Journal of Animal Science and Technology
BioMed Central
Research

Seunggun Won1, Naveed Ahmed2, Byung-Gu You2, Soomin Shim2, Seung-Su Kim2, Changsix Ra2
1Department of Animal Resources, College of Life & Environmental Science, Daegu University, Gyeongsan, 38453 South Korea
2Division of Animal Resource Science, College of Animal Life Science, Kangwon National University, Chuncheon, 24341 South Korea

Received: Nov 12, 2017 ; Accepted: Jan 9, 2018

Published Online: Feb 19, 2018

## Abstract

Background

Poultry breeding has increased by 306% in Korea, inevitably increasing the production of manure which may contribute to environmental pollution. The nutrients (NP) in the manure are essential for crop cultivation and soil fertility when applied as compost. Excess nutrients from manure can be accumulated on the land and can lead to eutrophication. Therefore, a nutrient load on the finite land should be calculated.

Methods

This study calculates the nutrient production from Korean poultry by investigating 11 broiler and 16 laying hen farms. The broiler manure was composted using deep litter composting while for layer deep litter composting, drying, and simple static pile were in practice. The effect of weight reduction and storing period during composting was checked. Three weight reduction cases of compost were constructed to calculate nutrient loading coefficients (NLCs) using data from; i) farm investigation, ii) theoretical P changes (ΔP = 0), and iii) dry basis.

Results

During farm investigation of broiler and layer with deep litter composting, there was a 68 and 21% N loss whereas 77 and 33% P loss was found, respectively. In case of layer composting, a loss of 10-56% N and a 52% P loss was observed. Drying manure increased the P concentrations therefore NLCs calculated using dry basis that showed quite higher reductions (67% N; 53% P). Nutrient loss from farm investigation was much higher than reported by Korean Ministry of Environment (ME).

Conclusions

Nutrients in manure are decreased when undergo storing or composting process due to microbial action, drying, and leaching. The nutrient load applied to soil is less than the fresh manure, hence the livestock manure management and conservation of environment would be facilitated.

Keywords: Poultry manure; Nutrient loading coefficient; Volatile solids; Total nitrogen; Total phosphorus

## Background

Global poultry breeding have gone under enormous industrialization since late 1950s that resulted in the generation of massive amounts of nutrients (N & P) concentrated in farms [1]. Traditionally, poultry litter is used for land amendment purposes and is spread on the soil as fertilizer. Poultry litter is composed of manure, bulking material, feed, bird feathers etc. and has a very high nutritional value [2]. Excessive use of poultry manure in cropping may result in over enrichment of the soil and may contribute to the nitrate pollution in the water bodies [3] and cause eutrophication [4]. The presence of very high nitrate concentrations in the drinking water may contribute to greenhouse gas emission, methamoglobinaemia, respiratory illnesses, and fetal abortions in livestock [5, 6].

In Korea, the main categories of livestock reported by the Ministry of Environment (ME) in 2012 are dairy cattle (0.47 M), beef cattle (3.16 M), swine (10.6 M), and chicken and ducks (205.9 M) [7]. The proportion of manure production related to the livestock type was 39% produced by swine, 34% produced by beef cattle, 13% produced by dairy cattle, and 14% produced by chicken. The total amount of manure produced in Korea was 45,306 kt/year in 2012. Prior to land application, manure produced in Korea is stored and composted by livestock farm owners. Despite having comparatively higher number of heads, chicken produce only 14% of the total manure produced by livestock in Korea.

Nutrient losses from livestock manure management systems occur in decreasing fashion based on reactivity, speciation, solubility, and fugacity of the nutrients in the following fashion: C, N, > > S > K, Na, Cl, B, > P and other minerals. The C and N show dual mobility in water soluble compounds and gases that cause very quick and complex losses compared to other minerals. Carbon losses are mainly in the gaseous form (CO2 and CH4), in dissolved forms (HCO3, DOC), and runoffs [8]. During composting, nitrogen is lost through NH3 volatilization, denitrification, and leaching; as a result there is a loss of nutrients to oxidation and microbial degradation depending on composting method and duration. Substantial discharges of NH3, CH4, and N2O occur during the composting process [9]. The N losses of raw material during poultry composting was seen as 38-46% of initial N as NH3 emission [10] and 0.2-6.0% N2O emissions [11, 12]. During storage period, the N losses are 20-40%.

