Effects of optimum fertilization practices on yield and nutrient use efficiency of radish

Objectives Excessive and unbalanced fertilization is common in radish production in China, which is unfavorable to ecological environment protection and sustainable agricultural production. The effects of optimized fertilization on fleshy root yield and fertilizer use efficiency of radish were studied using field experiment to provide basis for scientific fertilization of radish production.

Methods Field experiments were conducted in Tianjin, Shandong, Zhejiang, and Hebei provinces in autumn of 2016 and spring of 2017, respectively. Experiment comprised of seven treatments: farmers’practice (FP); optimized fertilization NPK (S), K fertilizer was potassium sulfate; a series of nutrient omission treatments, which excluded N, P, and K from the NPK (S) treatments; combined application of organic and inorganic fertilizer, K fertilizer was potassium sulfate or potassium chloride, namely NPKM (S) or NPKM (Cl). The fleshy root yield of radish, plant nutrient uptake, fertilizer use efficiency, and apparent N loss were investigated.

Results Compared with the FP treatment, NPK (S) treatment increased fleshy root yield and plant nutrient uptake, with an average increase of 3.9% in yield in two seasons, and with an average increase of 12.4%, 15.3%, and 4.4% in plant nitrogen, phosphorus, and potassium uptake in two seasons, respectively, and there was a significant difference in Hebei. There were no significant differences between NPK (S) and NPKM (S) treatments and between NPKM (S) and NPKM (Cl) treatments in fleshy root yield and plant nutrient uptake. The fertilizer use efficiency of NPK (S) was significantly higher than that of FP treatment. The agronomic efficiency of nitrogen (AEN), recovery efficiency of nitrogen (REN), and partial factor productivity of nitrogen (PFPN) in the NPK (S) treatment were increased by an average of 32.8 kg/kg, 18.9%, and 110.5 kg/kg in two seasons compared with FP treatment. The agronomy efficiency of phosphorus (AEP), recovery efficiency of phosphorus (REP), and partial factor productivity of phosphorus (PFPP) in the NPK (S) treatment were increased by an average of 53.0 kg/kg, 15.3%, and 296.7 kg/kg in two seasons compared with FP treatment, respectively. The agronomy efficiency of potassium (AEK) and recovery efficiency of potassium (REK) in the NPK (S) treatment were increased by an average of 17.6 kg/kg and 11.5% in two seasons compared with FP treatment. Compared with NPKM (S) treatment, AEN, REN, and PFPN in NPK (S) treatment were significantly increased by an average of 34.0 kg/kg, 13.5%, and 221.7 kg/kg in two seasons. AEP, REP, and PFPP in the NPK (S) treatment were increased by an average of 20.8 kg/kg, 6.6%, and 217.2 kg/kg in two seasons. AEK, REK, and PFPK in the NPK (S) treatment were increased by an average of 9.0 kg/kg, 3.6%, and 89.5 kg/kg in two seasons. Compared with NPKM (Cl) treatment, REP and REK in the NPKM (S) treatment were significantly increased by an average of 6.2% and 7.4% in two seasons. Compared with the FP treatment, the average apparent N loss was decreased by 106.7 kg/hm² and residual N average was decreased by 42.1 kg/hm² in NPK (S) treatment in the two seasons. The average apparent N loss was decreased by 84.6 kg/hm² and residual N average was decreased by 55.6 kg/hm² in NPK (S) treatment compared with NPKM (S) treatment in the two seasons. There were no significant differences between NPKM (S) and NPKM (Cl) treatments in apparent N loss and residual N.

Conclusions On the basis of guarantee the radish yield, optimizing the fertilizer rate and application period could improve the fertilizer use efficiency and reduce the apparent N loss. The fertilizer rate should be increased or reduced according to the practical uses in different areas, and both potassium chloride and potassium sulfate are good potassium source for radish production.