Study On Slow Release Fertilizers With Three-dimensional Framework By Extruded

As one of agricultural means of production, fertilizers play an important position and role in yield. Study on slow/control release (SRF/CRF) fertilizers receives much concern both at home and abroad for its long efficiency and easy application. In this paper, extrusion technique was applied. Mixture of stale corn and urea (mass ratio of corn and urea=4:6) was extruded and prepared a new type of SRFs. Slow release performance, structures of the fertilizers and its releasing mechanism all were introduced. This new study lays a foundation for the wide application of SRF on agriculture for its simple preparation technology, low price relatively and well biodegradability, which cause no secondary pollutions. All the research results were as follows:1) The relationship of die orifice dimension and extruding effect was studied during researching of extrusion technique and parameter. Series of SRFs were prepared on different die orifice fom 2 mm to 6 mm. The gelatinization degree reduced from 95% to 70 % as the die orifice increased.2) Curve was drawing basic on comparing nutrient release by leaching 253 h of urea and SRF, which show that: up 90 % nutrient of urea was leaching during 46 h, when only 1/3 SRFs loss; Urea caused 70 h to release all the nutrient, compared with SRF 253h; At the same release rate 92 %, the release period of the SRFs is 5 times as long as rational urea.3) The structure of the SRFs and which degradation under nature condition simulation for longtime, determined by scanning electron microscope (SEM). The photos show us a symmetrical three-dimensional framework and the degradation framework.4) The nutrient releasing mechanism was discussed base on the coated fertilizer. At the first stage, the micro porous of the SRFs particle prevents moisture from entering and the nutrient releasing. The three-dimensional framework gelatinized by water as a coasted membrane played the same role at the second stage.5) The dynamics model of the SRF slow releasing was established based on Fick's first law.The SRF by extrusion releases slower than urea significantly; the extrusion technique is easier and the parameter control easily; the use of stale corn do much for recycle economy and sustainable development. All of this show this extrusion SRFs have more value.