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Frame, J. (1991) Herbage production and quality of a range of secondary grass species at 5 rates of fertiliser nitrogen application. Grass and Forage Science, 46, 139-151.
Lalor, S. T. J. and Schulte, R. P. O (2008) Low-ammonia-emission application methods can increase the opportunity for application of cattle slurry to grassland in spring in Ireland. Grass and Forage Science 63, 531-544.
Lamb, J.F.S., Russelle, M.P. and Schmitt, M.A. 2005. Alfalfa and reed canary grass response to midsummer manure application. Crop Science, 45, 2293-2300.
Nitrogen Workshop 2012
Temporal dynamics of soil N mineralization during an oilseed rape (Brassica napus L.) growth cycle in one season´s growth under humid Mediterranean conditions Villar, N.a, Gallejones, P.b, Castellón, A.a, Besga, G.a,Aizpurura, A.a a NEIKER-Basque Institute for Agricultural Research and Development, Derio, Spain b BC3. Basque Centre for Climate Change. Bilbao, Spain
1. Background & Objectives Rapeseed (Brassica napus L.) cultivation has recently increased, due to its demand for biodiesel.
Rapeseed can accumulate N in its tissues during autumn (Malagoli et al., 2005), thus reducing N leaching during that season. In order to reduce N leaching, it is important to determine soil N mineralization and what can be done through the calculation of the N balance. There are many studies on oilseed rape but most have focused on the crop or the management of its residues (Hocking et al., 1997; Justes et al., 1999). Mineralization studies are mainly carried out under laboratory conditions (Sierra, 1997), and little is known about nitrogen balances in field. The aim of this work was to study the seasonal pattern of N mineralization throughout a whole year in a wheatrapeseed rotation, with and without fertilization, in a humid Mediterranean region.
2. Materials & Methods The study was conducted from August 23, 2006 (after the harvest of the previous wheat crop), along the whole growing cycle of rapeseed, until October 4, 2007 (before soil tillage previous to the following crop). Winter rapeseed (var. Standing) was sown on September 19, 2006 near Vitoria city (42º 49´N; 2º 30´W). The climate is Mediterranean humid with a mean annual temperature of 11,5 ºC and a total rainfall of 779 mm. During the rapeseed growing cycle, two N treatments were applied: no nitrogen application (0N) and 180 kg N ha-1 (180N) that was applied on two occasions (60 kg N ha-1 at beginning of stem elongation, and 120 kg N ha-1 at the beginning of inflorescence emergence). Oilseeds were harvested on July 18, 2007. Nitrogen balance was calculated as the difference between N outputs and inputs. Nitrogen outputs corresponded to: N absorbed by plants, N leached, N emitted and Nmin (the later three were measured every fortnight or when rainfall was over 20-30 mm). Nitrogen inputs corresponded to atmospheric deposition, N applied, Nmin at the beginning of each period and the N content in seeds at sowing. Mean N balance was calculated from the fortnightly balances among different periods. On the same sampling occasions, when N leached, Nemitted and Nmin were measured, soil humidity was also recorded to obtain the percentage of soil pores filled with water (PPFW), using equation  Where, H is soil humidity (%) and BD is the bulk density (g cm-3)  H * BD PPFW without stones.
1 (BD 2.65)
3. Results & Discussion Total N mineralization during the period of study was 70±22 kg N ha-1 for 0N and 99±15 kg N ha-1 for 180N treatments, but the difference was not significant. From the beginning of the experiment until stem elongation, mineralization was close to 0 for both treatments (Figure 1), due to low temperatures during winter (often below 5 ºC). After both N applications, fertilized plots showed immobilization, which was higher after the second N application. Microorganisms compete with plants for the N applied (Nielsen and Jensen, 1986). Plots without N (0N) also experienced a reduction in mineralization after inflorescence emergence (from 0.5 to 0.1 kg N ha-1 day-1). This may have been due to the heavy rain in March which saturated soil pores, limiting N mineralization
4. Conclusion Mineralization and immobilization patterns depend on environmental factors and also on the addition of mineral N fertilizer. Nitrogen immobilization was recorded after both N applications, but under favourable environmental conditions (field capacity and temperature above 15 ªC) N mineralization was also higher when N was applied.
