Impact of different nitrogen source on the compost quality and greenhouse gas emissions during composting of garden waste

Accepted Manuscript Title: Impact of Different Nitrogen Source on the Compost Quality and Greenhouse Gas Emissions during Composting of Garden Waste Authors: Mengli Chen, Yimei Huang, Huijuan Liu, Shuwen Xie, Fakher Abbas PII: DOI: Reference:

S0957-5820(18)31339-9 https://doi.org/10.1016/j.psep.2019.03.006 PSEP 1689

To appear in:

Process Safety and Environment Protection

Received date: Revised date: Accepted date:

6 December 2018 26 February 2019 5 March 2019

Please cite this article as: Chen M, Huang Y, Liu H, Xie S, Abbas F, Impact of Different Nitrogen Source on the Compost Quality and Greenhouse Gas Emissions during Composting of Garden Waste, Process Safety and Environmental Protection (2019), https://doi.org/10.1016/j.psep.2019.03.006 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Impact of Different Nitrogen Source on the Compost Quality and Greenhouse Gas Emissions during Composting of Garden Waste

Mengli Chena, Yimei Huanga*, Huijuan Liua, Shuwen Xiea, Fakher Abbasb a

SC R

IP T

Key Laboratory of Plant Nutrition and The Agri-environment in Northwest China, Ministry of Agriculture, College of Natural Resources and Environment, Northwest A & F University, 712100, Shaanxi, China b State Key Laboratory of Soil Erosion and Dry Land Farming on Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, 712100, Shaanxi, China

U

Abstract

N

To overcome the problems of difficult degradation of garden waste and long

A

composting period, some conditioner is often added in the composting process.

M

However, different conditioner has different effects on the material transformation and

ED

composting quality in composting. In order to explore the influence of different nitrogen source material on the greenhouse gas and compost quality in the composting

PT

of garden waste, taking garden waste as compost material and adding soil as control,

CC E

we respectively added chicken manure, pig manure and sheep manure as nitrogen source conditioner, and conducted a 48-day composting experiment in a forced 45-l ventilation compost reactor. The results showed that composting with livestock manure

A

reduced nitrogen loss and facilitated organic matter humification. Specially, compared to the control treatment of garden waste add soil (CK), the addition of chicken manure promoted the conversion of total organic carbon (TOC) to humic substances (HS), as well as reduced nitrous oxide (N2O) emissions during garden waste composting. Based

on a redundancy analysis, NH4+-N, organic nitrogen (OrgN), total nitrogen (TN) and HS directly affected CH4 emissions, while N2O emissions were directly influenced by dissolved organic carbon (DOC), TOC and NO3--N during garden waste composting. Based on a factor analysis, the compost quality was chicken manure(CM) > sheep

IP T

manure(SM) > pig manure(PM). These results suggested that garden waste composting with the addition of chicken manure improved the effectiveness compost product,

SC R

produced a mature and zero-side effect compost and reduced nitrogen losses.

U

Keywords: garden waste; livestock manure; greenhouse gas; composting quality;

A

N

redundancy analysis;

M

1. Introduction

With the rapid development of urban green land in China, urban garden waste,

ED

such as, park, garden litter and trimmings, have dramatically increased. For example,

PT

from 2010 to 2016, the green land area in Shaanxi province increased from 23,426 hectares to 58,679 hectares. Also, a large amount of garden waste brings many

CC E

environmental problems. Traditional garden waste disposal methods have primarily consisted of incineration and landfills, which normally cause environmental problems

A

such as air pollution, land occupation and water contamination (Gabhane et al., 2012). Composting is a method for recycling organic materials and nutrients that organic matter in compost material convert into stable humus by microorganisms (Sánchez monedero et al., 2010). Mature compost can be used as soil conditioner or organic fertilizer (Rawoteea et al., 2017). However, since the composition and physicochemical

properties of garden waste is always changing with different times or geographical locations (Table.1). Garden waste cannot be composted completely and generate low quality products because their high C/N ratio (Table.1) and high content of lignocellulose make them resistant to microbial attack (Ryckeboer et al., 2003, Zhang

IP T

& Sun, 2016a). Therefore, garden waste co-compost with additives can not only shorten compost period but improve the quality of compost product (Karak & Bhattacharyya,

SC R

2010).

Composting has major benefits, but there are many drawbacks. A major challenge

U

with garden waste composting is the production of gaseous emissions. Previous studies

N

have shown that methane (CH4) and nitrous oxide (N2O) emissions from composting

A

are of significant concern due to their high global warming potential. Studies based on

M

100-year measurements have estimated that the global warming potential of CH4 and

ED

N2O is 25 and 298 times, respectively, higher than that of carbon dioxide (CO2) (Solomon, 2007). Inorganic nitrogen concentration, carbon quality, and temperature are

PT

some of the key factors that influence greenhouse gas (GHG) emissions during

CC E

composting (Cayuela et al., 2012, Chowdhury et al., 2014). CH4 is primarily produced by high amount of labile carbon compounds in the composting matrix. The optimum growth temperature of nitrifying and denitrifying bacteria is less

A

than 45°C (Neergaard, 2015). N2O is emitted during the mesophilic phase of composting. Therefore, addition of livestock manure might influence GHG emissions during garden waste composting. For example, the addition of livestock manure might increase N2O emissions by increasing the bioavailability of mineral nitrogen for

nitrification and denitrification (Nigussie et al., 2017). Additionally, the addition of different types of livestock manure might change the concentration of labile carbon compounds and the porosity of the materials resulting in reduced CH4 emissions. Hence, the addition of livestock manure to the composting of garden waste not only directly

IP T

impacts GHG emissions due to the activity of microorganisms, but also indirectly influences GHG emissions due to carbon and nitrogen conversion. However, it is still

SC R

not clear if the addition livestock manure does or does not affect GHG emissions during garden waste composting.

U

In this study, livestock manure is used as an additive for garden waste composting.

N

The specific objectives of the study are to determine effects of different livestock

the final product.

ED

2. Materials and Methods

M

A

manures on (i) carbon and nitrogen conversion, (ii) GHG emissions, and (iii) quality of

2.1 Materials and the Composter

PT

Soil and garden waste (mainly including fallen leaves) were collected from the

CC E

Northwest Agriculture and Forestry University (Yangling District, Shaanxi Province, China). Livestock manure was collected from the Third Livestock Husbandry Station of Northwest A&F University. The primary physicochemical properties of these raw

A

composting materials (manure and garden waste) are listed in Table.2. Livestock manure was used to adjust the moisture content (~50%) and used as a nitrogen source material to maintain a C/N ratio of approximately 30. Four 45 L reactors (0.30 m in height, 0.50 m in diameter), which being covered with 0.08 m plastic foam for retaining

the heat generated, were used for garden waste aerobic composting. The reactor mainly made up with a sealed reaction chamber, sieve tray, holder, air pump and temperature detector (Jiang et al., 2015). Air was pumped from the bottom into the reactor with a constant air flow of approximately 0.17 and 0.04 m3·m-3·min-1 during the thermophilic

IP T

and mesophilic phase, respectively. 2.2 Experimental Design

SC R

Four treatments were used that included garden waste + pig manure (PM), garden

waste + chicken manure (CM), garden waste + sheep manure (SM), garden waste + soil

U

(set as the control experiment, CK). The pig, chicken and sheep manures are different

N

nitrogen sources, and contain many microorganisms that can promote the degradation

A

of organic matter. Soil and garden waste compost can simulate the decomposition of

M

garden waste under natural conditions, which is different from the rest of the treatments.

