Integrated assessment of yield,nitrogen use efficiency and ecosystem economic benefits of use of controlled-release and common urea in ratoon rice production

Controlled-release urea(CRU)is commonly used to improve the crop yield and nitrogen use efficiency(NUE).However,few studies have investigated the effects of CRU in the ratoon rice system.Ratoon rice is the practice of obtaining a second harvest from tillers originating from the stubble of the previously harvested main crop.In this study,a 2-year field experiment using a randomized complete block design was conducted to determine the effects of CRU on the yield,NUE,and economic benefits of ratoon rice,including the main crop,to provide a theoretical basis for fertilization of ratoon rice.The experiment included four treatments:(i)no N fertilizer(CK);(ii)traditional practice with 5 applications of urea applied at different crop growth stages by surface broadcasting(FFP);(iii)one-time basal application of CRU(BF1);and(iv)one-time basal application of CRU combined with common urea(BF2).The BF1 and BF2 treatments significantly increased the main crop yield by 17.47 and 15.99%in 2019,and by 17.91 and 16.44%in 2020,respectively,compared with FFP treatment.The BF2 treatment achieved similar yield of the ratoon crop to the FFP treatment,whereas the BF1 treatment significantly increased the yield of the ratoon crop by 14.81%in 2019 and 12.21%in 2020 compared with the FFP treatment.The BF1 and BF2 treatments significantly improved the 2-year apparent N recovery efficiency,agronomic NUE,and partial factor productivity of applied N by 11.47-16.66,27.31-44.49,and 9.23-15.60%,respectively,compared with FFP treatment.The BF1 and BF2 treatments reduced the chalky rice rate and chalkiness of main and ratoon crops relative to the FFP treatment.Furthermore,emergy analysis showed that the production efficiency of the BF treatments was higher than that of the FFP treatment.The BF treatments reduced labor input due to reduced fertilization times and improved the economic benefits of ratoon rice.Compared with the FFP treatment,the BF1 and BF2 treatments increased the net income by 14.21-16.87 and 23.76-25.96%,respectively.Overall,the one-time blending use of CRU and common urea should be encouraged to achieve high yield,high nitrogen use efficiency,and good quality of ratoon rice,which has low labor input and low apparent N loss.

Effects of Urea Ammonium Chloride of Different Fertilization Patterns on Maize Yield and Yield Components

[Objective] To understand the application effects of urea ammonium chloride fertilizer on maize production. [Methods] A field plot experiment was conducted to study the effects of urea ammonium chloride of different fertilization patterns on summer maize yield and yield components. [Results] Urea ammonium chloride had a long fertilizer effect and the same yield-increasing effect with urea, which could im- prove the agronomic traits and economic traits of maize apparently and the applica- tion of urea ammonium chloride with nutrient reduction of 40% （namely just use urea ammonium chloride equaled 60% pure nitrogen）, had the same yield-increasing effect with urea of traditional fertilization patterns, and input-output ratio was high and the economic benefit was remarkable. [Conclusion] To provide scientific theoretical direc- tion for large area popularization and application of urea ammonium chloride.

Increase in yield and nitrogen use efficiency of double rice with long-term application of controlled-release urea

Controlled-release urea(CRU)has better characteristics than conventional urea for synchronizing nitrogen(N)release with plant uptake.Understanding the effects of CRU on crop yield and N use efficiency(NUE)has long been the key to evaluate the performance of CRU.A long-term experiment over five consecutive years was conducted in Changsha,Hunan Province,China,to investigate the effects of polyethylene-coated urea with a 90-d release period on the yield and NUE of double rice(early and late crops are grown in the same year),the amount of residual soil mineral N and the soil–plant N balance,as well as on the economic benefits.Four N fertilizer treatments including CK(no N fertilizer),U(conventional urea),CRU1(polyethylene-coated urea with equal N application rate to U)and CRU2(20%reduction in N application rate of CRU1)were established.The results indicated that CRU1 application increased the yield and NUE of double rice by 11.0 and 13.5%,respectively,compared with U.Higher yield and NUE of late rice were found than in early rice in CRU treatments.Compared with conventional U,the yield and NUE of early rice in the CRU1 treatment were increased by 6.0 and 10.2%,respectively,and those of late rice were increased by 15.4 and 13.8%,respectively.There was no significant difference between CRU1 and CRU2 in double rice yield.Furthermore,CRU treatments(including CRU1 and CRU2)had higher apparent residual Nmin rate(ARNR)and apparent N recovery rate(ANRR),but lower apparent N loss(NS)than the conventional U treatment.Concentrations of NH_(4)^(+)-N and NO_(3)^(-)-N were greater in the surface soil(0–20 cm)and lower in the deeper soil layer(40–60 cm)with CRU treatments than in the U treatment after harvest.Moreover,CRU application produced a greater economic benefit than conventional U application.In general,CRU outperformed U fertilizer in terms of rice yield,NUE,soil–plant N balance,economic benefit,and CRU2 provided greater comprehensive benefits than CRU1.It is suggested that CRU application is beneficial for solving N management challenges in the production of rice.

