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Université de l’agriculture de Chine (2015)

Effects of Diversified Crop Rotations on Conserving Groundwater Resource and Lowering Carbon Footprint in the North China Plain

杨晓琳;

Titre : Effects of Diversified Crop Rotations on Conserving Groundwater Resource and Lowering Carbon Footprint in the North China Plain

Auteur : 杨晓琳;

Grade : Doctoral Dissertation 2015

Université : Université de l’agriculture de Chine

Résumé partiel
In the North China Plain, food production with high yiled persuing and intensified agricultural production resulted in huge resources and environment pressure and ecological cost. All these factors, such as the increasing serious groundwater table decline, the growing greenhouses gas emissions from the farmland, the low economic benefits of the current sole winter wheat-summer maize double cropping system, can affect the ecosystem health and the agricultural sustainable development. Based on the long term field experiment of crop rotations from2003to2014at Luancheng experiment station in the North China Plain interpreted using a soil-water-balance model, this research focused on the analysis of water-saving effects of five cropping systems including the characteristic of farmland water consumption, the annual average net groundwater use and the effects of five cropping sytems on the groundwater table decline and economic water use efficiency, the water-saving mechanism of crop rotation, and the carbon footprints of five cropping systems per unit area, per kg biomass, and per unit economic output according to the modified calculation of "Carbon footprint of Farmland ecosystem" with localized greenhouse gas emissions parameters. The five cropping systems included sweet potato→otton→weet potato→inter wheat-summer maize (SpCSpWS,4-year cycle), ryegrass-cotton→peanuts→inter wheat→ummer maize (RCPWS,3-year cycle), peanuts→inter wheat→ummer maize (PWS,2-year cycle), winter wheat-summer maize (WS,1-year cycle), and continuous cotton (Cont C). Main results are listed as follows :(1) Appropriate alternative crop rotations have obvious wate saving effect. During the period of2003-2014, the five cropping systems had a wide range of annual average actual evapotranspiration (ETa):WS rotation (724.5mm/year)> RCPWS (647.4mm/year)> PWS (615.0mm/year)> SpCSpWS (560.6mm/year)> Cont C (522.5mm/year). Overall, the annual average ETa of SpCSpWS rotation, PWS rotation and RCPWS rotation were lower about22.6%,15.1%and10.6%than that of WS rotation, respectively. SpCSpWS rotation has the most water-saving potential among others.(2) Crop rotations have the time and space complementary benefits on the soil water.①Time complementary effect, the preceding crops, such as cotton, peanuts and sweet potato, which have better rainfall coupling degree, can supply the good water condition for the succeeding crop such as winter wheat.②Space complementary effect, the annual average irrigation of PWS rotation, RCPWS rotation and SpCSpWS rotation are less than WS rotation, around90mm,45mm and116mm, respectively. The soil moisture contents of0-120cm soil layers of PWS rotation, RCPWS rotation and SpCSpWS rotation have no significant differnecs from WS rotation, however, the soil moisture contents of120-180cm of these three rotations have small variations but are slightly higher than WS rotation. It is obvious that it can provide the favourable moisture condition for the succeeding crop with deeper root by the rotation of crops with shallow roots. (3) Appropriate alternative crop rotations can effectively mitigate the groundwater table decline. During the period of2003-2104, the sequence of the simulated annual average groundwater decline due to the five cropping systems was WS (1.20m/year)> RCPWS (0.84m/year)> PWS (0.70m/year)> SpCSpWS and Cont C (0.40m/year). The

Mots clés : North China Plain; crop rotation; groundwater table; water-saving; carbon footprint; economic benifit;

Présentation (CNKI)

Page publiée le 4 octobre 2017