Limin Jiang

Soil degradation caused by soil salinization is an important factor affecting global food security. The soda saline–alkali soils in the Songnen Plain suffer from poor soil structure, hard topsoil and alkalized horizons, and high pH and Na⁺ concentrations, which pose a major threat to sustainable agricultural development. However, the development of demand-adapted agricultural machinery and agronomic technologies integrating physical and chemical amelioration remains a challenge for soda saline–alkali soil improvement under rain-fed dryland conditions. Based on the water solubility of aluminum sulfate, this study integrated novel equipment and technologies for efficient, engineering-oriented amelioration of soda saline–alkali soils. Experiment analysis of aluminum sulfate application rate experiments showed that the optimal amelioration effect was achieved at an ameliorant dosage of 0.6% of soil dry weight, with a pH reduction of 0.81 units. By means of installing liquid ameliorant spraying components on the base subsoiling machine, it was developed that integrated equipment for simultaneous subsoiling and ameliorant application across the entire plow layer was developed. Verification tests demonstrated that the soil disturbance coefficient, soil loosening degree, and coefficient of variation for liquid application uniformity among rows were 53.75%, 13.50%, and 4.83%, respectively; these operational performance indicators met the requirements of relevant industry standards. Comparisons of soil physicochemical properties under different amelioration treatments revealed that subsoiling combined with ameliorant spraying (SAS) outperformed subsoiling alone (S), surface ameliorant application (A), and the control (CK). Relative to CK, the SAS treatment increased soil water infiltration rate (WIR) by an average of 63.11%, reduced bulk density (BD) by 0.14 g/cm³, decreased pH by 0.86 units, and lowered soil salt content (SC) by 0.71 g/kg. Three-year field alfalfa cultivation experiments indicated that SAS increased alfalfa emergence rate, dry matter yield, and overwintering rate by 20.60%, 26.45%, and 20.29%, respectively, relative to CK. This study proposes an implementation strategy for integrated physical and chemical amelioration equipment and technologies for soda saline–alkali soils based on the SAS approach, which provides equipment, technical, and engineering application references for improving soil health, boosting crop yield, and promoting the efficient utilization of rain-fed soda saline–alkali land.

The implementation of scientific cultivation practices on soda saline–alkali land plays a pivotal role in safeguarding food security and promoting sustainable agro-economic development at the regional scale. However, there exists a critical knowledge gap regarding the optimization of tillage strategies for rain-fed maize (Zea mays L.) cultivation across heterogeneous saline–alkali soil matrices. This study selected meadow alkaline soil, saline meadow soil, and mild saline–alkali soil under the typical micro-landscape morphological characteristics of soda saline–alkali soil in the Songnen Plain as experimental plots. Under three tillage methods, namely no tillage (NT), rotary tillage + no tillage (RT), and subsoiling + rotary tillage + no tillage (SRT), the effects of the tillage methods on the soil physical properties at the seedling stage, root development at the V6 stage, and yield at the R6 stage during the process of cultivating maize in different types of soils were analyzed. The research results showed that compared with NT and RT, the SRT treatment better improved the physical properties, such as penetration resistance and the bulk density in micro-spaces (0–40 cm), of different soil types. The SRT treatment had a positive impact on the root development of maize seedlings in saline meadow soil and meadow alkaline soil. In terms of yield, compared with the NT treatment, the SRT treatment in meadow alkaline soil and saline meadow soil had a positive effect on the plant height, root dry weight, 1000–grain weight, and grain yield of maize. The increases in maize grain yield were 27.94% and 13.24%, respectively. Compared with NT, the differences in the effects of the SRT and RT treatments on maize yield in mild saline-alkali soil were the smallest, being 6.98% and 4.77%, respectively. The relevant results provide guidance on tillage methods and a theoretical basis for improving the properties of different types of soda saline–alkali soils and increasing maize yield.

Saline-alkali soil has the characteristics of high density, high firmness and poor permeability. Aiming at the problems of shallow subsoiling depth, large subsoiling specific resistance and small soil bulkiness in subsoiling operation in saline-alkali soil, this paper establishes a mathematical model of the specific resistance of a broken line subsoiler and uses genetic algorithm and the discrete element method to optimize the structure design of the subsoiler. Firstly, the mathematical model was developed by analyzing the force of the subsoiler in the working process. The genetic algorithm was used to solve the problem, and three geometric models of the broken line subsoilers were fitted. Then, EDEM software was used to simulate this, and the tillage performance was evaluated with draft force, soil disturbance area, subsoiling specific resistance and soil bulkiness as the indexes and verified by field experiment. The results showed that the subsoiling specific resistance of the three broken line subsoilers was significantly lower than that of the standard subsoiler in the simulation test. Compared to the standard subsoiler, the soil disturbance area of the broken line subsoiler-B increased by 12%, the draft force decreased by 19%, the subsoiling specific resistance decreased by 26% and the bulkiness increased by 6%. The field experiment results showed that the broken line subsoiler-B reduced the traction force and improved the tillage efficiency compared to the standard subsoiler, which was consistent with the analysis results of EDEM. The broken line subsoiler can effectively enhance the quality of cultivated land.

To improve the crushing efficiency and crushing pass rate of high-moisture corn ears (HMCEs), a multi-stage crushing scheme is proposed in this paper. A two-stage crushing device for HMCEs is designed, and the ear crushing process is analyzed. Firstly, a simulation model for HMCEs was established in EDEM software (2018), and the accuracy of the model was verified by the shear test. Subsequently, single-factor simulation experiments were conducted, with the crushing rate serving as the evaluation index. The optimal working parameter ranges for the HMCE device were identified as a primary crushing roller speed of 1200–1600 revolutions per minute (r/min), a secondary crushing roller clearance of 1.5–2.5 mm, and a secondary crushing roller speed of 2750–3750 r/min. A Box–Behnken experiment was conducted to establish a multiple regression equation. With the objective of maximizing the qualified crushing pass rate, the optimal combination of parameters was revealed: a primary crushing roller speed of 1500 r/min, a secondary crushing roller clearance of 2.5 mm, and a secondary crushing roller speed of 3280 r/min. The pass rate of corn cob crushing in the simulation test was 98.2%. The physical tests, using the optimized parameter combination, yielded a qualified crushing rate of 97.5%, which deviates by 0.7% from the simulation results, satisfying the requirement of a qualified crushing rate exceeding 95%. The experimental outcomes validate the rationality of the proposed crushing scheme and the accuracy of the model, providing a theoretical foundation for subsequent research endeavors.