nitrate (NO3-) leaching. Of these, NH3 volatilization contributing to an offensive odor, eutrophication and acidification of ecosystems. It results in nitrogen loss during manure composting and when applied onto field. When NH3 is released into the air, it can rapidly react with acidic compounds, such as nitric acid and sulfuric acid, to form very fine particulate matter has a diameter of <2.5 microns, which is health concern affecting respiratory function (Bittman and Mikkelsen, 2009). Furthermore, NH3 deposition may induce the formation of N2O in the atmosphere (Moiser, 2001). The N2O is a trace gas that cause global warming and reduces O3 in stratosphere (Rodhe, 1990), accounting for 5% of the total greenhouse effect (Houghton et al., 1990). It has 290 - 310 times higher global warming potential than carbon dioxide (Keith et al., 2005).

    Many strategies have been studied to reduce the NH3 and N2O. The acidification of manure has been widely studied and recently reviewed (Birkmose et al., 2013;Fanguerio et al., 2015;Park et al., 2018). Nitric acid or sulfuric acid can be used to drop the manure pH to 6.5 and then reduced NH3 emission by up to 75% (Rotz, 2004). Also, the urease and/or nitrification inhibitors delay the rapid hydrolysis of urea and NO3- production by depressing the activity of bacteria. The use of urease and/or nitrification inhibitors increased N use efficiency by reducing N loss via gas emission and leaching (Di and Cameron, 2002;Park et al., 2016). The zeolite has a porous structure that can accommodate a variety of cations, such as sodium (Na+), potassium (K+), calcium (Ca2+), magnesium (Mg2+) and others, and widely utilized as water moderator, deodorization, additives to animal feed, and gas adsorption. During manure composting process, addition of artificial zeolite caused to decrease the NH3 emission. Kithome et al. (1999) reported that the zeolite having a high affinity for NH4+ ions reduce NH3 volatilization via decreasing concentration of free NH4+ ions.

    Thus, the present study aimed to investigate the effect of natural zeolite and pig slurry application in mitigating of ammonia (NH3) and nitrous oxide (N2O) emission from pig slurry applied to maize.


    1. Experiment design

    The present study was conducted in Chonnam National University, located in Gwangju, South Korea. The experiment was allocated with three treatments; control (non-N fertilizer, only water), pig slurry (PS) and pig slurry mixed with zeolite (PZ). Natural zeolite was mixed with pig slurry and applied at a rate 5% of the pig slurry (w/w). The pig slurry was obtained from the ECOBIO farming/agricultural association corporation (Namwon, Korea). The nitrogen property of pig slurry was shown in Table 1. The natural zeolite is commercially supplied by Han- Doo Corporation (Gampo, Korea). The chemical components of the natural zeolite were shown in Table 2.

    2. Plant growth and harvest

    Forage corn (Zea mays, C.V. Pioneer-35P95) was planted at 25th May in randomized complete block design with three replications; each treatment block measured 2 m × 10 m. The maize seeding was performed in lines keeping maize to maize distance 20 cm of seed spacing and 65 cm of row spacing. The plot of pig slurry (without or with zeolite) treatments was evenly applied with a rate of 200 kg N ha-1 (340 L), before 2 weeks of seedling. Harvesting of maize was conducted 103 days after seeding (3rd September).

    3. Gas emission sampling

    To collect NH3 emission, modified acid trap system method described by Ndegwa et al. (2009). Each chamber (20 cm diameter × 30 cm depth) was connected to NH3-N trapping bottles containing 20 ml of 50 mM sulfuric acid and a vacuum system to pull air through the chambers. The ammonia traps flow a rate of approximately 1 L per minute. The N2O was collected from closed chamber using a syringe, then stored in 10 ml vacutainer tube prior to analysis. The gas sampling was done in the morning 09:00 in order to minimize diurnal variation in flux patterns. The gas emission was determined daily for the first 14 days, then at 7 d intervals afterward.

    4. Chemical analysis

    The concentration of NH3 in the acid trap solution (e.g. ammonium sulfate) was colorimetrically determined with Nessler’s ammonium color reagent after microdiffusion in a conway dish (Kim and Kim, 1996) and expressed as the content of NH3-N emitted per hectare. N2O concentration were analyzed by a gas chromatograph (7890A, Agilent technologies, USA) equipped with a thermal conductivity detector (TCD). Separation was achieved with a HP-Plot 5A column (30 m × 0.53 mm × 25 μm) using helium as the carrier gas, at a flow rate of 2 mL min-1. The N2O fluxes were calculated as described by Guo et al. (2012). Cumulative NH3 and N2O emissions over the entire experimental period were calculated by summing all daily measurements and period estimations (number of day × mean flux between sampling dates).

    N property of pig slurry was determined according to the method of Bremner (1996). Total nitrogen was determined by digestion using the Kjeldahl procedure. Inorganic N was extracted with 2 M KCl and the NH4+-N was determined by distillation in an alkaline medium (MgO). The same procedure was used for NO3--N after reduction with Devarda’s alloy (Lu, 2000).

    The nutrient value of maize harvested at cutting time was determined with the subsamples collected for dry matter (DM) yield. The maize samples were analyzed for crude protein (CP) according to the methods of the Association of Official Analytical Chemists (AOAC, 1990). The neutral detergent fiber (NDF) and acid detergent fiber (ADF) were determined by the method of Van Soest et al. (1991) using a Dosi-Fiber extractor (Dosi-fiber, Barcelona). TDN was estimated by the ADF-based equation: TDN = 88.9 – (0.779 × % ADF).