ED

The specific programs are listed in Table.3. 2.3 Compost Sampling

PT

Temperatures were monitored twice daily at 9:00 and 18:00. Greenhouse gases

CC E

(CH4 and N2O) were collected on the 6th, 9th, 13th, 18th, 23rd, 29th, 35th, and 42nd days using a syringe sampling method. During the 48 days composting process, after thoroughly mixing the raw material compost samples for each treatment, samples were

A

collected on the 1st, 3rd, 9th, 13th, 18th, 23rd, 29th, 35th, 42nd and 48th days. Collected samples were divided into two portions. One portion was stored at 4°C till analysis, while the other portion was air-dried, ground to be able to pass through a 1 mm sieve and stored in a desiccator.

2.4 Analytical Methods Methane (CH4) and nitrous oxide (N2O) levels were determined by gas chromatograph (7890B, Agilent corporation, American). Other chemical parameters, such as pH, electrical conductivity (EC), ammonium nitrogen (NH4+-N), nitrate

IP T

nitrogen (NO3--N), dissolved organic carbon (DOC), and the germination index (GI) were analyzed using standard laboratory analysis procedures (GF et al., 2004, Wang et

SC R

al., 2016). pH and EC were measured using a Delta 320 pH meter (Mettler Toledo Instruments (Shanghai) Co., Ltd.) and S30 EC meter (Mettler Toledo Instruments

U

(Shanghai) Co., Ltd.), respectively. GI was measured and calculated according to

N

(Zucconi, 1981). The number of germinating seeds and their root lengths were

A

measured. Distilled water was used as a reference. GI was used to assess phytotoxicity

𝑆𝑒𝑒𝑑𝑠 𝑔𝑒𝑟𝑚𝑖𝑛𝑎𝑡𝑖𝑜𝑛 𝑖𝑛 𝑡𝑟𝑒𝑎𝑡𝑚𝑒𝑛𝑡 (%) × 𝑅𝑜𝑜𝑡 𝑙𝑒𝑛𝑔𝑡ℎ 𝑖𝑛 𝑡𝑟𝑒𝑎𝑡𝑚𝑒𝑛𝑡 × 100% 𝑆𝑒𝑒𝑑𝑠 𝑔𝑒𝑟𝑚𝑖𝑛𝑎𝑡𝑖𝑜𝑛 𝑖𝑛 𝑐𝑜𝑛𝑡𝑟𝑜𝑙 (%) × 𝑅𝑜𝑜𝑡 𝑙𝑒𝑛𝑔𝑡ℎ 𝑖𝑛 𝑐𝑜𝑛𝑡𝑟𝑜𝑙

(1)

ED

GI(%) =

M

of the compost and calculated using equation (1).

NH4+-N and NO3--N were determined using a segmented flow analyzer

PT

(Technicon Auto-analyzer II System, Germany) after removing extract from the fresh

CC E

samples using KCl (2 mol/L). TN and TOC were determined from air-dried samples using the Kjeldahl and potassium dichromate titrimetric method according to the Chinese national standard (NY 525-2012), respectively. Humic substance content was

A

determined using the potassium dichromate volumetric method (Huang et al., 2006, Zhou et al., 2014). The accumulated temperature was calculated according to the formula (2): T = ∑(𝑇𝑖 − 15) × ∆𝑡 (2) , where T (°C·h) is the accumulated temperature, Ti (°C) is the temperature at the ith hour, 15°C is the biological zero

temperature for composting, and Δt (h) is the duration of Ti (Chen et al., 2002). The degree hour temperature was calculated according to the formula (3): DH = 𝑡

∫0 (𝑇𝑖 − 𝑇0 )𝑑𝑡 (3), where DH (°C·h·d-1) is degree hour temperature, Ti (°C) is the temperature at the ith hour, T0 (°C) is the ambient temperature for composting, and t (h)

IP T

is the composting time (Cáceres et al., 2015, Wojciech et al., 2015). Similarly, initial and final total N mass were used to calculate the N loss during

N Loss(%) =

SC R

the composting process according to the following equation (4): 𝑁𝑖𝑛𝑖𝑡𝑖𝑎𝑙 × 𝑀𝑖𝑛𝑖𝑡𝑖𝑎𝑙 − 𝑁𝑓𝑖𝑛𝑎𝑙 × 𝑀𝑓𝑖𝑛𝑎𝑙 𝑁𝑖𝑛𝑖𝑡𝑖𝑎𝑙 × 𝑀𝑖𝑛𝑖𝑡𝑖𝑎𝑙

(4)

U

where Minitial and Mfinal are the total dry mass (kg) of the compost mixture at the

N

initial and final stages of composting respectively. Ninitial and Nfinal represent the

A

nitrogen concentrations, that were calculated at the initial and final stage of composting

M

(Nigussie et al., 2017). The same principle was used to calculate the rates of change of

ED

NH4+-N, NO3--N, TOC, DOC, and HS during composting. All analyses performed in this study were carried out in triplicate.

PT

2.5 Statistical Analysis

All the figures were drawn using Origin-Pro 2017. The statistical analysis was

CC E

performed using SPSS 20.0 software with one-way ANOVA methods. The correlations between A and B was calculated using SPSS 20.0 software at 0.05 level. A redundancy

A

analysis(RDA) was performed to analyze the relationships between different carbon/nitrogen fractions and the GHGs. RDA were performed using CANOCO 5.0. Factor analysis was performed using R software and a probability defined as least Kaiser-Meyer-Olkin (KMO) greater than 0.7. 3. Results and Discussion

3.1 Variations in Temperature, EC, pH, GI and T Values during Composting The temperatures throughout the composting period are illustrated in Figure.1a. The treatments of PM, CM, SM and CK reached the thermophilic phase (temperature ≥ 50°C) at 32 d, 32 d, 31 d, and 36 d, lasted for 5 d, 5 d, 6 d, and 1 d, respectively. The

IP T

peak temperatures for the treatment of PM, CM, SM and CK were 50°C, 53°C, 56°C, and 50°C, respectively. Lignocellulose is the main component of garden waste. The

SC R

lignin structure is complex and irregular. And the cellulose molecules are embedded

therein to form a natural barrier that hinders the degradation of lignocellulose, thereby

U

limiting the degradation rate of garden waste (Ryckeboer et al., 2003). And compared

N

with the scale of the plant compost, the small volume of the reactor in this experiment

A

results in poor heat preservation. In addition, turnings immediately reduced compost

M

temperatures, but the speed of temperature recovery was linked to the phase of

ED

composting (Marina & Kari, 2011, Cáceres et al., 2015). Therefore, the temperature of composting reached thermophilic phase at the middle-end of the process. Although

