粒状配合肥料(BB肥料)原料の物性と施肥精度

抄録

We have examined size, hardness, pulverization ratio, bulk density and hygroscopicity of 63 samples among 15 species of raw materials which were used for BBFs manufacture. The values of the pulverization ratio were dramatically increased when the granule hardness rated less than 1.0 N. The granular Muriate of Potash(MOP)were pulverized, not relating its hardness bacause of its rugged shape. Furthermore, most of these materials reduced their cohesion and, therefore, the hardness of granules decreased. We have examined using two types of spreaders in segregation extents of BBFs during application processes. The first spreader, which attached to the rice transplanter, have been performed under ordinary field conditions using the BBFs, a mixture of ammonium sulfate(AS), diammonium phosphate and MOP, all of which have a different average granule size. The results indicated that the degree of segregation is much larger in a square hopper than in rectangular hopper. It was speculated that, in a square hopper, different size of granule pile conically up when BBF was poured in, and this could lead severe coning phenomena. With the second spreader, the granule blow applicator used for top dressing to paddy field was applied for the study on the segregation of AS and urea. Urea spread less uniformly on the ground than did AS, since urea received resistance of air owing to their low apparent density and scattered a short distance. Taken together, the following criteria should be considered to maintain the quality of BBFs. The average granule size should be distributed between 2mm and 3mm. Care must be taken during manufacturing to avoid granules less than 1mm in diameter. It is preferable to have the granule size of each raw material be the same to avoid segregation. Hardness of granule and pulverization ratio are recommended to be more than 1.5 N and less than 10%, respectively. We also must be very careful to avoid long storage and high humidity to prevent melting and caking of the ingredients.