Effects Of Oxamide Slow-Release Fertilizer On Growth Of Field Crops

In order to study nitrogen-release characteristics of different shapes of oxamide particles and select unfit granule of oxamide fertilizer which can meet nitrogen demand of a crop in its whole growth period,a column leaching experiment and a soil culture experiment were carried out.What's more,a series of filed experiments on different crops(rice?wheat?corn and sugarcane)were conducted to study fertilizer effect of oxamide(or oxamide-urea mixture)as a fertilizer contrasted which urea.The main results are showed as follows:(1)Compared with urea,oxamide type fertilizer can reduce the loss of nitrogen following with water in some degree.Also,among different shapes of oxamide particles,oxamide pellet has the best slow-release characteristic because its sum nitrogen leach-loss was lower than other two shapes of oxamide fertilizers.(2)The time which oxamide existed in soil could be extended through granulating.Soil culture experiment indicated that the time of coarse oxamide granule(2mm<?<3mm)releasing nitrogen was longer than that of oxamide powder.Oxamide granule was one kind of good slow release nitrogen fertilizer.(3)Through the field experiments of three major grain crops(rice?wheat and corn),the yields of them which applying oxamide-type fertilizer only once were higher than that of using urea for 2 or 3 times at the same amounts.what's more,the productions of the treatments which reducing 30%nitrogen does of oxamide and oxamide-urea mixture did not reduced even increased slightly compared with the treatment of 100%application of urea.Under condition of remaining yield,the nitrogen use efficiency of oxamide-tye fertilizers treatments all improved at some degree,especially the treatment of reducing 30%nitrogen application.(4)For commercial crop,the millable stalks,average per stem biomass,height and stem diameter of sugarcane of treatments applying oxamide type fertilizers were increased,and the yields of them increased by 3.6-13.6%compared with urea application.Applying oxamide type fertilizers could improve nitrogen use efficiency,especially at low nitrogen application level.The available N of oxamide treatments were significantly higher than that of urea treatments at jointing stage.However,the total N,available P and available K between oxamide and urea treatments had no significant change.(5)For crops which having long growth period(90-200days),the demand for nitrogen is different at different development stages.In general,nitrogen absorption of plants can be divided into three stages(seedling stage,vegetative stage,reproductive stage)and can be described as "s" type curve,that is,plant absorbs nitrogen slightly in seedling stage,quickly and largely in vegetative stage and slower in reproductive stage.At present,most nitrogen fertilizers are soluble and transform and loss quickly as applied to soil.The fertility of soluble nitrogen fertilizers only lasts for 7 to20 days.Fertilization only once can't meet the needs of nitrogen of crop during the whole growth period,top application is needed to guarantee high output.However,oxamide granules release nitrogen slowly in soil and last for 3 to 6 months,a base fertilization can meet the demands of nitrogen for most plants during the full stage.Particularly,application using oxamide and soluble nitrogen fertilizer mixture matches the nitrogen requirement of most of the crops as the soluble nitrogen fertilizer can provide the nitrogen for plant in the early stage and oxamide can supply nutrient steadily in the middle or later period.(6)Within the tested experiments,oxamide can be applied only once as base fertilizer for rice?wheat and corn It is appropriate that nitrogen application can be reduced to 70%of normal rate on consideration of yield and nitrogen use efficiency.