Effects of Fertilizer Reduction on the Growth of Stem Mustard and the Contents and Components of Water-Soluble Nitrogen and Phosphorus in Soil

Fertilizer reduction is an effective way to achieve environmental friendliness and maintain the quality of cultivated land, which is of great significance to prevent soil pollution and realize sustainable agricultural development. Using ″Yongan Microfoliar″ stem mustard as the experimental material, six fertilization treatments were set up in pot experiment, including blank group (T0), 90% reduction (T10), 70% reduction (T30), 50% reduction (T50), 30% reduction (T70), traditional fertilization (T100), to study the effects of fertilizer reduction on the growth of stem mustard and the contents and components of water-soluble nitrogen and phosphorus in soil, this study aims to provide reference for scientific fertilization and environmental protection in stem mustard cultivation. The results showed that no fertilization or excessive fertilization could affect the normal growth of stem mustard. With the increase of fertilizer application amount, soil pH decreased significantly, organic matter content increased first and then decreased, and the contents of water-soluble nitrogen and phosphorus in different forms of soil gradually increased, and the trend of water-soluble nitrate nitrogen > water-soluble ammonium nitrogen, water-soluble inorganic nitrogen > water-soluble organic nitrogen were basically presented in all treatment groups. In addition, the contents of water-soluble inorganic phosphorus and organophosphorus were similar, accounting for 41.98%-55.72% and 44.28%-58.02% of total phosphorus, respectively. In this study, the growth and quality of stem mustard in T30 group were the best among different treatments, manifested by the aboveground biomass order of T30>T50>T70>T100>T10>T0, the tumor weight order of T30>T70>T50>T100>T10>T0, the vitamin C content order of T30>T10>T0>T70>T50>T100, as well as the soluble protein order of T30>T50>T100>T10>T70>T0. Compared with traditional fertilization (T100 group), water-soluble nitrate nitrogen, ammonium nitrogen, total nitrogen, inorganic phosphorus and total phosphorus in T30 group were reduced by 73.78%, 30.16%, 71.45%, 69.76% and 70.85%, respectively, and organic matter content was increased by 18.32%. Therefore, it is feasible to implement chemical fertilizer reduction in the planting process, which is not only beneficial to improve the yield and quality, but also reduce the planting cost and the potential environmental pollution caused by residual nitrogen and phosphorus in the soil.