This study assessed the effect of turning on nitrous oxide (N2O) emissions during on-farm composting of cattle manure over an 11-day period in northern Spain. Turning of the manure piles occurred on the 8th day of monitoring. N2O emissions peaked on the day of turning for the dairy cattle manure pile that had been formed most recently, releasing over 80 mg N2O per m^2. In contrast, turning did not significantly increase N2O emissions from the older beef and dairy cattle manure piles. N2O emissions from the dairy pile returned to background levels two days after turning. The results suggest that turning induces N2O emissions from fresh cattle manure but

1. Short-term nitrous oxide emission after turning of composting
cattle manure
Viguria, M.1*, López, D.M.1, Alberdi, O.1, Arriaga, H.1, Merino, P.1
1NEIKER-Tecnalia, Environment Quality Department, 48160, Derio (Bizkaia), ES
*Corresponding author: mviguria@neiker.net
INTRODUCTION
10th April to 24th April 2012 in the North of Spain.
Turning: 13th April 2012.
MATERIAL & METHODS
Table 1. N2O measurement characteristics.
RESULTS
Acknowledgment. This work was cofinanced by the Ministry of Science and
Innovation (INIA. RTA 2011-00107-C02-01)
AERATION
Manure
heap
turning
Increase in
polluting
gases
emissions
N2O losses
(nitrification,
denitrification)
Important
factor in
manure
composting
Objective: to asses the effect of turning on N2O
emission during on-farm composting of beef and
dairy cattle manure.
Frequency 1st week: daily.
2nd - 3rd week: once/week.
Methodology 4 closed chambers/pile.
3.8 l volume, 314 cm2 area.
Sampling 0, 20, 50 min after chamber closure.
Collected in 9 ml gas vial.
Concentration Gas chromatography (GC-7890A, Agilent).
Emission Slope of the linear regression (R2>0.90)
between concentration and time.
Figure 1. (a) Beef and dairy cattle manure heaped since December
2011 (Bd and Dd, respectively) and dairy cattle manure heaped
since March 2012 (Dm).; (b) Gas sampling by closed chamber.
Manure (15 cm depth) and air temperature recorded
by 2 thermocouples/pile (TCdirect) and a datalogger
(HOBO U12-13), respectively.
Unaltered manure sampled 1 hour before and after
turning for density analysis.
Statistical analysis: repeated measurements of N2O
emission during 8 measuring days (SPSS 15.0).
Bd
Dm
Dd
Figure 2. N2O emission and temperature (ºC) during the study.
Turning was carried out on day pointed by an arrow.
Bd Dd Dm
Density before
turning (g l-1)
768 (122) 918 (91) 812 (57)
Density after
turning (g l-1)
767 (49) 914 (109) 504 (100)
N2O peak
(mg m-2 d-1)
0.0 21.4 (29.2) 80.8 (86.2)
Cumulative N2O
(8 days) (mg m-2)
8.7 52.4 157.7
Table 2. Density and N2O emission for Bd, Dd and Dm manure.
Mean (standard deviation).
(b)
(a)
Density in Dm decreased 38% after turning (p<0.05).
 Nitrous oxide emission from dairy cattle manure
decreased to background levels 2 days after turning.
CONCLUSION
Turning induced N2O emission in dairy cattle manure.
Higher maturity of manure heap could lead to lower N2O
emission after turning.