Polyurethane coated urea slow/controlled release fertilizer was prepared based on urea granules, isocyanate, polyols and paraffin. Isocyanate reacted with polyols to synthesize the polyurethane skin layer on urea gran...Polyurethane coated urea slow/controlled release fertilizer was prepared based on urea granules, isocyanate, polyols and paraffin. Isocyanate reacted with polyols to synthesize the polyurethane skin layer on urea granules surface. Paraffin serves as a lubricant during syntheses of polyurethane skin layers. The structure and nutrient release characteristics of the polyurethane skin layers were investigated by FTIR, SEM and TG. Urea nitrogen slow-release behavior of the polyurethane coated urea was tested. The experimental results indicated that compact and dense polyurethane skin layers with a thickness of 10-15 lam were formed on urea surface, the urea nitrogen slow-release time can reach 40-50 days. Paraffin proves to play a key role in inhibiting water to penetrate into urea, but excessive addition would decrease the polyurethane crosslinking density.展开更多
There is limited information about the influence of slow or controlled release fertilizer(S/CRF) on rice yield and quality. In this study, japonica rice cultivar Nanjing 9108 was used to study the effects of three d...There is limited information about the influence of slow or controlled release fertilizer(S/CRF) on rice yield and quality. In this study, japonica rice cultivar Nanjing 9108 was used to study the effects of three different S/CRFs(polymer-coated urea(PCU), sulfur-coated urea(SCU), and urea formaldehyde(UF)) and two fertilization modes(both S/CRF and common urea(CU) as basal fertilizer, S/CRF as basal and CU as tillering fertilizer) on rice yield and quality. CU only was applied separately as control(CK). Results showed that, rice grain yield, chalky kernel rate, chalky area, overall chalkiness, and the content of gliadin, glutenin, and protein, all showed the trends of UF〉PCU〉SCU within the same fertilization mode, and showed the trends of S/CRF as basal and CU as tillering fertilizer〉both S/CRF and CU as basal fertilizer within the same type of S/CRF. In contrast, the contents of amylose, amylopectin, and starch, as well as taste value, and peak and hot viscosity showed trends of SCU〉PCU〉UF, and the trends of both S/CRF and CU as basal fertilizer〉S/CRF as basal and CU as tillering fertilizer. Among S/CRF treatments and fertilization modes, taste values of cooked rice were positively correlated with amylose, amylopectin, and starch contents, as well as gel consistency, peak viscosity, hot viscosity, and cool viscosity, while negatively correlated with globulin, gliadin, glutenin, and protein contents. The types of S/CRF and fertilization modes are important for improving rice yield and quality. Compared to CK, higher yield and similar quality of rice was achieved with UF as basal and CU as tillering fertilizer, and similar yield with improved appearance and eating and cooking quality of rice was achieved with either both UF and CU as basal fertilizer, or PCU as basal and CU as tillering fertilizer.展开更多
This study examined the release characteristics of different N forms in an uncoated slow/controlled-release compound fertilizer (UCRF) and the N uptake and N-use efficiency by rice plants. Water dissolution, soil le...This study examined the release characteristics of different N forms in an uncoated slow/controlled-release compound fertilizer (UCRF) and the N uptake and N-use efficiency by rice plants. Water dissolution, soil leaching, and pot experiments were employed. The dynamics of N release from the UCRF could be quantitatively described by three equations: the first-order kinetics equation [N1=N0 (1-e^-kt)], Elovich equation (N1=a + blnt), and parabola equation (N1=a + bt^0.5), with the best fitting by the first-order kinetics equation for different N (r= 0.9569^**-0.9999^**). The release potentials (No values estimated by the first-order kinetics equation) of different N in the UCRF decreased in the order of total N 〉 DON 〉 urea-N 〉 NH4^+-N 〉 NO3^-N in water, and total N 〉 NH4^+-N 〉 DON 〉 urea-N 〉 NO3^--N in soil, respectively, being in accordance with cumulative amounts of N release. The constants of N release rate (k values and b values) for different N forms were in decreasing order of total N 〉 DON 〉 NH4^+-N 〉 NO3^--N in water, whereas the k values were urea- N 〉DON 〉 NH4^+-N 〉 total N 〉 NO3^--N, and the b values were total N 〉 NH4^+-N 〉 DON 〉 NO3^--N 〉 urea-N in soil. Compared with a common compound fertilizer, the N-use efficiency, N-agronomy efficiency, and N-physiological efficiency of the UCRF were increased by 11.4%, 8.32 kg kg^-1, and 5.17 kg kg^-1, respectively. The ratios of different N to total N in the UCRF showed significant correlation with N uptake by rice plants. The findings showed that the first-order kinetics equation [Nt=N0 (l-e^kt)] could be used to describe the release characteristics of different N forms in the fertilizer. The UCRF containing different N forms was more effective in facilitating N uptake by rice compared with the common compound fertilizer containing single urea-N form.展开更多