Hybrid rice yield response to potted-seedling machine transplanting and slow-release nitrogen fertilizer application combined with urea topdressing

Machine transplanting and the application of slow-release nitrogen(N) fertilizer(SRNF) have played vital roles in the modernization of rice production. We aimed to determine the effects of potted-seedling transplanting—a new machine-transplanting method—and SRNF on hybrid rice yields. A 2-year splitplot experiment(2016–2017) was conducted in Meishan, Sichuan province, China, using two machinetransplanting methods(potted-seedling and blanket-seedling) and three N treatments. Total green leaf area, high-effective leaf area and its rate at heading, net photosynthetic rate of flag leaves 7 days after heading, glutamate synthase(GOGAT) and glutamine synthase(GS) activity after heading, dry matter production, and N accumulation at heading and maturity increased under the potted-seedling method or 70% SRNF as a base + 30% urea application at the panicle initiation stage(SBUP). Stem diameter and number of small and of all vascular bundles at the neck–panicle node in potted-seedling plants increased as a result of increasing numbers of effective panicles, secondary branches, and spikelets. In pottedseedling plants, treatment with SBUP increased the number of large and total vascular bundles at the panicle–neck internode and the number of differentiated and surviving secondary branches and spikelets and decreased the number of ineffective tillers and degenerated secondary branches and spikelets. We conclude that the potted-seedling machine transplanting method and SRNF combined with urea topdressing can strengthen the source–sink relationship in rice, resulting in higher yields.

Combining controlled-release urea and normal urea with appropriate nitrogen application rate to reduce wheat stem lodging risk and increase grain yield and yield stability

A mixture of controlled-release urea and normal urea(CRUNU)is an efficient nitrogen(N)fertilizer type,but little is known about its effects on stem lodging resistance,grain yield,and yield stability of wheat.In this study,a 4-year field experiment(from 2017 to 2021)was conducted to analyze the effects of N fertilizer types(CRUNU and normal urea(NU))and application rates(low level(L),135 kg ha^(–1);medium level(M),180 kg ha^(–1);high level(H),225 kg ha^(–1))on population lodging resistance,basal internode strength,lignin content and synthetase activity,stem lodging resistance,grain yield,and yield stability of wheat.Our results showed that the two N fertilizer types had the highest lodging rate under high N application rates,and the M-CRUNU treatment showed the lowest lodging rate.Compared with NU,CRUNU improved the wheat population lodging resistance under the three N application rates,mainly related to improving wheat population characteristics and breaking the strength of the second basal internode.Correlation analysis showed that the breaking strength of the second basal internode was related to the physical characteristics,chemical components,and micro-structure of the internode.Compared with NU,CRUNU significantly increased wheat grain yield by 4.47,14.62,and 3.12%under low,medium,and high N application rates,respectively.In addition,CRUNU showed no significant difference in grain yield under medium and high N application rates,but it presented the highest yield stability under the medium N application rate.In summary,CRUNU,combined with the medium N application rate,is an efficient agronomic management strategy for wheat production.

