The aims of this study were: To introduce a new method, primary nutrient efficiency, for the evaluation of nutrient utilization. To demonstrate and find key factors to reach a high utilization rate of nutrients

Seuri, Pentti

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Baltic Ecological Recycling Agriculture and Society (BERAS) nr. 5vo

Jukuri

Evaluation of nitrogen utilization by means of the concept of primary nutrient efficiency

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E K O L O G I S K T   L A N T B R U K   N R   4 6   •  D E C E M B E R   2 0 0 5ENVIRONMENTALIMPACTS OF ECO-LOCAL FOOD SYSTEMS– final report fromBERAS Work Package 2Artur Granstedt, Olof Thomssonand Thomas Schneider (eds.)Centrum för uthålligt lantbrukBaltic Ecological Recycling Agriculture and Society (BERAS) Nr. 536     E K O L O G I S K T   L A N T B R U K   N R   4 6   •   D E C E M B E R   2 0 0 5C H A P T E R  IIEvaluation of nitrogen utilization bymeans of the concept of primary nutrient efficiencyThis work is also reported as Seuri and Kahiluoto (2005) “Evaluation ofnitrogen utilization by means of the concept of primary productionbalance” in Köpke et al. (2005) but is here somewhat revised. Nutrientbalances (farm-gate balance, surface balance1 and cattle balance) onlyindicate an absolute load of nutrients as a difference between inputnutrients and output nutrients (kg or kg/ha). Basically they do not sayanything about the efficiency of nutrient utilization.It is also possible to calculate a ratio between output and input.This type of ratio can be used as a measure of nutrient utilizationefficiency. As long as the system is simple enough, i.e. a farm withoutlivestock and with no recycling of nutrients, the output/input ratioindicates the efficiency of nutrient utilization. However, as soon as asystem involves recycled nutrients, the output/input ratio is difficultto interpret (Myrbeck 1999).From an ecological point of view there is only one production pro-cess in the agricultural system, i.e. crop production = primary produc-tion. Primary production can either be used directly as human food orfed to animals. Nutrient load and nutrient utilization, i.e. efficiency ofnutrient utilization, are two separate dimensions. If only crops areproduced, the nutrient load is less than if an equal amount (in kg nitro-gen) of animal products is produced but the efficiency to utilize nutrientsis equal. This is because more crop products are needed to produce anequal amount of animal products. This can be explained by two examples:A) If 1 kg nitrogen in crop products are produced and used as humanfood, there are some losses, let's say 0.4 kg nitrogen. These losses arealso the total load.B) If 1 kg nitrogen in animal products are produced and used as hu-man food there must first be produced some crops for fodder. Let'ssay we are able to produce1 kg nitrogen in animal products by 4 kgnitrogen in crops (fodder) (= cattle efficiency = 25 %). If each kg ni-trogen in fodder is produced with same efficiency than in case A,this means that total losses are 4 x 0,4 kg nitrogen = 1,6 kg nitrogen.The efficiency to utilize nitrogen on the field has been equal in bothcases A and B (60 %) and equal amount of human food has beenproduced (1 kg nitrogen), but the total load in case A is 0,4 kg nitro-gen and in case B 1,6 kg.In order to reduce the nutrient load there are two possibilities: eitherproduce less or improve the efficiency of nutrient utilization. Since theamount of primary production is highly dependent on the priorities inthe human diet, it can be taken as a given constant. According to thisassumption, the harvested yield (Y) to external nutrient input (= primarynutrients, P) ratio alone indicates the nutrient utilization in any system.Pentti Seuri, MTT Agrifood Re-search, Finland1 also referred to as field balance in this publication.37C H A P T E R   IIThe concept of primary nutrient efficiency (PNE) is based on this fact(Seuri 2002) but now renamed. Earlier it was called primary productionbalance (PPB).The aims of this