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First Workshop ESSP Bioenergy Bioenergy and Earth Sustainability University of São Paulo Centro de Energia Nuclear na Agricultura Escola Superior de Agricultura “ Luiz de Queiroz ” 19-21 July 2008 “ Nitrogen dynamics and sugar cane in Brazil ” Luiz A Martinelli (CENA/USP)
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First Workshop ESSP Bioenergy Bioenergy and Earth Sustainability University of São Paulo Centro de Energia Nuclear naAgricultura Escola Superior de Agricultura “Luiz de Queiroz” 19-21 July 2008 “NitrogendynamicsandsugarcaneinBrazil” Luiz A Martinelli (CENA/USP) Reynaldo L Victoria (CENA/USP) Janaina Braga do Carmo (UFSCar-Sorocaba) Jean Pierre Ometto (IGBP-INPE)
Brazil North Northeast Center-West Southeast South
Nitrogen fertilizers in sugar cane Sugar cane: 80 -100 kg N.ha-1.yr-1 Pasture: 0 kg N.ha-1.yr-1 Soybean: 0 kg N.ha-1.yr-1 (BNF) Corn: 150-200 kg N.ha-1.yr-1 Coffee: 250-300 kg N.ha-1.yr-1 Most as UREA – (CO(NH2)2) Losses of UREA: volatilization and nitrification Volatilization: 1.UREA is transformed in ammonium carbonate 2. Ammonium carbonate under high pH and temperature is transformed in NH3 Nitrification: 1. NH3 is oxidized into NH4+ 2. NH4 is nitrified to NO3- 3. NO3- is leached out of the soil profile or 4. NO3- is denitrified to N2O
? 15 N2 N-particle NH3 30 volatilization N-harvest Biological fixation 10 15 UREA denitrification 100 kg N/ha.yr N2O + N2 20* (if we close the balance) Cana Reciclagem OM NH4+ NO3- nitrification Mineralization 10 Fonte: Trivelin, Gava, Oliveira (CENA); Vitti (ESALQ), Cantarella (IAC) -15N labeled fertilizer
15 N2 N-particle NH3 30 volatilization N-harvest Biological fixation 10 15 UREA denitrification 100 kg N/ha.yr N2O + N2 20* (Only one measurement: 2-3 kgN/ha.yr as N2O) Dinailson (2003) Cana Reciclagem OM NH4+ NO3- nitrification Mineralization 10 Fonte: Trivelin, Gava, Oliveira (CENA); Vitti (ESALQ), Cantarella (IAC)
pH= 4.9 4.8 4.4 4.7
The Nitrogen Cycle – N-poor agricultural system N2 N-harvest NH3 Biological fixation N-fert volatilization 0 kg N/ha.yr N2O + N2 denitrification Pastagem Reciclagem OM NH4+ NO3- nitrification Mineralization Fonte: Cerri & Cerri (CENA), Melillo, Neill (WHOI), Bernoux (IRD)
The Nitrogen Cycle – N-poor natural system N2 NH3 deposition biological fixation volatilization Cerrado N2O + N2 denitrification reciclagem OM NH4+ NO3- nitrification mineralization Fonte: Bustamante, Miranda, Klink (UnB)
The Nitrogen Cycle – N-poor natural system N2 NH3 ? deposition biological fixation volatilization ? ? N2O + N2 denitrification ? reciclagem ? ? OM NH4+ NO3- nitrification mineralization ? Soil acidification <pH < Ca+2, Mg+2, Na+, K+ > Al+3
If Meq/M>1.0, there will be net climate warming, the greenhouse warming by in creased N2O release to the atmosphere then being larger than the quasi-cooling effect from “saved fossil CO2”.
15 50* N2 N-particle NH3 30 volatilization N-harvest Biological fixation 80 denitrification 15 UREA 100 kg N/ha.yr N2O + N2 20* (if we close the balance) Cana 20* Reciclagem OM NH4+ NO3- nitrification Mineralization 10 Fonte: Trivelin, Gava, Oliveira (CENA); Vitti (ESALQ), Cantarella (IAC), Urquiaga (Embrapa)