不犁田栽培對玉米田溫室氣體排放影響之研究

Abstract

為評估是否可藉由以不犁田方式栽培玉米，協助減少國家溫室氣體的排放量，本研究利用一個可以模擬玉米田生態系中碳和氮之動態變化的電腦模式，進行耕犁措施和氮肥用量處理對玉米田溫室氣體排放影響的模擬研究。研究結果指出，若以每作氮肥用量140 kg N ha-1 的不犁田栽培方式種植玉米，將比以現行栽培方式種植水稻，可大幅降低溫室氣體的淨排放量達10~30 MgCO2 eq. ha-1 y-1。若能推動20 萬公頃休耕稻田改以不犁田方式栽培玉米，將能減少國家溫室氣體排放量達2~6 Tg CO2 eq. y-1。為鼓勵農民將休耕稻田改作玉米，需克服國內生產成本高於進口成本的問題，以符合WTO 綠色措施之規範給予適當補貼，以及利用玉米藁稈產製纖維素酒精以增加農民的收益，都是值得考慮的作法。 Simulation studies were conducted, using a computer model which considered the dynamic changes of C and N in agro-ecosystems, to evaluate the potential of decreasing national greenhouse gases (GHGs) emissions through no-till cultivation of corn. Results indicated that the net GHGs emission could be reduced by 10~30 MgCO2 eq. ha-1 y-1, as compared to that from paddy rice, if nitrogen fertilizer was applied at the rate of 140 kg N ha-1 per crop season. National GHGs emission can be reduced by 2~6 Tg CO2 eq. y-1 if the practices are applied to the 200,000 hectarages of currently set-aside paddy fields. However, the barrier of high domestic production cost as compared to that of importation must be overcome first. Subsidization in accordance with World Trade Organization (WTO) green-box regulation and production of cellulose ethanol using corn stalks are measures that worth further exploration.