Quantitative evaluation and analysis was made to the soil nutrients,rice yield,rice and fertilizer utilization rate,and economic and ecological benefits of the slow controlled release fertilizer in typical rice fields...Quantitative evaluation and analysis was made to the soil nutrients,rice yield,rice and fertilizer utilization rate,and economic and ecological benefits of the slow controlled release fertilizer in typical rice fields with middle-low yield by comparing the one-time application and split applications of slow-or controlledrelease fertilizer( CRF) with farmers fertilizer practice as the control,with the aim to explore the effect of CRF. Results showed that compared with the control,the application of CRF could meet balance nutrients required for rice growth,and the effective panicles and seed-setting rate were higher in the treatment groups of FVOL,SVOL,LADVOLwhich applied CRF. As for soil nutrients,soil pH maintained balance in FVOL,FCAI,SVOL,LADVOL. In addition,differences in soil nutrient reduction amount reached the extremely significant level between FVOLand SXNK.SVOLwhich applied CRF provided reasonable regulation of N,P and K release rate,which showed advantages over blending fertilization and farmers fertilizer practice. Comprehensive analysis found that the application of CRF could make rice tillering growth and decline leveled off,which effectively improved the quality of rice population,and it also had higher input-output ratio than that of the control and good economic benefits. In general,CRF suits to be used widely on rice crop in the regions with medium-low yield.展开更多
Lignin is the main by-product of pulp and papermaking and is not effectively utilized. Conversion of industrial lignins into value-added materials is beneficial for the effective utilization of resources as well as fo...Lignin is the main by-product of pulp and papermaking and is not effectively utilized. Conversion of industrial lignins into value-added materials is beneficial for the effective utilization of resources as well as for environmental protection. Because of their adsorptivity, slow-release property,biocompatibility, and biodegradability, lignin and its derivatives find potential applications as eco-friendly slow/controlled release materials in agricultural fields. This report reviews the recent research advances in lignin-based slow/controlled release fertilizers and pesticides.展开更多
The fertiliser industry faces a continuing challenge to improve the efficiency of their products,particularly of nitrogenous fertilisers,and to minimise adverse impacts.Therefore,a new slow release fertilizer,ureaimpr...The fertiliser industry faces a continuing challenge to improve the efficiency of their products,particularly of nitrogenous fertilisers,and to minimise adverse impacts.Therefore,a new slow release fertilizer,ureaimpregnated woodchips from tropical plant biomass(oil palm frond and rubberwood),was developed.The morphology of the impregnated woodchips was investigated by scanning electron microscopy and the success of impregnation of urea and nitrogen deposition into the woodchips was confirmed by energy dispersive X-ray spectrometry.When nitrogen release patterns from impregnated woodchips fertiliser were simulated using a soil solution and distilled water as leaching solutions in a static condition for 768 h,release was slow and steady,although the release rate was lower in distilled water than in the soil solution.展开更多
The effect of slow-release fertilizer application on reducing the fertilization times of ratooning rice was explored by carrying out plot experiments using different slow-release fertilizer formulas.The results showed...The effect of slow-release fertilizer application on reducing the fertilization times of ratooning rice was explored by carrying out plot experiments using different slow-release fertilizer formulas.The results showed that compared with conventional fertilization of farmers(TCK),there were no significant differences in plant heights of the first rice crop and ratoon rice crop and the number of tillers was slightly increased,by applying different ratios and types of slow-release fertilizers,indicating that reducing fertilization times did not affect rice growth.Compared with the TCK,the yields of treatments T1,T2,T3 and T4 of slow-release fertilizers increased to a certain extent.The yield of the first rice crop increased by 14.7%,16.7%,23.5% and 17.5%,respectively,the yields of the ratoon rice crop increased by 6.3%,5.8%,7.4% and 8.1%,respectively,and the yields of the two rice crops increased between 10.8% and 16.1%,indicating that reasonable combined application of slow-release nitrogen and fast-acting nitrogen fertilizer could meet the nutrient requirements of ratooning rice at different growth stages,and the application of slow-release fertilizers could reduce the fertilization times of ratooning rice.Based on the combination of rice yield and slow-release fertilizer cost in the first rice crop and ratoon rice crop,the T 3 formula was preferred,that is,urea-formaldehyde slow-release nitrogen fertilizer was used as the base and tillering fertilizer,and polyurethane-coated slow-release nitrogen fertilizer was used as the panicle-sprouting fertilizer.展开更多
