Meta-analysis on maize and wheat yield under subsoiling in Northern China

Abstract: This study was to assess the effect of subsoiling & rotary tillage (SSRT) and subsoiling & no tillage (SSNT) on crop yield under conditions of different districts, crops, climate and experimental duration. Rotary tillage (RT) was taken as the control for SSRT while no tillage (NT) was taken as the control for SSNT. A total of 65 papers were selected from the published papers about North China in recent 30 years, including 111 pairs of trials and 357 observations. Data of experimental sites, treatments, crop strains, annual precipitations, average annual temperatures and experimental durations were abstracted from the selected papers. The planting district was divided into northeast, north and northwest. The annual precipitation was divided into three classes of ≤400mm, 400~600mm and ≥600mm. The experimental duration and the average annual temperature was classified as 2~3a and≥4a, <12℃ and ≥12℃, respectively. The effects of different condition on the relative yield change of SSRT against RT and SSNT against NT were analyzed by Meta-analysis. Results showed that SSRT significantly increased crop yield by 8.62% when compared with RT; SSRT significantly increased crop yield in Northeast, North and Northwest by 8.96%, 7.95% and 8.85%, respectively; Wheat yield and maize yield were significantly increased by 12.66% and 7.78% due to SSRT, respectively, however with no significant difference between these two crops; under different annual precipitation of ≤400, 400-600 and ≥ 600 mm, crop yield was significantly increased by 8%, 9.24% and 10.34% due to SSRT, respectively; significant increase in crop yield was also obtained with SSRT under different average annual temperature of <12℃ (8.47% ) and ≥12 ℃ (9.43%); SSRT significantly increased the crop yield by 10.37% when the experimental duration varied between 2 and 3 years, while no significant effect on crop yield change was observed when experimental duration was longer than 4 years. Generally, SSNT significantly increased crop yield by 10.17% when compared with NT; SSNT significantly increased crop yield in Northeast, North and Northwest by 11.25%, 10.63% and 9.17%, respectively; Wheat and maize yields were significantly increased by 8.73% and 11.56% due to SSNT, respectively, however with no significant difference between these two crops; annual precipitation, average annual temperature as well as experimental durations showed significant influence on crop yield increase of SSNT; the crop yield increase due to SSNT was 8.95% higher under the annual precipitation of 400-600 mm than that of ≥ 600mm; the crop yield increase due to SSNT was 7.08% higher with the average annual temperature of ≥12 ℃ than that of <12℃; the crop yield increase due to SSNT was 10.2% higher with the experimental duration of 2-3 years than that of ≥4 years. Therefore, SSNT would benefit the crop yield in areas with the higher annual precipitation and average annual temperature in North China. It suggested that subsoiling should be performed in alternate year or once in years since the positive effect of soiling on crop yield decreased with time. Our work could provide valuble information for the application of subsoiling technology in the northern region of China.