Effect of Different Spacing and Urea Application Rates on Fruit Nutrient Composition, Growth and Yield of Tomato in Derived Savannah Vegetation of Kogi State, Nigeria

Experiments were located at Lower Niger River Basin Development Authority, Ejiba and Horticultural Section College of Agriculture, Kabba in 2014 cropping season to investigate the effect of different spacing and urea application rates on fruit nutrient composition, growth and fruit yield of tomato in derived savanna vegetation of Nigeria. Field experiments were arranged in a randomized complete block design in factorial fashion with three replications. The row spacing were 75 × 40 cm (33,333 plant·ha-1, 75 × 50 cm (26,666 plant·ha-1) and 75 × 60 cm (22,222 plant·ha-1) while the urea rates comprised control (0 kg urea·ha-1), 54.3 and 108.6 kg urea·ha-1. Growth and yield parameters taken were as follows: average plant height, stem girth, leaf area (m2) and yield per land area. Data were collected from ten randomly selected plants in each plot. The data were statistically analyzed using GENSTAT. The analysis of variance (ANOVA) was performed to find out the significance of variation among the treatments while the significant difference between mean treatments was separated using least significance Difference at 5% level of probability. The result obtained from this study indicated that urea application and spacing affected significantly growth parameters of tomato and yield per land area. It could be concluded that there was a significant increase in plant height, number of leaves, number of fruits per plant and final fruit weight of tomato as a result of urea fertilizer application at the rate of 108.6 kg urea/ha. However, this was not significantly better than plots with urea application at 54.8 kg/ha in both Ejiba and Kabba. Row spacing of 75 × 50 cm showed better performance in number of fruit and fruit yield per plots. Farmers in Ejiba and Kabba should apply urea at the rate of 54.8 kg per hectare and plant the crop at a row spacing of 75 × 50 cm for optimum yield and for a more profitable production of tomato.

Effect of Combined Application of Humic Acid and Urea on the Wheat Growth and Yield

This paper aims to research the effects of combined application of humic acid and urea on the wheat yield and yield component,and establish rational fertilizer application scheme of wheat. Split plot experiment was adopted. Two types of phosphorus fertilizer( adding humic acid or not) was assigned to the main plot,and four types of top dressing modes( different amount of urea and humic acid urea) were used in subplots. Effects of combined application of humic acid and urea on the wheat yield and yield component were researched. 375 kg / ha ordinary DAP + 150 kg / ha urea was used as base fertilizer; topdressing of 300 kg / ha urea humate could effectively promote the plant height,leaf area coefficient and aboveground dry matter amount. Adding humic acid in urea in topdressing significantly enhanced the wheat yield and economic coefficient of wheat. Adding humic acid in urea in topdressing has better effects of yield increasing than base fertilizer,and can be used for large scale extension.

Effects of controlled-release urea application on the growth, yield and nitrogen recovery efficiency of cotton

Field experiments were conducted to study the effects of the controlled release urea (CRU) application on growth yield and nitrogen recovery efficiency of cotton in the main cotton zone of the Yangtze River basin in 2010. Different nitrogen levels were set in order to determine the suitable dosage of CRU on cotton. The special purpose was to provide evidence for the CRU application in cotton fields. The results show that the application of CRU promotes the growth of cotton significantly and enhances the nitrogen supply in the whole period. Compared to the treatment with total N as base fertilizer (UB), the bod, flower, little bolls and total bolls are increased significantly. There are no significant differences in the yield between the CRU treatment and the treatment of controlled release urea and urea combined application (60%CRU + 40%U), but an increase by 12.38%-22.67% compared to the UB treatment, and an increase by 4.49%-7.23% compared to the treatments of total N split application (UD). The nitrogen uptake of CRU treatment was significantly increased by 13.01%-48.32% and 30.27%-13.01% than UB treatment and UD treatment, respectively. The nutrient recovery efficiency of CRU treatment is increased by 16.42-20.59, 5.92-11.29 and 4.22-12.59 percentage points compared to the UB treatment, UD treatment and 60%CRU + 40%U treatment, respectively. In this study, there was a good linearity relationship between the cotton yield and amount of CRU in Wuxue site. The yield of cotton response to amount of CRU could be described by the model of linear plus plateau in Jingzhou site.

