Evaluating urea-based nitrogen fertilization practices on greenhouse tomato growth and nitrate leaching in cold regions

Abstract

There are serious problems in agricultural production, such as low nitrogen utilization rate and nitrate leaching. This study examined how different fertilization practices affect the yield, quality, and soil nitrate leaching of greenhouse tomatoes in the cold regions. The goal was to provide technical support for simple, high-quality, and efficient greenhouse vegetable production in these areas. Under integrated water-fertilization conditions in the cold regions, six fertilization treatments were applied: No nitrogen fertilizer, Conventional farmer practice (360 kg ha -1 N), Optimized nitrogen application (240 kg ha -1 N), Slow-release urea A mixed with conventional urea at 7:3 (240 kg ha -1 N), Slow-release urea B mixed with conventional urea at 7:3 (240 kg ha -1 N), Conventional urea mixed with modified slow-release polymer material (240 kg ha -1 N). The results showed that optimized nitrogen treatments improved plant height and SPAD values, which helped increase yield. Among them, conventional urea mixed with modified slow-release polymer material had the highest yield. Optimized fertilization treatments also improved quality. Agronomic efficiency and partial factor productivity under optimized nitrogen treatments were 59.08%-231.95% higher than under conventional farmer practice. These treatments also reduced nitrate accumulation in the 60-100 cm soil layer. Using a multi-objective evaluation model based on fuzzy mathematics membership function, conventional urea mixed with modified slow-release polymer material was identified as the best option. In summary, under integrated water-fertilization conditions, applying conventional urea mixed with modified slow-release polymer material can maintain tomato yield and quality while reducing soil nitrate leaching. This method meets the demands of modern agriculture and environmental protection.