PT

composting temperature of thermophilic phase is not too high, the accumulated

CC E

temperature of PM, CM, SM, and CK were 15888°C·h, 19176°C·h, 22152°C·h and 14424°C·h, respectively. The rule of compost stabilization states that, when the accumulated temperature reaches 10000°C·h, the compost has already harmlessness

A

(Chen et al., 2002). Also, degree hour temperature (DH) is the thermal integral of temperature curve which the value is equal to or less than 0 at the end of composting (Cáceres et al., 2015, Neugebauer & Sołowiej, 2017). The DH value in all treatments were equal to or less than 0 after 41 days which means the compost stabilization process

coming to an end (Fig.1b). If pH, EC, GI, and T values (the ratio of NH4+-N to NO3--N) at the final stages of composting were < 9 (Bertoldi et al., 1983), < 4 mS/cm (Garcíagómez et al., 2005), > 80% (Tiquia & Tam, 1998), 0.53 ≃ 0.72 (Bernal et al., 2009), it means that the compost

IP T

maturity and has zero side effect products. The pH, EC, GI, and T values of this study at the final stages of composting were 7.56 ≃ 7.98, 1.42 ≃ 2.41, 89.30 ≃ 126.40, and

SC R

0.51 ≃ 0.57, respectively (Table.4). These parameters satisfied the standard and all composts met the requirements of maturity and harmlessness.

3.2 Changes in NH4+-N, NO3--N and TKN during the Composting Process

N

U

Changes in the NH4+-N content can reflect nitrogen conversion and NH3

A

volatilization during composting (Ren et al., 2010). The NH4+-N content of the four

M

treatments reached their peaks at approximately the 13rd day. The NH4+-N content of the treatment of CM, SM, and CK reduced thereafter, and a high concentration of NH4+-

ED

N in the PM treatments lasted more than two weeks (Fig 2(a)). Similar results were

PT

obtained by Zhang (Zhang & Sun, 2015). The NH4+-N decreasing trend might be due to the ammonia volatilization and the conversion from NH4+-N to NO3--N (Rui Guo,

CC E

2012, Awasthi et al., 2015). Finally, NH4+-N losses reached 15.07%, 2.27%, 51.32%, and 35.34% in the treatment of PM, CM, SM and CK respectively after 48 days of

A

composting (Table.5). Therefore, compared with control, the addition of pig and chicken manure effectively reduced the nitrogen loss caused by ammonia volatilization during garden waste composting. However, the addition of sheep manure could have promoted the volatilization of ammonia during garden waste composting, because, the temperature of SM was significantly higher than that of the other treatments during the

thermophilic period. As shown in Figure 2(b), the NO3--N content in the PM and CM treatments decreased sharply at the beginning of composting. The NO3--N content gradually increased from the beginning of composting in the SM and CK. In the CM and PM

IP T

treatments, the NO3--N content reached minimum values at approximately the 13th and 35th days. Finally, the NO3--N concentration of the PM treatments reduced 19.64%,

SC R

while in CM, SM and CK, the NO3--N content was increased 8.52%, 17.57% and 48.97%, respectively (Table.5). Nitrification will occur when temperature <40 °C and

U

the favorable aeration (Sánchez monedero et al., 2001). Temperature has an inhibitory

N

effect on the activity and growth of the nitrifying bacteria (Tiquia et al., 2002, Santos

A

et al., 2016). Therefore, the PM and CM treatments had the loss or low accumulation

M

of NO3--N.

ED

Figure 2(c) shows the changes in total nitrogen. A typical decrease process is exhibited due to the loss of ammonia, and the lower pH resulted in less mineralization

PT

of organic matter (Wang et al., 2017). When the composting process was finished, the

CC E

total nitrogen losses reached 35.90%, 29.90%, 30.51%, and 55.20% in PM, CM, SM, and CK, respectively. Similar results are found by Arias (Arias et al., 2017). Hence, the addition of livestock manure significantly reduced nitrogen loss in comparison with the

A

control.

3.3 Changes in the TOC, DOC and HS during the Composting Process The TOC content in the four treatments decreased gradually (Fig 2(d)). Compared with control, all treated samples displayed a slight decrease in TOC during the mesophilic phase. This was possibly due to the rapid decomposition of degradable

carbon in livestock manure as well as the production of CO2 by bacterial and fungal metabolism (Cayuela et al., 2012). After 48 days of composting, the TOC retained in the CK was less than 30% and didn’t meet the criteria for a high quality organic compost (NY525, 2012). Therefore, livestock manures were used as a nitrogen source in this

IP T

study, as they are helpful for the production of a high quality organic fertilizer. Because of this, TOC retained in final product of three treatments were more than 30%. The

SC R

remaining treated samples showed a trend in the TOC content ranked as PM>CM>SM. It can be concluded that composting of garden waste by adding pig manure is more

U

conducive to the degradation of organic matter than the addition of chicken and sheep

N

manure. This could be due to the bulk density of PM being higher than CM and SM. A

M

degradable TOC (Chang et al., 2017).

A

study showed that an increase in bulk density positively correlated with a decrease in

ED

The DOC content in all the treatments slightly decreased and were constant at the end of the process(Fig 2(e)), which was consistent with previous studies

(Khan et al.,

PT

2014, Wang et al., 2016). Over the entire composting period, the change in DOC was

CC E

highest in the SM (76.05%) and lowest in the CM (58.75%). The DOC content declined during composting because microorganisms metabolized the available carbon (Paradelo et al., 2013). The decomposition and synthesis of HS in the DOC during

A

composting proceeded simultaneously. Compared to the PM, SM and CK samples, the DOC in the CM sample accumulated at the end of composting. This is why the lowest DOC reduction occurred in the CM. As shown in Figure 2(f), the HS content in the PM, CM, SM and CK slightly

increased during the mesophilic phase and reached their peak at the 18th, 23rd, 23rd, 35th days, respectively. Composting is a process of organic matter stabilization and humification

(Dias et al., 2010). Therefore, the HS content increased during the

mesophilic phase. In fact, HS can be utilized by humus-reducing microorganisms as a

IP T

terminal acceptor, and a reduction in HS can support microbial growth (Zhao et al., 2017). Hence, the HS content in the four treatments were decreased sharply during the

SC R

thermophilic and maturation phases of composting. By the end of composting, the HS

concentration in the PM treatment increased by 3.74%, while it in the PM, SM, and CK

U

decreased to 42.06%, 45.50%, and 50.96%, respectively (Table.6). Compared with the

N

pig and sheep manure, the addition of chicken manure to garden waste composting

A

facilitated the formation of HS, which would increase the molecular weight of

M

humification and production of humic-like substances, thereby increasing compost

ED

maturity and stability (Zhang & Sun, 2016a). 3.4 Emissions of GHGs during the Composting Process

PT

N2O emissions are primarily associated with nitrification and denitrification processes during composting (Sánchez monedero et al., 2010). As shown in Figures

CC E

3(a) and (b), high N2O emissions were observed during the first 29 days of composting in all treatments. This can be attributed to incomplete denitrification processes, which

A

usually novitiate NH4+ into N2O (Awasthi et al., 2016). N2O emissions were detected during the early stages of composting. These fluxes were similar to those recorded during the composting of different agro-industrial by-products, sewage sludge and chicken manure

(Sánchezmonedero et al., 2010, Wang et al., 2017, Chen et al., 2018).