study were:• To introduce a new method, primary nutrient efficiency, for theevaluation of nutrient utilization• To demonstrate and find the key factors to reach a high utilizationrate of nutrientsMaterial and methodsA deeper analysis was made of nitrogen utilization on nine organicfarms in eastern Finland, referred to as J-BERAS-farms earlier in thischapter and in Appendix 2. Data was collected in 2004 by personallyinterviewing farmers. An overall picture was drawn of how the farmswere functioning and, to ensure the validity of data, the results werediscussed personally with each farmer. The estimations of harvestedyield (dry matter & nitrogen) were adjusted with the number of animalsand total animal production. The nitrogen contents of all organicmaterials within the system (crops, fodder, bedding materials, seeds,animal products, and purchased manure) were estimated by means ofstandard figures, unless measured values were available. Atmosphericdeposition, 5 kg nitrogen/ha, was included as an input.All the main nutrient flows were identified. However, because ofthe steady-state assumption (i.e. balanced systems, no change in re-serve nutrients in soil) and estimation of biologically fixed nitrogen theresults may include some error.Biological nitrogen fixation (BNF) was estimated based on harves-ted legume yield: the assumption was 50 kg nitrogen per 1000 kgharvested dry matter of legume. That means that roughly 70 % of thetotal nitrogen content in the legume biomass originated from BNF. Thisassumption was derived from the Swedish STANK model (STANK1998), the Danish model by Kristensen et al. (1995) and the Finnish modelby Väisänen (2000).  On all farms the most important legume was redclover. However, some white clover and alsike clover were grown inperennial ley mixtures as well. Besides peas, which was the mostimportant annual legume crop, some annual vetch was grown.The farm-gate efficiency, surface efficiency and primary nutrientefficiency (PNE) were calculated for each individual farm (Table 2-2).The primary nutrient efficiency can be calculated from the followingtwo equations (Seuri 2002):(I) PNE = Y/Pwhere Y = total harvested yield and P = primary nutrients(= external nutrients)(II)PNE = U * Cwhere U = utilization rate (= surface efficiency) andC = circulation factor = (P + S)/PS = secondary nutrients (= recirculated nutrients)38     E K O L O G I S K T   L A N T B R U K   N R   4 6   •   D E C E M B E R   2 0 0 5C H A P T E R  IIEquation (I) follows the definition of PNE. Equation (II) illustrates twocomponents of PNE: utilization rate, which is equal to surface efficiency,and circulation factor, which indicates the extent of recirculated nutrientsin the system. There is a major difference between farms with andwithout livestock. Since there are no recirculated nutrients (S) on farmswithout livestock, the circulation factor is always 1.0. On farms withlivestock the circulation factor is always higher than 1.0.To illustrate the difference between primary and secondarynutrients and to point out the role of recirculation in improving nutrientutilization, some simple simulations were made on two farms withoutlivestock, farms 8 and 9. The farms produce some fodder and receivesome farmyard manure (FYM) from the neighbouring farm. The initialefficiency (A) indicates utilization in a case where manure from theneighbouring farm is an external nutrient input (primary nutrient). Thesimulated efficiency (B) indicates the utilization in a case where all theharvested fodder yield is used on the farm for dairy cattle. It is assumedthat 25 % of the nitrogen in the fodder is sold out from the farm in theform of milk and beef and 25 % is lost in the gaseous form before themanure is spread on the field. The rest of the nitrogen (50 %) remains inthe manure.The average utilization rate of the primary nitrogen in the agri-culture in Finland was calculated from statistics. Rough estimations andcomparisons were made between the farms in this study and nationalaverage utilization rates.Results and discussionThe PNE of