دانلود رایگان مقاله انگلیسی چرخش محصولات کشاورزی در دراز مدت و اثرات خاک ورزی در جذب گاز گلخانه ای خاک - الزویر 2018

ABSTRACT

Two of the most important agricultural practices aimed at improving soil properties are crop rotations and notillage, yet relatively few studies have assessed their long-term impacts on crop yields and soil greenhouse gas (GHG) emissions. The objective of this study was to determine the influence of tillage and crop rotation on soil GHG emissions and yields following 15 years of treatment implementation in a long-term cropping systems experiment in Illinois, USA. The experimental design was a split-plot RCBD with crop rotation as the main plot: (continuous corn [Zea mays L.] (CCC), corn-soybean [Glycine max (L.) Merr.] (CS), continuous soybean (SSS), and corn-soybean-wheat [Triticum aestivum L.] (CSW); with each phase of each crop rotation present every year) and tillage as the subplot: chisel tillage (T) and no-tillage (NT). Tillage increased the yields of corn and soybean. Tillage and crop rotation had no effect on methane (CH4) emissions (p = 0.4738 and p = 0.8494 respectively) and only rotation had an effect on cumulative carbon dioxide (CO2) (p = 0.0137). However, their interaction affected cumulative nitrous oxide (N2O) emissions significantly (p = 0.0960); N2O emissions from tilled CCC were the greatest at 6.9 kg-N ha−1 -yr−1 ; while emissions from NT CCC (4.0 kg-N ha−1 -yr−1 ) were not different than both T CS or NT CS (3.6 and 3.3 kg-N ha−1−yr−1 , respectively). Utilizing just a CS crop rotation increased corn yields by around 20% while reducing N2O emissions by around 35%; soybean yields were 7% greater and N2O emissions were not affected. Therefore results from this long-term study indicate that a CS rotation has the ability to increase yields and reduce GHG emissions compared to either CCC or SSS alone, yet moving to a CSW rotation did not further increase yields or reduce N2O emissions.

4. Conclusions

This study was conducted in Illinois on highly productive soils aiming to investigate the effects of crop rotation and tillage on crop yields, GHG emissions, and soil available N. Results from this study indicated that yields of rotated corn were significantly greater and yields seemed to be more stabilized during suboptimal conditions. Soybean yields were also significantly greater when grown in rotation compared to a monoculture. The benefit of chisel tillage to corn and soybean yields in high organic matter and high residue systems was significant and an increase in N2O and CO2 emissions was not observed in this study. In addition, growing corn in a rotation has the ability to significantly lower cumulative N2O emissions by nearly 2 kg-N ha−1 - yr−1 . Cumulative N2O emissions from rotated soybeans were also not different from SSS even though the corn phase of the CS rotation received N fertilizer. Therefore, shifting from a CCC rotation to a CS or CSW rotation will lower N2O and CO2 emissions, while also increasing yields during the corn and soybean phases of the rotation. The results of this study will add valuable information to the impact of long term agricultural management practices on GHG emissions in the US Corn Belt.