| The intensification of winter wheat-summer maize double cropping systems in the Huang-Huai-Hai Plain has led to substantial resource and environmental pressures,exacerbated by traditional irrigation practices that contribute to severe groundwater depletion,thereby impacting the sustainable development of agriculture in the region.Consequently,modifying cropping systems and optimizing irrigation regimes are essential for ensuring food security while promoting sustainable water use.In this study,we conducted a two years experiment from 2020 at Henan Agricultural University experimental site,utilized a splitplot design to assess the effects of three double cropping systems: winter wheat-summer maize(W-M,control),winter wheat-summer soybean(W-S),and a rotation of winter wheat-summer maize followed by winter wheat-summer soybean(W-M-S);alongside four irrigation regimes: I-4: irrigation to 60% field capacity(FC)at a soil depth of 40 cm;I-6: irrigation to 80% FC at a soil depth of 60 cm;FI: conventional farmer irrigation,matching the timing of I-6 with each irrigation event delivering 150 mm of water;and R: rain-fed(CK).Irrigation was applied during the winter wheat season,initiated when the soil moisture content at a depth of 40 cm to 40% FC.The study combined field experiments with WHCNS model simulations to evaluate the irrigation efficiency under different cropping systems with micro-sprinkler irrigation and systematically analyzed their impacts on soil moisture components,water balance,crop growth dynamics,groundwater level fluctuations,water use efficiency,and the agricultural water footprint.The main results are as follows:(1)Meta-analysis indicated that irrigation significantly increases the yields of winter wheat and summer maize in the Huang-Huai-Hai Plain,with winter wheat and summer maize yields increasing by17.69% and 31.33% respectively,leading to an annual yield increase of 29.74%.While the water use efficiency of winter wheat improved with increased irrigation,the efficiency and yield of summer maize declined when irrigation exceeded 60 mm.This suggests the need for further optimization of irrigation regimes across different growing seasons to enhance annual productivity and efficiency.(2)The efficiency of micro-sprinkler irrigation decreased with increasing water application,with the highest efficiency observed in the I-4 treatment at 94.7%,and the lowest in the FI treatment at 88.0%.Introducing soybean into the cropping system(W-S and W-M-S)enhanced irrigation efficiency,with a linear relationship observed between irrigation volume and efficiency across different cropping systems,ranking in the order of W-S>W-M-S>W-M.(3)Compared to the W-M system,the W-S system increased the transpiration of winter wheat by13.09%.The irrigation volume for two winter wheat seasons under the I-6 treatment increased by 56.67%and 47.20% compared to the I-4 treatment,while the transpiration only increased by 20.63% and 33.65%,respectively.Despite the largest volume per irrigation event in the FI treatment,its transpiration was not significantly different from the I-6 treatment,but it resulted in greater deep percolation and evaporation.Surface runoff and consumptive water loss during the growing season were primarily influenced by the cropping system,with the W-S system exhibiting the least loss.Moreover,the W-S system increased the soil moisture storage in the shallow soil layers under different irrigation treatments,providing favorable conditions for subsequent crops.The irrigation volume required to achieve an annual water balance was found to be 273.9 mm for W-M,209.1 mm for W-S,and 240.3 mm for W-M-S.(4)The W-S system enhanced the rate and total amount of dry matter accumulation in winter wheat,with the I-4 irrigation treatment significantly increasing the contribution of pre-anthesis dry matter translocation to grain yield.Additionally,the W-S system combined with the I-4 irrigation treatment increased the grain filling rate and maximum thousand kernel weight of winter wheat,whereas the FI irrigation treatment extended the active grain filling period.The biomass and yield of summer crops were primarily influenced by the cropping system and precipitation,with the W-S and W-M-S systems significantly increasing the annual yield by 37.82% to 86.33%,especially under the I-4 treatment.The W-S system combined with the I-4 irrigation treatment significantly reduced the risk of yield reduction under extreme precipitation conditions,enhancing crop yield stability and sustainability.(5)Combining the W-S cropping system with the I-4 irrigation regime significantly increased crop water productivity and irrigation water productivity,reducing the use of irrigation water while significantly decreasing the net consumption of groundwater.The W-S system had the lowest overall water footprint,reducing it by 25.1% to 43.3% compared to the W-M system.Increasing irrigation volume during the wheat season reduced the green water footprint and increased the blue water footprint;compared to summer maize,summer soybean reduced the green water footprint by 55.9% to 74.3%.Compared to the FI treatment in the W-M system,combining the W-S system with the I-4 treatment reduced the annual water footprint by 36.23% and the blue water footprint during the wheat season by21.5%.Groundwater level changes were influenced by both rainfall and irrigation,with groundwater levels decreasing with increasing irrigation volumes across all cropping systems during the study period.However,the W-S system combined with the I-4 treatment had the most significant effect on raising groundwater levels.In conclusion,implementing a winter wheat-summer soybean rotation system in the Huang-HuaiHai Plain,combined with micro-sprinkler irrigation to maintain 60% FC at a 40 cm soil depth during the winter wheat season,can significantly improve irrigation efficiency,optimize field water distribution and balance,promote stable grain yield,and enhance water resource utilization efficiency while alleviating groundwater depletion.This provides a theoretical basis for the sustainable development of agriculture in the region. |
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