The use of humic acid urea fertilizer for increasing yield and utilization of nitrogen in sweet potato

Abstract

Humic acid urea fertilizer (HA-N) is a new type of slow-release nitrogenous fertilizer that can enhance utilization rate of urea, and consequently increases crop yield. However, there were few researches about the effect of HA-N on the nitrogen absorption and utilization in sweet potato production. Hence, the effect of HA-N on nitrogen accumulation and distribution, nitrogen use efficiency (NUE), and yield of sweet potato was studied in the field using the <sup>15</sup>N tracer technique. Results showed that HA-N significantly increased the number of storage roots per plant and the average fresh weight per storage root, as well as the yield increased by 29.6% compared with urea fertilizer. Furthermore, nitrogen accumulation of total plant was higher under the HA-N. In addition, HA-N significantly increased nitrogen production efficiency of fertilizer and nitrogen production efficiency. Results of a <sup>15</sup>N tracer experiment revealed that the percentage of nitrogen absorbed by plant from fertilizer increased from 31.1% to 38.7% and NUE increased from 33.5% to 44.8% with application of HA-N when compared with single N treatment, respectively. HA-N significantly increased sweet potato storage root yield, nitrogen absorption and NUE, as well as it reduced the loss of nitrogen fertilizer.