Acknowledgements This work has been financially supported by the Spanish government (Project nº RTA2009-00028-C03-01) and the Department of the Environment, Regional Planning, Agriculture and Fisheries of the Basque Government. Besides, this work was supported by a grant from the Department of Education, Universities and Research of the Basque Government.
References Hocking, P.J., Randall, P.J. and DeMarco, D. 1997. The response of dryland canola to nitrogen fertilizer: partitioning and mobilization of dry matter and nitrogen, and nitrogen effects on yield component. Field Crops Research 54, 201Justes, E., Mary, B. and Nicolardot, B. 1999. Comparing the effectiveness of radish cover crop, oilseed rape volunteers and oilseed rape residues incorporation for reducing nitrate leaching. Nutrient Cycling in Agroecosystems 55 (3), 207Malagoli, P., Lainé, P., Rossato, L. and Ourry, A. 2005. Dynamics of nitrogen uptake and mobilization in field-grown winter oilseed rape (Brassica napus) from stem extension to harvest. I. Global N flows between vegetative and reproductive tissues in relation to leaf fall and their residual N. Annals of Botany 95, 853-861 Nielsen, N.E. andd Jensen, H.E. 1986. The course of nitrogen uptake by spring barley from soil and fertilizer nitrogen.
Plant and Soil 91, 391-395 Sierra, J. 1997. Temperature and soil moisture dependence of N mineralization in intact soil cores. Soil Biology and Biochemestry 29 (9/10), 1557-1563 Nitrogen Workshop 2012 The effect of measures implemented from 2003 to 2007 to reduce Nitrogen leaching from agricultural land in Denmark Børgesen, C. D., Vinther, F. P Department of Agroecology, Aarhus University P. O. Box 50, DK-8830 Tjele, Denmark
1. Background & Objectives The Danish Action Plan for the Aquatic Environment III (APAE III) from 2004 is a follow-up on earlier action plans with the first from 1987. The target of APAE I (1987) was to reduce the leaching of nitrate from the root zone with 50%, equal to 100.000 ton N (mean reduction of 36 kg N ha-1) within five years. The goal has been revised several times since then and with the APAE III agreement covering the period 2004-2015 the N reduction target to be achieved by 2015 - is a 13% reduction in nitrogen leaching compared to the 2003 level (total reduction 21.150 tons N, mean reduction of 8 kg N ha-1). A number of measures have been implemented through regulations up until 2007. These measures together with changes in cropping systems and N fertilization has been evaluated in the midterm evaluation of APAE III in 2008 and published in Børgesen et al., (2009).
The aim of this paper is to present the simulated N leaching results for Denmark for the period 2003-2007 and to obtain the different effects of the measures and other crop and N-fertilization changes on the N leaching. The analysis can be used to point out the uncertainty of the planed effectiveness of measures and as an example on how farmers in Denmark have adopted to the measure catch crop.
2. Materials & Methods Based on model analysis using two N leaching models the GNL N leaching model (based on Basic Daisy (Abrahamsen et al., 2001) model simulations and the empirical NLES4 leaching models Kristensen et al. (2008)) the leaching where calculated for all agricultural fields in Denmark (app.
2.7 mill. ha) for each of the year’s 2003, 2007. The input data to the leaching models are annual farm specific crop rotation and N fertilization schemes setup from annual farm data on crops and used N-fertilizers extracted from national farm databases. The simulation were conducted on field scale using soil data extracted from national soil databases, crop rotation and fertilization scheme obtained on farm scale and weather data for the period 1990-2005 obtained from regional meteorological stations. The mean annual field results are aggregated to farm, regional and national scale. The measures implemented to reduce N leaching with APAE III were: increase area with catch crops, afforestation, increase utilization of special type of animal manure, constructed wetlands, reduction in the agricultural area, reduction in farm production intensity, increased area with reduced N fertilization. The effect of constructed wetlands was only evaluated by the reduction in farm land. The other measures affected the actual farm register data on agricultural land, cropping and N fertilization and in this way is included in analysis.
