Herndl M.1, Marton S.M.R.R.2, Baumgartner D.U.2, Guggenberger T.1, Steinwidder A.1 and Gaillard G.1
1AREC Raumberg-Gumpenstein, Irdning-Donnersbachtal, Austria; 2Agroscope, Life Cycle Assessment Group, Zurich, Switzerland; markus.herndl@raumberg-gumpenstein.at
Abstract
In Austria 70% of all dairy farms are located in grassland areas. Although grassland-based milk production is dominating, concentrate and N fertiliser are used in varying amounts to increase farm milk output.
These agricultural inputs are purchased externally or produced internally on the own arable farm area. In a case study, we analysed how the concentrate and nitrogen input and origin influenced the environmental performance of thirteen grassland-based and nine arable-based dairy farms in Austria. As a main result of the life cycle assessment, the amount and origin of concentrate significantly influenced the environmental impact categories P resource use, land competition, terrestrial ecotoxicity, deforestation and aquatic eutrophication N per kg milk at farm gate. Total and purchased N input correlated positively with the P resource use, deforestation and aquatic eutrophication nitrogen, purchased N input correlated negatively with global warming potential and land competition. Grassland-based dairy farms showed a higher global warming potential and land competition, but a lower P resource use and deforestation potentials per kg milk compared to the arable-based farms.
Keywords: life cycle assessment, agricultural inputs, environmental impacts, milk production
Introduction
On arable land, both the direct production of feed as well as those of feed as silage maize or clover grass is possible. In areas with natural or other specific constraints, an arable use is less viable. Thus, grassland to produce fodder for roughage consuming animals is predominant. These main differences have not only implications on dairy farm management, milk cow feeding and agricultural inputs use, these distinctions have also effects on the environmental impacts of the output. Model studies from O’Brien et al. (2012) and Bystricky et al. (2014) showed differentiated pictures of the environmental impacts depending on feeding and agricultural resource input. In this paper, we analysed if the theoretical observed differences between grassland and arable based production can be observed in a sample of practical farms.
Materials and methods
Farm management data were obtained from the project ‘FarmLife’ where in total 22 dairy farms were examined with regard to their environmental performance (Herndl et al., 2016). The farms were classified based on the dry matter intake of dairy cows. If dry matter intake from grass was higher than 80% of the ration, farms were considered as grassland-based (GB, n=13), otherwise as arable-based (AB, n=9).
To test the impact of the different agricultural input use to environmental impacts, the parameters concentrate input (home-grown, purchased) and nitrogen input (manure from own animals, purchased – mineral and organic) were used. The environmental performance was analysed using life cycle assessment.
The life cycle inventory was computed with the tool FarmLife-Calculate (Herndl et al., 2016), the impact assessment was performed with the software SimaPro v7.3. The system-boundary is limited to the dairy enterprise of the farm and the functional unit is kg milk at farm gate. The attribution of emissions to milk and its coproduct meat was based on economic allocation. The analysed environmental impacts are described in Bystricky et al. (2014) and are as follows: land competition, P resource use, deforestation, non-renewable energy demand, global warming potential, aquatic eutrophication nitrogen and phosphorous
and terrestrial ecotoxicity. Statistical analyses were conducted using procedures of the SAS program (SAS Institute, 2000). Linear regressions were performed with Excel.
Results and discussion
The average annual milk production of the GB farms was 129,698 kg and of the AB farms 231,365 kg.
The total concentrate input, home-grown concentrate, and N purchased were higher in AB farms and N originated from animals (own production) was lower than in GB farms (Figure 1). Significant differences (P<0.05) of the two farm types regarding environmental impacts were observed for land competition, P resource use, deforestation and global warming potential. Similar differences were also observed by a model study of Bystricky et al. (2014).
The high scattering of some environmental impacts refers to a possible optimising potential. To identify influencing variables, a linear regression analysis was made. A higher total concentrate input per kg milk led to higher P resource use, deforestation and terrestrial ecotoxitcity per kg milk (Table 1). The same correlation was observed for concentrate purchased, which had in addition a positive correlation with aquatic eutrophication nitrogen. This was also found in the study of and Hörtenhuber et al. (2013).
