This study was carried out for the purpose of increasing the production of sweet potato in the sandhill.
Using five kinds of fertilizers, Ammonium sulphate, ammonium nitrate, urea, solid fertilizer and synthetic fertilizer, we performed experiments of nitrogen effect upon sweet potato. All fertilizers used contained 1.5 Kan per Tan nitrogen, but another experiment was made with ammonium sulphate containing 0.8 Kan per Tan.
By random method, the field was divided into four blocks, each of which consisted of six plots respectively, with one of the five kinds of fertilizers given. And two of the four blocks were dressed by slag.
As a result of the experiments, the yield of sweet potatoes was increased in the plots of solid and synthetic fertilizers, but there was no difference between all six plots in the growth of leaves and stems.