Whippo Craig W, Saliendra Nicanor Z, Liebig Mark A
USDA-ARS, Northern Great Plains Research Laboratory, P.O. Box 459, Mandan, ND, 58554, USA.
Heliyon. 2024 Apr 20;10(8):e29838. doi: 10.1016/j.heliyon.2024.e29838. eCollection 2024 Apr 30.
Soybean ( max (L.) Merr.) planting has increased in central and western North Dakota despite frequent drought occurrences that limit productivity. Soybean plants need high photosynthetic and transpiration rates to be productive, but they also need high water use efficiency when water is limited. Crop residues and cover crops in crop rotations may improve soybean drought tolerance in northern Great Plains. We aimed to examine how a management practice that included cover crops and residue retention impacts agronomic, ecosystem water and carbon dioxide flux, and canopy-scale physiological attributes of soybeans in the northern Great Plains under drought conditions. The experiment consisted of two soybean fields over two years with business--usual (no-cover crops and spring wheat residue removal) and aspirational management (cover crops and spring wheat residue retention) during a drought year. We compared yield; aboveground biomass; green chromatic coordinates, and CO and HO fluxes from eddy covariance, Phenocam images, and ancillary micrometeorological measurements. These measurements were used to derive ecosystem-scale physical, and physiological attributes with the 'big leaf' framework to diagnose underlying processes. Soybean yields were 29 % higher under drought conditions in the field managed in a system that included cover crops and residue retention. This yield increase was associated with a 5 day increase in the green-chromatic-coordinate defined maturity phenophase, increasing agronomic and intrinsic water use efficiency by 27 % and 33 %, respectively, increasing water uptake, and increasing the rubisco-limited photosynthetic capacity (V) by 42 %. The inclusion of cover crops and residue retention into a cropping system improved soybean productivity because of differences in water use, phenology timing, and photosynthetic capacity. These results suggest that farmers can improve soybean productivity and yield stability by incorporating cover crops and residue retention into their management suite because these practices to facilitate more aggressive water uptake.
尽管北达科他州中部和西部经常发生干旱，限制了生产力，但大豆（大豆属（L.）Merr.）的种植面积仍在增加。大豆植株要高产就需要高光合速率和蒸腾速率，但在水分有限时，它们也需要高水分利用效率。作物轮作中的作物残茬和覆盖作物可能会提高大平原北部大豆的耐旱性。我们旨在研究一种包括覆盖作物和残茬保留的管理措施如何影响干旱条件下大平原北部大豆的农艺、生态系统水分和二氧化碳通量以及冠层尺度的生理特性。该实验在两年内包括两个大豆田，在干旱年份采用常规管理（无覆盖作物且春季小麦残茬清除）和理想管理（覆盖作物且春季小麦残茬保留）。我们比较了产量、地上生物量、绿色色度坐标，以及通过涡度协方差、Phenocam图像和辅助微气象测量得到的二氧化碳和水汽通量。这些测量用于通过“大叶”框架得出生态系统尺度的物理和生理特性，以诊断潜在过程。在采用包括覆盖作物和残茬保留的系统管理的田间，干旱条件下大豆产量高出29%。产量增加与绿色色度坐标定义的成熟物候期延长5天有关，农艺水分利用效率和内在水分利用效率分别提高了27%和33%，水分吸收增加，羧化酶限制的光合能力（V）提高了42%。由于水分利用、物候时间和光合能力的差异，将覆盖作物和残茬保留纳入种植系统提高了大豆生产力。这些结果表明，农民可以通过将覆盖作物和残茬保留纳入其管理措施来提高大豆生产力和产量稳定性，因为这些措施有助于更积极地吸收水分。
