Objective The aims were to investigate the effects of straw returning to the field and shallow-buried drip irrigation on maize material accumulation and transport, as well as water and nitrogen (N) use efficiency, in order to provide the basic information for increasing high-yield and high-efficiency maize production.

Methods This study employed a split-plot design, with straw returning to the field as the primary treatment, comprising straw secondary crushing and deep ploughing to the field and deep ploughing without straw returning. For straw returning to the field, a straw incorporation machine was used to secondary-crush the straw into 5 - 10 cm lengths prior to sowing, then deep plough it into the soil. For straw non-returning to the field, baling and transporting the straw out of the field before sowing, followed by deep plowing. The irrigation patterns as secondary treatments, comprising shallow buried drip irrigation and traditional border irrigation, evaluated through two consecutive years of field positioning experiments.

Results Results indicated that maize biomass accumulation, transport volume and transport rate were significantly higher under the treatment of straw returning to the field than that of straw non-returning conditions. Furthermore, the shallow-buried drip irrigation method was significantly higher than the traditional border irrigation method under straw returning conditions. Nitrogen accumulation was higher under straw returning than that of straw non-returning. Under straw returning conditions, N accumulation in the shallow-buried drip irrigation method was 3.04% higher than in the traditional border irrigation method, and 2.19% higher under non-returning conditions. Under conditions of straw returning to the field, the shallow-buried drip irrigation method was higher than the traditional border irrigation method by 6.06% in N transfer rates. Under conditions of straw not returning to the field, it was higher by 3.75%. Grain filling rate peaked at 21 days after silking, with the highest rate observed under the shallow-buried drip irrigation method with straw returning to the field. This advantage persisted even after 49 days after post-silking. Under straw returning conditions, the active grain filling period of strong grains was 1.06 days longer in shallow-buried drip irrigation than that in traditional border irrigation, and 0.66 days longer under straw non-returning conditions while that of weak grains was 0.33 days and 0.37 days longer. Soil water storage in the 0 - 40 cm soil layer was higher when straw was returned to the field at harvest than that removed. Under the same straw return pattern, the shallow-buried drip irrigation pattern performed better than the traditional border irrigation patten. In soil layers of 40 - 60 cm, soil water storage was higher when straw was returned to the field than straw was removed. The shallow-buried drip irrigation method with straw returned to the field performed lower than the traditional border irrigation pattern, whilst the shallow-buried drip irrigation method with straw non-returning to the field performed better than the traditional border irrigation method. Grain yield and irrigation water use efficiency were consistently higher in the straw returning treatment than in the straw non-returning treatment. Under the same straw return method, the shallow-buried drip irrigation method significantly higher than the traditional border irrigation pattern. Water use efficiency was higher in straw returning to the field than in straw non-returning. Under the same straw return method, the shallow-buried drip irrigation pattern significantly exceeded the traditional border irrigation pattern. Under straw-returning conditions, the partial factor productivity of N in the shallow-buried drip irrigation pattern was 4.05% to 6.05% higher than those in the traditional border irrigation pattern and under straw non-returning conditions (5.15% to 7.57% higher). The interaction between straw returning and irrigation patterns exerted a significant or highly significant effect on partial factor productivity of N.

Conclusion The straw secondary crushing, deep ploughing returning to the field and shallow -buried drip irrigation pattern promotes maize material accumulation and transport, enhances grain filling rate, has higher grain yield and water and nitrogen use efficiency, which is a suitable method for high-yield and high-efficiency maize cultivation in the irrigation area of Xi Liao He plain.