Characteristics of farmland water consumption under two-year wheat-maize interannual rotation patterns in Heilonggang Plain.

In order to solve the contradiction of water and grain about the traditional continuous winter wheat (Triticum aestivum L.) and summer maize (Zea mays L.) double-cropping system (W-M→W-M, CK) in the groundwater funnel area of Heilonggang Plain, the new rotation patterns with two-year cycle of "one-year traditional W-M + one-year other crops" were designed, trying to find out a water-saving and green stable cropping system suitable for this region. The field experiment was carried out in Wuqiao, Hebei province from October 2018 to September 2020. Setting spring maizes→W-M (Ms→W-M), winter wheat→W-M (W→W-M), spring sweet potato (Dioscorea esculenta (Lour.) Burkill)→W-M (Psw→W-M), spring peanut (Arachis hypogaea Linn.)→W-M (As→W-M), winter wheat-summer peanut→W-M (W-A→W-M) and potato (Solanum tuberosum L.)-silage corn→W-M (P-C→W-M) six rotation patterns with two years cycle, we tried to analyze the characteristics of farmland water consumption. The results showed that: (1) Compared with CK, the annual water consumption of rotation patterns reduced by 3.1%-15.2%, expect W-A→W-M. The annual average water consumption of Ms→W-M, P-C→W-M, As→W-M and Psw→W-M decreased by 6.1%, 7.2%, 9.2%, and 15.2%, respectively, and the annual average net groundwater consumption of the four patterns also decreased by 9.0%, 10.3%, 16.2%, and 32.9%, respectively. (2) The combination of crops at different water consumption levels could achieve water complementary spatially. Winter wheat mainly consumed 0-160 cm soil moisture, which was reduced by 20% compared with sowing. Potato mainly consumed 0-100 cm soil moisture, which was reduced by 12% compared with sowing. Spring peanut mainly consumed 20-80 cm soil moisture, which was reduced by 4% compared with sowing. (3) Partial rotation patterns could reduce the demand for irrigation water and increase soil water storage. In 2019 rotation year, when the irrigation amount of Ms→W-M and As→W-M patterns were 145 mm and 175 mm less than CK, the soil water storage of 2 m increased by 27.2 mm and 12.6 mm compared with the start of rotation year, respectively. When the irrigation amount of W-M→W-M was 300 mm, the soil water storage of 2 m increased by 18.4 mm compared with the start of rotation year. (4) Partial rotation patterns had better economic water use efficiency (EWUE), which were 1.2-1.5 times of CK. The EWUE of As→W-M and W-A→W-M were 1.5 times and 1.2 times significantly higher than that of CK, respectively. Based on the characteristics of farmland water consumption and EWUE, the two-year rotation patterns of As→W-M, Psw→W-M, P-C→W-M, Ms→W-M could reduce the farmland water consumption, meanwhile, maintain and improve the economic water use efficiency, and could be implemented to partially replace the winter wheat and summer maize double-cropping system in Heilonggang Plain. [ABSTRACT FROM AUTHOR]