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Showing 25 results for Vaezi
Short-Term Effects of Tillage Direction and Amount of Mulch Consumption on Soil Physical Properties in a Wheat Rainfed Land
A.r. Vaezi, S. Rezaeipour, M. Babaakbari, F. Azarifam,
Volume 27, Issue 3 (Fall 2023)
Abstract
Improving soil physical properties and increasing water retention in the soil are management strategies in soil and water conservation and enhancing crop yield in rainfed lands. This study was conducted to investigate the role of tillage direction and wheat stubble mulch level in improving soil physical properties in rainfed land in Zanjan province. A field experiment was done at two tillage directions: up to the downslope and contour line, and five stubble mulch levels: zero, 25, 50, 75, and 100% of land cover equal to 6 tons per hectare. A total of 30 plots (2 m×5 m) were created. The results indicated that water infiltration and water content were considerably affected by tillage direction, whereas its effect on water holding capacity was not significant. This physical property of the soil was influenced by the inherent properties of the soil, including particle size distribution. The change of up to down tillage direction to the contour line increased soil infiltration to 11% and water content to 6%. The physical soil properties were wholly influenced by mulch consumption. Soil water content increased in mulch treatments along with water holding capacity and infiltration rate. The highest volumetric water content was at 100% mulch level (10.62%) which was 11% more than the control treatment. However, there was no significant difference between 100% and 75% mulch treatment. This revealed that the application of 75% stubble mulch in contouring tillage is a substantial strategy for improving soil physical properties and controlling water loss in rainfed lands of semi-arid regions.

The Relationship between the Sensitivity to Rill Erosion and Soil Physical Degradability Due to the Land Use Change in Semi-Arid Pastures
A.r Vaezi, Kh. Sahandi, F. Haghshenas,
Volume 28, Issue 3 (Fall 2024)
Abstract
Water erosion can be affected by land use change and soil degradation by agricultural activities. This study was conducted to investigate the effects of land use change in poor pastures on soil physical degradation and water erosion in semi-arid regions. Experiments were performed in 42 soil samples taken from seven areas covering the two land uses: poor pasture and rainfed agriculture, which have different soil textures (clay loam, silty clay loam, sandy clay loam, silt loam, loam, sandy loam, and sandy loam). The physical characteristics of soils were measured in the samples of both types of land use and its changes were expressed as physical degradation of the soil. The soil's susceptibility to water erosion was measured under simulated rainfall with 50 mm h-1 intensity for 60 min. The results showed that the land use change in pastures leads to the physical deterioration of soils; so bulk density, porosity, macropore, field capacity, saturated point, aggregate size, and aggregate stability were degraded with a rate of 28, 22, 41, 11, 5, 62, and 63 percentages. The structural characteristics of soil (aggregate size and stability) had the highest physical deterioration due to the land use change in the pastures. The change in land use change greatly increased the sensitivity of soils to water erosion. A significant relationship was found between the susceptibility of water erosion and the soil's physical degradation. The soils with coarser and more stable aggregates have higher physical degradation by the land use change and in consequence show more susceptibility to water erosion.

The Effect of Temporal Distribution Pattern of Rainfall Intensity on Runoff and Soil Loss in a Hillslope in a Semi-Arid Region
A.r. Vaezi, F. Besharat, F. Azarifam,
Volume 28, Issue 4 (Winter 2024)
Abstract
The temporal distribution pattern of rainfall can play a role in the production of runoff and soil loss during rainfall. This study investigated four rainfall patterns: uniform, advanced, intermediate, and delayed rainfall under field conditions. The rainfall height in all rainfall patterns was 20 mm. In the uniform rainfall pattern, a constant rainfall intensity (40 mm h-1) was used and in the non-uniform rainfall patterns, a maximum rainfall intensity of 40 mm h-1 was applied for a 15-minute duration. The experiments were carried out in 60 cm × 80 cm plots on a hillslope with a slope gradient of 9% at three replications. Rainfall patterns were set up on the plots in five events with an interval of one week. The results showed a significant difference between rainfall patterns in runoff and soil loss (p<0.01). This difference was due to the destruction of surface soil structure and the reduction of water infiltration rate, especially during peak time of rainfall intensity (40 mm h-1). The highest runoff occurred in the delayed rainfall (3.43 mm) while, the highest soil loss (61.47 g m-2) was observed in the intermediate rainfall, which was associated with the peak intensity of rainfall at the end of the rainfall and its role in the destruction of the soil structure on the one hand, and the loss of infiltration rate on the other hand. Variation of runoff and soil loss from one event to another indicated that soil loss is in line with runoff production in uniform rainfall, while soil loss did not follow runoff in other rainfalls. Soil loss in these rainfalls was affected by both runoff production and availability of erodible soil particles. These results revealed the necessity of studying the rainfall intensity distribution pattern for accurate prediction of soil erosion and determining soil loss variation event by event in the semi-arid region.