3. Results & Discussion The different measures has gradually been implemented over the period along with changes in cropping systems, farm structural changes (increase in number of dairy cows, a small reduction in number of pigs), N fertilization, which affects the N leaching. In Table 1 is shown the annual total N use (N input) and the N leaching calculated with the two models. The total N input is quite stable throughout the period, although there are changes in total N input due to reduction in N fixation, year to year variation in mineral and organic N fertilizer. The simulated nitrogen leaching decreased over the period for both models. As the simulated results are based on a number of assumptions,
Nitrogen Workshop 2012
generalizations and data uncertainties, there is a high uncertainty on the results. The analysis showed that the effect of the implemented measures was generally lower than the effect of other factors. Especially the change in cropping systems over the period has been found to have a high effect on leaching. The land use changes in the period showed an increase in winter cereals, grass in rotation and maize for silage, and a decrease in the area with spring barley and peas. The total use of nitrogen for Denmark is regulated so it can’t exceed the maximum of 10% below the actual demand in 2003. In reality the N fertilization level is by 2007 reduced to app. 14% below the optimal N rate. This is caused by change in cropping systems (more winter crops with higher N rates) which has increased the total N demand. The catch crop area was planned with APAE III to increase with 40.000 ha during the period but the area only increased with app 13.000 ha. The primary reason was that the rules for growing catch crops after cereals was changed in 2005, so that the farmers could avoid catch crops by instead having 100% winter grown crops. The general rule for catch crops in Denmark (2007) was that each farmer should have 6% or 10% of the cultivated land grown with catch crops depending on live stock density (LSU). 0.8 LSU/ha = 6%,
0.8LSU/ha =10%. In 2012 this demand has been increased to 10% and 14% respectively. The changes in rules in 2005 was especially adopted by the plant- and pig farmers which together with other factors resulted in increase in winter grown cereals and winter rape and a reduction in spring grown crops. All together the changes in cropping systems have been found to reduce the simulated N leaching more than the different implemented measures.
Table 1. Annual Nitrogen input and simulated N leaching for the agricultural area in Denmark Min.
N Org. N N N- Total Year GNL/ N- Mean fertilizer fertilizer fixation deposition N input Les4 DAISY
-------------------N input --------------------------- --------------N leaching ----------Conclusion The effect of land use changes on N leaching was found higher than the effects of the measures implemented with APAE III. The two models showed the same level and the same trend in the simulated N leaching on national level – but not on regional scale. The reduction was not found to be clear due to uncertainty in models and farm data. Many farmers adapted to alternative regulation (100% green fields) to avoid catch crops.
Abrahamsen, P. and Hansen, S. 2000. Daisy: an open soil-crop-atmosphere system model. Environmental Modelling and Software 15, 313-330.
Børgesen, C.D., Waagepetersen, J., Iversen, T.M., Grant, R., Jacobsen, B. and Elmholt S. 2009 Midtvejsevaluering af vandmiljøplan III : Hoved- og baggrundsnotate. (DJF Plant Science 142).
Reestimation and further development in the model N-LES - N-LES3 to N-LES4. 2008. Kristensen K, Waagepetersen J, Børgesen C.D, Vinther F. P, Grant R, Blicher-Mathiesen G. Aarhus University, Det Jordbrugsvidenskabelige Fakultet,
2008. 25 s. (DJF Plant Science; 139).
Nitrogen Workshop 2012
The Environmental Virtual Observatory (EVO): can cloud-based modelling provide new understanding of nutrient cycling processes from catchment to national scale?
Greene, S.a, Johnes, P.J.a, Freer, J.b, O’Doni, N.b, Bloomfield, J.Pc, Reaney, S.M.d, MacLeod, C.J.A.e a School of Human and Environmental Sciences, University of Reading, Reading, RG6 6DW, UK b School of Geographical Sciences, University of Bristol, University Road, Bristol, BS8 1SS, UK c British Geological Survey, Maclean Building, Crowmarsh Gifford, Wallingford Oxfordshire, OX10 8BB, UK d Department of Geography, Durham University, Durham, DH1 3LE,UK e The James Hutton Insitute, Craigiebuckler, Aberdeen, AB15 8QH, UK
1. Background & Objectives Increasing anthropogenic demands on the environment, coupled with legislative pressures exerted by environmental policies, provide a major challenge for the management of water resources, especially in the context of nutrient enrichment (Sims et al., 2005; Vitousek et al., 2009).