黄土高原不同降水区休闲期土壤贮水效率及其对冬小麦水分利用的影响

土壤贮水是影响黄土高原冬小麦生产力的最重要因素,分析休闲期贮水效率对有效利用水资源具有重要意义。利用黄土高原旱作区4个农业气象观测站土壤水分长期观测资料和冬小麦产量资料,探讨了不同气候区休闲期土壤贮水和耗水特征及对冬小麦水分利用的影响。结果表明:(1)黄土高原旱作区休闲期1 m土层多年平均贮水量半湿润区为9 1mm,贮水效率为30.7%,半干旱区为32 mm,贮水效率为16.5%,且不同降水年型、不同气候区休闲期贮水量和贮水效率差别较大;(2)黄土高原旱作区1 m土层贮水量从土壤解冻至封冻期间基本呈波谷型分布,休闲期为主要贮水阶段,冬小麦返青—开花期为休闲期贮水的主要消耗阶段。半湿润区休闲期土壤贮水量主要消耗在起身至开花期,半干旱区主要消耗在越冬至拔节期;(3)黄土高原旱作区播种—越冬前消耗0—40 cm土层贮水,越冬-起身期各土层贮水量都有消耗,起身—开花期半湿润区主要消耗0—40 cm土层贮水量、半干旱区主要消耗0—60 cm土层贮水量,开花—成熟期半湿润区主要消耗40 mm以下土层贮水量、半干旱区主要消耗60 cm以下土层贮水量;(4)黄土高原休闲期贮水效率与冬小麦产量显著相关,半湿润区水分利用效率远高于半干旱区。黄土高原不同区域降水时空分布不均和土壤贮水能力的差异是造成不同气候区休闲期水分贮存差异的主要原因,通过调整耕作方式、水肥管理、种植结构进一步实现冬小麦增产和水分高效利用。

Effects of soil water storage efficiency on winter wheat water use efficiency in different precipitation areas during the fallow period in the Loess Plateau, western China

Soil water storage is the primary factor affecting crop productivity in the Loess Plateau in western China. It is important to analyze soil water storage efficiency in the fallow period for utilizing water resources efficiently. In the present study, we collected data on soil water content and winter wheat production over multiple years from four agronomic observatory stations located in semi-arid and semi-humid areas. We also analyzed the effects of soil water storage and consumption in the fallow period on winter wheat water use efficiency and yield in different precipitation areas of the Loess Plateau. The results showed that:(1) in semi-humid and semi-arid areas, the average soil water storage and efficiency in the fallow period were 91 mm (30.7%) and 32 mm (16.5%) in 1 m depth, respectively, which were very different in different rainfall years. (2) The soil water storage in 1 m depth was trough type distribution from the soil thawed to frozen. The storage was mainly consumed in the fallow period and from standing to flowering in semi-humid areas and from over wintering to jointing in semi-arid areas. (3) Soil water storage in the fallow period of the Loess Plateau was consumed in 0-40 cm depth during the seeding period and was consumed in 1 m depth from over wintering to standing. In semi-humid areas, the storage was mainly consumed in 0-40 cm depth from standing to flowering and below 40 cm depth from flowering to maturity. In semi-arid areas, the storage was mainly consumed in 0-60 cm depth from standing to flowering and below 60 cm depth from flowering to maturity. (4) Soil water storage efficiency in the fallow period was significantly correlated with yield of winter wheat. In semi-humid areas, water use efficiency of winter wheat was higher than that in semi-arid areas. The difference of soil water storage in the fallow period in different climate regions of the Loess Plateau was due to uneven spatial and temporal distribution of precipitation and different soil water storage capacity by adjusting the modes of farming, water and fertilizer management, and planting structure to further increase winter wheat yield and water use efficiency.