By the end of the composting process, the N2O accumulated emissions in the PM, CM,

SM, and CK samples reached 12.06, 13.06, 15.76 and 15.05 g, respectively. The ranking of N2O accumulated emissions was SM>CK> CM>PM. From this study, it can be seen that when pig manure was added to garden waste compost, this addition effectively reduced the emission of N2O. This is may be due to a low NO3--N quantity

IP T

were insufficient to maintain such a significant N2O emission through denitrification, especially during the thermophilic phase (Awasthi et al., 2017, Zhao et al., 2018).

SC R

Methane(CH4) emissions are an indicator of the production of CO2 and acetic acid

by methanogenic bacteria during composting (Yang et al., 2013, Santos et al., 2016).

U

As shown in Figures 3(c) and (d), the highest CH4 production was noticed in the PM,

N

and CH4 reached a peak value on the 9th day (13.60 g/m3) of composting then gradually

A

decreased. However, small CH4 emission concentrations CM, SM and CK were noticed

M

during composting, especially in the CK, whose CH4 emission concentration remained

ED

below 0.2 g/m3. The accumulated emissions of CH4 in the PM, CM, SM and CK were 122.42, 8.24, 6.12 and 1.82 g at the end of composting, respectively. Similarly, CH4

PT

emission fluxes have been detected during the early stages or the thermophilic phase of

CC E

composting process in livestock manure and in different agro-industrial by-products mixtures in sheep manure (Sánchezmonedero et al., 2010, Chen et al., 2018, Wang et al., 2018). The CH4 accumulated emissions of the PM was higher than other treatments.

A

Because the nitrogen content in PM and CM is than SM and CK (Fig.2c). High nitrogen content can enhance carbon substrate availability for methanogens and increase CH 4 emissions (Lindau et al., 1991, Lu et al., 2000, Schimel, 2000). But NH4+-N content (Fig.2a) and pH (Table.4) in CM is higher than other treatment. High NH4+-N content

and pH can inhibit methanogens activity and reduce CH4 emissions (Hao et al., 2005, Kebreab et al., 2006). Compared with the CK, the livestock manure had a high DOC concentration. Because the high concentration of DOC was decomposed, the oxygen consumption rate was likely lower than the oxygen supply rate. Eventually, DOC is

decreased, resulting in CH4 production (Jiang et al., 2011).

IP T

decomposed into acetic acid by anaerobic. The redox potential of acetic acid was

SC R

3.5 Relationships between Greenhouse Gas, Different Carbon/Nitrogen Forms and Physicochemical Properties during the Composting Process

U

During the composting process, physical and chemical factors influence the

N

emission of greenhouse gases. Redundancy analysis (RDA) was used to examine the

A

relationships between greenhouse gases, different forms of carbon/nitrogen and the

M

physicochemical properties (Fig 4(a) and (b)). Specifically, the first two axes of the

ED

RDA accounted for 82.10% of the total variance between greenhouse gases and different forms of carbon/nitrogen (Fig 4(a)). The organic nitrogen (OrgN, 33.00%),

PT

DOC (20.50%), TN (14.60%), and TOC (10.20%) of the compost were identified as

CC E

key factors that affected the emissions of greenhouse gases. CH4 was negatively correlated with HS. In this experiment, the negative correlation between CH4 and HS may be due to the anaerobic conditions during degradation, that resulted in an increase

A

in CH4 production and reduction in HS production (Awasthi et al., 2018). Whereas, CH4 was positively correlated with NH4+-N, OrgN and TN. This correlation may have been due to the degradation of NH4+-N, OrgN and TN as they consumed oxygen, thereby providing a suitable environment for the growth of methanogens (Jiang et al.,

2011). The results showed that, N2O was negatively correlated with DOC and TOC and positively correlated with NO3--N. Denitrifying bacteria use nitrate as a substrate for denitrification (Sigman et al., 2001). Denitrifying bacteria use carbon sources to rapidly propagate and reduce nitrogen oxides to N2O, and perhaps because of this reason, the

IP T

N2O concentration found was negatively correlated to the DOC and TOC (Peter Czepiel et al., 1996, Huang et al., 2004). Compared to pig manure, degradation of garden waste

SC R

and the rest nitrogen resource additives possibly provided more NO3--N and boosted the growth of denitrifying bacteria. The RDA between greenhouse gases and the basic

U

physicochemical properties of the compost are shown in Figure 4(b). The explained

N

variation between RDA1 and RDA2 was 68.28% and 12.50%, respectively. The key

A

factors that influenced the emission of greenhouse gases were, identified as GI (53.90%)

M

and EC (19.10%). CH4 was positively correlated with moisture content (MC) and GI,

ED

while negatively correlated with EC. The reason for this result could be because the methanogens were affected by changes in the EC concentration. N2O was negatively

PT

correlated with pH and positively correlated with temperature and GI. The best pH

CC E

range for denitrification is between 7.0 and 8.0 (Akunna & Clark, 2000). The best pH range for nitrification is between 6.6 and 8.0 (Zhongjun & Ralf, 2010, Xia et al., 2011). Therefore, increased pH may destroy the denitrification and nitrification microbial

A

community structure and N2O emissions will be reduced (Bertoldi et al., 1983, Tiquia & Tam, 1998). 3.6 Quantitative Evaluation of the Impact of Adding Livestock Manure on the Quality of Garden Waste Compost Generally, compost quality is evaluated based on numerous, more or less, reliable

parameters, such as the carbon to nitrogen ratio, the cation exchange capacity, and germination and humification indexes (Tiquia & Tam, 1998, Bernal et al., 2009). However, compost quality can hardly be appraised simply using a single parameter, mainly due to the great variety of composting feedstock and management practices.

IP T

Moreover, an evaluation of compost quality is usually based on a qualitative description (Tognetti et al., 2007, Unmar & Mohee, 2008, Som et al., 2009, Jiang et al., 2018).

SC R

Hence, it is necessary to quantitatively evaluate the compost quality after added

different nitrogen resource based on compost stability and maturity indicators assessing.

U

The value of TOC loss, DOC/TN, NH4+-N/NO3--N, NH4+-N/TKN, GI and EC can

N

indicate the security and maturity of a compost (Bertoldi et al., 1983, Garcia et al., 1992,

A

Bernai et al., 1998, Garcíagómez et al., 2005). The value of TOC loss and Nfinal can

M

also describe the nutritional value of compost. A correlation analysis of the compost

ED

quality indexes are shown in Table.7. TOC loss is negatively correlated with EC (P<0.01). DOC/TKN showed a positive relationship with NH4+-N/NO3—N, NH4+-

PT

N/TKN (P<0.05). Nfinal (P<0.01). NH4+-N/NO3--N was positively correlated with Nfinal

CC E

(P<0.01), NH4+-N/TKN and EC (P<0.05), while it was highly negative correlated to GI (P<0.01). NH4+-N/TKN showed a significant negative correlation with GI (P<0.01), while it showed positive correlation with EC (P<0.05) and Nfinal. There is also a highly

A

significant negative correlation between GI and EC (P<0.01). Factor analysis is a multivariate statistical method commonly used for the comprehensive evaluation of multiple indicators(Harman, 1962, Osborne, 2008). As shown in Table.8, the accumulated contribution rate of the first two common factors is

98.775%, and the eigenvalues are all greater than 1, which contains most of the information on compost quality indicators. The contribution rate of the first common factor was 64.825%, and this was primarily determined by DOC/TKN, NH4+-N/NO3-N, NH4+-N/TKN and Nfinal. Additionally, their factor loads were 0.980, 0.838, 0.818,

IP T

and 0.997, respectively, and these values primarily reflect the nitrogen content and maturity of the final compost product. The contribution rate of the second common

SC R

factor was 39.607%, and this was determined using the TOC loss, GI and EC. Their factor loads were -0.922, -0.897, and 0.975, respectively, and these values reflect the

U

degree of degradation and security of the compost.