After the sewage treatment, putting the wet sludge in which the heavy metal content is extremely low, corrupt and broken straw, bentonite, urea in proportioning according to the certain ratio, mixing well-distributed,...After the sewage treatment, putting the wet sludge in which the heavy metal content is extremely low, corrupt and broken straw, bentonite, urea in proportioning according to the certain ratio, mixing well-distributed, taking the shape of Nitrogen slow-release fertilizers, doing the dynamic bioleaching test by the method of Artificial rainfall simulation, researching the slow-release characteristic, water retention. When the mass ratio of the wet sludge whose water content is 82.5%: bentonite: corrupt and broken straw: urea is 62.5: 12.5: 12.5: 12.5, drip washing the 10g Nitrogen slow-release fertilizers by the 80ml distilled water after 48h, the residue rate of urea is 29.63%; Under the room temperature of 25 ℃, 77%RH, moisture evaporate 46.32% after 60 h. The results demonstrate that the slow-release fertilizer has a good release-effect of nitrogen and water conservation effect. It provides the basic for the development and application of the sewage in the aspect of Nitrogen slow-release fertilizers.展开更多
This paper investigates the yield and nitrogen use efficiency (NUE) of machine-transplanted rice cultivated using mechanized deep placement of N fertilizer in the rice–wheat rotation region of Chuanxi Plain,China.It ...This paper investigates the yield and nitrogen use efficiency (NUE) of machine-transplanted rice cultivated using mechanized deep placement of N fertilizer in the rice–wheat rotation region of Chuanxi Plain,China.It provides theoretical support for N-saving and improves quality and production efficiency of machine-transplanted rice.Using a single-factor complete randomized block design in field experiments in 2018 and 2019,seven N-fertilization treatments were applied,with the fertilizer being surface broadcast and/or mechanically placed beside the seedlings at (5.5±0.5) cm soil depth when transplanting.The treatments were:N0,no N fertilizer;U1,180 kg N ha^(–1) as urea,surface broadcast manually before transplanting;U2,108 kg N ha^(–1) as urea,surface broadcast manually before transplanting,and 72 kg N ha^(–1) as urea surface broadcast manually on the 10th d after transplanting,which is not only the local common fertilization method,but also the reference treatment;UD,180 kg N ha^(–1) as urea,mechanically deep-placed when transplanting;M1,81.6 kg N ha^(–1) as urea and 38.4 kg N ha^(–1) as controlled-release urea (CRU),mechanically deep-placed when transplanting;M2,102 kg N ha^(–1) as urea and48 kg N ha^(–1) as CRU,mechanically deep-placed when transplanting;M3,122.4 kg N ha^(–1) as urea and 57.6 kg N ha^(–1) as CRU,mechanically deep-placed when transplanting.The effects of the N fertilizer treatments on rice yield and NUE were consistent in the 2 yr.With a N application rate of 180 kg ha^(–1),compared with U2,the N recovery efficiency (NRE),N agronomic use efficiency (NAE) and yield under the UD treatment were 20.6,3.5 and 1.1% higher in 2018,and 4.6,1.7 and 1.2% higher in 2019,respectively.Compared with urea alone (U1,U2 or UD),the NRE,NAE and yield achieved by M3 (combined application of urea and controlled-release urea) were higher by 9.2–73.3%,18.6–61.5% and 6.5–16.5%(2018),and 22.2–65.2%,25.6–75.0% and 5.9–13.9%(2019),respectively.Compared with M3,the lower-N treatments M1 and M2 significantly increased NRE by 4.0–7.8% in 2018 and 3.1–4.3% in 2019,respectively.Compared with urea surface application (U1 or U2),the yield under the M2 treatment was higher by 4.3–12.9% in 2018 and 3.6–10.1% in 2019,respectively.Compared with U2,the NRE and NAE under the M2 treatment was higher by 36.9 and 36.3% in 2018,and 33.2 and 37.4% in 2019,mainly because of higher N uptake.There was no significant difference in the concentration of nitrate in the top 0–20 cm soil under U1,U2 and M2 treatments during the full heading and maturity stages.During the full heading stage,U2 produced the highest concentration of nitrite in 0–20 cm and 20–40 cm soil among the N fertilizer treatments.In conclusion,mechanized deep placement of mixed urea and controlled-release urea (M2) at transplanting is a highly-efficient cultivation technology that enables increased yield of machine-transplanted rice and improved NUE,while reducing the amount of N-fertilization applied.展开更多
基金the National Key Technology R&D Program of the 11th Five-Year Period (No.2006BAD10B08)
文摘Polyurethane coated urea slow/controlled release fertilizer was prepared based on urea granules, isocyanate, polyols and paraffin. Isocyanate reacted with polyols to synthesize the polyurethane skin layer on urea granules surface. Paraffin serves as a lubricant during syntheses of polyurethane skin layers. The structure and nutrient release characteristics of the polyurethane skin layers were investigated by FTIR, SEM and TG. Urea nitrogen slow-release behavior of the polyurethane coated urea was tested. The experimental results indicated that compact and dense polyurethane skin layers with a thickness of 10-15 lam were formed on urea surface, the urea nitrogen slow-release time can reach 40-50 days. Paraffin proves to play a key role in inhibiting water to penetrate into urea, but excessive addition would decrease the polyurethane crosslinking density.
