【目的】添加脲酶抑制剂( Urease inhibitor, UI)是提高肥料利用率的有效途径,在尿素( Urea,U)中添加1%的脲酶抑制剂NBPT( N-丁基硫代磷酰三胺)是目前研究使用证明效果最可靠的添加比例。针对当前稻田氮肥施用水平过高的问题,本文采用田间小区试验研究了目前脲酶抑制剂添加比例下稻田氮肥的减施潜力以及脲酶抑制剂的节肥增效机理。【方法】本试验在我国长江中下游的双季稻田进行,脲酶抑制剂用量NBPT为尿素用量的1%。尿素用量设五个水平为N 90、112.5、135、157.5和180 kg/hm2,分别依次记为U1、U2、U3、U4和U5,7个处理为CK(不施氮肥)、U1+UI、U2+UI、U3+UI、U4+UI、U5+UI、U5(U5为传统施氮量, N 180 kg/hm2为农民习惯施氮量),三次重复。 U1 U5处理施氮量分别是在农民习惯施氮量的基础上降低50%、37.5%、25%、12.5%、0%。通过取样分析水稻分蘖期和孕穗期各处理对土壤脲酶活性、硝酸还原酶活性、土壤铵态氮含量、硝态氮含量以及微生物量碳、氮的含量,研究NBPT对水稻两个主要生育期土壤氮素供应的影响,比较各处理的产量以及氮肥利用率来得出氮肥的减施潜力,在此基础上通过逐步回归分析研究以上各指标对产量的影响,探明脲酶抑制剂(NBPT)在双季稻田的增效机理。【结果】1)在双季稻田,添加NBPT后,施氮量为N 135 kg/hm2的籽粒产量达到最高。与传统施氮(单施尿素N 180 kg/hm2)处理相比,早、晚稻可分别增产8.54%和12.87%,氮肥当季利用率分别提高6.78%和9.46%,可节约氮肥25%；2)与传统施氮相比,添加NBPT显著降低了水稻分蘖期的土壤脲酶活性和铵态氮含量,显著提高了孕穗期的铵态氮含量,而对此时期的脲酶活性无显著影响,NBPT对两个时期的硝酸还原酶活性、硝态氮含量及微生物量碳、氮含量均无明显影响,可见基施的NBPT主要是降低尿素水解速率方面效果显著,并且NBPT具有时效性,其主要是在水稻孕穗期之前起作用,在生态上较为安全；3)从各项土壤指标与水稻产量相关性的逐步回归分析结果来看,水稻分蘖期与孕穗期稻田土壤中铵态氮含量对水稻产量影响显著,而且孕穗期的影响大于分蘖期,其余指标则对产量无明显影响。【结论】由于脲酶抑制剂NBPT减缓了分蘖期尿素的水解作用,提高了孕穗期土壤中的铵态氮含量,为水稻后期生长提供充足的氮肥,在双季稻减肥方面具有显著的效果。在本试验土壤条件下,尿素中添加1%的NBPT,可在提高产量的同时,将传统施氮肥量减少25%,是适于稻田应用的脲酶抑制剂。
【目的】添加脲酶抑製劑( Urease inhibitor, UI)是提高肥料利用率的有效途徑,在尿素( Urea,U)中添加1%的脲酶抑製劑NBPT( N-丁基硫代燐酰三胺)是目前研究使用證明效果最可靠的添加比例。針對噹前稻田氮肥施用水平過高的問題,本文採用田間小區試驗研究瞭目前脲酶抑製劑添加比例下稻田氮肥的減施潛力以及脲酶抑製劑的節肥增效機理。【方法】本試驗在我國長江中下遊的雙季稻田進行,脲酶抑製劑用量NBPT為尿素用量的1%。尿素用量設五箇水平為N 90、112.5、135、157.5和180 kg/hm2,分彆依次記為U1、U2、U3、U4和U5,7箇處理為CK(不施氮肥)、U1+UI、U2+UI、U3+UI、U4+UI、U5+UI、U5(U5為傳統施氮量, N 180 kg/hm2為農民習慣施氮量),三次重複。 U1 U5處理施氮量分彆是在農民習慣施氮量的基礎上降低50%、37.5%、25%、12.5%、0%。通過取樣分析水稻分蘗期和孕穗期各處理對土壤脲酶活性、硝痠還原酶活性、土壤銨態氮含量、硝態氮含量以及微生物量碳、氮的含量,研究NBPT對水稻兩箇主要生育期土壤氮素供應的影響,比較各處理的產量以及氮肥利用率來得齣氮肥的減施潛力,在此基礎上通過逐步迴歸分析研究以上各指標對產量的影響,探明脲酶抑製劑(NBPT)在雙季稻田的增效機理。【結果】1)在雙季稻田,添加NBPT後,施氮量為N 135 kg/hm2的籽粒產量達到最高。與傳統施氮(單施尿素N 180 kg/hm2)處理相比,早、晚稻可分彆增產8.54%和12.87%,氮肥噹季利用率分彆提高6.78%和9.46%,可節約氮肥25%；2)與傳統施氮相比,添加NBPT顯著降低瞭水稻分蘗期的土壤脲酶活性和銨態氮含量,顯著提高瞭孕穗期的銨態氮含量,而對此時期的脲酶活性無顯著影響,NBPT對兩箇時期的硝痠還原酶活性、硝態氮含量及微生物量碳、氮含量均無明顯影響,可見基施的NBPT主要是降低尿素水解速率方麵效果顯著,併且NBPT具有時效性,其主要是在水稻孕穗期之前起作用,在生態上較為安全；3)從各項土壤指標與水稻產量相關性的逐步迴歸分析結果來看,水稻分蘗期與孕穗期稻田土壤中銨態氮含量對水稻產量影響顯著,而且孕穗期的影響大于分蘗期,其餘指標則對產量無明顯影響。【結論】由于脲酶抑製劑NBPT減緩瞭分蘗期尿素的水解作用,提高瞭孕穗期土壤中的銨態氮含量,為水稻後期生長提供充足的氮肥,在雙季稻減肥方麵具有顯著的效果。在本試驗土壤條件下,尿素中添加1%的NBPT,可在提高產量的同時,將傳統施氮肥量減少25%,是適于稻田應用的脲酶抑製劑。
