چکیده:
The current study was conducted to investigate the effect of tillage methods, residue rates, and forward speeds on the soil-water characteristic curve (SWCC) of Haploustepts soil over the course of one crop year (2014-2015). The treatments consisted of conventional mechanized tillage (CT: moldboard plough+disc) and reduced tillage (RT1: chisel peker+plough and RT2: combined tillage) , different surface residues, including three levels of no residue, 40% residue, and 80% residue, and forward speeds at three levels: low (4 km/h) , normal (7 km/h) , and high (10 km/h). The experimental water retention data were fitted to uni-modal van Genuchten (termed uni-modal vG) and bi-modal Dexter (termed bi-modal Dex) models. No significant impact was observed on different physical parameters, except for parameter n. In the slope at the inflection point of SWCC, 11. 8% and 8. 9% reductions were observed in CT and RT1 treatments, respectively, compared to RT2. Based on the results, measured under CT tended to be higher than that of other tillage treatments. Residual covers and higher forward speeds tended to increase both and. Changes in PSD were more pronounced in larger (macro) and medium (meso) pore diameter classes. The highest value of structural void ratio as transmission pores was observed in RT2. This finding indicates that with respect to , , , and values, the soil PSD descriptive system is a bi-peak distribution such as H-L; therefore, due to the hierarchical nature of soil structure, van Genuchten equation cannot appropriately describe multi-modal soils inherently.
خلاصه ماشینی:
ir Desert 24-2 (2019) 307-318 Short-Term Effect of Tillage Methods, Residue Levels, and Forward Speeds on Soil- Water Characteristic Curve (SWCC): A Case Study on the Eastern Soils of Karun River, Khuzestan Province, Iran A.
Moradib a Department of Soil Science, Agricultural Sciences and Natural Resources university of Khuzestan, Ahvaz, Iran b Department of Soil Science, Shiraz university, Shiraz, Iran Received: 1 May 2019; Received in revised form: 16 June 2019; Accepted: 24 Agust 2019 Abstract The current study was conducted to investigate the effect of tillage methods, residue rates, and forward speeds on the soil-water characteristic curve (SWCC) of Haploustepts soil over the course of one crop year (2014-2015).
Due to their repeated application, effective depth range extending up to tens of centimetres, and impact on type and residue management, tillage practices are deemed as the most important method for manipulating or changing the physical properties of agriculture soils (Blanco- Canqui et al.
Numerous studies have been conducted on the effect of different tillage system types and crop residue levels on the changes in soil physical properties (Strudley et al.
The overall objectives of this work were to investigate the impacts of various short- term tillage experiments, residue levels, and forward speeds on (1) SWCCs obtained by uni- modal van Genuchten (termed uni-modal vG) and bi-modal Dexter (termed bi-modal Dex) models, (2) soil physical quality, (3) residual, matrix, and structural void ratios, and (4) capability of uni- and bi-peak pore size distribution (PSD) curves to describe the resulting changes.
Mean values of considered soil physic-hydraulic properties affected by tillage methods, residue levels, and forward speeds are presented in Table 4.