基金the National Key R&D Program of China (2016YFD0300503)the Key Research Program of Jiangsu Province, China (BE2016344)+3 种基金the National Rice Industry Technology System, China (CARS01-27)the National Nature Science Foundation of China (31701350)the Program for Scientific Elitists of Yangzhou University, Chinaa Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions, China
文摘There is limited information about the influence of slow or controlled release fertilizer(S/CRF) on rice yield and quality. In this study, japonica rice cultivar Nanjing 9108 was used to study the effects of three different S/CRFs(polymer-coated urea(PCU), sulfur-coated urea(SCU), and urea formaldehyde(UF)) and two fertilization modes(both S/CRF and common urea(CU) as basal fertilizer, S/CRF as basal and CU as tillering fertilizer) on rice yield and quality. CU only was applied separately as control(CK). Results showed that, rice grain yield, chalky kernel rate, chalky area, overall chalkiness, and the content of gliadin, glutenin, and protein, all showed the trends of UF〉PCU〉SCU within the same fertilization mode, and showed the trends of S/CRF as basal and CU as tillering fertilizer〉both S/CRF and CU as basal fertilizer within the same type of S/CRF. In contrast, the contents of amylose, amylopectin, and starch, as well as taste value, and peak and hot viscosity showed trends of SCU〉PCU〉UF, and the trends of both S/CRF and CU as basal fertilizer〉S/CRF as basal and CU as tillering fertilizer. Among S/CRF treatments and fertilization modes, taste values of cooked rice were positively correlated with amylose, amylopectin, and starch contents, as well as gel consistency, peak viscosity, hot viscosity, and cool viscosity, while negatively correlated with globulin, gliadin, glutenin, and protein contents. The types of S/CRF and fertilization modes are important for improving rice yield and quality. Compared to CK, higher yield and similar quality of rice was achieved with UF as basal and CU as tillering fertilizer, and similar yield with improved appearance and eating and cooking quality of rice was achieved with either both UF and CU as basal fertilizer, or PCU as basal and CU as tillering fertilizer.
文摘This study examined the release characteristics of different N forms in an uncoated slow/controlled-release compound fertilizer (UCRF) and the N uptake and N-use efficiency by rice plants. Water dissolution, soil leaching, and pot experiments were employed. The dynamics of N release from the UCRF could be quantitatively described by three equations: the first-order kinetics equation [N1=N0 (1-e^-kt)], Elovich equation (N1=a + blnt), and parabola equation (N1=a + bt^0.5), with the best fitting by the first-order kinetics equation for different N (r= 0.9569^**-0.9999^**). The release potentials (No values estimated by the first-order kinetics equation) of different N in the UCRF decreased in the order of total N 〉 DON 〉 urea-N 〉 NH4^+-N 〉 NO3^-N in water, and total N 〉 NH4^+-N 〉 DON 〉 urea-N 〉 NO3^--N in soil, respectively, being in accordance with cumulative amounts of N release. The constants of N release rate (k values and b values) for different N forms were in decreasing order of total N 〉 DON 〉 NH4^+-N 〉 NO3^--N in water, whereas the k values were urea- N 〉DON 〉 NH4^+-N 〉 total N 〉 NO3^--N, and the b values were total N 〉 NH4^+-N 〉 DON 〉 NO3^--N 〉 urea-N in soil. Compared with a common compound fertilizer, the N-use efficiency, N-agronomy efficiency, and N-physiological efficiency of the UCRF were increased by 11.4%, 8.32 kg kg^-1, and 5.17 kg kg^-1, respectively. The ratios of different N to total N in the UCRF showed significant correlation with N uptake by rice plants. The findings showed that the first-order kinetics equation [Nt=N0 (l-e^kt)] could be used to describe the release characteristics of different N forms in the fertilizer. The UCRF containing different N forms was more effective in facilitating N uptake by rice compared with the common compound fertilizer containing single urea-N form.
