Effect of Organic and Chemical Fertilizer Application on Growth, Yield, and Soil Biochemical Properties of Landrace Brassica napus L. Leaf-and-Stem Vegetable and Landrace (Norabona)

Norabona is generally cultivated in Japan under management systems that use chemical fertilizers and synthetic chemical pesticides. However, the continuous use of these fertilizers and pesticides damages the soil environment and reduces the number of soil microorganisms. There has been little research investigating the effect of organic and chemical fertilizer applications on soil biochemistry and the growth and yield of norabona. In this study, we investigated the effect of organic and chemical fertilizer application on these factors during the norabona growing season from September 2019 to May 2020. Leaf length, shoot height, and shoot width were significantly higher under organic fertilizer management in the early stage of cultivation (in March) than under chemical fertilizer management. However, there was no significant difference between treatments for these growth parameters in later months, nor for any other parameters. Soil TN, and TP contents were significantly higher in the organic fertilizer treatment after harvest than prior to cultivation or after the chemical fertilizer treatment. In addition, soil TC, and volumetric water content were significantly higher in the organic fertilizer treatment than in chemical fertilizer treatment. The higher TC, TN, and C/N ratio in organic fertilizer treated soil appeared to increase the bacterial biomass, leading to enhanced nutrient circulation via N and P circulation activity, producing a rich soil environment with active soil microorganisms.