    5. Statistical analysis

    Duncan’s multiple range tests were used to compare the means of three replications between treatments. Unless otherwise stated, conclusions are based on differences between the means, with the significant level at p 0.05 by using SAS 9.1.3 software.


    The application of pig slurry into the grassland and crop is a meaningful practice to recycle organic resources, however it accompanies with emission of hazardous gas and nitrogen loss. In the present study, we attempt to estimate the effectiveness of zeolite in mitigating NH3 and N2O emission. The total NH3 emission throughout the experimental period in the plots applied with pig slurry was 5.32-fold higher than that of non-N fertilized control (Fig. 1). In the plots applied with pig slurry, higher emission which includes the highest emission within 3 days occurred dominantly up to 14 days after application of pig slurry (Fig. 1). When pig slurry is applied to maize field, a large portion of NH3 volatilization is occurred at the early period (Rochette et al., 2001;Sommer and Hutching, 2001). Li and Li (2014) reported that most of NH3 emitted within 7 days in laboratory aerobic incubation from chicken, pig and cattle manure. In this study, total NH3 emission through whole period of measurement was 0.31, 1.33, and 1.14 kg ha-1, respectively, in the non-N fertilized control, pig slurry alone and treated pig slurry with zeolite (inlet of Fig. 1). This results reflected the mitigation of NH3 emission by zeolite application during the early 14 days (-20.1%) when a larger proportion NH3 emission occurred. Similarly, several studies have reported that the reduction of NH3 emission was decreased by adsorption in zeolite (He at al., 2002;Park et al., 2014;Kim, 2016). Lee at al. (2000) also reported that the NH3 emission in cattle manure composting was decreased by 54~70% by application of artificial zeolite, in addition the more zeolite applied, the less ammonia was emitted. These alleviatory effects of zeolite application on NH3 emission would be possibly associated with the property of zeolites which have a porous structure that can accommodate a wide variety of cations, such as Na+, K+, Ca2+, Mg2+ and others and these positive ions are rather loosely held and can readily be exchanged for others as known as "molecular sieves" (Pabalan and Bertetti, 2001).

    The N2O emission occurs mainly through both aerobic nitrification, in which NH4+ is oxidized NO2- and further NO3-, and anaerobic microbial denitrification, in which NO3- is reduced to gaseous nitrogen compounds (Gilsanz et al., 2016). Therefore, the factor of determination of N2O emission are the amount of NH4+-N available for nitrification to NO3--N and soluble organic C available for denitrification. In this study, daily N2O emission in both plots of pig slurry treated with or without zeolite was always higher within a range of 2.8 – 7.0 g ha-1, while 1.3 – 2.4 g ha-1 in the non-N fertilized control (Fig. 2). As a time-course kinetics, daily N2O emission was the highest at 21 days after pig slurry treatment and then it slightly decreased (Fig. 2.). This later peak of N2O emission, comparing to that of NH3 pattern, reflected the process of nitrification from to NH4+ to NO3-, which is the initial required substrate for denitrification to produce N2O (Subbarao et al., 2006;Gilsanz et al., 2016). Total N2O emission throughout whole period of measurement 38.8, 94.7, and 82.0 g N ha-1, respectively, in the non-N fertilized control, pig slurry alone and treated pig slurry with zeolite (inlet of Fig. 2). This result indicated that zeolite reduced the N2O emission by 13.4% from pig slurry applied to forage corn cultivation. Ates et al. (2011) reported that natural zeolite and iron exchanged natural zeolites decreased the nitrous oxide decomposition activity.

    Forage yield and nutrient composition as affected by pig slurry application with/without zeolite are summarized at Table. 3. Forage DM yield was significantly higher in both plots applied pig slurry, with an increase of 64% in the Zeolite treated and 57% in pig slurry alone compared to non-N fertilized control. Pig slurry application also increased ear yield by 35% on average. These results were consistent with the results of Cairo et al. (2017) who reported a positive effect of zeolite and organic fertilizer on sugarcane yield. In addition, CP and TDN content was also higher in both plots applied with pig slurry than non-N fertilized control, whereas NDF and ADF were not significantly affected (Table 3). However, the effect of zeolite overall on the variables of yield and nutrient composition was statistically poor or not significant.

    The results obtained indicated that a proper utilization of zeolite in the pig slurry application for the forage production may represent an effective means to mitigate the emission of ammonia and nitrous oxide without disturbing forage corn growth and yield.


    This study was financially supported by the National Research Foundation of South Korea (NRF-2019R1A6A3A01092319).



    Changes in daily emission of ammonia (NH3) and total cumulative NH3 emission throughout the whole period of measurement (inlet of Fig. 1) in the plot of non-N fertilized control (C), only pig slurry (PS), and pig slurry mixed with zeolite (PZ). Data are mean ± SE (n=3). Different letters indicate significantly different at p <0.05 according to the Duncan’s multiple range test.


    Changes in daily emission of nitrous oxide (N2O) and total cumulative N2O emission throughout the whole period of measurement (inlet of Fig. 2) in the plot of non-N fertilized control (C), only pig slurry (PS), and pig slurry mixed with zeolite (PZ). Data are mean ± SE (n=3). Different letters indicate significantly different at p <0.05 according to the Duncan’s multiple range test.


    Nitrogen compounds of the pig slurry

    Chemical analysis of the natural zeolite

    The effects of pig slurry applied without or with zeolite on herbage, ear yield, neutral detergent fiber (NDF), acid detergent fiber (ADF), crude protein (CP) and total digestible nutrients (TDN)


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