PRODUCTIVITY OF HIGH-YIELD CROPS .2. COMPARISON OF N, P, K, CA, AND MG ACCUMULATION AND DISTRIBUTION AMONG HIGH-YIELDING CROPS

By using good varieties (lines) and by applying coating urea which releases nitrogen slowly, extremely high yields were obtained in several crops. Based on the high yields and appropriate fertilizer application, it was difficult to consider in this experiment that deficiency or excess of nutrient elements (minerals) occurred in plant, so that the mineral status of crops could be adopted as criterion for high yield. The results obtained were as follows. 1) Amount of minerals absorbed was calculated by the following equation: Ym = Ym/Yb x Yb = MRI x Yb, where Yb is the biological yield, Ym is the mineral yield (amount of minerals absorbed), MRI is the mineral requirement index. The MRI did not show any significant difference between the "high yield" and "standard yield" treatments in each crop with a few exceptions, indicating that the Yb is the main factor which determines the Ym in each crop. 2) The MRI differed clearly among crops in the "high yield" treatment. MRI(N) was higher in soybean and winter wheat than in rice, maize, and potato. The MRI(P) was high in soybean, low in winter wheat and maize. The MRI(K) values were almost identical among the crops except for the "standard yield" treatment in winter wheat and maize. The MRI(Ca) and the MRI(Mg) were high in only soybean. 3) For the "high yield" treatment, the Ym(N), the Ym(Ca), and the Ym(Mg) were high in winter wheat, and soybean, the Ym(P) was high in soybean, the Ym(K) was high in winter wheat, maize, and potato. 4) The HI(DM) was 46% in soybean, 92% in potato, and 47-59% in gramineous plants, but the HI(N), the HI(P), and the HI(K) were higher in soybean and potato than in gramineous plants. Thus, harvesting organs required carbohydrate, N, P, and K intensively in potato, but only N, P, and K intensively in soybean.