The nutrient loadings on land in Korea were calculated using standard unit for manure production by ME or foreign agencies e.g. The Organization for Economic Co-operation and Development (OECD) and were excessively reported due to nutrient production calculations based on number of livestock heads and the excretion rates. The nutrient values were reported as if manure was directly applied to the land after production. Contrary to the usually reported nutrient loadings most of the manure (88.7%) generated in Korea is usually composted and a small liquid portion (9.1%) is released into the environment after treatment. The nutrient losses during composting or drying period were not considered when nutrient production was calculated by ME or OECD. Therefore, the purposes of this study were; (i) to evaluate composting methods used in poultry manure management, (ii) to calculate weight loss and nutrient loss during composting period, (iii) to estimate practical nutrient loadings on agricultural land from poultry manure after composting period and to calculate the coefficients for organics, nitrogen, and phosphorus through the composting and storage period.

## Methods

The field survey and sampling methods:

Raw manure and compost samples were collected for over a period of 6 months (March to August 2014). A total of 27 poultry farms were investigated including 11 broiler farms at Gapyeong County, Hongcheon, Chuncheon, and 16 laying farms at Hwacheon area. To obtain basic information and manure management practices a survey of individual farms was carried out using questionnaire. Information for farm address, number of heads, excretion type, barn area, annual manure production and treatment methods, bulking material and annual composting production and methods etc., were collected. Fresh manure and compost were sampled on site in a 20-L bucket and later analyzed.

Analytical methods

All samples were stored at − 4 °C until analyzed. Pre-treatment of samples was done by mixing with H2SO4 and heating in block digester (BD40, LaChat, USA) at 320 °C, prior to the measurement of total nitrogen (TN) and total phosphorus (TP) using auto water analyzer (QuikChem 8500, LaChat, USA) for poultry manure and compost samples. Total solids (TS) and water content were calculated by drying samples at 105 °C for 24 h and then volatile solids (VS) were measured by heating a pre-dried sample in a muffle furnace at 550 °C for 2 h. All analyses were done according to the standard methods [13]. The bulk density (weight per unit volume) of the samples was done on site using 18 L of bucket according to Cooperband method [14].

The nutrient loading is the amount of nutrients from poultry manure released into the environment, particularly soil and water resources. Typically, livestock manure is composted or stored and converted into organic fertilizer prior to land spreading. Through this process, oxidation and volatilization of organic matter and nitrogen occurs and causes loss of nutrients depending on the composting method and period. Therefore, nutrient loss ratio is the reciprocal of nutrient loading coefficients (NLCs) which helps in calculating nutrient variations in the form of a factor, as manure is composted [7]. All the calculations for NLCs were carried out using following equations;