nitrogen fell in the range 1.0–1.2 on all mixed farms exceptfor farm 7, i.e. the farms were able to harvest more nitrogen than theyreceived as an input into the crop production from outside the farm(including fixation). Both farms without livestock reached a PNE downaround 0.5; the dairy farm simulation increased the PNE up to 0.8.Table 2 2. Comparison between primary nutrient efficiency (PNE), surface efficiency (SE) and farm-gate efficiency(FGE) of nitrogen on nine organic farms in eastern Finland. Farms 8B and 9B are simulated from 8A and 9A,respectively.Farm Production Primary Total N Harvested Primary Surface Farm-gate Circulation Ntype N input on field N yield nutrient efficiency efficiency factor surplus(kg/ha) (kg/ha) (kg/ha) efficiency (kg/ha)1 Dairy 60 92 69 1.15 0.75 0.34 1.53 402 Dairy 68 108 75 1.11 0.69 0.3 1.60 493 Dairy 53 83 53 1.00 0.64 0.3 1.56 444 Beef 69 113 84 1.22 0.74 0.18 1.64 605 Beef 65 113 73 1.13 0.65 0.20 1.74 536 Beef (+crop) 52 89 55 1.05 0.62 0.17 1.70 487 Goat (+crop) 63 73 45 0.72 0.62 0.30 1.16 558A Crop 87 87 49 0.56 0.56 0.56 1.0 398B ‘Dairy’ 63 87 49 0.77 0.56 0.19 1.39 519A Crop 66 66 34 0.51 0.51 0.51 1.0 339B ‘Dairy’ (+crop) 48 66 42 0.87 0.63 0.3 1.38 3439C H A P T E R   IIThe surface efficiency (SE) of nitrogen fell in the range 0.6–0.75 onall mixed farms and by definition PNE and SE are identical (around0.5) in a system without livestock, i.e. in any system without recirculatednutrients. The Farm Gate Efficiency (FGE) of nitrogen correlated stronglywith production type, being around 0.3 on dairy farms and around 0.2on beef farms. Analogously to PNE and SE, also FGE was identical onfarms with no livestock (around 0.5). The dairy farm simulation dec-reased the FGE down to 0.19 on farm 8 and down to 0.3 on farm 9.Simulation on farm 8 shows clearly the role of recirculation andthe difference between PNE and SE. On farm 8, the only differencebetween the real farm and the simulated farm is the method of defini-tion of the origin of input nitrogen, i.e. the initial yield harvested andthe initial amount of nitrogen available in the field are exactly the same.On farm 8A, all the nitrogen in the farm yard manure (FYM) from theneighbouring farm is considered as primary nitrogen analogous to thenitrogen in artificial fertilizers or the nitrogen from BNF. This isanalogous to any nitrogen input that increases the total amount of ni-trogen in the system. On farm 8B, the nitrogen in the FYM from theneighbouring farm is considered as secondary nitrogen analogous tothe nitrogen in FYM originating from the farm. This is analogous toany recycled nitrogen that does not increase the total amount of nitro-gen in the system. However, the SE method does not identify the originof the nutrients in the field, i.e. unlike PNE, SE remains constant onfarm 8. The higher PNE value on the simulated farm 8B indicates higherefficiency of primary nitrogen utilization, thereby a lower nitrogen loadpotential.On farm 9B there are some green manure fields, from where yieldis harvested instead of ploughing directly. Therefore also the SE isinfluenced by simulation on farm 9, but otherwise it is analogous tofarm 8.In Finland (1995–1999), calculations of nitrogen balance in agri-culture show that the annual total primary nitrogen input (artificialfertilizers, atmospheric deposition and symbiotically fixed nitrogen) isabout 100 kg/ha. The total harvested nitrogen yield is about 74 kg/ha,(Lemola & Esala 2004). Thus, the PNE in agriculture averages 74 kg/ha/100 kg/ha = 0.74, indicating a serious lack of nutrient re-cycling.However, there is huge potential to recycle nutrients in agriculture,because 80 % of the total crop yield is used as animal fodder.In this study, all the livestock farms exceeded the value 0.74. Theyranged from 0.8–1.2, with an average around 1.0. The high PNE fornitrogen was due not only to recycling but also to biological nitrogenfixation. The main source of primary nitrogen input was symbiotic fixednitrogen by legumes. The utilization rate of nitrogen by legumes isclearly higher than