Water and Soil

Abstract Introduction Tillage management is one of the main factors affecting soil quality and the sustainability of agricultural systems. Intensive conventional tillage can weaken soil structure, accelerate organic matter decomposition, and alter microbial activity due to continuous mechanical disturbance of the soil. In contrast, conservation tillage systems such as reduced tillage and no‑tillage minimize soil disturbance and often retain crop residues on the soil surface, which can improve soil aggregation, enhance soil organic carbon storage, and increase nutrient retention. These systems also help reduce soil erosion, improve water infiltration, and create more favorable conditions for soil microorganisms. In semi‑arid regions, where soil moisture is limited and soil degradation can occur rapidly, maintaining soil structure and fertility is particularly important for crop production. Durum wheat is an important cereal crop in many semi‑arid areas, and its productivity is closely related to soil health and nutrient availability. Therefore, understanding how different tillage systems influence soil properties is essential for developing sustainable management strategies. This study was conducted to evaluate the effects of different tillage systems and crop presence on selected physical, chemical, and biological properties of soil. Materials and Methods The experiment was conducted as a split-split-plot arrangement within a randomized complete block design (RCBD) with three replications. The treatments consisted of three tillage systems, including conventional tillage (CT), reduced tillage (RT), and no-tillage (NT), assigned to the main plots. The subsoiling treatments, including subsoiling and no-subsoiling, were allocated to the subplots, and two crop treatments, including control (uncultivated soil) and durum wheat (Triticum durum), were assigned to the sub-subplots. Soil samples were collected after the crop growing period from the experimental plots and prepared for laboratory analysis. A set of soil quality indicators representing physical, chemical, and biological aspects of soil functioning was measured. Physical and chemical assessments included pH, electrical conductivity (EC), water‑dispersible clay (WDC), and mean weight diameter (MWD) of aggregates, which were used to evaluate salinity condition and aggregate stability. Chemical analyses included soil organic matter (SOM), soil organic carbon (SOC), total nitrogen (TN), available phosphorus (P), and available potassium (K) as the main indicators of soil fertility and nutrient status. Biological properties were determined through basal soil respiration (BR) and substrate‑induced respiration (SIR), in order to estimate microbial activity and the potential metabolic response of soil microorganisms to an added substrate. In addition, microbial biomass carbon was considered in the interpretation of biological responses where relevant. The collected data were statistically analyzed using analysis of variance (ANOVA) to test the significance of the main effects of tillage and crop treatment as well as their interaction effects on soil properties. Mean comparisons were performed using appropriate post hoc tests at the selected probability level. Results and Discussion The results showed that tillage management significantly influenced the measured soil properties. Conventional tillage generally resulted in higher EC and water‑dispersible clay, indicating weaker structural stability, whereas no‑tillage improved aggregation and produced the highest mean weight diameter of soil aggregates. These results confirm that reduced soil disturbance promotes aggregate formation and protects soil structure. Soil organic matter and soil organic carbon increased as tillage intensity decreased, with the highest values observed under no‑tillage. This trend indicates that conservation systems reduce oxidation of organic materials and favor carbon accumulation within stable aggregates. Nutrient availability also improved under conservation practices, particularly in the no‑tillage treatment, where nitrogen, phosphorus, and potassium values were generally higher than in conventional tillage. Crop treatment had a positive effect on several soil properties. Soils under durum wheat showed higher soil organic matter, soil organic carbon, and nutrient concentrations than uncultivated control soils, probably because of root residues, rhizosphere activity, and enhanced microbial interactions. Biological indicators also responded significantly to management practices. Basal respiration was greater under conventional tillage, suggesting more rapid decomposition of soil organic matter under intensive disturbance. In contrast, lower respiration values under no‑tillage reflected greater stabilization of organic carbon. Substrate‑induced respiration was significantly affected by tillage, crop treatment, and their interaction, indicating that microbial activity was highly sensitive to both soil disturbance and plant presence. Conclusion The findings demonstrate that tillage management has an important role in controlling soil quality in durum wheat systems. Conservation practices, especially no‑tillage, improved soil structure, increased soil organic carbon and organic matter, and enhanced nutrient availability compared with conventional tillage. Durum wheat cultivation also contributed positively to soil improvement through rhizosphere effects and organic inputs. Overall, the combination of no‑tillage and durum wheat cultivation appears to be a suitable management strategy for improving soil quality and supporting sustainable production in semi‑arid conditions.