$\text{Nutrient loading coefficient}\phantom{\rule{0.25em}{0ex}}\left(\mathrm{NLC}\right)=\frac{\text{Total nutrients in compost}\phantom{\rule{0.25em}{0ex}}{\left(\mathrm{VS},\mathrm{N},\mathrm{P}\right)}^{\left(a\right)}}{\text{Total nutrients in manure}\phantom{\rule{0.25em}{0ex}}{\left(\mathrm{VS},\mathrm{N},\mathrm{P}\right)}^{\left(b\right)}}$
1
$\begin{array}{l}\left(a\right)\phantom{\rule{0.25em}{0ex}}\text{Total Nutrients in Compost}=\text{Total amount of compost produced}\phantom{\rule{0.25em}{0ex}}{\left(\frac{\mathrm{kg}}{\mathrm{d}}\right)}^{\left(e\right)}×\text{Concentration of nutrients in compost}\phantom{\rule{0.25em}{0ex}}\left(\mathrm{VS},\mathrm{N},\mathrm{P}\right)\left(\frac{g}{\mathrm{kg}}\right)\end{array}$
2
$\begin{array}{l}\left(b\right)\phantom{\rule{0.25em}{0ex}}\text{Total Nutrients in Manure}=\text{Total amount of manure produced}\phantom{\rule{0.25em}{0ex}}{\left(\frac{\mathrm{kg}}{\mathrm{d}}\right)}^{\left(c\right)}×\text{Concentration of nutrients in manure}\phantom{\rule{0.25em}{0ex}}\left(\mathrm{VS},\mathrm{N},\mathrm{P}\right){\left(\frac{g}{\mathrm{kg}}\right)}^{\left(d\right)}\end{array}$
3
$\begin{array}{l}\left(c\right)\phantom{\rule{0.25em}{0ex}}\text{Quantity of manure produced}\phantom{\rule{0.25em}{0ex}}\left(\frac{\mathrm{kg}}{\mathrm{d}}\right)=\text{Questionnaire}=\mathrm{ME}\phantom{\rule{0.25em}{0ex}}\text{value}\phantom{\rule{0.25em}{0ex}}\left(\frac{\mathrm{kg}}{1000\phantom{\rule{0.25em}{0ex}}\text{head}}·\mathrm{d}\right)×\text{The number of heads}\end{array}$
4
$\begin{array}{l}\left(d\right)\phantom{\rule{0.25em}{0ex}}\text{Nutrient concentration in manure}\phantom{\rule{0.25em}{0ex}}\left(\mathrm{VS},\mathrm{N},\mathrm{P}\right)\phantom{\rule{0.25em}{0ex}}\left(\frac{g}{\mathrm{kg}}\right)=\text{Values from sample}=\text{Values from}\phantom{\rule{0.25em}{0ex}}\mathrm{ME}\end{array}$
5
$\begin{array}{l}\left(e\right)\phantom{\rule{0.25em}{0ex}}\text{Quantity of compost produced}\left(\frac{\mathrm{kg}}{\mathrm{d}}\right)=\text{Mixture of manure and bulking material}\phantom{\rule{0.25em}{0ex}}{\left(\frac{\mathrm{kg}}{\mathrm{d}}\right)}^{\left(f\right)}×\left(1-\text{weight loss rate}\phantom{\rule{0.25em}{0ex}}{\left(%\right)}^{\left(g\right)}\right)\end{array}$
6
$\begin{array}{l}\left(f\right)\phantom{\rule{0.25em}{0ex}}\text{Mixture of manure and bulking material}\phantom{\rule{0.25em}{0ex}}\left(\mathrm{MMB}\right)\left(\frac{\mathrm{kg}}{\mathrm{d}}\right)=\text{Manure from questionnaire}\phantom{\rule{0.25em}{0ex}}{\left(\frac{\mathrm{kg}}{\mathrm{d}}\right)}^{\left(c\right)}+\text{Bulking material}\phantom{\rule{0.25em}{0ex}}\left(\frac{\mathrm{kg}}{\mathrm{d}}\right)=\text{Manure from}\phantom{\rule{0.25em}{0ex}}\mathrm{ME}\phantom{\rule{0.25em}{0ex}}\left(\frac{\mathrm{kg}}{\mathrm{d}}\right)+\text{Bulking material}\phantom{\rule{0.25em}{0ex}}\left(\frac{\mathrm{kg}}{\mathrm{d}}\right)\phantom{\rule{0.25em}{0ex}}\end{array}$
