Regulation effect of spring irrigation combined with straw interlayer on saline-alkali soil temperature in Hetao Irrigation District

Objectives The soil temperatures during the sunflower growing season were monitored continuously in Hetao Irrigation District of Inner Mongolia, and scientifically evaluate the spring irrigation combined with straw interlayer measures from the perspective of temperature changes.

Methods The field micro-area experiment was conducted in Wuyuan County of Inner Mongolia. The tested crops were edible sunflower (Helianthus annuus L.), and the varieties were JK601 (2016–2017) and HT361 (2018). The conventional spring irrigation amount of 2250 m³/hm² without straw interlayer was used as control (CK), the treatments were all using the straw interlayer combined with conventional spring irrigation of 100% (W100), 90% (W90), 80% (W80). The straw interlayer was arranged at once, and then used for three consecutive years, the 5TE-sensor was used to measure the soil moisture, electrical conductivity and temperature at 10, 20, 30 and 40 cm below the ground surface within the film during the growth period of the sunflower. During the harvest period, the yield and yield components of sunflower were investigated.

Results In the whole growth period of sunflower, 0–40 cm soil temperature of W100 treatment was higher than that of CK, but the increasing range of temperature decreased with the increase of implementation year. In 2016, there was a significant increase in soil temperature of 0.7℃–1.8℃ during the bud, florescence and maturity stages of the sunflower, and a significant increase in temperature of 0.6℃–1.7℃ during the growth stage of the seedling, bud and florescence of the sunflower in 2017 (P < 0.05). There was no significant difference in soil temperature between the two treatments in 2018. Compared with W90 and W80 treatments, W100 treatment showed the highest soil temperature in 0–40 cm at the seedling and bud stage, and its average soil temperature during three years was increased by 0.3℃–0.4℃ and 0.2℃–0.5℃, respectively. However, W80 treatment showed the highest soil temperature in flowering and maturity period relative to W100 and W90 treatments, and its average temperature was increased by 0.8℃–1.0℃ and 0.5℃–1.0℃ (P < 0.05), respectively. W100 and W90 treatments could increase sunflower yield. Compared with CK in the three years, W100 treatment increased production by 34.63%, 18.83% and 6.57% respectively, and W90 treatment increased production by 30.42%, 15.91% and 0.64%, respectively.

Conclusions Comprehensive considering soil temperature regulation, water conservation and crop yield improvement, reducing irrigation of local conventional amount by 10% combined with every two years’ straw interlayer treatment is a comparatively good option.