The Manufacture And Nutrient Release Characteristics Of Coated Urea And Their Compound Fertilizer

The nitrogen fertilizer as one of the most important fertilizer for plant growth, and madegreat contributions to our grain growth, but nitrogen use efficiency was only30%~35%，lowerthan the average in the world. How to reduce nitrogen loss and improve nitrogen utilization hasbecome a key link of farmland nitrogen management. In this paper, by the way of coated andcompound to slow release fertilizer, relief the intensity of nutrient apply at the beginning offertilization, extend the time of fertilizer effect, increase content of available nutrients, improvenitrogen use efficiency. Because the cow dung as raw materials used in the process of composite,the residual coating not only won’t produce secondary pollution, but also to solve the problemof non-point source pollution in rural areas, and discover a new use value point of waste.The first part of this study, using urea as nitrogen carrier, using cheap accessible andnon-polluting organic waste、inorganic mineral for coating materials, exploring the most suitablepreparation conditions, try to preparing two kinds of coated urea (FU and YU), using cow dungmix peat as an organic raw material, with the common urea、homemade coated to preparingcompound fertilizer in different mode.Second part of this study was to using static absorption and soil column leaching method,studied the release of NH3and N leaching characteristics. The self-made coated urea mixed withdifferent waste applying in soil,and measured soil aggregates composition and stability,choosethe most suitable waste as cover layer,in order to strengthen the effect of soil fertility.Throughsoil column leaching method to study the impact of urea nitrogen behaviors after compoundfertilizer was applied into the soil. Using the same specifications device in soil column cultivateexperiment, sampling and analysis nutrient release characteristics in the soil at different growthstages of plant. At the same time, the composite fertilizer blocks into the corn field to study theeffect in practical application. The main results are as follows:(1) In normal granular urea and abandoned corn, inorganic zeolite as raw material, usingpolyvinyl alcohol (PVA) as a binder, was prepared two kinds of environment-friendly coatedurea (YU and FU). With cow dung mixed peat, granular urea, self-made corn coated urea as rawmaterials, in mixing composite and sandwich composite, prepare compound fertilizer of urea,urea, self-made coated urea, BB fertilizer directly composite.(2) Through the ammonia volatilization under different nitrogen application rate and soilcolumn leaching experiments show that: in the low-and high-nitrogen application,two kinds of fertilizer treatments can reduce NH3volatilization and N leaching losses, compared withUrea,FU and YU the total ammonia volatilization maximum reduction21.22%and38.00%.Two fertilizers were significant differences in the pH and EC. At high nitrogen fertilizer,compared with Ur, FU and YU initial dissolution rate reduction of maximum is9.39%and15.6%, at low nitrogen fertilizer, the reduction is4.65%and7.12%. On the first day,NH4+－Nleaching rate of YU was lower than those of FU, maximum leaching rate of NO－3－N appear in8,9days,in the late the NH4+－N, NO－3－N leaching rate increased.(3) After cow dung mixed different wastes applied in soil,>0.25mm mechanical stabilityaggregates contents were greatly improved,CT>SH>YM>YS>CK,and increase>0.25~0.5mm,>1mm water-stable aggregates contents,CT reached the significant level,from the MWD andGMD,CT works best,as a whole,application of cow dung mix peat can improving soilfertility.On the basis of this, cow dung mix peat as the coated layer.(4) Soil column leaching experiments showed that：after compositing of urea (Ur-S),self-made coated urea (YU-S), BB fertilizer (BB-S) can reduce nitrogen dissolution, lowervolatility of the pH and EC, and self-made coated urea block (YU-S) work best. Adopt differentways of composite, in comparison with ordinary cow dung and urea, the leaching time ofnutrients and nutrient release were significantly different, the composite fertilizer block candelay nutrient leaching time4~5days, reduce the dissolution rate of nitrogen fertilizer in early,reduce nitrogen emissions about10%, and cow dung sandwich self-made block to reduce asmuch as29.14%, the best effect. Through soil nitrogen content in different levels of soil columnfound，compared with Ur-D，YU-S remain available nitrogen content increased at most by58.83%. On these treatments,CWY-S is better than the other treatments.(5) The cultivated in soil column experiment showed that: in different growth period, soilavailable nitrogen and inorganic nitrogen of YU-S was significantly greater than the othertreatments, and less volatility, nitrogen release is relatively uniform. With cow dung compositenitrogen fertilizer treatments, due to CWY-S and CWU-S adopt sandwich composite way,inorganic nitrogen content in soil is significantly higher than other treatments, compared withCWU-S, CWY-S has higher available nitrogen content, significant difference. All treatments hadno effect on soil organic matter.(6) Field experiments showed that: application results of fertilizer composite blocks aresatisfactory, after coated and sandwich composite means and make CWY-S has most soilavailable nitrogen, inorganic nitrogen content, the best application effect.