for any other source of nitrogen into a system. Inmost cases about the same amount of nitrogen was harvested as wassymbiotically fixed, i.e. the utilization rate is approximately 100 %.In addition, the balance between livestock and field area (fodder40     E K O L O G I S K T   L A N T B R U K   N R   4 6   •   D E C E M B E R   2 0 0 5C H A P T E R  IIproduction) was of major importance in reaching a high PNE. Wheneverthe livestock density was increased by means of purchased fodder, theutilization of farmyard manure was poor and resulted in lower PNE(farms 3, 6 and 7). Self-sufficient fodder production was the optimum.The farms with high PNE had also a slightly higher yield level thanfarms with lower PNE.On the other hand, the two organic farms without livestockindicated that without recirculation an organic system cannot utilizenitrogen very efficiently. On these farms the primary source of nitro-gen consisted of legumes, but because the legume crop was partly usedas green manure, there were heavy losses of nitrogen resulting in alower total PNE.ConclusionsIt was fairly easy to calculate the primary nutrient efficiency (PNE) foreach of the nine farms included in this study. The estimation of biologicalnitrogen fixation and harvested nitrogen yield are, however, obvioussources of error. The assumption of steady state is not necessarily validin all cases.Even though crop production causes only minor nutrient loadcompared with animal production, it does not necessarily mean thatcrop farms utilize nutrients effectively. Using the PNE it is easy tocompare different farms. The results of this study show clearly thatlivestock farms are able to reach a remarkably higher PNE comparedwith crop farms despite the very low farm-gate efficiency on livestockfarms.ReferencesAnon.  2001. The Bichel Committee 1999. Report from the BichelCommittee – Organic Scenarios for Denmark. Report from theInterdisciplinary Group of the Bichel Committee. http://www.mst.dk/udgiv/Publications/2001/87-7944-622-1/html/default_eng.htm , 1-118.Berntsen, J., Petersen, B. M., Kristensen, I. S., and Olesen J. E. 2004.Nitratudvaskning  fra  økologiske  og  konventionelleplanteavlsbedrifter. - simuleringer med FASSET bedriftsmodellen.http://www.foejo.dk/publikation/a_rap.html#Anchor-Nitratudvasknin-62817 . DJF rapport.Markbrug 107, 1-43.Brandt, M. & Ejhed, H. 2002. TRK Transport – Retention – Källfördelning.Belastning på havet. Naturvårdsverket, SE-106 48 Stockholm, Rap-port 5247, 120 p.Brink, N. 1990. Land Use Changes in Europe. Process of Change,Environmental Transformation and Future Patterns (F. M. Browereditor). Kluwer Academic Publishers; London.Granstedt, A. 2000 Increasing efficiency of plant nutrient recycling withinthe agricultural system as a way of reducing the load to the environ-ment – Experience from Sweden and Finland. Agriculture Eco-41C H A P T E R   IIsystems and Environment 80(1-2), 169-185.Granstedt, A., Seuri, P. & Thomsson, O. 2004. Effective recyclingagriculture around the Baltic Sea. Background report. BERAS 2.Ekologiskt lantbruk 41. Centre for Sustainable Agriculture. SLU.UppsalaHELCOM 1998. The Third Baltic Sea Pollution Load Compilation (PLC-3). Baltic Sea Environ proc. No. 70.HELCOM. 2004. The Fourth Baltic Sea Pollution Load Compilation(PLC-4). Helsinki Commission, Baltic Marine EnvironmentProtection Commission, Baltic Sea Environment Proceedings No.93.Høgh-Jensen, H., Loges, R., Jensen, E. S., Jørgensen, F. V., and Vinther,F. P. 2003. Empirical model for quantification of symbiotic nitro-gen fixation in leguminous crops. Agricultural Systems http://www.orgprints.org/, 1-31.Jordbruksverket. 1998. Statens Jordbruksverks dataprogram förväxtnäringsbalansberäkning.  Stallgödsel och växtnäring i krets-lopp (STANK) Jordbruksverket, Jönköping. (Plant nutrient balancecalculation program)Knudsen, M. T., Kristensen, I. S., Berntsen, J., Petersen, B. M., and Kristen-sen, E. S.  2005. The effect of organic farming on N leaching. Sub-mitted. Journal of Agricultural Science , 1-35.Kristensen, I. S.  2002. Principles and methods for collecting andevaluation nutrient balances, 29-40.  