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Stand Density Texture pH O.M. (%) N (%) C/N Pine 1,20 Loam 4.71 4.99 0.26 11.16 Douglas Fir 1,26 Clay-Loam 4.25 7.55 0.32 13.72 Beech 1,02 Clay-Loam 4.41 8.38 0.42 11.60 Nitrous oxide emissions were measured using a closed chamber technique (Menendez et al., 2008) every two weeks from January 2010 to December 2011. Emission rates were calculated taking into account the concentration increase in time within the chamber. Samples were analysed by gas chromatography (Agilent, 7890A) with an electron capture detector. A capillary column (IA KRCIAES 6017: 240ºC, 30 m × 320 µm) was used. The column’s temperature ramped from 40ºC to 80ºC and ECD’s temperature was 350ºC, and 5% mixture of Ar with CH4 was used as carrier and N2 as make up (15 ml min-1). A headspace autosampler (Teledyne Tekmar HT3) was connected to the gas chromatograph. Standards of N2O were stored and analysed at the same time as samples.
Cumulative N2O emissions along the experiment were estimated by averaging the fluxes of two successive determinations, multiplying that average flux by the length of the period between the measurements, and adding that amount to the previous cumulative total.
3. Results & Discussion Among the coniferous species stands, Douglas fir had higher soil organic matter and nitrogen (N) contents than radiata pine (Table 1). These differences in soil properties are likely responsible for the approximately four times higher cumulative N2O emissions determined in the Douglas fir stand than in radiata pine over the two years of the study. These cumulative emissions were of 522 and 126 g N2O-N ha-1 for Douglas fir and radiata pine, respectively (Figure 1). In the case of Douglas fir
4. Conclusion In the Basque Country edaphoclimatic conditions, N2O emissions from measured stands soils are higher in radiata pine and Douglas fir, being around 10 and 50 times higher respectively, than in beech stands.
Acknowledgement: This project was funded by the Spanish Government (AGL2009-13339-CO2-01), by the Basque Government (K-EGOKITZEN, ETORTEK 2010-2012) and by the University of the Basque Country (IT526-10). I.
Barrena is the recipient of a predoctoral fellowship from the Department of Education, Universities and Investigation of the Basque Government.
References Dallal, R.C. and Allen, D.E. 2008. Greenhouse gas fluxes from natural ecosystems. Australian Journal of Botany 56, 369-407.
Inventario Forestal 2005. 2005. Departamento de Agricultura, Pesca y Alimentación, Gobierno Vasco.
Menéndez, S., Lopez-Bellido, R.J., Benitez-Vega, J., Gonzalez-Murua, C., Lopez-Bellido, L. and Estavillo, J.M. 2008.
Long-term effect of tillage, crop rotation and N fertilization to wheat on gaseous emissions under rainfed Mediterranean conditions. European Journal of Agronomy 28, 559-569.
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Nitrate leaching to the groundwater investigated for different management practices of organic farming and wine growing Feichtinger, F., Scheidl, A.
Federal Agency for Water Management, Institute for Land and Water Management Research, Petzenkirchen, Austria
1. Background & Objectives Exceeding the limit value of the nitrate concentration for drinking water in a regional groundwater body caused a scientific programme addressing this issue. The nitrate concentration of the seepage water should be investigated for different management practices of organic farming and of vine yard cultivation.
2. Materials & Methods Different types and dates of tillage with and without intercropping have been investigated for organic farming. Bare soil, permanent grassland and temporary grassland between the vine stocks have been investigated as varieties of vineyard management. The experiment is designed in that way that soil water has been collected at the lower end of the rooting zone during periods of leaching using suction cups, collecting bottles and a vacuum pump, which is controlled by a soil water sensor.
3. Results The instrumentation in the field was finished in October 2011 and during the coming winter half year percolating water will be collected for the first time. The experiment will be described in detail and first results will be presented.
4. Conclusion The investigations are a contribution to find management practices for organic farming and wine growing, where the nitrate concentration of the seepage meets the limit value for drinking water.
