Environmental controls on carbon and water fluxes of a wheat-maize rotation cropland over the Huaibei Plain of China

Wanqiu Xing, Lilin Yang, Weiguang Wang, Zhongbo Yu, Quanxi Shao, Shiqin Xu and Jianyu Fu

Agricultural Water Management, 2023, vol. 283, issue C

Abstract: It has become increasingly important to quantify carbon and water fluxes due to their roles in global warming and climate change, particularly for the agroecosystems. However, the dynamics of carbon and water fluxes have not been clearly recognized in rotation croplands with complex and changeable climate. Here, the variations of net ecosystem productivity (NEP), evapotranspiration (ET) and the water use efficiency (WUE, defined as NEP/ET), and their responses to the environmental factors were investigated in a wheat-maize rotation cropland across the Huaibei Plain of China over 2013–2015. The total average NEP, ET and average WUE respectively were 489.1 gC m-2, 315.8 kgH2O m-2, 4.4 gC kg-1H2O for wheat and 192.5 gC m-2, 249.0 kgH2O m-2, 3.6 gC kg-1H2O for maize, implying that wheat season sequestered more CO2 than maize season. Spring drought and summer flood affected WUE of wheat and maize, respectively. Daily wheat WUE seemed to be more sensitive to changes in photosynthetically active radiation (PAR), vapor pressure deficit (VPD), soil water content (SWC) and canopy conductance (Gc). PAR was the dominant factor controlling diurnal dynamics of NEP and ET, while the opposite effect of VPD on NEP was recognized. NEP increasing with PAR was limited by high VPD, which obviously when VPD exceeded 2 kPa during the maize season. Maize NEP was limited with VPD under high solar radiation (> 500 μmol m-2 s-1). WUEs of wheat and maize were negatively related to SWC and Gc, and the sensitivity of WUE response to SWC and Gc increased with the increase of PAR or VPD range. Sub-diurnal NEP against PAR, VPD or temperature showed clockwise hysteresis but ET against PAR or windspeed showed counter-clockwise hysteresis, and these hystereses were mainly caused by the interplay between evaporative demand and moisture supply, photosynthesis and carbon allocation of the agroecosystems.

Keywords: Net ecosystem productivity; Evapotranspiration; Water use efficiency; Controlling factors; Hysteresis; Rotation cropland (search for similar items in EconPapers)
Date: 2023
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Citations: View citations in EconPapers (2)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:agiwat:v:283:y:2023:i:c:s0378377423001750

DOI: 10.1016/j.agwat.2023.108310

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