7
$\left(g\right)\phantom{\rule{0.25em}{0ex}}\text{Rate of weight loss}\phantom{\rule{0.25em}{0ex}}\left(%\right)=1-\frac{\text{Quantity of compost produced}\phantom{\rule{0.25em}{0ex}}\left(\frac{\mathrm{kg}}{\mathrm{d}}\right)}{\text{Mixture of manure and bulking material}\phantom{\rule{0.25em}{0ex}}\left(\frac{\mathrm{kg}}{\mathrm{d}}\right)}\phantom{\rule{0.25em}{0ex}}\mathit{\text{in}}\phantom{\rule{0.25em}{0ex}}\text{Questionnaire}\phantom{\rule{1.5em}{0ex}}$
8
$\begin{array}{l}\begin{array}{l}\text{Weight loss rate}\phantom{\rule{0.25em}{0ex}}\left(%\right)=\text{Theoretical}\phantom{\rule{0.25em}{0ex}}\mathrm{P}\phantom{\rule{0.25em}{0ex}}\text{content changes}=0=\mathrm{\Delta P}=0=\phantom{\rule{0.5em}{0ex}}1\phantom{\rule{0.5em}{0ex}}-\phantom{\rule{0.5em}{0ex}}\frac{\left(\frac{\text{Total concentration of}\phantom{\rule{0.25em}{0ex}}\mathrm{P}\phantom{\rule{0.25em}{0ex}}\text{in manure}\phantom{\rule{0.25em}{0ex}}\left(\frac{\mathrm{kg}}{\mathrm{d}}\right)}{\text{Total concentration of}\phantom{\rule{0.25em}{0ex}}\mathrm{P}\phantom{\rule{0.25em}{0ex}}\text{in compost}\phantom{\rule{0.25em}{0ex}}\left(\mathrm{kg}\right)}\right)}{\text{Mixture of manure and bulking material}\phantom{\rule{0.25em}{0ex}}\left(\frac{\mathrm{kg}}{\mathrm{d}}\right)}\phantom{\rule{0.5em}{0ex}}\mathit{\text{in}}\phantom{\rule{0.5em}{0ex}}\text{Deep}\phantom{\rule{0.5em}{0ex}}\text{litter}\phantom{\rule{0.5em}{0ex}}\text{compost}\phantom{\rule{0.5em}{0ex}}\left(\text{broiler}\phantom{\rule{0.5em}{0ex}}\text{and}\phantom{\rule{0.5em}{0ex}}\text{layer}\right)\\ \end{array}\\ =\phantom{\rule{0.5em}{0ex}}1\phantom{\rule{0.5em}{0ex}}-\phantom{\rule{0.5em}{0ex}}\frac{\text{Total concentration of}\phantom{\rule{0.25em}{0ex}}\mathrm{P}\phantom{\rule{0.25em}{0ex}}\text{in}\phantom{\rule{0.25em}{0ex}}\mathrm{MMB}\phantom{\rule{0.25em}{0ex}}\text{before composting}\left(\frac{\mathrm{mg}}{\mathrm{kg}}\right)}{\text{Total concentration of}\phantom{\rule{0.25em}{0ex}}\mathrm{P}\phantom{\rule{0.25em}{0ex}}\text{in compost}\phantom{\rule{0.25em}{0ex}}\left(\frac{\mathrm{mg}}{\mathrm{kg}}\right)}\phantom{\rule{0.5em}{0ex}}\mathit{\text{in}}\phantom{\rule{0.25em}{0ex}}\text{drying and simple static pile compost}\end{array}$
9
$\begin{array}{l}\text{Weight loss rate}\phantom{\rule{0.25em}{0ex}}\left(%\right)=\mathrm{Dry}\phantom{\rule{0.25em}{0ex}}\text{basis of}\phantom{\rule{0.25em}{0ex}}\mathrm{dry}\phantom{\rule{0.25em}{0ex}}\text{compost}=1-\frac{100-\text{Moisture content of manure}\phantom{\rule{0.25em}{0ex}}\left(%\right)}{100-\text{Moisture content of compost}\phantom{\rule{0.25em}{0ex}}\left(%\right)}\phantom{\rule{0.25em}{0ex}}\mathit{\text{in}}\phantom{\rule{0.25em}{0ex}}\mathrm{dry}\phantom{\rule{0.25em}{0ex}}\text{basis of}\phantom{\rule{0.25em}{0ex}}\mathrm{dry}\phantom{\rule{0.25em}{0ex}}\text{compost}\end{array}$
10