【목적】첨가뇨매억제제( Urease inhibitor, UI)시제고비료이용솔적유효도경,재뇨소( Urea,U)중첨가1%적뇨매억제제NBPT( N-정기류대린선삼알)시목전연구사용증명효과최가고적첨가비례。침대당전도전담비시용수평과고적문제,본문채용전간소구시험연구료목전뇨매억제제첨가비례하도전담비적감시잠력이급뇨매억제제적절비증효궤리。【방법】본시험재아국장강중하유적쌍계도전진행,뇨매억제제용량NBPT위뇨소용량적1%。뇨소용량설오개수평위N 90、112.5、135、157.5화180 kg/hm2,분별의차기위U1、U2、U3、U4화U5,7개처리위CK(불시담비)、U1+UI、U2+UI、U3+UI、U4+UI、U5+UI、U5(U5위전통시담량, N 180 kg/hm2위농민습관시담량),삼차중복。 U1 U5처리시담량분별시재농민습관시담량적기출상강저50%、37.5%、25%、12.5%、0%。통과취양분석수도분얼기화잉수기각처리대토양뇨매활성、초산환원매활성、토양안태담함량、초태담함량이급미생물량탄、담적함량,연구NBPT대수도량개주요생육기토양담소공응적영향,비교각처리적산량이급담비이용솔래득출담비적감시잠력,재차기출상통과축보회귀분석연구이상각지표대산량적영향,탐명뇨매억제제(NBPT)재쌍계도전적증효궤리。【결과】1)재쌍계도전,첨가NBPT후,시담량위N 135 kg/hm2적자립산량체도최고。여전통시담(단시뇨소N 180 kg/hm2)처리상비,조、만도가분별증산8.54%화12.87%,담비당계이용솔분별제고6.78%화9.46%,가절약담비25%；2)여전통시담상비,첨가NBPT현저강저료수도분얼기적토양뇨매활성화안태담함량,현저제고료잉수기적안태담함량,이대차시기적뇨매활성무현저영향,NBPT대량개시기적초산환원매활성、초태담함량급미생물량탄、담함량균무명현영향,가견기시적NBPT주요시강저뇨소수해속솔방면효과현저,병차NBPT구유시효성,기주요시재수도잉수기지전기작용,재생태상교위안전；3)종각항토양지표여수도산량상관성적축보회귀분석결과래간,수도분얼기여잉수기도전토양중안태담함량대수도산량영향현저,이차잉수기적영향대우분얼기,기여지표칙대산량무명현영향。【결론】유우뇨매억제제NBPT감완료분얼기뇨소적수해작용,제고료잉수기토양중적안태담함량,위수도후기생장제공충족적담비,재쌍계도감비방면구유현저적효과。재본시험토양조건하,뇨소중첨가1%적NBPT,가재제고산량적동시,장전통시담비량감소25%,시괄우도전응용적뇨매억제제。
Objectives The addition of urease inhibitor is proved to be an effective measure to improve the efficiency of mineral fertilizer. Addition of urease inhibitor N-( n-butyl) thiophosphoric triamide [ NBPT] at a rate of 10 g/kg of urea has been widely used in researches. From the point of the high urea input in present rice production, the highest potential of saving nitrogen fertilizer through adding 1% of NBPT in urea was studied using a field experiment in paddy soils, and the mechanism of saving fertilizer and synergism from urease inhibitor were investigated. [Methods]A field experiment was conducted in a double-cropping paddy field in middle and lower reaches of the Yangtze River area, Southern China. Urea was mixed with urease inhibitor NBPT at a rate of 10 g/kg urea, five urea levels:N 90, 112. 5, 135, 157. 5 and 180 kg/ha were designed and recorded as U1, U2, U3, U4 and U5 in turn, plus a no N control and a normal urea of N 180 kg/ha in the experiment. A completely randomized design with seven treatments and three replicates was as follows, 1) CK (no N control);2) U1+UI;3) U2+UI;4 ) U3+UI;5 ) U4+UI;6 ) U5+UI;7 ) U5. The subtracting ratio of N fertilizer for U1 , U2 , U3 , U4 and U5 is 50%, 37. 