Objective To study the regulatory effects of farming methods on soil compaction and corn water use efficiency in compacted farmland in the black soil region of the southern Songnen Plain.

Method The maize variety 'Liangyu 99' was used as the experimental material, and the large-area experimental design was adopted to compare and analyze the changes of soil physical properties, maize yield related characters and water use in seedling belt and fallow zone under three tillage methods: conventional tillage (CK), strip tillage (ST) and strip tillage + subsoiling (ST + SS).

Result The farmland survey before sowing found that the soil compaction obstacle at the seedling belt position existed in the 0-20 cm soil layer, and the compaction obstacle at the fallow zone existed in the 0-30 cm soil layer. The soil penetration resistance of the fallow zone position was significantly greater than that of the seedling belt. However, under different tillage methods, comared with CK, ST treatment reduced soil penetration resistance by 59.18%-68.36%, soil bulk density by 6.01%-9.09%, and increased total soil porosity by 7.06-8.64 percentage points in 0-20 cm soil layer of seedling belt. The soil penetration resistance of 0-35 cm soil layer in ST + SS treatment decreased by 91.79%-92.27%, the soil bulk density of 0-5 cm soil layer decreased by 13.64%, and the soil total porosity of 0-30 cm soil layer increased by 6.52-18.45 percentage points. At the same time, ST + SS treatment increased the soil water content of 0-20 cm soil layer in seedling belt by 9.29%-20.87%, and the soil water content of 0-30 cm soil layer in fallow zone by 9.51%-15.32%. In addition, the water consumption during maize growth period of ST + SS treatment decreased by 30.60 mm, while the water storage after harvest increased by 36.53 mm, and the precipitation use efficiency and water use efficiency increased by 12.86% and 21.28% compared with CK. The maize yield of ST and ST + SS treatments increased by 7.53% and 11.65%, respectively, compared with CK treatment.

Conclusion Strip tillage with subsoiling tillage practice can significantly reduce soil penetration resistance, increase soil porosity, and thereby improve crop water use efficiency and maize yield. It serves as an effective approach for alleviating farmland compaction constraints in the black soil region of the southern Songnen Plain.