Effects of tillage and straw returning method on the nutrient accumulation, distribution and yield of maize in black soil of semi-arid region

Objective In semi-arid area of Heilongjiang Province, maize production generally use traditional rotary tillage, and straw resources are not recycled properly. We studied different tillage and straw returning methods to increase the nutrient use efficiency and the yield of maize in this area.

Methods The maize field experiment was carried out in Zhaozhou County, Heilongjiang Province in 2019 and 2020. A total of seven treatments were set, including rotary ridge tillage (Con), no-tillage with straw removal (T1), no-tillage with straw returning (T2), straw returning with deep plowing + ridge tillage with subsoiling (T3), straw returning with deep plowing + flat tillage with subsoiling (T4), straw shredding and returning to field + ridge tillage (T5), straw shredding and returning to field + flat tillage (T6). At the key growing stages, maize plant samples were collected for the determination of biomass and nutrient accumulation, and the yield and yield components were investigated at harvest.

Results Tillage and straw returning methods significantly affected the yield and nutrient accumulation (P<0.01 ). Compared with Con, T2, T3, T4 all increased the effective panicle number per unit area, grain number per panicle and yield of maize. Among them, T3 exhibited the best effect, with an increase of 15.4%, 12.0% and 17.7%, respectively. Compared with Con, the nitrogen and potassium accumulation of T4 treatment were significantly increased by 24.8% and 15.3%, and the nitrogen accumulation of T3 was significantly increased by 20.4%. Among all treatments, T1 had the lowest N, P and K accumulation in maize, T2 treatment had 17.5%, 10.7% and 5.8% higher N, P and K accumulation than T1; T4 had 18.6%, 11.8% and 10.6% higher N, P and K accumulation than T6; and T3 had 9.9%, 1.4% and 6.3% higher N, P and K accumulation than T5. Under straw returning, T4 had similar nutrient accumulation and yield with T3.

Conclusions Compared with conventional rotary ridge tillage, straw deep plowing in autumn combined with subsoiling at seedling stage of maize in the coming spring, no matter flat or ridge planting, can significantly promote the NPK accumulation and harvest index, increase the dry matter transport capacity, panicle number per unit area, 100-grain weight and yield of maize. Straw returning to shallow field offset the increase effect.