Scenario construction for NLC calculation

Nutrient concentrations were calculated for the total amount of manure and compost nutrients. The statement of farmers through questionnaire is not precise, so, to get accurate picture several combinations of scenarios were considered.

1. The total amount of nutrients in manure:

There were total three cases constructed for total amount of nutrients produced from manure using Eq. 4 and Eq. 5. Case I was calculated by multiplying the total amount of manure produced in farm investigation by the concentration of nutrients present in farm samples. The volume (m3) of manure as claimed by farmers was first converted into weight (kg) through bulk density of sample (kg/m3) and then was divided by number of days (kg/d). Case II was calculated by considering the manure production from reports of (ME) and then multiplied by the concentration of nutrients in farm samples. For Case III both the manure production and concentrations of the nutrients were taken from ME reports. For broiler and layer deep litter method, only case II was used for manure production calculations because it was not possible to investigate on farm due to the immediate mixing of manure with litter whereas for layer-drying and layer simple static pile composting all three cases of manure production were considered.

• b. The total amount of nutrients in compost:

The quantity of compost was calculated using Eq. 6 and Eq. 7. The scenarios for total amount of nutrients present in compost based on weight reduction rate were total of three cases. All three scenarios are denoted by capital alphabets (A, B, and C). Scenario A was the amount of weight reduction as observed in the farm compost in this study (Eq. 8). The compost volume (m3) was converted to weight (kg) through bulk density of compost (kg/m3) and then it was divided by number of days (kg/d). Scenario B was the comparison of phosphorus concentrations in manure and compost Eq. (9), assuming the theoretical P losses during the composting process, concentration in the manure, and to estimate the production of compost. It means that the total amount of Phosphorus in the composting process is theoretically unchanged. Phosphorus losses during the composting process are theoretically zero (ΔP = 0) but it is reported as it was lost, actually loss occurs due to leakage caused by leachate or run-off [15], discharge of nutrients due to leachate or run-off should be included in the nutrient load due to soil movement and water environment (Eq. 9). Scenario C was the weight reduction rate based on dry basis of the manure and compost by ignoring moisture content (Eq. 10).

## Results and discussions

Farm investigation

Table 1. Basic information obtained from investigated farms through questionnaire
Contents Broiler Layer
The number of farms 11 16
Breeding period (days) 35 365
Farm size (The number of poultry at a time) 73,363 ± 30,303 59,813 ± 48,410
The number of heads per farm 115,000 ± 92717a
Annual litter reuse (times/year) 1.5 ± 0.7
Bulking material used Rice hull Rice hull and sawdust or no bulking material
Daily litter usage per head (g/head.day) 10.4 ± 13 17.3 ± 17.6
Daily manure production (kg/day) 9833 ± 7927 7223 ± 6057
Daily compost production (kg/day) 1092 ± 942 2405 ± 3057
Daily compost produced per head (g/head.day) 14.8 ± 12 35.9 ± 21

acalculated from the number of the litter exchange

The survey of 16 layer hen farms was done. The number of heads averaging 59,813 ± 48,410 and ranged from 6500 to 150,000, bred throughout the year. The laying hens’ manure management is largely divided into two types, either litter is spread on the flat surface there manure is excreted directly on litter or in caged breeding where manure is accumulated under the cage and later on it is transferred to composting facility for composting. First method of litter composting is similar to the broiler composting method while caged composting method is divided into dry composting and simple static pile composting. Dry composting uses a method of in-house drying or machine drying. In simple static pile composting the manure is mixed with bulking material. A total of 3 farms were using littering compost, 4 farms were using dry composting, and 9 farms were using simple static pile composting. The excretion of manure by laying hens was 116 ± 16 g/head.day, which was similar to that of 127 g/head.day, reported by ME. Either rice hull or sawdust was used as bulking material averaging 17.3 ± 17.6 g/head·day per laying hen while in dry composting no bulking material was used. The average daily amount of compost produced was 35.9 ± 21 g/head·day.

Nutrient production in poultry manure and compost:

Since, broiler manure could not be sampled because manure was mixed with litter immediately after excretion, hence, nutrient values of 12.9 g N/kg and 4.7 g P/kg of broiler N and P reported by the ME were obtained. Production of nutrients in manure and compost can be observed in Table 2. The mean VS, N, and P concentrations of compost were 157.0 g VS/kg, 29.8 g N/kg, and 8.7 g P/kg.