Nitrogen Workshop 2012 Nitrogen balances of Swiss agriculture from 1975 to 2009 Spiess, E.a a Agroscope Reckenholz-Tänikon Research Station ART, Reckenholzstrasse 191, CH-8046 Zurich, Switzerland
1. Background & Objectives The progressive intensification of Swiss agriculture after World War II, characterized by growing inputs of nitrogen (N), resulted in a strong increase in productivity but also in rising environmental and health problems. An efficient reduction of ammonia and nitrous oxides emissions to air and nitrate losses to water requires a thorough knowledge of N flows in agriculture, e.g. by calculating N balances. In 1994 the first farm-gate balance of N was calculated for Swiss agriculture on behalf of the International Commission for the Protection of the Rhine (ICPR) and the Oslo and Paris Conventions for the Prevention of Marine Pollution (OSPAR). In 1996 N balance became a major agri-environmental indicator for monitoring the environmental performance after the introduction of direct payments bound to integrated production (IP), organic agriculture and other ecological programmes. The objective of this paper is to present the time course of N balances of Swiss agriculture in the last decades.
2. Materials & Methods The farm-gate balance is mainly encouraged by OSPAR and essentially considers the agricultural production system to be a "black box". This balance is calculated as the difference between total imports from abroad and other economic sectors into agriculture, on the one hand, and total exports of agricultural products, on the other (OSPAR 1995). Inputs into agriculture comprise imported feedstuffs, mineral fertilizers, recycling and other fertilizers (sewage sludge, compost, etc.), imported seed (negligible for Switzerland and, therefore, not presented in the following), biological N fixation and atmospheric deposition. Outputs from agriculture encompass plant (bread cereals, table potatoes, etc.) and animal foodstuffs (milk, meat, eggs, etc.) and other animal products (byproducts of meat production such as hides, animal meal, etc.). The balance, i.e. the difference between nutrient inputs and outputs, is in most cases positive (= surplus) and comprises the changes in soil nutrient stocks (increase or decrease in nutrient contents of soil) and total nutrient losses. A detailed description of used methods is found in Spiess (2011).
3. Results & Discussion In 2009, 150 kg N ha-1 of utilized agricultural area (UAA) entered the agricultural sector of Switzerland, with mineral fertilizer, imported feedstuffs and biological N fixation being the largest input sources (Figure 1a). In contrast, 44 kg N ha-1 left agriculture, with N quantities in animal foodstuffs and other products being more than three times larger than N in plant foodstuffs (Figure 1b). The resulting surplus amounted to 106 kg N ha-1. As changes in soil stocks are generally supposed to be insignificant for N, most of the N surplus may be lost through ammonia volatilization, nitrate leaching and denitrification.
Between 1975 and 1996, N input in imported feedstuffs was halved (Figure 1a). Demand for feed decreased because of lower animal numbers and N contents of pig feed. On the other hand, imported feedstuffs were partly replaced by a higher domestic production. Since 1996, however, imports of feedstuffs have been increasing by some 20 kg ha-1. More soybean meal has been imported following the ban on feeding animal meal due to the mad-cow disease (BSE) crisis in Switzerland. Use of mineral N fertilizer nearly doubled between 1975 and 1988. It then decreased until 1997 and has been more or less constant since then. The use of recycling and other fertilizers
Nitrogen Workshop 2012
decreased after 1997 because of the ban on sewage sludge application announced for 2006.
Biological N fixation, mainly originating from the large grassland area with grass-clover swards, remained constant over the whole period. N deposition steadily decreased after a slight increase until 1980. Not only nitrogen oxides emissions from traffic and industry but also ammonia emissions were reduced, the latter following a reduction in the animal population and thus the quantity of animal manure produced.
N outputs in foodstuffs and other products changed only slightly over time (Figure 1b). N surplus initially rose sharply to a maximum of 145 kg ha-1 in 1980, then decreased to 106 kg ha-1 in 1997 and remained at the same level until 2009. The accentuated reduction between 1992 and 1997 was principally due to the introduction of direct payments for ecological programmes such as integrated production in 1993. As a result, many farmers had to reduce their fertilizer use in order to comply with an equilibrated whole-farm nutrient balance. In 1997, most farmers were already participating in these programmes. Regarding the input items, substantial decreases were seen especially in deposition over the whole period and mineral fertilizer from 1988 onwards. The overall reduction in surplus between 1980 and 2009 amounted to 29%.