Inclusion of Yeast Cultures (<i>Saccharomyces cerevisiae</i>) to Dairy Cows’ Urea-Treated Rice Straw Diets Improves Mozzarella Cheese Processing and Yield

This research paper addresses the hypothesis that adding yeast cultures (Saccharomyces cerevisiae) to urea-treated cereal crop residues could improve milk composition to the level of milk produced on pastures for the manufacture of Mozzarella cheese. In three equal groups, Nine Friesian cows were randomly assigned to three treatment diets in a completely randomized design. The treatments were pasture (P), urea treated rice straw (UTRS), and urea treated rice straw with yeast inclusion (UTRS + Y). Urea inclusion was at 3.8% of the dry matter to treat rice straw, while yeast culture inclusion was 10 g/cow/day. The experimental period was 21 days, with 14 days of adaptation. Data analysis used general linear model procedure of SAS, fitting diet as a fixed effect and milk composition, syneresis, curd firmness and cheese yield as the response variables. Milk produced on UTRS diet yielded (p < 0.05) the highest fat content (4.79%) and the lowest density (1016.37 Kg·m-3) and casein-to-fat ratio (0.51). Yeast inclusion in the diet (UTRS + Y) significantly improved milk density (1022.68 Kg·m-3) with marginal reduction in milk fat content (4.53%). In cheese making, milk produced on URTS diets had significantly lower renneting time (1.4 minutes vs 3.47 minutes and 2.39 minutes), least viscous gel, lowest syneresis (755 mL vs 860 mL and 836 mL from 1000 mL), and lowest cheese yield (9.0% vs 11% and 10.5%) compared to P and UTRS + Y diets. Milk produced from P and UTRS + Y did not show any significant difference in cheese yield. The findings indicated that urea treated rice straw with yeast cultures improves syneresis, gel viscosity and Mozzarella cheese yield. Therefore, we recommend the inclusion of yeast to urea treated cereal crop residues to produce milk destined for Mozzarella cheese making.

Strip deep rotary tillage combined with controlled-release urea improves the grain yield and nitrogen use efficiency of maize in the North China Plain

Inappropriate tillage practices and nitrogen(N) management have become seriously limitations for maize(Zea mays L.) yield and N use efficiency(NUE) in the North China Plain(NCP). In the current study, we examined the effects of strip deep rotary tillage(ST) combined with controlled-release(CR) urea on maize yield and NUE, and determined the physiological factors involved in yield formation and N accumulation during a 2-year field experiment. Compared with conventional rotary tillage(RT) and no-tillage(NT), ST increased the soil water content and soil mineral N content(Nmin) in the 20–40 cm soil layer due to reduction by 10.5 and 13.7% in the soil bulk density in the 0–40 cm soil layer, respectively. Compared with the values obtained by common urea(CU) fertilization, CR increased the Nmin in the 0–40 cm soil layers by 12.4 and 10.3% at the silking and maturity stages, respectively. As a result, root length and total N accumulation were enhanced under ST and CR urea, which promoted greater leaf area and dry matter(particularly at post-silking), eventually increasing the1 000-kernel weight of maize. Thus, ST increased the maize yield by 8.3 and 11.0% compared with RT and NT, respectively, whereas CR urea increased maize yield by 8.9% above the values obtained under CU. Because of greater grain yield and N accumulation, ST combined with CR urea improved the NUE substantially. These results show that ST coupled with CR urea is an effective practice to further increase maize yield and NUE by improving soil properties and N supply, so it should be considered for sustainable maize production in the NCP(and other similar areas worldwide).

A combination of straw incorporation and polymer-coated urea offsets soil ammonia and nitrous oxide emissions in winter wheat fields

The combined effects of straw incorporation(SI)and polymer-coated urea(PCU)application on soil ammonia(NH_(3))and nitrous oxide(N_(2)O)emissions from agricultural fields have not been comprehensively evaluated in Northwest China.We conducted a two-year field experiment to assess the effects of combining SI with either uncoated urea(U)or PCU on soil NH_(3)emissions,N_(2)O emissions,winter wheat yields,yield-scaled NH_(3)(/NH_(3)),and yield-scaled N_(2)O(/N_(2)O).Five treatments were investigated,no nitrogen(N)fertilizer(N_(0)),U application at 150 kg N ha-1 with and without SI(SI+U and S_(0)+U),and PCU application at 150 kg N ha^(-1) with and without SI(SI+PCU and S_(0)+PCU).The results showed that the NH_(3);emissions increased by 20.98-34.35%following Sl compared to straw removal,mainly due to increases in soil ammonium(NH_(4)^(+)-N)content and water-flled pore space(WFPS).SI resulted in higher N_(2)O emissions than under the So scenario by 13.31-49.23%due to increases in soil inorganic N(SIN)contents,WFPS,and soil microbial biomass.In contrast,the PCU application reduced the SIN contents compared to the U application,reducing the NH_(3)and N_(2)O emissions by 45.99-58.07 and 18.08-53.04%,respectively.Moreover,no significant positive effects of the SI or PCU applications on the winter wheat yield were observed.The lowest /NH_(3) and /N_(2)O values were observed under the S_(0)+PCU and SI+PCU treatments.Our results suggest that single PCU applications and their combination with straw are the optimal agricultural strategies for mitigating gaseous N emissions and maintaining optimal winter wheat yields in Northwest China.