Table 2. Nutrient production and concentrations in manure and compost of broiler and laying hens
Contents Daily production per head (g/head·d) Moisture content (%) Bulk density (kg/m3) Nutrients Concentrations (g/kg)
Broiler Manure 85.5a VS b
N 12.9a
P 4.7a
Compost 14.8 ± 11.5 33.1 ± 9.3 257.3 ± 75.8 VS 157.0 ± 55.8
N 29.8 ± 22.9
P 8.7 ± 5.6
Layer Manure 116 ± 16.2 74.0 ± 2.3 998.0 ± 68.8 VS 175.2 ± 30.1
N 13.3 ± 2.7
P 3.9 ± 1.3
Compost Deep litter 52.8 ± 44.8 51.1 ± 11.8 462.7 ± 116.1 VS 333.3 ± 36.0
N 19.5 ± 8.3
P 5.5 ± 0.7
Drying 35.4 ± 15.1 24.4 ± 2.2 431.7 ± 199.0 VS 642.5 ± 61.6
N 29.4 ± 12.9
P 13.8 ± 3.7
Simple static pile 30.4 ± 7.6 39.1 ± 22.7 338.3 ± 90.3 VS 387.0 ± 148.3
N 21.2 ± 8.1
P 6.6 ± 1.8
Average 35.9 ± 20.5 385 ± 131 VS 441 ± 166
N 23 ± 9.6
P 8.2 ± 4.0

bOrganic component of the ME is not to be compared referred to as BOD

The VS, TN, and TP contents of layer hens’ manure was 175.2 ± 30.1, 13.3 ± 2.7, and 3.9 ± 1.3 g/kg respectively. TN and TP both had higher values than reported by ME (8.8 g N/kg and 3.2 g P/kg). The average nutrients obtained in layer compost were 441 ± 166 g VS/kg, 23 g N/kg, and 8.2 g P/kg. Whereas, in case of laying hens’ deep litter compost the concentrations were 333.3 ± 36.0, 19.5 ± 8.3, and 5.5 ± 0.7 g/kg for VS, TN, and TP respectively. For the dry compost, the concentrations were 642.5 ± 61.6, 29.5 ± 12.9, 13.8 ± 3.7 g/kg for VS, TN, and TP respectively, while for simple static pile compost the concentrations were 387.0 ± 148.3, 21.2 ± 8.1, and 6.6 ± 1.8 g/kg while for the dry compost, it was 642.5 ± 61.6, 29.5 ± 12.9, 13.8 ± 3.7 g/kg for VS, TN, and TP respectively. Nutrient concentrations in the dry compost were higher and there was no significant difference found between litter compost and simple static pile compost. Since, dry compost only evaporates water from manure and it will not have same characteristics as of other compost i.e. humification and pathogen removal.

Weight reduction during composting and storage process:

In order to calculate the weight loss during composting period, the amount of manure and compost should be investigated but the total amount of broiler manure could not be surveyed. The weight reduction rates for broiler and layer can be seen in Table 3. The field survey showed that the weight loss rate during the composting process was reduced by 86% and the weight loss rate calculated by the phosphorus concentration difference between manure and compost (ΔP = 0) decreased by 45%.

Table 3. Weight reduction cases (%) for broiler and laying hen according to composting method
Weight reduction cases Broiler (% weight reduction) Layer (% weight reduction)
Deep litter Deep litter Drying Simple static pile
A (Farm Investigation) 86 ± 11 67 ± 28 64 ± 15 77 ± 5
B (ΔP = 0) 45 ± 18 54 ± 6 68 ± 12 49 ± 15
C (Dry basis) 86 ± 4

The weight loss rate of each laying hen’s composting method was obtained to calculate the NLCs. The weight loss rate was calculated as the ratio of manure to compost, but in case of litter, the manure could not be sampled on site because it was mixed with litter immediately as it was excreted. Therefore, the weight loss rate was calculated by citing the data of the ME only in the portion of manure generated in the litter house. During the composting process the weight loss rate decreased by 67% in litter compost, 64% in dry compost, and 77% in simple static pile compost. The weight reduction rate calculated by P concentration change (ΔP = 0) was found to be reduced by 54% in litter composting, 68% in dry composting, and 49% in simple static pile composting. The dry contents of the dry compost were calculated by using the water content difference between manure and compost. The weight loss rate of 86% was calculated by this method. Thompson et al. (1996) has reported a 67.2% weight reduction of raw manure of egg laying hen while 72-82% weight reduction after composting with pine shavings for 246 days using deep litter system [21].

