Objectives In the cold and dry farming areas along the Greater Khingan Mountains, soil moisture in spring is often too low for maize to sow. Straw mulching during winter and no-tillage before sowing in next spring had been promoted to preserve soil moisture. However, the technology often leads to poor germination and is hard for topdressing of nitrogen fertilizer. In this study, we modified the strawmulch and tillage method, andtried to avoide topdressing by basal application of controlled release fertilizer and common urea in suitable ratio, to overcome the shortcomings of the technology.
Methods Tillage method (trial 1) and fertilization experiment (trial 2) were carried out simultaneously in Zhalaite Banner of Xing’an League, Inner Mongolia from 2021 to 2022. In trial 1, four tillage treatments were setup, as: conventional ridging without straw mulch (CP), no-tillage without straw mulch (NT), no-tillage with straw mulch (RNT), and strip tillage with straw mulch (RST). In trial 2, strip tillage with straw mulch were used as tillage method (RST), three fertilization modes were set: conventional fertilization (Sd), controlled release nitrogen fertilizer mixed with common urea in ratio of 3∶7 (30%Cr), and 5∶5 (50%Cr). Before sowing and after harvesting, soil samples were collected from 0–20, 20–40, 40–70, 70–100 cm soil layers to determine the content of inorganic nitrogen, and calculate the residual nitrogen and apparent loss. Plant samples were collected at silking and maturing stage for the analysis of biomass and N content. The yield and yield components were investigated at harvest.
Results Compared with NT, CP and RNT, RST increased the maize generation rate by 1.6%, 9.3% and 9.1%, the population biomass by 2.7%, 9.1%, and 9.1%, grain yield by 4.2%, 6.0% and 7.2%, the nitrogen agronomic efficiency by 29.7%, 45.5% and 60.0%, respectively. Compared with 30%Cr and Sd under straw mulch and strip tillage, the population biomass of 50%Cr increased by 3.3% and 10.6%, the pre-silking biomass increased by 4.1% and 9.9%, the post-silking biomass increased by 2.9% and 10.4%, the N accumulation increased by 3.6% and 14.6%, the pre-silking N accumulation increased by 3.8% and 12.8%, and the post-silking N accumulation increased by 4.3% and 21.4%, respectively. 50%Cr increased maize yield by 3.6% and 8.9%, nitrogen agronomic efficiency by 16.3% and 49.0%, the soil inorganic nitrogen residue decreased by 2.8% and 4.5%, and the apparent nitrogen loss decreased by 8.2% and 21.3%, and net income increased by 3.5% and 6.9%.
Conclusions The modified tillage method: straw mulching during winter, clearing a seeding belt next spring and then subsoiling the seeding belt soil for fertilization and sowing, significantly increased the germinate rate. Under the modified tillage method, applying the whole fertilizer before sowing, with the controlled release nitrogen fertilizer and common urea in ratio of 5∶5, will not impact the germination rate, but effectively improve the pre- and post-silking dry matter and N accumulation, and the transfer rate of maize population, significantly improve grain yield, nitrogen use efficiency and economic benefit of maize, and reduce the soil nitrogen residue and apparent N loss. So, the mix ratio of nitrogen fertilizers is adapted to the modified tillage method, being a light and simple management in production of maize in cold and arid regions.
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