Effects of optimized fertilization on the growth of open-field tomato and the soil environment

Field experiments were conducted in 2024 and 2025 in suburban Beijing to evaluate fertilization strategies for improving yield, fertilizer use efficiency, and soil quality in open-field tomato production under uniform irrigation conditions.Four treatments were established: T1 (no fertilizer), T2 (conventional fertilization), T3 (optimized fertilization), and T4 (optimized fertilization combined with a soil conditioner).Differences in soil nutrient status, plant growth, yield, and fruit quality were observed among treatments.Compared with the other treatments, T4 consistently improved soil fertility, enhanced yield formation, and promoted fruit quality, while also increasing fertilizer use efficiency.Specifically: (1) The contents of available phosphorus (AP), available potassium (AK), total nitrogen (TN), ammonium nitrogen (NH₄⁺-N), and nitrate nitrogen (NO₃⁻-N) in the 0-60 cm soil profile, together with soil organic matter (OM), were significantly increased.(2) The average yield over the two-year period was increased by 26.21% relative to T2.(3) Relative to T2, the two-year average fruit soluble solids content (SSC), sugar-acid ratio (SAR), and vitamin C (VC) content were increased by 9.99%, 8.11%, and 26.55%, respectively.However, the two-year averages masked year-to-year differences: SSC rose significantly only in 2025, SAR only in 2024 (p<0.05),whereas VC improved in both years.(4) Relative to T2, the utilization efficiencies of nitrogen, phosphorus, and potassium fertilizers were comprehensively enhanced, particularly in terms of productivity and agronomic efficiency.The agronomic efficiency of potassium fertilizer was increased by an average of 1.76-fold over the two-year period.This study provides a basis for improving the yield and quality of open-field tomatoes in the suburbs of Beijing, while promoting efficient use of agricultural resources.