N

Using factor analysis, scores (fi) of the first two common factors were calculated.

A

A mathematical model for composing the comprehensive quality score of the compost

M

(fz) was established by taking the contribution ratio of each factor (all factors came from

ED

Table.8) as the weight, then accumulating the common factor score of the product and 64.825

34.015

the corresponding weight (5): 𝑓𝑧 = 98.775 𝑓1 + 98.775 𝑓2 (5). The compost quality scores

PT

of the three treatments were calculated using a mathematical model. The ranking of the

CC E

compost quality was based on the score of each factor and a comprehensive score (Table.9). Based on factor 1, the ranking of the compost found to be SM>CM>PM. Similarly, the SM represented a more nitrogen enriched mature compost than the rest,

A

of the treatments, possibly due to the addition of sheep manure, which can promote nitrogen conservation and reduce nitrogen loss by evaporation during the composting process. According to factor 2, the ranking of compost treatments was PM>CM>SM. The degree of degradation and security was greater in the treatment of PM than in the

other treatments. This result was possibly due to the high bulk density of the PM as compared to the other treatments. The results of Chang et al showed that an increase in the bulk density positively correlated with a decrease in the degradable TOC (Chang et al., 2017).

IP T

As shown in Figure 5, the ranking of the compost quality of the different treatments is CM>SM>PM. As compared with pig and sheep manure, the addition of

SC R

chicken manure converted garden waste into a stable and nitrogen-enriched compost. The humic substance and DOC in CM is higher than other treatment. Humus can fix

U

ammonium nitrogen to form complex nitrogen compounds and thereby increased

N

compost maturity and stability (Sugahara & Inoko, 1981, Zhang & Sun, 2016a).

A

Meanwhile, the degradation of DOC provide ATP and nutrients for nitrogen-fixing

M

microorganisms that inorganic nitrogen synthesis of cellular material (Fang et al., 1999,

ED

Li et al., 2013). Therefore, nitrogen reduction in the CM was significantly lower than in the rest of the treatments.

PT

4. Conclusion

CC E

According to the results of this study, the following conclusions can be made: (1) composting of garden waste with livestock manure can reduce nitrogen loss and facilitate organic matter humification. In particular, chicken manure promoted the

A

conversion of NH4+-N to NO3--N and TOC to HS. (2) Garden waste composted with chicken manure can reduce N2O and CH4 emissions. (3) Based on a redundancy analysis, CH4 emissions were significantly correlated with NH4+-N, OrgN, TN, HS and MC. Also, N2O was significantly correlated with DOC, TOC, NO3--N, and GI. (4)

Based on a factor analysis, composting quality was CM>SM>PM. The results showed that garden waste composted with chicken manure not only boosted the product maturity and security, but also reduced nitrogen losses. Acknowledgement

IP T

This research was funded by the National Science and Technology Support Program of China(2012BAD15BO4-4-3) and the Social Development Projects of

A

CC E

PT

ED

M

A

N

U

SC R

Shaanxi Province of China(No.2010K11-02-09)

References

Akunna JC & Clark M (2000) Performance of a granular-bed anaerobic baffled reactor (GRABBR) treating whisky distillery wastewater. Bioresource Technology 74: 257-261. Andersen JK, Boldrin A, Samuelsson J, Christensen TH & Scheutz C (2016) Quantification of greenhouse gas emissions from windrow composting of garden waste. Journal of Environmental Quality 39: 713-724.

IP T

Arias O, Viña S, Uzal M & Soto M (2017) Composting of pig manure and forest green waste amended with industrial sludge. Science of the Total Environment 586: 1228.

Awasthi MK, Pandey AK, Bundela PS & Khan J (2015) Co-composting of organic fraction of municipal microbial enzymatic dynamic. Bioresource Technology 182: 200-207.

SC R

solid waste mixed with different bulking waste: Characterization of physicochemical parameters and

Awasthi MK, Pandey AK, Bundela PS, Wong JWC, Li R & Zhang Z (2016) Co-composting of gelatin industry sludge combined with organic fraction of municipal solid waste and poultry waste employing zeolite mixed with enriched nitrifying bacterial consortium. Bioresource Technology 213: 181-189.

U

Awasthi MK, Wang Q, Chen H, Wang M, Awasthi SK, Ren X, Cai H, Li R & Zhang Z (2017) In-vessel co-composting of biosolid: Focusing on mitigation of greenhouse gases emissions and nutrients

N

conservation. Renewable Energy.

Awasthi MK, Awasthi SK, Wang Q, Awasthi MK, Zhao J, Chen H, Ren X, Wang M & Zhang Z (2018)

A

Role of Ca-bentonite to improve the humification, enzymatic activities, nutrient transformation and end

M

product quality during sewage sludge composting. Bioresource Technology. Bernai MP, Paredes C, Sánchez-Monedero MA & Cegarra J (1998) Maturity and stability parameters of composts prepared with a wide range of organic wastes. Bioresour Technol 63: 91-99.

ED

Bernal MP, Alburquerque JA & Moral R (2009) Composting of animal manures and chemical criteria for compost maturity assessment. A review. Bioresource Technology 100: 5444-5453. Bertoldi MD, Vallini G & Pera A (1983) The biology of composting: A review. Waste Management & Research 1: 157-176.

PT

Cáceres R, Coromina N, Malińska K & Marfà O (2015) Evolution of process control parameters during extended co-composting of green waste and solid fraction of cattle slurry to obtain growing media.