Table 4. Nutrient loading coefficients according to manure production & weight reduction cases (Deep litter composting)
Weight reduction scenarios Manure production casesa
Nutrients Broiler Layer
A (Farm Investigation) VS b b
N 0.32 0.79
P 0.23 0.67
B (ΔP = 0) VS b b
N 1.22 1.51
P c c

aManure production reported from ME x nutrient concentrations in compost from farm samples

bOrganic component of the ME is not to be compared referred to as BOD

cP coefficient is 1.0

In case of drying manure, the NLCs calculated from farm investigation for the [Case I x A], the VS, N, and P with the values of 1.44, 0.90, and 1.33 respectively (Table 5). For [Case I x B] the VS, N, and P were 1.36, 0.64, and 1.00 respectively. For [Case I x C] the values were 0.56, 0.33, and 0.47 respectively. The Case I and Case II had similar values. The reduction of N for case I was 10% for scenario A, 36% for scenario B, and 67% for scenario C while for P an increase of 33% was seen for scenario A and 0% for scenario B. The NLCs for P should not be more than 1.00 as NLC for farm investigation increased P due to drying therefore; NLCs were calculated on dry basis of the manure and compost (scenario C) that gave lowest NLCs among all scenarios (VS, 0.56; N, 0.33; P, 0.47) and are considered to be the most reliable. Because the composting method is drying in the house or drying by the machine, it seems that the nitrogen stored at high temperature and caused high reduction due to volatilization and since the decrease of nutrients seems to be large due to the occurrence of the leachate in the anaerobic state. In order to calculate the nutrient loading including the nutrients of the leachate, farm investigations scenarios 1 and 4 are considered to be appropriate for the reason of mixed feeds, instead of Scenario 2 and 5. For case III, N and P has shown an increase of 35% and 64% for scenario A while reduction of 20% and 0% for scenario B and 50% and 42% for scenario C respectively.

Table 5. Nutrient loading coefficients according to manure production & weight reduction cases (Dry composting)
Weight reduction scenarios Manure production cases
Nutrients Case Ia Case II Case III
A (Farm Investigation) VS 1.44 1.44 b
N 0.90 0.90 1.35
P 1.33 1.33 1.64
B (ΔP = 0) VS 1.36 1.36 b
N 0.64 0.64 0.80
P c c b
C (Dry basis) VS 0.56 0.56 b
N 0.33 0.33 0.50
P 0.47 0.47 0.58

aCase I, manure production from questionnaire x nutrient concentrations in compost from farm sample; Case II, manure production reported by ME x nutrient concentrations in compost from farm sample; Case III, manure production reported from ME x nutrient concentrations in compost from ME

bOrganic component of the ME is not to be compared referred to as BOD

cP coefficient is 1.0

In case of simple static pile, the NLCs calculated are summarized in the Table 6. The NLCs calculated from farm investigation for the [Case I x A], the VS, N, and P with the values of 0.52, 0.44, and 0.48 respectively. For [Case I x B] the VS, N, and P values were 1.2, 0.95, and 1.00 respectively. The manure Case I and Case II had more or less similar values. The reduction of N was 56% for scenario A and 5% for scenario B while for P, 52% and 0% reduction was seen for scenario A and scenario B. For case III that was calculated using ME reports for manure data, N and P has shown a reduction of 38% and 48% for scenario A, respectively while an increase of 19% and 0% for scenario B, respectively. The nitrogen reduction rate was lower than that of the dried compost, and VS and phosphorus were similar. Even lower than the scenario 2 and 4 that was because the laying manure was deposited for a certain period of time before mixing with sawdust and the nutrients were decreased due to leaching.

