Optimizing Nutrient Management to Improve Tobacco (nicotiana Tabacum) Production While Reducing Nutrient Losses in Tobacco Fields

Efficient nutrient management is essential for mitigating nutrient losses from farmland in the Erhai Lake Basin (ELB). This 2-year field study (2021-2022) in the northern ELB investigated the effects of different fertilizer application methods on nitrogen and phosphorus losses. The four fertilizer treatments included: no fertilizer, farmer practice of solely organic fertilizer application (FP), mineral fertilizer, and a combination of organic and mineral fertilizers (OMC). Over the study period, total N (TN) losses ranged from 17 to 34 kgha-1 and total P (TP) losses from 1.0 to 1.4 kgha-1. Peak N and P losses occurred during June and July, with N lost primarily as nitrate and P lost primarily in dissolved forms. Compared with the FP treatment, the OMC treatment significantly reduced nutrient losses throughout the tobacco season; TN runoff decreased by 2.7 kgha-1, TP runoff by 0.1 kgha-1, TN leaching by 21% and TP leaching by 17%. Also, the OMC treatment increased the average tobacco yield by 3.8% (to 2.55 tha-1) compared to the FP treatment, which in turn enhanced the gross value. Fertilizer treatments significantly affected soil properties. These altered soil properties, particularly alkaline hydrolysis N and soil organic matter levels, subsequently regulated N and P loss dynamics. These results provide a scientific basis for mitigating nutrient loss from farmland in the ELB through optimized fertilizer application.