Development of controlled release phosphate fertilizer

对控释肥(磷酸盐)的研制进行了基础试验。由相同摩尔的CaHPO4和α-环糊精(CD)(简写为α凝胶：4、40和84 mm三种)或仅不含α-CD的CaHPO4(简记为4、40和84 mm P凝胶)，通过共同使用4%的G型海藻酸盐溶液作为材料制成本身的凝胶珠(直径约3 mm)。将这些凝胶珠用水洗涤并在不同温度(10、20、25和30℃)和几个间隔下储存在培养箱中，测定了磷酸根离子在水中的释放量。在10和20℃时，4 mm凝胶中的磷酸盐离子在约2个月内释放，在25和30℃时，在约1个月内释放。另一方面，40和84 mM P凝胶在整个实验90天期间继续释放磷酸盐离子，而40和84 mMα凝胶在20天后继续释放磷酸盐离子，并出现峰值。总PHOS…为探讨其释放机理，采用表面探针法测定了4℃凝胶的核磁共振谱，结果表明α凝胶中水的^1H松弛时间(T2)比P凝胶中的长。这些结果表明，α凝胶中的水比P凝胶中的水以更自由的非缔合状态存在，因此比P凝胶更容易溶解和释放磷离子。采用40 mm凝胶进行了40或45天的盆栽试验，以1/10000的A.Pots和油菜(Komatsuna)为试材。在春季夏季，60%田间持水量盆栽的产量高于40%田间持水量盆栽。60%α胶盆40d收获产量超过P胶盆，磷利用率最高可达40%。在秋冬季节，45d 60%盆栽的产量是35%盆栽的10倍以上，但与春季夏季相比，产量减少了一半。在田间栽培试验中，α凝胶、磷凝胶、化肥和不施磷的空白地分别设置了4个垄条(N：P_2O_5：K=16：15：16 kg/10a)。土壤在15厘米宽，20厘米深的地方混合。秋冬季经过60d的生长期后，对每一垄条的油菜干重进行称量，产量大小顺序为P凝胶>α凝胶>化肥>空白垄条。P胶膜和α胶膜的干重分别是化肥胶膜的1.76倍和1.66倍，说明α胶膜在水分充足、温度较高的条件下效果较好，而P胶膜在水分较低、温度较低的情况下效果较好。较少

Basic experiments were performed regarding the development of controlled-release fertilizer (phosphates). Fertilizer gel beads (ca. 3 mm diameter) were made from the same moles of CaHPO_4 and α-cyclodextrin (CD)(abbreviated as α gel : 3 kinds of 4, 40, and 84 mM), or CaHPO_4 only without α-CD (abbreviated as 4, 40, and 84 mM P gel), by co-use of 4 percent of G-type alginate solution as the material to make the gel beads themselves.After these gel beads were bathed with water and stored in incubators at several temperatures (10, 20, 25, and 30 ℃) and at several intervals, the quantities of phosphate ions released in water were measured. Phosphate ions from 4 mM gel were released within ca. 2 months at 10 and 20 ℃ and within ca. 1 month at 25 and 30 ℃. On the other hand, 40 and 84 mM P gels continued to release phosphate ions ascending through out the experimental periods of 90 days, and 40 and 84 mM α gels continued to release phosphate ions showing a peak after the 20th day. Total phos … More phate released ions of every gel reached its peak at 25 and 30 ℃ among the four temperatures.To investigate the mechanism of release, NMR of 4 mM gel was measured by means of a surface probe method, the results showing that water had a longer relaxation time (T_2) of ^1H of water contained in α gel than it did in P gel. These results suggest that the water of α gel existed in a freer not-associative state than it did in P gel and thus dissolved and released phosphate ions more easily than did P gel.Potting cultivation tests using 40 mM gels were performed over a period of 40 or 45 days using 1/10000 a. pots and Brassica campestris (Komatsuna in Japanese). During the vernal summer term, the yields of 60% field capacity pots were higher than those of 40% field capacity pots. As well, the harvest yields at the 40th day of 60% α gel pots exceeded those of P gel pots, with their phosphorus utilization rate reaching a maximum of 40 %. In the autumn/ winter term, the yields of the 60% pots at the 45th day were more than 10 times those of the 35% pots, but the yields were half in comparison to those of the vernal summer term. Further, the phosphorus utilization rate of 60% P gel pots was only a maximum of 8 percent.For the field cultivation test, four ridges were prepared for α gel, P gel, chemical fertilizer, and the blank without phosphate, respectively (N : P_2O_5 : K = 16 : 15 : 16 Kg/10 a.). The soil was mixed at a 15 cm width and 20 cm depth. After a growing period of 60 days in the autumn/winter term, dry weights of Brassica campestris for every ridge were weighed, showing lighter yields in the order of P gel, α gel, chemical fertilizer, and the blank ridge. The dry weights from the P gel ridge and the α gel ridge became 1.76 and 1.66 times that of the chemical fertilizer ridge, respectively.The above results showed that α gel was more effective with an adequate amount of water and with a high temperature, though P gel was more effective with a low amount of water and with a low temperature. Less