نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشیار گروه علوم و مهندسی خاک، دانشگاه رازی، کرمانشاه، ایران.
2 استادیار گروه مهندسی تولید و ژنتیک گیاهی، دانشکده علوم و مهندسی کشاورزی، دانشگاه رازی، کرمانشاه، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
This study evaluated the effects of three tillage systems (conventional, reduced, and no-tillage), subsoiling, and safflower cultivation on soil physical, chemical, and biological properties using a split-split-plot design. Results indicate that tillage management significantly affects soil quality. Compared to conventional tillage, no-tillage and reduced tillage systems offer superior conditions by minimizing mechanical disturbance and retaining plant residues. These practices were associated with increased soil organic matter, organic carbon, and microbial biomass carbon. While conventional tillage exhibited higher basal soil respiration, this is indicative of accelerated organic matter mineralization and structural disturbance, rather than improved biological quality. In contrast, conservation tillage systems fostered more stable conditions for carbon retention and biological activity. Safflower cultivation further improved biological indicators through root exudates and residue integration, while the impact of subsoiling varied by tillage system. In conclusion, conservation tillage, particularly no-tillage, shows significant potential for maintaining and enhancing soil properties in the short term.
کلیدواژهها [English]
This study was conducted to evaluate the response of selected soil physical, chemical, and biological properties to different tillage systems, subsoiling, and plant presence under safflower cultivation conditions. The main objective was to identify soil management practices that could help maintain or improve soil quality under the conditions of the experiment. Soil management practices are widely recognized as important drivers of soil structural stability, nutrient dynamics, and microbial activity, particularly in semi-arid regions where soil degradation and organic matter depletion can limit crop production. Intensive soil disturbance may accelerate organic matter mineralization, disrupt soil aggregates, and increase carbon loss from soil. In contrast, conservation-oriented practices can improve soil conditions by minimizing disturbance, maintaining crop residues on the soil surface, and providing a more stable habitat for soil microorganisms. In addition, subsoiling is often used to alleviate soil compaction and improve root penetration and water movement, although its effectiveness may depend on the prevailing tillage system and soil conditions. Therefore, this research aimed to investigate the combined effects of tillage systems, subsoiling, and safflower presence on key indicators of soil quality.
The experiment was conducted during the 2022–2023 growing season at the research farm of Razi University in Kermanshah, Iran, located in a cold semi-arid climatic region at an altitude of 1320 m above sea level, 34°19′21″ N and 47°06′07″ E. The experimental field had been managed under conservation-oriented practices for seven years prior to the study. The experiment was arranged as a split-split-plot design within a randomized complete block design with three replications. The main plots consisted of three tillage systems: conventional tillage, reduced tillage, and no-tillage. The subplots included two subsoiling levels: with subsoiling and without subsoiling. The sub-subplots consisted of two plant conditions: safflower cultivation and no-crop condition. Subsoiling was performed before sowing at an approximate depth of 60 cm under suitable soil moisture conditions. In the conventional tillage treatment, the soil was plowed using a moldboard plow followed by disking. In the reduced tillage system, soil disturbance was limited to a single chisel pass, whereas in the no-tillage treatment, no mechanical soil disturbance was applied. Safflower (Carthamus tinctorius L.), cultivar Farman, was sown at a seeding rate of 20 kg. ha-1 using a direct drill, while crop residues were retained on the soil surface. Soil samples were collected from a depth of 0–30 cm before sowing and after harvest. The measured chemical properties included soil pH, electrical conductivity, available phosphorus, available potassium, organic carbon, organic matter, and total nitrogen. The physical properties evaluated were mean weight diameter of aggregates and water-dispersible clay. Biological properties included basal respiration, substrate-induced respiration, and microbial biomass carbon. Data were analyzed after testing the assumptions of normality and homogeneity of variance, and treatment means were compared using Duncan’s multiple range test at the 5% probability level.
