Release Characteirstics Of Controlled Release Coated Urea And Effects On Tomato Growth, Quality And Yield Of Mixed Fertilizing

Coated controlled-release fertilizer, as a kind of new fertilizers, has higher fertilizerutilization ratio than traditional fertilizers. It reduces environmental contamination andimproves yield and quality of crops, which makes it become the focus of the field of fertilizerstudying. In the21st century, the research in fertilizer science focus on coated controlled-release nitrogenous fertilizer for its remarkable results in cutting down fertilizer dosage,improving nutrient utilization, reducing leaching Losses of nitrogen to environment andpromoting yield and quality of crops. This experiment chose tomato as material to studyrelease characteristics of sulfur-coated controlled-released urea and resin-coatedcontrolled-released urea and the impact to the plant of tomato growth power, dry weight,photosynthetic characters, activity of nitrogen metabolism related enzymes, readily availablenutrient of soil, the enzymes activity in soil and the yield and quality of fruit by fertilizingdifferent dosage of mixed fertilizer in potting and under sunlight greenhouse conditions. Theobjective of this experiment is to provide a theory and scientific basis of the application andpopularization of mixed fertilizer of sulfur-coated controlled-released urea and resin-coatedcontrolled-released urea. The results are as followed:1. The release rule of controlled-released urea in the soil with tomato brought intocorrespondence with the soil without tomato. The release rate of treatment with tomato wasslightly higher than treatment without tomato under the same treatment: T1>T4, T2>T5,T3>T6. The release of mixed fertilizer was between sulfur-coated controlled-releasednitrogenous fertilizer and resin-coated controlled-released nitrogenous fertilizer. At thebeginning (1d-10d), the release rate was low, and then increased after10th day. It was a linearrelationship in the10th day to60th day. The increase amplitude of release rate decreased after60th day.2. The variation trends of nitrate nitrogen were same in both soils which were both increased.The content of nitrate nitrogen in no-tomato soil was much higher than that in soil withtomato. The variation rule of nitrate nitrogen in soil with tomato was that mixed fertilizer wasbetween sulfur-coated controlled-released nitrogenous fertilizer and resin-coated controlled-released nitrogenous fertilizer. The variation trends of the content of ammoniumnitrogen were almost the same in soils with or without tomato. They both increased in the beginning, andthen became lower. They were highest after80th day. The activities of nitrite reductase (NR), nitritereductase (NiR), urease (UR), protease (PR) and hydroxylamine reductase (HyR) in soil withtomato were higher than that in no-tomato soil.3. The results showed that at all sampling periods, DW, the content of Chla, Chlb and Car, Pn,as well as the activities of NR, GS, GOGAT and soil enzyme and the content ofalkalined-nitrogen decreased with a reduction in the amount of nitrogen, following with thetomato plant height and stem diameter decreasing. Under the same nitrogen level,30daysafter planting, DW, the content of alkalined-nitrogen, the activities of UR, NR, PR, GS andGOGAT of SCU and RCU controlled release urea fertilizer mixture were lower than thetreatment of U, while no difference of the content of Chla，Chlb，Car and Pn.60and90daysafter planting, all the indexes of SCU and RCU controlled release urea fertilizer mixture werehigher than the treatment of U. Besides,60days after planting, under30%nitrogen reducinglevel of SCU and RCU controlled release urea fertilizer mixture, DW, the content of Chla,Chlb and Car, Pn, as well as the activities of UR, NR, NiR, PR, HyR, NR, GS and GOGAThad no significant difference with100%U. At all sampling periods, the activities of NiR andHyR under treatment of SCU and RCU controlled release urea fertilizer mixture were higherthan the treatment of U.4. SCU and RCU controlled release urea fertilizer mixture effectively lowered nitrate contentin tomato fruits, raised Vc content and sugar-acid rate, and improved fruit quality.5. Compared with the control (T1), mixed fertilizing of SCU and RCU treatment and commonurea treatment could both increase maximum fruit weight, minimum fruit weight, number oftomatoes and yield per plant which were significantly different. Number of fruits and yieldper plant were highest under T3treatment, and number of fruits was31.99%higher and yieldwas27.72%higher than T1. Mixed fertilize of SCU and RCU had1.78%-7.71%higher yieldsthan common urea treatment.