In the heart of Iran’s cold, rainfed regions, a critical study is reshaping how we think about nitrogen management in chickpea cultivation. Led by Yaser Azimzadeh from the Natural Resources Management Research Department at the Dryland Agricultural Research Institute in Maragheh, this research is not just about optimizing yields—it’s about redefining sustainability in agriculture.
Chickpea, a staple legume in the Fabaceae family, is primarily grown under rainfed conditions in the western and northwestern parts of Iran. As a key player in cereal-based rotations, optimizing its cultivation practices is essential for sustainable agriculture. The study, published in the journal ‘پژوهشهای حبوبات ایران’ (translated to English as ‘Legume Research of Iran’), delves into the intricate balance of nitrogen fertilization, a critical factor for plant growth and yield enhancement.
Nitrogen, the most crucial macronutrient for plant development, is required in larger quantities than any other element. While chickpeas fulfill much of their nitrogen needs through biological nitrogen fixation (BNF), a minimal “starter” dose of nitrogen is essential for robust seedling establishment and early growth. The challenge lies in determining the precise amount of starter nitrogen required. Too much can increase costs, risk environmental contamination, and suppress yields, while too little can compromise productivity.
Azimzadeh’s study employed a randomized complete block design (RCBD) with three replications during the 2022–2023 growing season. The research evaluated the nitrogen requirements of rainfed chickpea (cv. Ana) under cold conditions in Bukan (autumn sowing) and Maragheh (autumn and spring sowing). Treatments included five urea levels: 0, 25, 50, 75, and 100 kg ha⁻¹.
The results were enlightening. Environmental effects significantly influenced root traits, plant height, biological yield, grain yield, and rainwater use efficiency. Nitrogen levels significantly affected all parameters, except for 100-seed weight. Autumn-sown chickpea in Bukan exhibited superior root traits, plant height, and yields compared to Maragheh.
“Precise determination of starter N for rainfed chickpea is critical,” Azimzadeh emphasized. “Excessive application increases costs, risks environmental contamination, and suppresses yields, whereas insufficient doses compromise productivity.”
The study found that grain yield plateaued at 25 kg ha⁻¹ N in autumn-sown Bukan, while Maragheh achieved maxima at 75 kg ha⁻¹ (autumn) and 50 kg ha⁻¹ (spring). The highest harvest index (48%) occurred at 50 kg ha⁻¹ N in spring-sown Maragheh. Starter N bolstered early growth and photosynthetic capacity, enhancing yields. Moderate N optimized the harvest index by favoring grain over biomass allocation.
Rainwater use efficiency (RUE) was higher in autumn-sown chickpea in Bukan compared to both autumn- and spring-sown crops in Maragheh. Regression analysis of grain yield against urea application rates revealed maximum achievable yields of 1535 and 940 kg ha⁻¹ for autumn-sown rainfed chickpea in Bukan and Maragheh, respectively. To attain these yields, starter urea doses of 62 and 61 kg ha⁻¹ were required for Bukan and Maragheh. For spring-sown chickpea in Maragheh, the peak grain yield was 835 kg ha⁻¹, achievable with a urea input of 43 kg ha⁻¹.
The minimal urea requirements for maximizing net economic returns were 60 kg ha⁻¹ for autumn-sown chickpea in both regions, whereas spring-sown systems in Maragheh required 42 kg ha⁻¹. Simple correlation analyses between grain yield and yield components demonstrated that grain yield showed the strongest positive correlations with biological yield, plant height, and root dry weight, in descending order of magnitude.
This research is not just about optimizing yields—it’s about redefining sustainability in agriculture. As Azimzadeh noted, “Precision in N management is critical to balance productivity, sustainability, and environmental stewardship in rainfed chickpea cultivation.”
The implications for the agricultural sector are profound. By optimizing nitrogen management, farmers can enhance productivity while minimizing environmental impact. This balance is crucial for sustainable agriculture, particularly in regions where water and nutrient resources are limited.
As the world grapples with the challenges of climate change and resource depletion, studies like Azimzadeh’s offer a beacon of hope. They demonstrate that with careful management and innovative practices, we can achieve both economic and environmental sustainability. The future of agriculture lies in such