文摘Quantitative evaluation and analysis was made to the soil nutrients,rice yield,rice and fertilizer utilization rate,and economic and ecological benefits of the slow controlled release fertilizer in typical rice fields with middle-low yield by comparing the one-time application and split applications of slow-or controlledrelease fertilizer( CRF) with farmers fertilizer practice as the control,with the aim to explore the effect of CRF. Results showed that compared with the control,the application of CRF could meet balance nutrients required for rice growth,and the effective panicles and seed-setting rate were higher in the treatment groups of FVOL,SVOL,LADVOLwhich applied CRF. As for soil nutrients,soil pH maintained balance in FVOL,FCAI,SVOL,LADVOL. In addition,differences in soil nutrient reduction amount reached the extremely significant level between FVOLand SXNK.SVOLwhich applied CRF provided reasonable regulation of N,P and K release rate,which showed advantages over blending fertilization and farmers fertilizer practice. Comprehensive analysis found that the application of CRF could make rice tillering growth and decline leveled off,which effectively improved the quality of rice population,and it also had higher input-output ratio than that of the control and good economic benefits. In general,CRF suits to be used widely on rice crop in the regions with medium-low yield.
基金financial support from the Independent Innovation and Achievements Transformation Project of Shandong Province (2014CGZH0302)
文摘Lignin is the main by-product of pulp and papermaking and is not effectively utilized. Conversion of industrial lignins into value-added materials is beneficial for the effective utilization of resources as well as for environmental protection. Because of their adsorptivity, slow-release property,biocompatibility, and biodegradability, lignin and its derivatives find potential applications as eco-friendly slow/controlled release materials in agricultural fields. This report reviews the recent research advances in lignin-based slow/controlled release fertilizers and pesticides.
基金supported by Research University Grant Scheme(RUGS)University Putra Malaysia(No.03-02-12-2293RU)
文摘The fertiliser industry faces a continuing challenge to improve the efficiency of their products,particularly of nitrogenous fertilisers,and to minimise adverse impacts.Therefore,a new slow release fertilizer,ureaimpregnated woodchips from tropical plant biomass(oil palm frond and rubberwood),was developed.The morphology of the impregnated woodchips was investigated by scanning electron microscopy and the success of impregnation of urea and nitrogen deposition into the woodchips was confirmed by energy dispersive X-ray spectrometry.When nitrogen release patterns from impregnated woodchips fertiliser were simulated using a soil solution and distilled water as leaching solutions in a static condition for 768 h,release was slow and steady,although the release rate was lower in distilled water than in the soil solution.
基金Supported by National Key Research and Development Project(No.2018YFD0301302).
文摘The effect of slow-release fertilizer application on reducing the fertilization times of ratooning rice was explored by carrying out plot experiments using different slow-release fertilizer formulas.The results showed that compared with conventional fertilization of farmers(TCK),there were no significant differences in plant heights of the first rice crop and ratoon rice crop and the number of tillers was slightly increased,by applying different ratios and types of slow-release fertilizers,indicating that reducing fertilization times did not affect rice growth.Compared with the TCK,the yields of treatments T1,T2,T3 and T4 of slow-release fertilizers increased to a certain extent.The yield of the first rice crop increased by 14.7%,16.7%,23.5% and 17.5%,respectively,the yields of the ratoon rice crop increased by 6.3%,5.8%,7.4% and 8.1%,respectively,and the yields of the two rice crops increased between 10.8% and 16.1%,indicating that reasonable combined application of slow-release nitrogen and fast-acting nitrogen fertilizer could meet the nutrient requirements of ratooning rice at different growth stages,and the application of slow-release fertilizers could reduce the fertilization times of ratooning rice.Based on the combination of rice yield and slow-release fertilizer cost in the first rice crop and ratoon rice crop,the T 3 formula was preferred,that is,urea-formaldehyde slow-release nitrogen fertilizer was used as the base and tillering fertilizer,and polyurethane-coated slow-release nitrogen fertilizer was used as the panicle-sprouting fertilizer.
