Development And Evaluation Of Nugget Slow-release Fertilizer

Nugget slow-release fertilizer(NSRF) which has big granule is one kind of the matrix composites fertilizers or felted fertilizers.Before the extruding and granulating, NPK fertilizers are mixed evenly with slow release agent,binder,hardener,etc. NSRF is mainly used in forest, fruit trees, economical forest and garden afforestation trees.Tree fertilizer is commonly used in cave application and the fertilizer rate is dozens of grams or even hundreds of grams.With the use of NSRF,not only the fertilizer rate is accurate,but also the mount of the slow release agent is reduced in fertilizer production.In this study, seven slow release agents are selected. In the granulation process, the best process conditions of each slow release agent are got from changing the mixing sequence,the quantity and adding method of slow release agent,etc. On this basis,the slow release agents are composited with MO-HP. The products with better slow release characterization are analysised to get the nutrient release method of NSRF.The results show that:(1)In the extrusion and granulation,10MPa is chose as the minimum critical pressure.In the text,15MPa is selected to meet the requirements of the particle strength and minimize the energy consumption. The introduction of water should not exceed4%wt.(2)The selection of the slow release agents:With the increase of PVA modified starch, The release rate of nitrogen is gradually slowing down. When the amount adds to5%wt, the change of the nitrogen release rate is no longer significant and some of the water and fertilizer is squeezed out of the mold in the extrusion granulation process.So the mount of the PVA modified starch is selected as5%wt; L85paraffin compound with rosin as the mass ratio of8:2and the amount of them is5%wt;Monoammonium phosphate impact the form of agar gel greater in the four fertilizers.Before adding monoammonium phosphate,urea,potassium chloride,calcium magnesium phosphate and hot agar solution are mixxed together.And in the process, too acidic or alkaline environment should be avoided;Polyacrylamide(PAM) should pass120mesh sieve. The amount of PAM is2%wt and the amount of water is3%wt; The amount of sodium metasilicate pentahydrate saturated solution is8%wt; The amount of organosilicon waterproofing agent is1%wt; The more the amount of polyurethane the better the slow release effect of NSRF. The addition amount of polyurethane is9%wt for Economic reasons.(3) In the composite experiment, the nitrogen release rate of the product is:G5-2<B10-2<E2-2<D9-2<Fl-2.So the release effect of the slow release agents is: Polyurethane>paraffin-rosin>sodium metasilicate pentahydrate> PAM> organosilicon waterproofing agent.(4) The nitrogen release rate curve of product G5is:Y=10.74+0.53X.The nitrogen of NSRF release property in water is in accordance with linear relationship.