Document Type : Research Article
Authors
1
Agrotechnology Student, Department of agronomy, Gorgan University of Agricultural Sciences and Natural Resources, Iran.
2
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3
Associate Professor, Department of agronomy, Gorgan University of Agricultural Sciences and Natural Resources, Iran.
4
Ph.D. graduated of agronomy, Department of agronomy, Gorgan University of Agricultural Sciences and Natural Resources, Iran.
10.22067/jcesc.2026.98851.1458
Abstract
Abstract
Introduction: Applying mulch from crop residues can be effective in increasing water use efficiency by reducing soil surface evaporation, particularly in arid regions. This study investigated the effect of wheat residue mulch on soybean yield and net water applied in Golestan province, using a simulation model under both full and limited irrigation scenarios, for optimal management conditions (assuming no nutrient deficiencies or damage from pests, diseases, and weeds) and farmer field conditions. The investigation under full irrigation demonstrated the mulch’s effectiveness in reducing irrigation water, while under limited irrigation, it quantified the mulch’s role in increasing yield.
Materials and Methods: The SAWA (System for Agro-ecological Zoning) system was employed for Golestan province. In this system, the irrigated lands of the province are divided into 10 homogeneous agro-ecological zones, covering over 90% of the mentioned lands. The SSM-iCrop2 crop simulation model, forming the core of the system, is used to simulate plant growth, field water balance, and crop yield under experimental conditions (optimal management) and actual farmer field conditions. In the present study, the model was first parameterized based on recorded actual yields to estimate conditions in farmer fields. Subsequently, the impact of different mulch rates was simulated for both experimental and farmer field conditions across four main soybean cultivation zones in the province. In the next step, the effect of two mulch rates, specifically 2 and 3.65 tons/ha, was examined on yield and irrigation water volume under optimal irrigation (automatic) and limited irrigation (including 3 irrigations at pre-sowing stages, when 40% and 60% of the growth stage had passed). Simulations were conducted based on long-term meteorological data (at least the last 10 years) in the aforementioned 10 zones. Meteorological information was obtained from various stations across the province.
Results and Discussion: This study revealed that under optimal irrigation conditions (automatic), the application of 2 tons/ha of mulch reduced irrigation water by 9% under potential conditions and 12% under farmer conditions. Under water-limited conditions, the application of mulch significantly enhanced soybean yield. Specifically, at a mulch rate of 2 t ha−1 (under constant irrigation volume), yield increased by 18% under farmer management conditions and 16% under potential conditions. Furthermore, increasing the mulch rate to 3.65 t ha−1 further boosted yield increments to 23% and 19% under farmer and potential conditions, respectively. In the potential irrigation scenario, the irrigation water depth for the control, 2 t ha−1 mulch, and 3.65 t ha−1 mulch treatments was 458, 410, and 393 mm, respectively. Similarly, under farmer management, the irrigation depths for the control, 2 t ha−1 mulch, and 3.65 t ha−1 mulch were 584, 536, and 514 mm. Regarding soybean grain yield under water-limited conditions, the values for the control, 2 t ha−1 mulch, and 3.65 t ha−1 mulch were estimated at 2.98, 3.2, and 3.57 t ha−1 under potential conditions, and 1.8, 1.97, and 2.02 t ha−1 under farmer management conditions.
Overall Conclusion: Based on the estimations from this study, under automatic irrigation conditions, maintaining at least 2 tons/ha of mulch would result in water savings of 8.53 million cubic meters (5.8 million m³) for farmer conditions and 9.78 million cubic meters (7.9 million m³) for potential conditions, compared to the same conditions without mulch application. In light of contemporary water resource limitations, the application of mulch and the retention of crop residues on the soil surface represent a critical and efficacious approach to climate adaptation.
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