Water-salt Displacement in Different Width Strip Tillage by Concentrated Straw Return Increased Wheat Yield in Coastal Saline-alkali Land

This study investigated an innovative strip straw returning and tillage system to evaluate its impacts on water-salt transport and winter wheat yield in coastal saline-alkali land. The experimental design implemented strip-wise tillage with deep plowing (2.4 m width) intervals of 4.8 m (DR_4.8) or 2.4 m (DR_2.4), and rotary tillage in other strips. Combined with two straw returning methods: concentrated (C) and uniform (U) straw return. The concentrated straw treatment specifically transferred straw from rotary-tilled strips into deep-plowed strips. Four experimental treatments of tillage combined with straw returning: CDR_4.8, UDR_4.8, CDR_2.4, UDR_2.4, and rotary tillage combined with uniform straw returning were used as the routine treatment (UR). Our results in coastal mild (Chang Yi) to moderate (Wu Di) saline-alkali land demonstrated that deep-plowed strips concentrated straw within the 0-30 cm soil layer, creating localized modifications in water-salt distribution that drove transverse displacement of solute-laden water from rotary-tilled to deep-plowed strips. The lateral migration of water and salt from the rotary-tilled strip to the deep-plowed strip significantly increases with an increase in the straw returned in the deep-plowed strip (Wu Di: water- 73.50%; salt-77.62%, Chang Yi: water- 78.62%; salt-57.67%). It is worth noting that the lateral migration rate of water and salt in each treatment gradually decreased with the advancement of the growth period. The transverse transport efficiency of CDR_2.4 and UDR_2.4 was significantly higher than that of CDR_4.8 and UDR_4.8 (Wu Di- 18.68%; Chang Yi- 34.63%), and the transverse transport efficiency of Wu Di was significantly higher than Chang Yi (22.82%). Two years of field trials in both places showed that the highest yield was achieved with the CDR_4.8 treatment (Wu Di- 9.52%; Chang Yi- 8.98% increase compared to R). These findings establish that integrated strip tillage with straw redistribution offers a promising approach for sustainable coastal saline-alkali land improvement.