Optimum combination of tillage system and fertilization method enhances soil nutrient availability and crop productivity in fluvo-aquic soil region

Objectives This study was conducted in the fluvo-aquic soil region of northern Henan Province to investigate the effects of different tillage modes and fertilization on the photosynthetic characteristics, dry matter translocation, and yield of wheat and maize. The aim was to provide a theoretical basis for optimizing field management in this region.

Methods The long-term tillage experiment, located in Yuanyang City, Henan Province, was started in 2016. A two-factor split-plot design was used in the experiment, the main plot was fertilization: mere chemical fertilizers (NPK) and combination of organic and chemical fertilizers (MNPK); the sub-plots was tillage system. In every 3-year cycle, three tillage methods composted of a total of four modes: continuous rotary tillage (R-R-R), deep tillage-rotary tillage-rotary tillage (D-R-R), deep tillage-rotary tillage-shallow rotary tillage (D-R-S), deep tillage-shallow rotary tillage-shallow rotary tillage (D-S-S). In the second year of the third rotation cycle (June and October 2023), the photosynthetic parameters of wheat and maize at the main growth stages were monitored, the dry matter accumulation before flowering and maturity was investigated. The soil samples of 0−20 and 20−40 cm soil layers were taken at the maturity stage for nutrient content analysis.

Results Among the eight fertilization and tillage system treatments, MNPK+D-S-S yielded the highest soil nutrient contents in wheat season. Compared with NPK+R-R-R, the soil organic matter, total N, NO₃⁻-N, and available P in 0−20 cm soil layer in MNPK+D-S-S were increased by 32.3%, 30.0%, 64.3% and 292.4%, respectively, soil bulk density decreased by 16.4%, and porosity increased by 32.5%. At the flowering stage of wheat, the net photosynthetic rate, stomatal conductance and transpiration rate of wheat in MNPK+D-S-S were significantly higher than those in NPK+R-R-R treatment, the contribution of dry matter to grain after flowering was 29.6% higher than that of NPK+R-R-R treatment, and the yield was increased by 31.1%. In maize season, MNPK+D-R-S treatment outperformed other treatments in soil nutrient content, structure and photosynthetic characteristics of maize. Compared with NPK+R-R-R treatment, MNPK+D-R-S increased soil organic matter, total N, NH₄⁺-N and available P in 0-20 cm soil layer by 39.7%, 56.1%, 101.9% and 168.7%, respectively, decreased soil bulk density by 8.5%, and increased soil porosity by 21.5%; The net photosynthetic rate, stomatal conductance and transpiration rate of maize at flowering stage increased significantly; the contribution of dry matter to grain after flowering increased by 8.2%, and the yield increased by 20.0%.

Conclusions Implementing a three-year cycle of deep tillage with rotary or showllow rotary tillage, in combination with organic and chemical fertilizers, can improve soil structure and nutrient content, and consequently improve the photosynthetic characteristics of wheat and maize, enhance the efficiency of dry matter transport and accumulation after anthesis, and increase the yield at last. The approach is recommended as a local suitable farmland management measure.