4. Conclusion Mineral fertilizer and imported feedstuffs turned out to be the major input items of N balance of Swiss agriculture. A further decrease in surplus requires farm managers to reconsider the size of these inputs into their farms. This might be achieved by increasingly using feeding and nutrient management plans, leading above all to lower nutrient excretion of livestock and an improved application of manure in time and space. Mineral fertilizer use, in return, might be reduced by better manure management.
References OSPAR (1995) PARCOM guidelines for calculating mineral balances. Summary record of the meeting of the programmes and measures committee (PRAM), Oviedo, 20–24 February 1995. Oslo and Paris Conventions for the Prevention of Marine Pollution (OSPAR), Annexe 15. http://www.ospar.org/documents/dbase/decrecs/agreements/95e.doc. Accessed 20 December 2011.
Spiess, E. 2011. Nitrogen, phosphorus and potassium balances and cycles of Swiss agriculture from 1975 to 2008.
Nutrient Cycling in Agroecosystems 91, 351-365.
Nitrogen Workshop 2012
Nitrogen dynamics in soil amended with acidified and non acidified cattle slurry and derived liquid fraction Fangueiro, D.a, Surgy, S.a, Coutinho J.b, Cabral, F.a a UIQA, Instituto Superior de Agronomia – Technical University of Lisbon, 1349-017 Lisbon, Portugal b C. Química, Dep Biologia e Ambiente, UTAD, Ap. 1013, 5001-911 Vila Real, Portugal
1. Background and Objectives Acidification of animal slurries is promoted to reduce ammonia emissions but there is little knowledge about the effect of such treatment on nitrogen dynamics after soil application. Previous works (Eriksen et al., 2008; Sorensen and Eriksen, 2009) showed that incorporation of acidified slurries can affect soil processes, namely the carbon and nitrogen dynamics and recently, Fangueiro et al. (2010), observed a delay in nitrification in soils amended with acidified pig slurry or derived liquid fraction, relative to untreated materials. However, no information is available concerning the effect of cattle slurry acidification on N dynamics in soil, and considering the different composition of pig and cattle slurries, it is to believe that acidification may lead to distinct effects in both slurries. Hence, in the present work, N mineralization and nitrification were monitored in a soil amended with untreated and acidified cattle slurry or derived liquid fraction.
2. Materials & Methods The liquid fraction (LF) of cattle slurry was obtained by centrifugation. Following this half of the LF and of the untreated slurry (US) were maintained at the original pH (10) and the second half was acidified to pH 5.5 to obtain the acidified slurry (AS) and acidified liquid fraction (ALF). 500 g of dry soil were mixed with US, AS, ALF or LF and placed into closed 1 L plastic containers. Distilled water was then added to reach 75% of soil water holding capacity. An aerobic incubation was performed over 58 days at 25°C. On days 0, 3, 6, 13, 22, 36, 50, 58 of the incubation period, 10 g of soil were sampled from each container and soil mineral N (NH4+-N and NO3--N) content was quantified. Based on the values of the NO3--N and total mineral-N concentrations obtained in each treatment, the net nitrification (NN) and net N mineralization (NNM), respectively, was calculated
at time t as follows:
NNt (mg N kg–1) = [NO3--N]t – [NO3--N]t=0 NNMt (mg N kg–1) = [total mineral N]t – [total mineral N]t=0.
Results were analyzed by analysis of variance (one way-ANOVA) to test the effects of each treatment and time independently. The statistical significance of the mean differences was determined by the least significant difference (LSD) tests based on a t-test at a 0.05 probability level. The statistical software package used was R.
3. Results & Discussion The NH4+-N concentration of US and LF amended soils rapidly decreased during the first days of incubation to reach the base line (control) on day 14 (Figure 1). The NH4+-N concentration remained constant during the first 3 days in the AS amended soil, then decreased until day 22 and finally stabilized but values were always significantly higher than in US amended soil. The NH4+ concentration in the ALF amended soils increased slightly during the first 5 days and then remained significantly higher than in all other treatments over the whole experiment. A similar trend of NH4+ concentration in soil amended with acidified and non acidified pig slurry and/or liquid fraction was observed in previous works (Plaza et al., 2005; Fangueiro et al., 2010) Net N mineralization was observed in all treatments over the incubation period and the N mineralization in soils amended with acidified slurry or LF was always significantly lower than in
Nitrogen Workshop 2012
soils amended with non acidified materials, in agreement with previous results reported by Sorensen and Eriksen (2009).