http://www.agrsci.dk/jbs/demolit/Principles%20and%20methods.pdf , Danish Institute ofAgricultural Science. Lithuanian Dairy Farms DemonstrationProject.Kristensen, I. S.  2005. Nitrogen balance from dairy farms (2002). http://www.lcafood.dk/processes/agriculture/N_balance_dairyfarms_2002.htm#table_1 .Kristensen, I. S., Dalgaard, R., Halberg, N., and Petersen, B. M. 2005a.Kvælstofbalance og -tab fra forskellige bedriftstyper. Plantekong-res 2005. http://www.lr.dk/planteavl/diverse/PLK05_11_1_3_I_S_Kristensen.pdf  og http://www.lr.dk/planteavl/diverse/plk05_11_1_3_i_s_kristensen.ppt . Planteproduktion i landbruget,1-2.Kristensen, I. S., Halberg, N., Nielsen, A. H., and Dalgaard, R. 2005b. N-turnover on Danish mixed dairy farms. Part II. In: Bos, J.; Pflimlin,A., Aarts, F. and Vertés, F.(Eds): "Nutrient management on farmscale. How to attain policy objectives in regions with intensive dairyfarming. Report of the first workshop of the EGF Workshop. http://www.agrsci.dk/var/agrsci/storage/original/application/57b9a70804960c2c9f54ad255b11f22d.pdf . Plant Research Interna-tional. 83, 91-109.Kristensen, E. S., Høgh-Jensen, H. & Halberg, N. 1995. A simple modelfor estimation of atmospherically-derived nitrogen in grass/cloversystems. Biol Agric Hortic 12: 263-276.42     E K O L O G I S K T   L A N T B R U K   N R   4 6   •   D E C E M B E R   2 0 0 5C H A P T E R  IIKus, J., Kopinski, J., Stalenga J. & Tyburski, J. 2004.  Rolnictwoekologiczne a spoleczenstwo i srodowisko. Raport naukowy.Lipiec.Köpke, U., Niggli, U., Neuhoff, P.C., Lockeretz, W. & Willer, H. (eds.)2005. Researching Sustainable Systems. Proceedings of the FirstScientific Conference of the International Society of OrganicAgriculture Research (ISOFAR), Held in Cooperation with the In-ternational Federation of Organic Agriculture Movements(IFOAM) and the National Association for Sustainable Agriculture,Australia (NASAA), 21–23 September 2005, Adelaide ConventionCentre, Adelaide South Australia. pp. 48–51Lemola, R. & Esala, M. 2004. Typen ja fosforin virrat kasvintuotannossa.AESOPUS-hankkeen loppuseminaari 4.11.2004. SYKE, Helsinki.(Nitrogen and phosphorus flows in agriculture. Seminar on theAESOPUS project 4.11.2004. Finnish Environment Institute,Helsinki.)Mikkelsen, M.H., Gyldenkærne, S., Poulsen, H. D., Olesen, J. E., andSommer S. G. 2005. Opgørelse og beredningsmetode for landbru-gets emissioner af ammoniak og drivhusgasser 1985-2002. Arbejds-rapport fra DMU. [204].1-84Myrbeck, Å. 1999. Nutrient flows and balances in different farmingsystems - A study of 1300 Swedish farms. Bulletins from the Divi-sion of Soil Management, Department of Soil Sciences, SwedishUniversity of Agricultural Sciences. 30: 1-47, 11 app.Nielsen, A. H. & Kristensen, I. S., 2005. Nitrogen and phosphorussurpluses on Danish dairy and pig farms in relation to farm char-acteristics. Livestock prod. science no. 96, 97-107.Seuri, P. 2002. Nutrient utilization with and without recycling withinfarming systems. In: eds. Magid et al. Urban Areas - Rural Areasand Recycling - the Organic Way Forward? DARCOF Report 3: p.175-181. http://www.agsci.kvl.dk/njf327/papers/NJF-Co-development.pdfSCB. 2002. Kväve och fosforbalanser för svensk åkermark och jordbruks-sektor 2000. (In Swedish with English summary: Nitrogen- andphosphorus balances in arable land and agricultural sector inSweden 2000). Statistics Sweden, 34 pp.Stein-Bachinger,  K.,  Bachinger,  H.  &  Schmitt,  L.  2004.Nährstoffmanagement im Ökologischen Landbau. Ein Handbuchfür Beratung und Praxis. KTBL Schrift 423. Kuratorium für Technikund Bauwesen in der Landwirtschaft e.v. (KTBL), Darmstadt.Väisänen, J. 2000. Biological nitrogen fixation in organic andconventional grass-clover swards and a model for its estimation.Licentiate's thesis. University of Helsinki Department of PlantProduction Section of Crop Husbandry. 42 p. + 2 app.

Evaluation of nitrogen utilization by means of the concept of primary nutrient efficiency

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