Effects of HA-K fertilizer on potassium content of soil and absorption and utilization of potassium in sweet potato

Humic acid was compounded with K2SO4 to produce a kind of HA-K fertilizer in this study. The evaluation results of using the potassium sand leaching method indicate that the HA-K fertilizer has slow-releasing effect on potassium. In order to clarify the effects of the HA-K fertilizer on the contents of different forms of potassium of soil, the field study was conducted to investigate the effects of HA-K on the contents of different forms of potassium of soil, the yield of storage root, and the absorption and utilization of potassium in sweet potato. The results show that compared with the control, the application of the HA promotes the absorption of potassium in sweet potato, reduces the rapidly available potassium and slowly available potassium contents in soil during the whole growth period, reduces available potassium content in soil during the early growth period of sweet potato, and increases the available potassium content in soil from intermediate to later periods of sweet potato. Compared with the equivalent K2O contrast, the application of HA-K promotes the absorption of potassium in sweet potato, reduces the slowly available potassium content in soil during the whole growth period of sweet potato, reduces the rapidly available potassium and available potassium contents in soil during the early growth period while increases the rapidly available potassium and available potassium contents in soil during the later period. Compared with the equivalent K2O contrast, the recovery efficiency of potassium fertilizers (REK), agronomy efficiency of potassium fertilizers (AEK), partial factor productivity from applied K (PFPK) and the yield of storage root are increased by 20.09%, 42.69%, 5.89% and 22.83% in the HA-K treatment.