Investigating the Soil Susceptibility to Splash Erosion in Drylands in the Semi-Arid Region of Northwestern Iran
Dr. Ali Reza Vaezi, Saeideh Akbari, Fereshteh Haghshenas,
Volume 30, Issue 1 (spring 2026)
Abstract
Splash erosion is the initial stage of soil erosion by water, which can be significantly influenced by soil properties. The rate of this type of soil erosion in drylands of semi-arid regions is high due to sparse vegetation cover, particularly during the early stages of plant growth. This study was conducted to investigate the soil properties determining splash erosion in semi-arid drylands. Soil aggregates with a diameter of 6 to 8 mm were taken from the soil surface (0-30 cm depth) in thirty dryland farms at three replications. Soil aggregates were purred into splash bowls and exposed to simulated rainfalls with an intensity of 60 mm h-1 for 30 minutes. Different soil properties were determined in ninety soil samples. Based on the results, the highest splash erosion occurred in clay loam (0.0021 gm⁻²s⁻¹), while the lowest value was in loamy sand texture (0.0008 gm⁻²s⁻¹). Splash erosion was significantly affected by grain size distribution; so that positive correlations were found with silt (r= 0.43), clay (r= 0.44), and dispersible clay (r= 0.47), whereas negative correlations existed with sand (r= -0.46) and gravel (r= -0.53). Furthermore, splash erosion was considerably influenced by organic matter (r= -0.23), calcium carbonate (r= -0.22), bulk density (r= -0.60), aggregate stability (r= -0.44), and hydraulic conductivity (r= -0.44). This study revealed that the drylands with fine-textured soils and having a lower amount of organic matter as well as calcium carbonate, have a higher susceptibility to splash erosion in semi-arid regions.  

Spatial Variability of Precipitation Use Efficiency in Wheat Rainfed Lands in a Semi-Arid Region, Zanjan Province
Ali Reza Vaezi, Fatemeh Babaei, Hadiseh Safiloo,
Volume 30, Issue 2 (summer 2026)
Abstract
Precipitation use efficiency (PUE) is defined as crop yield per unit of annual precipitation in a region. Proper management of rainfed lands requires investigation of the spatial variation of PUE. In this study, two hundred ninety-eight rainfed lands were investigated in the Khodabandeh region in the south of Zanjan province. PUE was calculated as the ratio of wheat grain yield to precipitation. In addition, climatic characteristics and soil physical properties (particle size distribution and water retention) were measured, along with soil chemical properties (pH, EC, organic matter, calcium carbonate, and macro- and micronutrients) in rainfed soils. Results indicated that the mean PUE in rainfed lands is 4.43 kg mm-1. Higher values were found in the northeast, south, and west regions of the area, although these parts had lower wheat grain yields. Geostatistical analysis showed moderate spatial variation in wheat grain yield and PUE, with patterns associated with climatic variables (precipitation and temperature) and land conditions such as soil properties (particle size distribution, organic matter, and nitrogen). Rainfed lands with fine-textured soils and higher amounts of organic matter and nitrogen had higher PUE. Adjusting tillage direction and using conservation tillage are important strategies to improve organic matter content and soil productivity in rainfed lands.

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