文摘After the sewage treatment, putting the wet sludge in which the heavy metal content is extremely low, corrupt and broken straw, bentonite, urea in proportioning according to the certain ratio, mixing well-distributed, taking the shape of Nitrogen slow-release fertilizers, doing the dynamic bioleaching test by the method of Artificial rainfall simulation, researching the slow-release characteristic, water retention. When the mass ratio of the wet sludge whose water content is 82.5%: bentonite: corrupt and broken straw: urea is 62.5: 12.5: 12.5: 12.5, drip washing the 10g Nitrogen slow-release fertilizers by the 80ml distilled water after 48h, the residue rate of urea is 29.63%; Under the room temperature of 25 ℃, 77%RH, moisture evaporate 46.32% after 60 h. The results demonstrate that the slow-release fertilizer has a good release-effect of nitrogen and water conservation effect. It provides the basic for the development and application of the sewage in the aspect of Nitrogen slow-release fertilizers.
基金supported by the National Key Research and Development Program of China(2016YFD0300108)the Application and Basic Research Project of Sichuan Province,China(2018JY0630)the Financial Innovation Capacity Improvement of Sichuan Province,China(2017QNJJ-031)。
文摘This paper investigates the yield and nitrogen use efficiency (NUE) of machine-transplanted rice cultivated using mechanized deep placement of N fertilizer in the rice–wheat rotation region of Chuanxi Plain,China.It provides theoretical support for N-saving and improves quality and production efficiency of machine-transplanted rice.Using a single-factor complete randomized block design in field experiments in 2018 and 2019,seven N-fertilization treatments were applied,with the fertilizer being surface broadcast and/or mechanically placed beside the seedlings at (5.5±0.5) cm soil depth when transplanting.The treatments were:N0,no N fertilizer;U1,180 kg N ha^(–1) as urea,surface broadcast manually before transplanting;U2,108 kg N ha^(–1) as urea,surface broadcast manually before transplanting,and 72 kg N ha^(–1) as urea surface broadcast manually on the 10th d after transplanting,which is not only the local common fertilization method,but also the reference treatment;UD,180 kg N ha^(–1) as urea,mechanically deep-placed when transplanting;M1,81.6 kg N ha^(–1) as urea and 38.4 kg N ha^(–1) as controlled-release urea (CRU),mechanically deep-placed when transplanting;M2,102 kg N ha^(–1) as urea and48 kg N ha^(–1) as CRU,mechanically deep-placed when transplanting;M3,122.4 kg N ha^(–1) as urea and 57.6 kg N ha^(–1) as CRU,mechanically deep-placed when transplanting.The effects of the N fertilizer treatments on rice yield and NUE were consistent in the 2 yr.With a N application rate of 180 kg ha^(–1),compared with U2,the N recovery efficiency (NRE),N agronomic use efficiency (NAE) and yield under the UD treatment were 20.6,3.5 and 1.1% higher in 2018,and 4.6,1.7 and 1.2% higher in 2019,respectively.Compared with urea alone (U1,U2 or UD),the NRE,NAE and yield achieved by M3 (combined application of urea and controlled-release urea) were higher by 9.2–73.3%,18.6–61.5% and 6.5–16.5%(2018),and 22.2–65.2%,25.6–75.0% and 5.9–13.9%(2019),respectively.Compared with M3,the lower-N treatments M1 and M2 significantly increased NRE by 4.0–7.8% in 2018 and 3.1–4.3% in 2019,respectively.Compared with urea surface application (U1 or U2),the yield under the M2 treatment was higher by 4.3–12.9% in 2018 and 3.6–10.1% in 2019,respectively.Compared with U2,the NRE and NAE under the M2 treatment was higher by 36.9 and 36.3% in 2018,and 33.2 and 37.4% in 2019,mainly because of higher N uptake.There was no significant difference in the concentration of nitrate in the top 0–20 cm soil under U1,U2 and M2 treatments during the full heading and maturity stages.During the full heading stage,U2 produced the highest concentration of nitrite in 0–20 cm and 20–40 cm soil among the N fertilizer treatments.In conclusion,mechanized deep placement of mixed urea and controlled-release urea (M2) at transplanting is a highly-efficient cultivation technology that enables increased yield of machine-transplanted rice and improved NUE,while reducing the amount of N-fertilization applied.