トウモロコシと大豆の輪作の利点とトレードオフを新たに定量化(Corn after soy: New study quantifies rotation benefits and trade-offs)

ad

2025-06-23 イリノイ大学アーバナ・シャンペーン校

トウモロコシと大豆の輪作の利点とトレードオフを新たに定量化(Corn after soy: New study quantifies rotation benefits and trade-offs)
Credit: Ziyi Li

イリノイ大学の研究により、トウモロコシ–大豆輪作は収量を平均6.4%向上させ、窒素排出や流亡も抑制する一方、土壌有機炭素の減少というトレードオフがあると明らかになった。大豆残渣の分解が春の窒素供給を助けるが、施肥量が多いとその効果は低減。経済的には、施肥量が標準であれば輪作が年間最大1,133ドル/haの利益増をもたらすが、価格や施肥条件により逆転する可能性もある。輪作の環境・経済バランスの調整が持続可能な農業に重要とされた。

<関連情報>

アメリカ中西部におけるトウモロコシ連作とダイズ・トウモロコシ輪作体系の比較: 作物収量、養分損失、土壌有機炭素の変化のトレードオフ Comparing continuous-corn and soybean-corn rotation cropping systems in the U.S. central Midwest: Trade-offs among crop yield, nutrient losses, and change in soil organic carbon

Ziyi Li, Kaiyu Guan, Wang Zhou, Bin Peng, Emerson D. Nafziger, Robert F. Grant, Zhenong Jin, Jinyun Tang, Andrew J. Margenot, DoKyoung Lee, Carl J. Bernacchi, Evan H. DeLucia, Ignacio Ciampitti, Tongxi Hu, Lexuan Ye, Jessica Till, Mengqi Jia
Agriculture, Ecosystems & Environment  Available online: 7 June 2025
DOI:https://doi.org/10.1016/j.agee.2025.109739

Highlights

  • Soybean-corn boosts corn yield over continuous-corn by increasing nitrogen mineralization.
  • Soybean residue accelerates SOC loss but reduces N₂O and NH₃ emissions under normal N fertilizer rates.
  • Soybean-corn rotation increases economic returns at low N rates but loses this advantage at higher rates.
  • Nitrogen fertilizer rate shifts the trade-offs in yield, SOC, and nitrogen losses between soybean-corn and continuous-corn systems.

Abstract

Soybean-corn (S-C) is the most common cropping sequence in the U.S. Midwest, known for improving corn yield compared with continuous corn (C-C). However, the underlying mechanisms and impacts on crop productivity, environmental sustainability, and economic returns are not fully understood. Using the agroecosystem model, ecosys, we simulated S-C and C-C systems under different nitrogen (N) fertilizer application rates, demonstrating good performance in capturing N rate-corn yield responses and CO2 fluxes across 10 Illinois sites. Our analysis revealed: (1) under normal N rates (151 kg N/ha), soybean residues contributed an average of 36% less carbon but 47% more N than corn, resulting in higher early spring soil temperatures and net mineralization in the subsequent corn year, boosting corn yields for S-C relative to C-C. This yield benefit was reduced with higher N rates. (2) S-C reduced soil organic carbon (SOC) relative to C-C due to faster decomposition of soybean residue under normal N rates, but mitigated nitrous oxide (N2O) and ammonia (NH3) emissions. Effects on N leaching varied, with reductions during soybean years and increases in the following corn years. N rates shifted the relative differences of SOC and N losses between S-C and C-C. (3) Economically, S-C provided $1133/ha higher returns than C-C at low N rates (50 kg N/ha) under typical market conditions (soybean: $410/Mg, corn: $178/Mg, and N fertilizer: $193/Mg). However, this advantage diminished at higher N rates due to increased costs and smaller corn yield gains, especially under extreme market scenarios with high corn prices and lower soybean-to-corn and fertilizer-to-corn price ratios. These findings highlight trade-offs among crop yield, nutrient losses and soil carbon change by adopting S-C in the U.S. central Midwestern cropping systems.

1900環境一般
ad
ad
Follow
ad
タイトルとURLをコピーしました