The results indicated that soil management practices influenced several soil properties, although the magnitude and direction of these responses varied among the studied variables. Soil pH was not significantly affected by tillage system, subsoiling, plant condition, or their interactions, suggesting that short-term variations in soil disturbance and management intensity had limited influence on this relatively stable soil property. In contrast, soil electrical conductivity was significantly affected by tillage system, plant condition, and the interaction between tillage system and plant condition at the 1% probability level. The highest electrical conductivity values were observed under conventional tillage, whereas the lowest values occurred under no-tillage, indicating that reduced soil disturbance contributed to more favorable soil chemical conditions. The no-crop condition showed higher electrical conductivity than safflower cultivation, and in all tillage systems, the presence of safflower reduced soil electrical conductivity relative to the no-crop condition. The highest electrical conductivity value was recorded under conventional tillage without crop, while the lowest value occurred under no-tillage without crop. Overall, the pattern of results suggested that conservation-based tillage systems, particularly no-tillage and reduced tillage, provided more favorable conditions for maintaining several soil quality indicators than conventional tillage. These systems improved soil physical stability by reducing mechanical disturbance and maintaining plant residues on the soil surface, which likely contributed to aggregate preservation and reduced susceptibility to structural degradation. In addition, reduced soil disturbance helped preserve soil organic carbon and organic matter by slowing their mineralization and limiting oxidation processes. By contrast, intensive tillage operations increased soil aeration and aggregate disruption, thereby accelerating the decomposition of organic matter and increasing the risk of carbon loss from soil. The biological indicators further highlighted the sensitivity of soil microbial processes to management practices. Basal respiration was highest under conventional tillage, reflecting increased microbial respiration associated with greater soil aeration, disruption of soil aggregates, and rapid decomposition of readily available organic substrates. However, the higher basal respiration observed under conventional tillage should not necessarily be interpreted as an indicator of improved biological soil quality. Rather, it may indicate accelerated mineralization of organic matter and greater carbon loss from soil. In contrast, microbial biomass carbon was generally greater under less intensive tillage systems, particularly where soil structure remained relatively undisturbed and organic substrates were more consistently available. No-tillage also appeared to provide a more stable habitat for soil microorganisms by preserving soil aggregates, moderating fluctuations in soil temperature and moisture, and maintaining carbon inputs near the soil surface. Safflower cultivation influenced biological properties through rhizosphere processes, root exudates, and root-derived carbon inputs, which can stimulate microbial activity and contribute to improved biological functioning compared with the no-crop condition. The effect of subsoiling varied depending on the soil property considered and its interaction with the tillage system. In some cases, subsoiling improved the soil physical environment by reducing compaction and facilitating the movement of water and air through the soil profile. However, the response of biological indicators, including microbial biomass carbon and respiration, depended on the interaction between subsoiling and the overall tillage regime. This suggests that the effectiveness of deep soil loosening practices should be evaluated within the broader context of soil management intensity rather than as an isolated intervention.
Overall, the results of this study showed that soil physical, chemical, and biological properties responded differently to tillage systems, subsoiling, and plant presence. However, the general trend supported the relative advantages of conservation-based soil management under the conditions of this experiment. No-tillage and reduced tillage were more effective than conventional tillage in maintaining several soil quality indicators, as they minimized soil disturbance, preserved plant residues on the soil surface, enhanced the retention of soil organic matter, and provided relatively more favorable conditions for soil microbial communities. Although conventional tillage increased basal respiration, this response was more likely associated with accelerated organic matter decomposition and carbon loss rather than improved biological sustainability. Safflower cultivation also contributed positively to some soil properties through rhizosphere processes and organic carbon inputs, while the effects of subsoiling were context-dependent and influenced by the prevailing tillage system. Taken together, these findings indicate that reducing tillage intensity and adopting conservation-oriented soil management practices can help maintain or improve some physical, chemical, and biological properties of soil in safflower-based cropping systems in semi-arid environments. However, further long-term studies with more detailed soil-depth sampling are needed to confirm the persistence of these responses over time.
This research was conducted without receiving any financial support from universities, research institutions, or governmental organizations. All expenses related to this study were covered by the authors.
All authors contributed equally to all stages of the research, including study design, data collection, statistical analysis, interpretation of results, as well as the drafting, reviewing, and finalization of the manuscript
The authors declare that no generative AI or AI-assisted technologies were used in the writing or preparation of this manuscript
The data supporting the findings of this study are available from the corresponding author upon reasonable request.
The authors sincerely appreciate the Research Deputy of Razi University, Kermanshah, for their valuable moral support and collaboration in the implementation of this study.
The authors avoided data fabrication, falsification, and plagiarism, and any form of misconduct.
The authors declare no conflict of interest.
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