CC E

Bioresour Technol 179: 398-406. Cayuela ML, Sánchez-Monedero MA, Roig A, Sinicco T & Mondini C (2012) Biochemical changes and GHG emissions during composting of lignocellulosic residues with different N-rich by-products. Chemosphere 88: 196-203. Chang R, Guo Q, Chen Q, Bernal MP, Wang Q & Li Y (2017) Effect of initial material bulk density and

A

easily-degraded organic matter content on temperature changes during composting of cucumber stalk. Journal of Environmental Sciences. Chen H, Awasthi MK, Liu T, Zhao J, Ren X, Wang M, Duan Y, Awasthi SK & Zhang Z (2018) Influence of clay as additive on greenhouse gases emission and maturity evaluation during chicken manure composting. Bioresource Technology 266: 82. Chen T, Huang Q, Gao D, Huang Z, Zheng Y & Li Y (2002) Accumulated Temperature as an Indicator to Predict the Stabilizing Process in Sewage Sludge Composting. Acta Ecologica Sinica 22: 911-915. Chowdhury MA, Neergaard AD & Jensen LS (2014) Potential of aeration flow rate and bio-char addition

to reduce greenhouse gas and ammonia emissions during manure composting. Chemosphere 97: 16-25. Dias BO, Silva CA, Higashikawa FS, Roig A & Sánchezmonedero MA (2010) Use of biochar as bulking agent for the composting of poultry manure: effect on organic matter degradation and humification. Bioresource Technology 101: 1239-1246. Fang M, Wong JWC, Ma KK & Wong MH (1999) Co-composting of sewage sludge and coal fly ash: nutrient transformations. Bioresource Technology 67: 19-24. Gabhane J, William SP, Bidyadhar R, Bhilawe P, Anand D, Vaidya AN & Wate SR (2012) Additives aided composting of green waste: effects on organic matter degradation, compost maturity, and quality of the finished compost. Bioresour Technol 114: 382-388.

IP T

Garcia C, Hernandez T, Costa F & Ayuso M (1992) Evaluation of the maturity of municipal waste

compost using simple chemical parameters. Communications in Soil Science & Plant Analysis 23: 15011512.

SC R

Garcíagómez A, Bernal MP & Roig A (2005) Organic Matter Fractions Involved in Degradation and Humification Processes During Composting. Compost Science & Utilization 13: 127-135.

GF H, JW W, QT W & BB N (2004) Effect of C/N on composting of pig manure with sawdust. Waste Management 24: 805-813.

Hao X, Larney FJ, Chang C, Travis GR, Nichol CK & Bremer E (2005) The effect of phosphogypsum

U

on greenhouse gas emissions during cattle manure composting. Journal of Environmental Quality 34: 774-781.

N

Harman HH (1962) Modern factor analysis. Journal of the American Statistical Association 56: 219-219. sawdust. Waste Management 24: 805-813.

A

Huang GF, Wong JW, Wu QT & Nagar BB (2004) Effect of C/N on composting of pig manure with

M

Huang GF, Wu QT, Wong JW & Nagar BB (2006) Transformation of organic matter during cocomposting of pig manure with sawdust. Bioresource Technology 97: 1834-1842. Jiang J, Liu X, Huang Y & Huang H (2015) Inoculation with nitrogen turnover bacterial agent

ED

appropriately increasing nitrogen and promoting maturity in pig manure composting. Waste Management 39: 78-85.

Jiang J, Kang K, Chen D & Liu N (2018) Impacts of delayed addition of N-rich and acidic substrates on

PT

nitrogen loss and compost quality during pig manure composting. Waste Manag 72: 161-167. Jiang T, Schuchardt F, Li G, Guo R & Zhao Y (2011) Effect of C/N ratio, aeration rate and moisture content on ammonia and greenhouse gas emission during the composting. Journal of Environmental

CC E

Sciences 23: 1754-1760.

Karak T & Bhattacharyya P (2010) Heavy metal accumulation in soil amended with roadside pond sediment and uptake by winter wheat (Triticum aestivum L. cv. PBW 343). Thescientificworldjournal 10: 2314.

Kebreab E, Clark K, Wagner-Riddle C & France J (2006) Methane and nitrous oxide emissions from

A

Canadian animal agriculture: A review. Canadian Journal of Animal Science 86: 135-158. Khan N, Clark I, Sánchez monedero MA, Shea S, Meier S & Bolan N (2014) Maturity indices in cocomposting of chicken manure and sawdust with biochar. Bioresource Technology 168: 245-251. Li Y, Li W, Wu C & Ke W (2013) New insights into the interactions between carbon dioxide and ammonia emissions during sewage sludge composting. Bioresource Technology 136: 385-393. Lindau CW, Bollich PK, Delaune RD, Patrick WH & Law VJ (1991) Effect of urea fertilizer and environmental factors on CH 4 emissions from a Louisiana, USA rice field. Plant & Soil 136: 195-203. Liu L, Wang S, Guo X, Zhao T & Zhang B Succession and diversity of microorganisms and their

association with physicochemical properties during green waste thermophilic composting. Waste Management. Lu YH, Wassmann R, Neue HU & Huang CY (2000) Dynamics of dissolved organic carbon and methane emissions in a flooded rice soil. Soil Science Society of America Journal 64: 2011-2017. Marina H & Kari HN (2011) Composting of bio-waste, aerobic and anaerobic sludges--effect of feedstock on the process and quality of compost. Bioresource Technology 102: 2842-2852. Neergaard AD (2015) Greenhouse gas emissions from passive composting of manure and digestate with crop residues and biochar on small-scale livestock farms in Vietnam. Environmental Technology 36: 2924-2935. composting of organic household waste. Journal of Cleaner Production 156: 865-875.

IP T

Neugebauer M & Sołowiej P (2017) The use of green waste to overcome the difficulty in small-scale Nigussie A, Bruun S, Kuyper TW & De NA (2017) Delayed addition of nitrogen-rich substrates during Chemosphere 166: 352-362.

SC R

composting of municipal waste: Effects on nitrogen loss, greenhouse gas emissions and compost stability.

NY525 (2012) Agricultural Industry Standard of the People's Republic of China - Organic Fertilizer (NY525-2012). Osborne JW (2008) Best Practices in Exploratory Factor Analysis.

U

Paradelo R, Moldes AB & Barral MT (2013) Evolution of organic matter during the mesophilic composting of lignocellulosic winery wastes. Journal of Environmental Management 116: 18-26.

N

Peter Czepiel, †, Ellen Douglas, Robert Harriss A & Crill† P (1996) Measurements of N2O from Composted Organic Wastes. Environmental Science & Technology 30: 2519-2525.

A

Rawoteea SA, Mudhoo A & Kumar S (2017) Co-composting of vegetable wastes and carton: Effect of

M

carton composition and parameter variations. Bioresource Technology 227: 171-178. Ren L, Schuchardt F, Shen Y, Li G & Li C (2010) Impact of struvite crystallization on nitrogen losses during composting of pig manure and cornstalk. Waste Management 30: 885-892.

ED

Rui Guo GL, TaoJiang, Frank Schuchardt, Tongbin Chen, Yuanqiu Zhao, Yujun Shen (2012) Effect of aeration rate, C/N ratio and moisture content on the stability and maturity of compost. Bioresource Technology 112: 171-178.

PT

Ryckeboer JR, Mergaert J, Vaes K, Klammer S, Clercq DD, Coosemans J, Insam H & Swings J (2003) A survey of bacteria and fungi occurring during composting and self-heating processes. . Annals of Microbiology 53: 349-410.