Table 6. Nutrient loading coefficients according to manure production & weight reduction cases (Simple static pile composting)
Weight reduction scenarios Manure production cases
Nutrients Case Ia Case II Case III
A (Farm Investigation) VS 0.52 0.51 b
N 0.44 0.43 0.62
P 0.48 0.47 0.52
B (ΔP = 0) VS 1.20 1.20 b
N 0.95 0.95 1.19
P c c c

aCase I, manure production from questionnaire x nutrient concentrations in compost from farm sample; Case II, manure production reported by ME x nutrient concentrations in compost from farm sample; Case III, manure production reported from ME x nutrient concentrations in compost from ME

b = Organic component of the ME is not to be compared referred to as BOD

c = P coefficient is 1.0

The NLCs for VS were higher than 1.0 due to the addition of bulking material except for simple static pile where 48% VS was lost may be due to long period of composting. In case of ME values (case III) the VS were reported as BOD so it was not considered. Maximum N reduction was seen for broilers (69%) and for Layer in the range of 10-56% in farm investigation. Morand et al. 2005 reported a decrease of 61-74% of initial N in poultry manure composting while Ghaly et al. 2013 has reported a 44-55% N loss during poultry manure drying [10, 22]. The loss of phosphorus for broiler was78% and for layer it was in the range of 33-52% in farm investigation. Phosphorus is usually lost either by leaching or run off during composting. Vadas et al. (2004) has reported that the P contents of poultry manure decreased by 50% before composting due to dilution with low P composting materials [23]. Theoretically, the amount of P cannot be changed as the VS and N are reduced due to the oxidation of the materials. The P amount can be the indicator for weight loss as P is not removed from compost [7]. Uptake of P by microbes occurs but it remains in the system (as poly-PO4) hence weight reduction rates for P in scenario B were 1.0. The NLCs were largely influenced by the weight reduction due to composting method and storing period instead of manure production amount [7].

## Conclusions

Overestimation of the nutrients for the agricultural land has surpassed cropland demand. So, to stop eutrophication and over nourishment of the land it is feasible to calculate nutrient budget. In this study, the nutrients in manure from farm investigation were lost due to microbial action, storing, and drying during composting period. During farm investigation of broiler and layer litter, there was a 68 and 21% N loss whereas 77 and 33% P loss was found, respectively. In case of layer composting, a loss of 10-56% N and a 52% P loss was observed. Drying manure increased the P concentrations therefore NLCs calculated using dry basis that showed quite higher reductions (67% N; 53% P). In all cases the nutrient losses calculated were higher than those of ME. This suggests that the mass balance of poultry manure nutrients applied over cropland is overestimated and needs to be corrected and updated. To stop over nutrient application the proper national nutrient management program should be created.

#### Abbreviations

BOD

Biological oxygen demand

C

Carbon

°C

Degree Celsius

CH4

Methane

Cl

Chlorine

CO2

Carbon dioxide

d

Day

DOC

Dissolved organic carbon

Eq.

Equation

g

Gram

h

Hour

HCO3

Bicarbonate

K

Potassium

kg

Kilogram

kt

kilo tons

L

Litter

M

Million

m3

Cubic meter

ME

Ministry of Environment

mg

Milligram

MMB

Mixture of manure and bulking material

N

Nitrogen

N2O

Nitrous oxide

Na

Sodium

NH3

Ammonia

NLC

OECD

The Organization for Economic Co-operation and Development

P

Phosphorus

PO4

Phosphate

S

Sulfur

TN

Total nitrogen

TP

Total phosphorus

TS

Total solids

VS

Volatile solids

ΔP

Changes in phosphorus concentrations

## Acknowledgements

This research was achieved with the financial supports by the Rural Development Administration of Korea (project number, PJ011623) and partially by Kangwon National University. Thanks are also extended to the Poultry farms supplying samples.

Ethical approval and consent to participate

Not applicable.

Funding

Funded by Rural Development Administration of South Korea and Kangwon National University.

Availability of data and materials

Upon reasonable request, the datasets of this study can be available from the corresponding author.

## Authors’ contributions

CR and SW conceptualized and designed the study, BGY, SS, and SK collected data, SW, BGY, and NA analyzed and interpreted the data, SW and NA drafted the manuscript, and CR supervised the study and critically revised the manuscript. SW and NA contributed equally. All of the authors have read and approved the final manuscript.

## Notes

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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