Impact of seedbed preparation and macro-fertilizers on yield and radiation use efficiency (RUE) of rainfed chickpea growth under weed competition

Sustainable intensification of rainfed chickpea (Cicer arietinum L.) production relies on optimizing agronomic practices, especially in seedbed preparation, fertilization, and weed control. To address this, a 2-year (2019–2020) split-plot field experiment was conducted in Kermanshah Province, Iran, to evaluate four seedbed preparation methods: T1—no tillage (direct row planting without plowing); T2—reversible plowing (using a moldboard plow to 25 cm depth) followed by surface seed broadcasting; T3—reversible plowing combined with disking (twice) and surface seed broadcasting; and T4—reversible plowing followed by row planting (representing conventional tillage). Subplots were arranged in a factorial design, testing fertilization (control vs. soil test-based NPK application) and weed management (weedy vs. weed-free). The results revealed significant treatment effects (*p* < 0.05), with the highest grain yield (1346.41 kg ha⁻1) achieved under T4 (conventional tillage) combined with NPK fertilization and weed control. This represented a 32.7% yield increase compared to conventional practices. Radiation use efficiency (RUE) also improved consistently across all tillage systems when both NPK fertilization and weed control were applied, peaking at 0.98 g MJ−1 under T4—a 28.9% enhancement over control treatments. The synergistic effects of optimized tillage (T4), balanced nutrition, and weed suppression reduced interspecific competition by 38.4% while increasing photosynthetically active radiation interception by 22.6%. A key finding was that reversible plowing combined with row planting (T4) improved soil physical properties and root development, leading to better nutrient uptake and water infiltration. These results demonstrate that an integrated approach—combining T4 tillage, soil-test-based NPK fertilization, and timely weed control—can substantially enhance both yield (27–34% increase) and resource use efficiency (25–29% improvement) in rainfed chickpea systems. This strategy offers a practical solution for sustainable legume production in water-limited environments while maximizing input efficiency.