CC E

Sánchez monedero MA, Roig A, Paredes C & Bernal MP (2001) Nitrogen transformation during organic waste composting by the Rutgers system and its effects on pH, EC and maturity of the composting mixtures. Bioresour Technol 78: 301-308. Sánchez monedero MA, Serramiá N, Civantos CG, Fernández hernández A & Roig A (2010) Greenhouse gas emissions during composting of two-phase olive mill wastes with different agroindustrial by-

A

products. Chemosphere 81: 18-25. Sánchezmonedero MA, Serramiá N, Garcíaortiz Civantos C, Fernándezhernández A & Roig A (2010) Greenhouse gas emissions during composting of two-phase olive mill wastes with different agroindustrial by-products. Chemosphere 81: 18. Santos A, Bustamante MA, Tortosa G, Moral R & Bernal MP (2016) Gaseous emissions and process development during composting of pig slurry: the influence of the proportion of cotton gin waste. Journal of Cleaner Production 112: 81-90. Schimel J (2000) Rice, microbes and methane. Nature 403: 375, 377.

Sigman DM, Casciotti KL, Andreani M, ., Barford C, ., Galanter M, . & B?Hlke JK (2001) A bacterial method for the nitrogen isotopic analysis of nitrate in seawater and freshwater. Analytical Chemistry 73: 4145-4153. Solomon S (2007) IPCC (2007): Climate Change The Physical Science Basis. p.^pp. 123-124. Som MP, Lemée L & Amblès A (2009) Stability and maturity of a green waste and biowaste compost assessed on the basis of a molecular study using spectroscopy, thermal analysis, thermodesorption and thermochemolysis. Bioresource Technology 100: 4404-4416. Sugahara K & Inoko A (1981) Composition analysis of humus and characterization of humic acid obtained from city refuse compost. Soil Science & Plant Nutrition 27: 213-224.

IP T

Tiquia SM & Tam NFY (1998) Elimination of phytotoxicity during co-composting of spent pig-manure sawdust litter and pig sludge. Bioresource Technology 65: 43-49.

Tiquia SM, Richard TL & Honeyman MS (2002) Carbon, nutrient, and mass loss during composting.

SC R

Nutrient Cycling in Agroecosystems 62: 15-24.

Tognetti C, Mazzarino MJ & Laos F (2007) Improving the quality of municipal organic waste compost. Bioresource Technology 98: 1067-1076.

Unmar G & Mohee R (2008) Assessing the effect of biodegradable and degradable plastics on the composting of green wastes and compost quality. Bioresource Technology 99: 6738-6744.

U

Wang M, Awasthi MK, Wang Q, Chen H, Ren X, Zhao J, Li R & Zhang Z (2017) Comparison of additives amendment for mitigation of greenhouse gases and ammonia emission during sewage sludge co-

N

composting based on correlation analysis. Bioresource Technology 243: 520. Wang Q, Awasthi MK, Ren X, Zhao J, Li R, Wang Z, Wang M, Chen H & Zhang Z (2018) Combining

A

biochar, zeolite and wood vinegar for composting of pig manure: The effect on greenhouse gas emission

M

and nitrogen conservation. Waste Management 74.

Wang Q, Wang Z, Awasthi MK, Jiang Y, Li R, Ren X, Zhao J, Shen F, Wang M & Zhang Z (2016) Evaluation of medical stone amendment for the reduction of nitrogen loss and bioavailability of heavy

ED

metals during pig manure composting. Bioresource Technology 220: 297-304. Wojciech CA, Krystyna M, Rafaela C, Damian J, Jacek D & Andrzej L (2015) Co-composting of poultry manure mixtures amended with biochar - The effect of biochar on temperature and C-CO2 emission.

PT

Bioresource Technology 200: 921.

Xia W, Zhang C, Zeng X, et al. (2011) Autotrophic growth of nitrifying community in an agricultural soil. ISME J 5: 1226-1236.

CC E

Yang F, Li GX, Yang QY & Luo WH (2013) Effect of bulking agents on maturity and gaseous emissions during kitchen waste composting. Chemosphere 93: 1393-1399. Zhang L & Sun X (2015) Effects of earthworm casts and zeolite on the two-stage composting of green waste. Waste Management 39: 119-129. Zhang L & Sun X (2016a) Influence of bulking agents on physical, chemical, and microbiological

A

properties during the two-stage composting of green waste. Waste Management 48: 115-126. Zhang L, Sun X, Yun T & Gong X (2013) Effects of brown sugar and calcium superphosphate on the secondary fermentation of green waste. Bioresource Technology 131: 68-75. Zhao J, Sun X, Awasthi MK, Wang Q & Zhang Z (2018) Performance evaluation of gaseous emissions and Zn speciation during Zn-rich antibiotic manufacturing wastes and pig manure composting. Bioresource Technology 267: 688-695. Zhao X, He X, Xi B, Gao R, Tan W, Zhang H, Huang C, Li D & Li M (2017) Response of humic-reducing microorganisms to the redox properties of humic substance during composting. Waste Management 70.

Zhongjun J & Ralf C (2010) Bacteria rather than Archaea dominate microbial ammonia oxidation in an agricultural soil. Environmental Microbiology 11: 1658-1671. Zhou H, Zhao Y, Yang H, Zhu L, Cai B, Luo S, Cao J & Wei Z (2018) Transformation of organic nitrogen fractions with different molecular weights during different organic wastes composting. Bioresource Technology 262: 221-228. Zhou Y, Selvam A & Wong JW (2014) Evaluation of humic substances during co-composting of food waste, sawdust and Chinese medicinal herbal residues. Bioresource Technology 168: 229-234.

A

CC E

PT

ED

M

A

N

U

SC R

IP T

Zucconi F (1981) Evaluating Toxicity of Immature Compost. Biocycle 22: 54-57.

CC E

PT

ED

M

A

N

U

SC R

IP T

Figure captions

A

Fig.1. Variation in temperature and degree hour temperature values of different treatments during composting process. AM is the abbreviation of ambient temperature. PM is the abbreviation of first treatment (pig manure + fallen leaves). CM is the abbreviation of second treatment (chicken manure + fallen leaves). SM is the abbreviation of third treatment (sheep manure + fallen leaves). CK is the abbreviation of control treatment (soil + fallen leaves). The straight line means the degree hour temperature equal to zero.

IP T SC R U

A

CC E

PT

ED

M

A

N

Fig.2 Changes in different carbon/nitrogen forms during the composting process. The left Y-axis of (a) is the NH4+-N concentrations of PM, SM, and CK. The right Y-axis of (a) is the NH4+-N concentrations of CM. NH4+-N is the abbreviation of ammonium nitrogen. NO3--N is the abbreviation of nitrate nitrogen. TN is the abbreviation of total nitrogen. TOC is the abbreviation of total organic carbon. DOC is the abbreviation of dissolved organic carbon. HS is the abbreviation of humus.

IP T SC R U N

A

CC E

PT

ED

M

A

Fig.3 Emissions of N2O and CH4 during the composting process. The left Y-axis of (c) is the CH4 emission rates of CM, SM, and CK. The right Y-axis of (c) is the CH4 emission rates of PM. The left Y-axis of (d) is the CH4 accumulated emissions of CM, SM and CK. The right Y-axis of (d) is the CH4 accumulated emissions of PM. N2O is the abbreviation of nitrous oxide. CH4 is the abbreviation of methane.