Home-grown concentrate showed only a positive correlation to the impact category land competition.
A positive linear correlation was found between total N input (mineral fertiliser and farm manure) and P resource use, deforestation and aquatic eutrophication N. Organic nitrogen originating from own animals positively correlated with the non-renewable energy demand whereas N purchased had a positive relation to aquatic eutrophication N.
Figure 1. Agricultural inputs and environmental impacts per kg milk at farm gate of grassland and arable-based dairy farms (results are expressed as common logarithm to harmonise the scale. Means are significant different at P<0.05, n=22; outliers are marked with circles).
Conclusions
There are several differences in farm management between GB and AB dairy farms. These distinctions range from varying milk cow feeding to different agricultural inputs use, however, with effects on the environmental impacts of the output. The analysis performed in this paper showed not only the differences in the environmental performance of the two farm types, it also showed how agricultural inputs influence environmental impacts of the output milk. Concluding, the efficient use of especially purchased concentrate can be an optimising potential for GB farms, whereas an effective use of particularly purchased N can help in lowering the environmental impacts for AB farms.
References
Bystricky M., Alig M., Nemecek T. and Gaillard G. (2014) Ökobilanz ausgewählter Schweizer Landwirtschaftsprodukte im Vergleich zum Import. Agroscope Science 2.
Herndl M., Baumgartner D.U., Guggenberger, T., Bystricky M., Gaillard G., Lansche, J., Fasching, C., Steinwidder, A. and Nemecek T. (2016) Abschlussbericht FarmLife – Einzelbetriebliche Ökobilanzierung landwirtschaftlicher Betriebe in Österreich. HBLFA Raumberg-Gumpenstein, Irdning-Donnersbachtal, Österreich und Agroscope, Zürich, Schweiz, Abschlussbericht, BMFLUW.
Hörtenhuber S., Kirner L., Neumayr C., Quendler E., Strauss A., Drapela T. and Zollitsch W. (2013) Integrative Bewertung von Merkmalen der ökologischen, ökonomischen und sozial-ethischen Nachhaltigkeit landwirtschaftlicher Produktionssyteme am Beispiel von Milchproduktionssystemen (‘Nachhaltige Milch’). Universität für Bodenkultur Wien, Bundesanstalt für Agrarwirtschaft, Abschlussbericht, BMFLUW.
O’Brien D., Shalloo L., Patton J., Buckley F., Grainger C. and Wallace M. (2012) Evaluation of the effect of accounting method, IPCC v. LCA, on grass-based and confinement dairy systems’ greenhouse gas emissions. Animal 6, 1512-1527.
SAS Institute Inc (2000) SAS/STAT user’s guide. Cary, NC, USA.
Table 1. Correlation coefficients between environmental impacts and agricultural inputs per kg milk at farm gate.
Environmental impacts Milk yield
Non-renewable energy demand -0.47* +0.03 +0.29 -0.38 +0.26 -0.19 +0.58**
Global warming potential -0.61** +0.24 +0.03 -0.46 -0.10 -0.52* +0.82***
P resource uses +0.41 +0.66*** +0.62** +0.23 +0.56** +0.66*** -0.44*
Land competition +0.60*** -0.06 +0.02 +0.51* -0.16 -0.62** +0.70***
Deforestation +0.50* +0.53* +0.53* +0.13 +0.71*** +0.89*** +0.44*
Aquatic eutrophication N +0.49* +0.38 +0.48* -0.13 +0.57** +0.55** -0.08
Aquatic eutrophication P -0.20* +0.03 +0.29 -0.37 +0.24 -0.10 +0.36
Terrestrial ecotoxicity +0.20 +0.48* +0.65** -0.11 +0.41 0.35* -0.23
* P<0.05; ** P<0.01; *** P<0.001.