5%, 25%, 12. 5% and 0% respectively. The activities of urease and nitrate reductase, the contents of NH4+-N, NO3--N and microbial biomass carbon ( MBC ) and microbial biomass nitrogen ( MBN ) in soil were analyzed in tillering and booting stages. The rice yield and N efficiency were investigated. [Results]1) With the addition of UI, the highest yield was obtained at N rate of 135 kg/ha. Compared with the normal urea N rate of 180 kg/ha, the grain yields were increased by 8. 54% and 12. 87% in early and late rice, the recovery of applied N improved by 6. 78% and 9. 46%, respectively, and 25% of N fertilizer could be saved as a result. 2)The addition of NBPT in urea notably reduced urease activity, and soil NH4+-N content at the tillering stage and increased soil NH4+-N content at the booting stage, while there were no obvious effects on nitrate reductase activity ( NRA) , soil NO3--N content and MBC and MBN. There was no significant difference in urease activity between with and without NBPT at the booting stage. Therefore, the urease inhibitor NBPT was effective before the booting stage and had less long term negative influence on soil environment. 3)The stepwise regression analysis reveals that the grain yield of rice is significantly associated with NH4+-N content in soil at the tillering and booting stages, especially, the latter. However, other properties in soil have no obvious effects on the grain yield. [Conclusions]The potential of saving N fertilizer from NBPT is outstanding in double-cropping paddy fields. Compared with the normal urea, N fertilizer is saved by 25% when NBPT is used. NBPT slows down the hydrolytic action of urea and dramatically improves soil NH4+-N content in the booting stage, which appears to be the dominant factor of saving N fertilizer. The above results suggest that NBPT could remain adequate N resources at late growth stage for rice and serve as a urease inhibitor for developing slow release fertilizer in paddy soils.
