Effects of polyolefin-coated fertilizer on nutritional quality of spinach plants

Pot experiments were conducted in order to evaluate the effects of four dif ferent urea or ammonium containing polyolefin-coated fertilizers (POCFs) on the nutritional quality of spinach (Spinacia oleracea L.) and to investiga te the mechanisms of these effects in comparison with conventional, rapidly available fertilizer. Compared to the conventional fertilization method yi eld was decreased in all the four POCF treatments due to less available fer tilizer nitrogen (N) and/or realized ammonium nutrition. However, applicati on of POCFs decreased oxalate and nitrate contents and increased ascorbate concent in spinach. Decreased oxalate and nitrate contents were attributed to lower nitrate availability in the soil having caused by the controlled-r eleased characteristic of POCFs and/or ammonium nutrition. Increased ascorb ate content was due to both decreased oxalate and decreased nitrogen conten ts of the spinach plants. It was concluded that band applications of urea o r ammonium containing POCFs improved the nutritional quality of spinach due to realized ammonium nutrition and/or less amount of available fertilizer N.