Document Type : Research Paper
Authors
1 Dryland Agricultural Research Institute, Agricultural Research Education and Extension (AREEO), Maragheh, Iran
2 Sararood Branch, Dryland Agricultural Research Institute, Agricultural Research Education and Extension (AREEO), Kermanshah, Iran
3 Agricultural and Natural Resources Research and Education Center of West Azarbaijan Province, Agricultural Research, Education and Extension Organization (AREEO), Urmia, Iran
Abstract
Introduction: In dryland agroecosystems, limited soil moisture, uneven rainfall distribution, and temperature fluctuations are among the major constraints to sustainable crop production. Under such conditions, conservation tillage systems, particularly reduced tillage and no-tillage, are considered effective strategies for sustaining agricultural productivity. Forage vetch, as an important legume in rotation with wheat, not only provides high-quality forage but also contributes substantially to improving soil fertility and enhancing the sustainability of cropping systems. However, its response to nutrient inputs, particularly nitrogen and phosphorus, may be influenced by the tillage system and the climatic conditions prevailing in each growing season. Therefore, the present study aimed to investigate the effects of conservation tillage systems and different rates of nitrogen and phosphorus fertilizers on the quantitative traits and yield of dryland forage vetch grown in rotation with wheat.
Methodology: A split-plot experiment based on a randomized complete block design with three replications was conducted over four growing seasons (2020–2024) at the Maragheh Dryland Agricultural Research Station, Iran. The main-plot factor consisted of two tillage systems reduced tillage and no-tillage whereas the subplot factor comprised four application rates of either nitrogen or phosphorus fertilizer: 0, 22, 43, and 65 kg ha⁻¹, supplied as urea and triple superphosphate, respectively. Forage and grain yields were evaluated. The data were analyzed using combined analysis of variance, followed by mean comparisons. Quadratic regression models were fitted to determine the optimum fertilizer application rates.
Research findings: Cropping year, tillage system, and fertilizer application rate significantly affected the studied traits. The highest grain yield was recorded in the 2023–2024 cropping season. Furthermore, no-tillage resulted in a significant increase in grain yield and 100-grain weight compared with reduced tillage. Application of 22 kg ha⁻¹ of urea and triple superphosphate significantly improved most of the measured traits relative to the control, with the highest response generally observed at 43 kg ha⁻¹; however, increasing the application rate to 65 kg ha⁻¹ did not confer any significant advantage. Estimation of optimum fertilizer rates revealed that the favorable application rate ranged from 43 to 59 kg ha⁻¹ for urea and from 39 to 58 kg ha⁻¹ for triple superphosphate, depending on the trait. To achieve 90% of the maximum forage dry matter yield of vetch cv. Golsefid under cold dryland conditions in rotation with wheat, an application rate of up to 12 kg ha⁻¹ triple superphosphate, along with 18 and 32 kg ha⁻¹ urea for the reduced-tillage and no-tillage systems, respectively, is recommended.
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