Effects of Reduced Chemical Nitrogen Fertilizer Combined with Organic Fertilizer and Magnesium Hydroxide on Soil Amelioration, Sweet Potato Yield and Economic Benefits

To clarify the effects of reduced chemical nitrogen fertilizer combined with organic fertilizer and agricultural magnesium hydroxide on soil amelioration effects, sweet potato yield and economic benefits, a field experiment was conducted with Pushu 32 as the test cultivar, based on the investigation of regional soil status in Nan'an City. Under the condition of equal total input of nitrogen, phosphorus and potassium nutrients, three fertilization treatments were set: conventional recommended chemical fertilization（T1), 25% reduction of chemical nitrogen fertilizer combined with organic fertilizer（T2), and 25% reduction of chemical nitrogen fertilizer combined with organic fertilizer and agricultural magnesium hydroxide（T3).The results showed that compared with T1, the fresh sweet potato yields of T2 and T3 significantly increased by 13.75% and 21.28%, respectively. T3 achieved the best comprehensive performance: its soil pH was significantly increased by 0.45 units compared with T1; soil exchangeable magnesium content and partial factor productivity of nitrogen fertilizer were significantly increased by 47.70% and 61.71% respectively; and the economic benefit was increased by 10 572.5 yuan·hm⁻² compared with T1.The study indicates that the fertilization mode of 25% reduction of chemical nitrogen fertilizer combined with organic fertilizer and agricultural magnesium hydroxide can realize higher yield and income of sweet potato, reduce soil acidity and increase soil magnesium content, and provide a scientific basis for fertilization management of sweet potato planted in acid soil.