Nitrogen Release Characteristics And Effects Of Special Nano Slow-release Fertilizer On Yield And Quality Of Tumorous Stem Mustard

Tumorous stem mustard（also named Cabbage head）is an important vegetable in Brassica of Cruciferae,mainly used for production of pickled mustardand,is widely cultivated in Fuling District of Chongqing on the upper reaches of Yangtze River.With the development of tumorous stem mustard industry in Fuling District,Chongqing,there are some problems such as excessive fertilization,partial application of nitrogen fertilizer,soil acidification and environmental pollution in the cultivation of tumorous stem mustard.These problems not only lead to increased production costs,but also cause tumors.The reduced yield and quality of mustard have severely restricted the healthy development of the tumorous stem mustard industry.Slow-release fertilizer can reduce the release rate of nutrients,has the characteristics of slow release of nutrients and high utilization of nutrients,and is known as“environmentally friendly fertilizer”.Nano-specific slow-release fertilizer for tumorous stem mustard was developed according to the requirement and growth rules of tumorous stem mustard.The ammonia volatilization rate and total ammonia volatilization of fertilizer were studied by“ventilation method”.The nitrogen release characteristics of fertilizers were studied by“good gas culture-batch leaching method”.The potted experiment combined with field experiment was used to study the effects on yield,quality and soil nutrients of tumorous stem mustard.The main results are as follows:（1）Nano-specific slow-release fertilizer（NBSRF）can reduce the ammonia volatilization rate of fertilizer.The ammonia volatilization rate increased firstly and then decreased after fertilizer application,and the peak value of ammonia volatilization rate was 5-10 days after fertilizer application.The peak ammonia volatilization rate of NBSRF was lower than that of MZF,OCF,BCF and BSRF,respectively reducing 4.78,2.13,1.33 and 0.44 mg·kg^-1·d^-1,and reduction rates were 48.77%,29.79%,20.99%and8.11%.（2）NBSRF can reduce the total ammonia volatilization of fertilizer.The total apparent ammonia volatilization of NBSRF accounted for 5.27%-9.36%of total nitrogen application.Ammonia volatilization mainly occurred within 20 days after fertilizer application,and the total amount of ammonia volatilization increased rapidly in the early period but slowly in the later period.The total apparent ammonia volatilization of NBSRF was lower than that of MZF,OCF,BCF and BSRF,which decreased by 19.28,9.96,8.49 and 2.98 mg·kg^-1,respectively,the reduction percentage were 41.20%,26.59%,23.57%and 9.78%,respectively.（3）NBSRF has the function of nitrogen slow release.The slow-release period of NBSRF was about 70 days,and the cumulative dissolution rate of total nitrogen on the70th day was 89.74%.At the same time,total nitrogen cumulative dissolution rate of different treatment roughly is OCF>MZF>BCF>BSRF>NBSRF>MSRF.（4）NBSRF could increase the yield of tumorous stem mustard.The pot experiment showed that the stem biomass of NBSRF increased by 7.85-10.56 g·pot^-1and19.52-25.97 g·pot^-1,and the increase rate is 2.70%-3.80%and 7.26%-9.54%,respectively,compared with that of OCF and MSRF.Field experiments showed that the yield of NBSRF increased by 291.58-553.05,397.31-694.80 and 24.90-197.32kg·667m^-2,respectively,compared with that of MZF,OCF and MSRF.The increase rates were 11.38%-24.24%,16.70%-32.47%and 0.88%-7.48%,respectively.（5）NBSRF can improve the quality of tumorous stem mustard to a certain extent.Pot experiment showed that the free amino acid content of NBSRF was higher than that of other fertilization treatments,with an increase of 17.01%-64.83%.The total volatile matter and allyl isothiocyanate content of NBSRF were higher than those of OCF.The total volatile matter and allyl isothiocyanate content of NBSRF were 46.13%-86.70%and 42.86%-94.67%higher than those of OCF.Field experiments showed that compared with other fertilization treatments,the total amount of volatile substances in NBSRF increased by 20.83%-187.76%,and the content of allyl isothiocyanate increased by 22.21%-166.05%,and the total amount of free amino acids increased by0.66%-50.43%.（6）The leaves SPAD value of NBSRF was generally lower than that of common fertilizer.On the 50th day,the leaf SPAD value of NBSRF in Yonganxiaoye was lower than that of MZF,OCF and BCF,which decreased by 1.73,2.04 and 1.29（4.80%,5.60%and 3.62%）,respectively.On the 85th day,the leaf SPAD value of NBSRF in Yonganxiaoye was lower than that of MZF,OCF and BCF,which decreased by 0.34,1.14 and 1.17,respectively.The reduction percentage was 0.99%,3.23%and 3.29%,respectively.The differences on the 85th day were lower than that on the 50th day.On the 50th day,the leaf SPAD value of NBSRF of Fu Za NO.2 was lower than that of MZF,OCF and BCF,which decreased by 0.18,2.11 and 1.64（0.52%,5.81%and4.58%）,respectively.On the 85th day,the leaf SPAD value of Fu Za NO.2.NBSRF was lower than OCF,decreased by 0.59（1.65%）,but higher than MZF and BCF,increased by 1.53（4.67%）and 0.55（1.62%）,respectively.（7）NBSRF can keep soil p H stable and reduce the risk of soil acid.The pot experiment showed that the soil p H of OCF and MSRF decreased by 0.74-0.78 and0.50-0.56,respectively,compared with that before the experiment,while the soil p H of NBSRF increased by 0.02-0.10.（8）NBSRF can improve the efficiency of nitrogen fertilizer.Compared with OCF,the nitrogen use efficiency of NBSRF was increased by 4.41%-10.05%,and that of MSRF was increased by 10.67%-11.16%.Field experiments showed that the nitrogen content of NBSRF stems increased by 12.64%-14.93%and 19.01%-27.97%compared with MZF and OCF.