Soil sensors have a vital role in precision agriculture. In smart agriculture, soil moisture sensors, soil temperature–humidity sensors, soil pH sensors, soil nutrient sensors, soil pollutant and pest sensors, and wearable sensors detect data to improve crop yields and advance agricultural development. This paper summarizes the types and applications of the above sensors. Soil sensors serve as the core technological engine of smart agriculture, and this review also illustrates that the integration of the Internet of Things and sensors—including plant wearable sensors, which indirectly reflect soil conditions through plant physiological signals—can simultaneously measure or infer parameters, e.g., moisture, temperature, pH, and nutrients, that play a crucial role in precision agriculture. This paper concludes with the future prospects and challenges of soil sensors in smart agriculture, emphasizing the need to address bottlenecks in data fusion, model optimization, and cost control, as well as to advance the implementation of smart agriculture through the development of standards and ecological construction.

A new method for finite element simulation analysis of the interaction between complex structured tillage implements and soil was established in this study. This method accurately analyzes soil fragmentation during subsoiling using tillage tools with complex structures. It also accurately reflects the force on bionic subsoilers during cultivation, the interaction law between the subsoiler and the soil, and the impact of subsoiling operations on the soil properties. Bionic subsoilers were introduced to establish a dynamic analysis model for subsoiling cultivation. The novelty lies in introducing bionic subsoilers inspired by mole claws to reduce draft force and optimize soil failure patterns. Experiments have shown that compared with standard subsoilers, the stress distribution of the bionic subsoiler-H is significantly reduced, with a maximum stress reduction of 52.96%. The stress distribution of the subsoilers after subsoiling cultivation was directly proportional to the wear of the subsoiler, and the draft force of the subsoiler was inversely proportional to the size of the soil block at the front of the subsoiler. Compared with the soil model with a plough layer, the average stress values of the standard subsoiler, bionic subsoiler-H, and bionic subsoiler-C in the models without a plough pan layer were reduced by 13.97%, 6.67%, and 7.1% lower, respectively. Abaqus finite element analysis could not only effectively reflect the actual situation of soil in the field, but also accurately simulate and analyze the effect of soil fragmentation in the subsoiling process via tillage tools with complex structures, providing a digital analysis foundation for the collection of intelligent tillage information.

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.

Returning crop residues to soil is fundamental to sustainable agriculture, yet its adoption in cold-climate regions is hampered by an agronomic paradox: surface mulching conserves water but suppresses the spring soil temperatures required for crop establishment. In the present study, through a nine-year field experiment in a Mollisol under continuous maize cultivation, it was demonstrated that the method of maize straw incorporation, not merely its rate, is the decisive factor in resolving this conflict. While surface mulching maximized water conservation, it induced severe soil cooling and showed minimal gains in soil fertility. In contrast, incorporation via rotary tillage or deep plowing mitigated this cooling effect and proved superior for nutrient cycling. Among all strategies, rotary tillage of 50% residue (ROT-50) delivered the most balanced performance: it achieved the highest total nitrogen, substantially increased soil microbial biomass, and maintained one of the highest levels of Shannon diversity among incorporation treatments. These biogeochemical enhancements were driven by a fundamental, method-induced shift in the bacterial community from an oligotrophic to a copiotrophic structure. These findings shift the paradigm from a focus on residue quantity to one on incorporation method, providing a robust framework for reconciling crop productivity with long-term soil health in temperate agroecosystems.