Effects of pre-sowing irrigation and post-sowing soil compaction on water use and growth of winter wheat

In order to clarify the effect of pre-sowing irrigation and post-sowing soil compaction on water use, growth and yield of winter wheat, a field experiment was conducted in Hengshui City in 2013–2014 and 2014–2015. The experiment included 4 treatments of pre-sowing irrigation of winter wheat — irrigation dates of Sep. 15 (I9.15), Sep. 20 (I9.20), Sep. 25 (I9.25) and Sep. 30 (I9.30) and no irrigation as control (CK) treatment. Each treatment consisted of 3 levels of soil compaction intensity after sowing per meter— 120 kg (G120), 95 kg (G95) and 0 kg (G0). The ‘Heng 4399’ winter wheat variety was used in the field experiment and the soil moisture content, growth and grain yield monitored during the wheat growth period. The results of the study showed that evapotranspiration of wheat before winter wheat overwinter time was positively associated with soil moisture at sowing time. There were significant differences in evapotranspiration among different soil compaction treatments under the same irrigation date. Comparison among different irrigation dates showed that early irrigation lowered soil moisture and evapotranspiration at wheat sowing stage, which was the reverse for late irrigation treatments. The minimum evapotranspiration was observed in G95 treatment under I9.30 irrigation date, while it was observed in G120 treatment under others irrigation dates. For different soil compaction treatments under the same irrigation date treatment, the order of the number of spikes was G120 > G95 > G0. Biomass accumulation, leaf area, stem number and grain yield were lowest in G0 treatment, while were higher under both G120 and G95 conditions. Stem number, spikes number and grain yield were lowest in CK treatment. Although irrigation time significantly influenced spike number, no significant interaction was noted between soil compaction and pre-sowing irrigation. The results demonstrated that the most suitable soil moisture for seed germination depended on the degree of soil compaction. Thus it was possible to use soil compaction to regulate soil moisture and invigorate seedling. The study suggested that the best period for early irrigation was from Sep. 20th to Sep. 25th. The most appropriate weight of roller was about 95 kg per meter.