Controlled Release Urea Manufacture And Nutrient Releasing Characteristics In Soil

The abundance of nitrogen in soil is the main factor limiting crop growth and yield formation, and plays an important role in high quality and high yield of crops. As the high nitrogen content,low pollution and suitable for a variety of different types of soil and plants,urea is the most ideal chemical fertilizer application now. However, due to common urea applied qualitative light, easy hygroscopic, fast dissolving and low fertility efficency, its nutrient easy to loss. In this paper, a simple process was processed on the ordinary urea for ordinary urea shortcomings, which deal with common urea and prepare three different size fractions slow controlled urea(HKN1, HKN2, HKN), and two coated urea YMN, BMN for comparison, through laboratory leaching test, culture tests to verify its physical properties, sustained-release, on seed germination and seedling growth. Throgh a field experiment and pot experiment to verify the effects of slow control release urea applied to soil, the soil organic nitrogen, inorganic nitrogen and spring maize crop growth, yield and quality of Chinese cabbage. The results showed that:(1)Under the same nitrogen dose added, the sum of HKN, YMN, BMN of the amount of nitrogen leaching is significantly less than common urea. The loss of ammonium nitrogen leaching shows the same change law, and the amount of urea nitrogen and nitrate nitrogen leaching of common urea is more than HU, YU, NU. The p H of leachate with different treatments are rise in the first stage, and then decrease, the p H range is between 5.89 to 8.68. Roughly the EC(electrical conductivity) has trendedn down, the range is 0.16~3.70 m S/cm. After the fifth elution, the value changed little, and tends towards stability. The results of the incubation experiment showed that, After HKN, YMN, BMN applied into soil, ammonia volatilization losses significantly less than common urea treatment. The four treatments of ammonia volatilization rate is CGN>YMN>HKN>BMN.The treatments of HKN and BMN are better than others.(2)The treatments of HKN、YMN、CGM soil ammonium nitrogen and nitrate nitrogen generally expressed decrease trend in different Growth period. The BMN nitrate nitrogen is elevated. Ammonium nitrogen were rise in the first stage, and then decrease. The treatments of BMN、HKN have much nitrogen residual compared others. Slow controlled release urea Amide nitrogen is more than common urea and CK, HKN, BMN treatments is better than others in mature stage. Microbial biomass nitrogen changing law is similar to the urea nitrogen. BMN is best, and HKN is second, which suggests that the nitrogen release is slow and a lot of nitrogen are used by microbial.The soil alkaline hydrolysis nitrogen content is generally expressed decrease trend from tasseling stage to mature stage. But the slow controlled release urea decline more slowly. The total nitrogen dynamic is similar than alkaline hydrolysis nitrogen.in autumn and the treatment of BMN is higher than pusttulation period. In three different growth period, BMN、HKN are the highest content,which show the well release characteristics.Under the same nitrogen dose added, soil nitrate nitrogen generally expressed decrease trend in different Growth period with the growth period extended. But the decrease trend of slow controlled release urea treatments is less than common urea and CK. From seeding stage to harvest, the change of soil ammonium nitrogen like “V”, but the change of soil total N applied slow controlled release urea is small and even increase in harvest of HKN1 and HKN2.(3)In different growth stage of spring corn, the acidolysis total nitrogen is rise in the first stage and then decrease, but its proportion in total nitrogen is decreaes. The trend of non-acidolysis total nitrogen is contrary to acidolysis total nitrogen. The treatment of tusing fertilizer have higher acidolysis total nitrogen than CK(no fertilizer), and slow release urea is better than normal urea. The organic nitrogen constituent contents of slow release urea and coat urea treatments are higher than ones in normal urea, whereas each proportion in rotal nitrogen have no obvious regularity. The different forms of soil organic N contents in all treatments followed the order of unidentified hydrolysable N>ammonia N>amino acid N>amino sugar N. The soil ammonium nitrogen, amino acid nitrogen, unknown acidolysis nitrogen and non-acid acidolysis nitrogen in using nitrogen fertilizer treamnets are all higher than CK treamnet, whereas amino sugar N do not have the same regular. Different slow release urea compared with contrast have strong effect on soil organic nitrogen constituent contents and can enhance the content of total organic nitrogen.(4)Different slow control release urea has unconspicuous effects on seed germination and seedling growth, but has distinct effects on plant height, panicle characteristics, root shoot ratio in medium-term, yield traits, quality, nutrient content of spring corn and soil inorganic nitrogen. The discrepancy of plant height expanded obviously after dressing different control release urea, the panicle characteristics are increase and the ratio of medium-term is decline in all treatment compared with CK. Yield treated by HKN is the highest,the value compared with the Ck is increase by 12.74%、12.14%、8.03%、9.52% respectively, and the starch and protein are increase, while fat are decrease in all sample. The nitrogen fertilizer compared with CK can promote the content of P and K in seeds. Therefore, the HKN can improve the yield, quality of spring maize and have better economical efficiency and potential for marketing generalize.(5)Compared with the common urea, slow urea can improve the yield per plant of cabbage. HKN1、HKN2、BMN treatments are better than others in mature stage. The yield per plant size is HKN2>HKN1>BMN>HKN3>GYN>CGN>CK. At the same time, it can decrease 29.71%-50.95% for the nitrate of leaf blade. In addition to, the slow controlled release urea can improve the total N、P and K contents of harvest leaf blade. The treatment of HKN2 is best especially. The quality of Chinese cabbage is higher than CGN(common urea) treatment. In other words, it can increase the sugar-acid ratio, soluble sugar and Vc contents at the harvest stage compared with the common urea and decrease the organic acid contents by a certain extent in the functional leaves and improve the quality of cabbage.