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The contribution of biogas plants to nutrient management planning. Adviser Torkild Birkmose, DAAS, Denmark. Photo: Torben Skøtt, BioPress. Biogas. Biogas rests on tree legs. Energy. Agriculture. Environment. Agricultural advantages. Improved fertilizer value of nitrogen
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The contribution of biogas plants to nutrient management planning Adviser Torkild Birkmose, DAAS, Denmark Photo: Torben Skøtt, BioPress
Biogas Biogas rests on tree legs Energy Agriculture Environment
Agricultural advantages • Improved fertilizer value of nitrogen • Balanced P and K-balance in slurry • Homogeneous and light fluid • Full declaration of nutrients • Free from germs and seeds • Reduced costs for transportation of slurry
Environmental advantages • Reduced nitrate leaching • Reduced odour problems • Reduced green house gas emission • Controlled recycling of organic waste
Mixing and digesting slurry change the characteristic of the slurry
Ammonia evaporation in spring barley 50 -N 4 40 30 -loss, % of spread NH 20 10 3 NH 0 2002 2003 Untreated pig slurry Digested pig slurry
Improved fertilizer effect of nitrogen- trials in winter wheat Digested slurry, trailing hoses Pig slurry, trailing hoses Cattle slurry, trailing hoses Digested slurry, injected Pig slurry, injected Cattle slurry, injected 0 20 40 60 80 100 N-utilization, % (fertilizer equivalent)
Fertilizer plan for nitrogen for 1 ha grass Per hectare Cattle slurry Digested slurry N-requirement, kg 250 250 N in slurry, kg total 170 170 N-utilization, % 40 60 N- in slurry, utilized, kg 68 102 Mineral fertilizer 182 148 Saved, kg Saved, £ - - 34 17
Digested slurry is low on germs 6 Test results from Ribe Biogas, bacteria per ml. slurry (1998) Log10 germs per ml. slurry 3 Date Before After Mar. 18 May 13 July 15 Sept. 9 Nov. 11 1,300,000 140,000 690,000 9,000,000 62,000 <5 <5 <5 <5 <5 5 10 Time, weeks Slurry tank, 6-8°C Mesofile biogas, 35°C Thermofile biogas, 53°C