IP T SC R U N A M

A

CC E

PT

ED

Fig.4 Redundancy analysis (RDA) of the relationship between greenhouse gases, different carbon/nitrogen forms and physicochemical properties and the percentages of variance explained by factor. OrgN is the abbreviation of organic nitrogen. EC is the abbreviation of electrical conductivity. GI is the abbreviation of germination index. MC is the abbreviation of moisture content.

IP T SC R

A

CC E

PT

ED

M

A

N

U

Fig.5 Principal component scores and comprehensive scores of different compost product quality

Table

Table.1 The composition, total organic carbon and total nitrogen of garden waste from different times of year or geographical locations C/N

Locatio n

37.41

0.63

59.38

Beijing

49.52 ±0.36

1.25 ±0.01

39.61

Beijing

41.83 ±0.14

1.56 ±0.02

26.81

Garden waste

38.57

1.4

27.55

fallen leaves and branch cutting

48.02

0.9

53.36

grass and fallen leaves

55

0.78

Galicia

Harbin

U

N

A

Fallen leaves and branch cuttings Fallen leaves and branch cuttings Chestnut leaves, chestnut burr, chestnut pruned branches and undergrowth vegetation

70.51

references Lu Zhang et al., 2013 Lu Zhang et al., 2015

IP T

TN/ %

O. Arias et al., 2017

SC R

TOC/ %

Composition

Beijing Tunis

Zhou Haixuan et al., 2018 Liu ling et al., 2018 Nedra et al., 2018

A

CC E

PT

ED

M

TOC is the abbreviation of total organic carbon. TN is the abbreviation of total nitrogen. C/N is the abbreviation of the ratio of total organic carbon to total nitrogen.

Table.2 Characteristics of the defoliation, Livestock manure and soil Moisture content % Defoliation 12.83±0.08 Pig manure 65.05±0.01 Chicken manure 82.67±0.03 Sheep manure 66.15±1.12 Soil 26.10±0.18

TOC g/kg 420.60±0.14 356.40±0.26 278.30±0.04 327.80±0.08 8.91±0.12

TN g/kg 13.10±0.01 29.90±1.15 22.60±0.07 23.10±0.05 1.30±0.04

C/N 32.11 11.92 12.31 14.19 6.85

A

CC E

PT

ED

M

A

N

U

SC R

IP T

Material

Table.3 Composting treatments and material ratio Treatment

PM

CM SM Usage amount/Kg 9.58 10.77 17.68 13.65 -

Material

Defoliation

8.52 20.3 -

6.9 -

22.5

A

CC E

PT

ED

M

A

N

U

SC R

IP T

Pig manure Chicken manure Sheep manure Soil

CK

Table.4 Changes of chemical properties during the composting process treatment Compost cycle EC/mS·cm-1

pH

GI/%

T Value

54.50±0.09

1

initial

0.99±0.02

8.82±0.08

final

1.42±0.05

7.90±0.10 126.40±0.10

initial

1.60±0.01

8.08±0.09

9.40±0.12

1

final

2.41±0.01

7.98±0.06

89.30±0.08

0.57

initial

1.16±0.04

8.66±0.07

34.30±0.05

1

final

1.87±0.05

7.56±0.02 118.30±0.09

initial

1.83±0.02

8.19±0.08

final

2.26±0.06

7.78±0.08 102.30±0.16

PM 0.51

SM

SC R

23.20±0.11

CK

CC E

PT

ED

M

A

N

U

Standarda <4 <9 >80 a Standard means the maturity requirements in previous studies

A

0.57

IP T

CM

1

0.55

0.53~0.72

Table.5 Changes of different forms nitrogen during the composting process

g/Kg

initial

24.60±0.03

final

18.50±0.16

initial

26.60±0.03

Loss rate %

The rate of change %

NO3--N g/Kg 0.70±0.04

PM

35.9

CM final

19.20±0.12

initial

19.70±0.09

SM

19.64

0.74±0.05

final

14.30±0.52

0.87±0.02

initial

10.60±0.06

CK

0.50±0.02 0.80±0.04

A M ED PT CC E A

0.070±0.01

U

5.10±0.12

51.32

0.160±0.06

-48.97

N

final

2.27

0.276±0.03 -17.57

55.20

15.07

2.520±0.04

0.50±0.04 0.70±0.03

0.865±0.02 4 2.380±0.03

-8.52

30.51

g/Kg

The rate of change %

0.868±0.01

0.66±0.04

29.90

NH4+-N

IP T

TN

SC R

treatment

Compost cycle

0.050±0.02

35.34

Table.6 Changes of different forms carbon during the composting process

initial

420.15±0.24

g/Kg

PM

Loss rate %

The rate of change %

DOC g/Kg 20.01±2.12

67.56 final

159.91±1.34

initial

460.94±4.34

CM

g/Kg

8.88±1.23

42.06 5.67±0.76

21.08±2.32

5.65±0.35 58.75

-3.74

final

208.72±0.55

9.42±1.46

6.35±0.52

initial

380.86±2.56

17.46±1.35

9.2±0.67

final

201.12±0.46

4.98±0.76

initial

228.62±4.43

18.59±0.57

final

60.32±2.34

75.43

A M ED PT CC E

45.50

5.97±0.69 9.55±0.34

72.08

5.43±0.78

N

CK

76.05

SC R

60.06

The rate of change %

8.34±0.44 62.18

60.20

SM

A

HS

IP T

TOC

U

treatment

Compost cycle

5.03±0.67

50.96

Table.7 Correlation analysis of compost quality indexes DOC/TKN

NH4+-N/NO3--N

NH4+-N/TKN

Nfinal

TOC Loss

1

DOC/TKN

0.438

1

NH4+-N/NO3--N

-0.156

0.757*

1

NH4 -N/TKN

-0.209

0.744*

0.990*

1

Nfinal

0.399

0.976**

0.821**

0.803**

1

GI

0.656 -0.826**

-0.354 0.136

-0.843** 0.671*

-0.873** 0.718*

-0.424 0.186

+

EC

U N A M ED PT CC E A

1 -0.962**

SC R

Notes: * correlation is significant at the 0.05 level. **correlation is significant at the 0.01 level.

GI

EC

IP T

TOC Loss

1

Table.8 Principal factor analysis of different composting product quality Principal factor

Compost quality index

0.382 0.980 0.838 0.818 0.997 -0.441 0.205 4.538 64.825 64.825

-0.922 -0.0816 0.525 0.570 -0.199 -0.897 0.975 2.381 34.015 98.840

SC R

IP T

𝑓2

A

CC E

PT

ED

M

A

N

U

TOC Loss DOC/TKN NH4+-N/NO3--N NH4+-N/TKN Nfinal GI EC Characteristic Value Contribution Rate% Accumulated Contribution Rate %

𝑓1

Table.9 Principal component scores, comprehensive scores and ranking of different compost product quality 𝑓𝑎𝑐𝑡𝑜𝑟1

Ranking

𝑓𝑎𝑐𝑡𝑜𝑟2

Ranking

Comprehensive score

Ranking

PM CM SM

0.482 0.822 -1.304

3 2 1

-1.237 1.046 0.191

1 2 3

-0.110 0.899 -0.789

3 1 2

A

CC E

PT

ED

M

A

N

U

SC R

IP T

treatment