Abstract Introduction
Optimum yield production under rainfed cultivation directly depends on the amount of rainfall and moisture storage in the soil. The tillage system directly influences soil moisture retention as well as the soil’s physical and chemical properties. Selecting the appropriate tillage system can significantly impact crop yields. Oilseeds are particularly important among crops, representing the second-largest food reserve in the world after grains. These products are rich in fatty acids. Today, the oil extraction and production industry is one of the most strategic industries in most countries. Iran has vast arable land and favorable conditions for cultivating oilseeds. However, according to available statistics, over 80% of the country's oil needs are met through imports. Given the increasing demand for higher-quality oil products and the challenges posed by climate issues, such as recurring droughts, cultivating and developing crops with lower water requirements and greater resilience appears to be a promising solution. Implementing effective management practices and appropriate fertilizers aligned with conservation agriculture could help increase crop yields while maintaining and improving long-term soil quality. To explore the potential of oilseed cultivation, an experiment was conducted to examine the effects of tillage and fertilization on the yield and yield components of safflower under rainfed conditions.
 
Materials and Methods
This experiment was carried out as split plots based on random complete blocks design, with three replications under rainfed conditions. The treatments included tillage systems (conventional tillage, reduced tillage, and no-tillage) as the main factor and NPK fertilizer (a mixture of urea, triple superphosphate, and potassium sulfate) at four levels of zero, 33, 66, and 100% as a secondary factor. Potassium and phosphorus fertilization and 50% of nitrogen fertilizer were used at the same time as planting, and the remaining 50% of nitrogen fertilizer was used four months after planting. Each block had three main plots; the distance between each block was 3 meters, and between the main plots was 2 meters. In each main plot, four sub-plots were created, and the distance between the sub-plots was 1 meter. The area of the main plots was 21 × 15 meters, and the area of each sub-plot was 4.5 ×15 meters. The amount of seed used for safflower was 25 kg per hectare. The safflower seeds were sown in 5 rows and planted at a distance of 50 cm and a distance between plants of 10 cm. At all stages of planting, maintenance, and harvesting, agricultural management followed the traditional practices of the study area, as performed by the local farmers. The final sampling, or harvesting, was carried out manually at the physiological maturity stage. Before conducting variance analysis, a normality test was performed on the data. In this research, the LSD test was used to compare the mean at the 5% probability level, Excel software was used to draw graphs, and SAS 9.4 software was used to analyze the data.
 
Results and Discussion
The research showed that the traits examined, including leaf area index, dry matter content, thousand seed weight, seed yield, and biological yield, were affected by the tillage system, fertilizer, and their interaction effect. The highest safflower seed yield of 195.6 g/m² was obtained from the fertilizer ratio of 33% and conventional tillage, and the lowest seed yield of 116.2 g/m² was obtained from no-tillage and no fertilizer use. The results indicated that the conventional tillage system outperformed both reduced tillage and no-tillage systems. In reduced and no-tillage systems, the changes in the leaf area index of the safflower plant were similar, with the 100% fertilizer application under reduced tillage having a more pronounced effect compared to no-tillage. Additionally, in the absence of fertilizer in the no-tillage system, the leaf area index was lower. Fertilizer application increased the plant's biological yield, but its impact was greater under conventional tillage compared to reduced and no-tillage systems. Applying 33% of the required fertilizer in the conventional tillage system resulted in the highest biological yield for safflower, leading to a 94% increase in biological performance compared to the control.
 
Conclusion
In most of the examined traits, the application of 33 and 66% of the fertilizer requirement caused the best results, and the 100% fertilizer ratio left adverse effects, which indicates the lower fertilizer requirement of this cultivar in the studied conditions compared to cultivars in other regions. Since the research was conducted in rainy years, conventional tillage was better than low tillage. It is suggested that this plant's production amount be evaluated under different irrigation conditions and moisture limitations so that tillage systems and management methods can be examined and selected more carefully.