Nutrient and growth elucidation of a novel coated urea on oilseed rape in three main cultivation areas

A novel coated urea(MVCU)was prepared,and its application effect was verified by field trials of oilseed rape in three main cultivation areas.Meanwhile,the nutrient release and coating layer changes of MVCU in static water at 25C and different soils were systematically evaluated.MVCU showed a long nutrient release time under static water(77 days)and soil incubation(140 days)conditions due to the slow degradation of the coating layer in MVCU,and its nitrogen release coincided well with oilseed rape nitrogen demand.The above results were further confirmed by FT-IR spectra and SEM analysis.Compared with conventional urea(U),the field trials of MVCU in the three main cultivation areas showed high nitrogen utilization efficiency and yield advantages in oilseed rape.The field trials results indicated that the MVCU significantly enhanced the aboveground dry matter(28.7%),the seed nitrogen concentration(9.5%)and aboveground nitrogen accumulation(42.5%)of oilseed rape at the mature stage as compared to that of the U.The oilseed rape yield enhanced by 932.8 kg/hm^(2),the average growth rate was 65.1%,and nitrogen utilization efficiency increased by 21.2%.In short,MVCU has the advantages of excellent slow-release performance and strong applicability,and its yield-increasing effect on oilseed rape could reach or even be better than that of traditional fertilization.

Effect of Transplanting Density on Rice Yield,Nitrogen Uptake and ^(15)N-fertilizer Fate

[Objective] The aim of this study was investigated the rice yield, nitrogen uptake and ^15-fertilizer fate at different transplanting density to provide scientific ba- sis for improving the yield of rice and applying reasonably fertilizer. [Method] A field experiment was carried out to study the effect of different transplanting density on rice yield, nitrogen （N） absorption, sources of N uptake by rice and the N balance in the plant-soil systems by using ^15-labelled urea. [Result] There were no significant differences in rice yields and total N uptakes by rice between treatments 30 cm × 30 cm and 40 cm × 40 cm, but the yield of rice and total N absorption in the two treatments were remarkably higher than those in 50 cm × 50 cm treatment. The amounts of total N uptake by rice were in the range of 112.3-162.7 kg/hm2 in the three transplanting densities. The result showed that about 1/3 of the total N uptake by rice was supplied by application fertilizer and the other 2/3 was obtained from the soil N pool. The ^15N-labelled urea absorbed by rice, residual in soil and lost accounted for 16.3%-26.1%, 17.0%-20.9% and 53.0%-66.7% of the total fertilizer, respectively. A great deal of ^15N-labelled urea was lost during the rice growing season. [Conclusion] Considering the rice yield and environmental protection, the transplanting density of 30 cm×30 cm was recommended in the hilly area of Sichuan basin in the southwest China.

Effects of mechanized deep placement of nitrogen fertilizer rate and type on rice yield and nitrogen use efficiency in Chuanxi Plain, China

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.

Influence of Organic and Inorganic Nitrogen on Grain Yield andYield Components of Hybrid Rice in Northwestern Pakistan

Field experiments were conducted to assess the impact of various organic sources, inorganicnitrogen （N） and the different combinations of inorganic N （urea） ＋ organic source on the yieldcomponents （YC） and grain yield （GY） of hybrid rice （Oryza sativa L., Pukhraj） under rice-wheat system.The experiments were conducted at Batkhela （Malakand）, Northwestern Pakistan, in 2011 and 2012.Our results revealed that YC and GY ranked first for the hybrid rice when applied with sole inorganic N（urea）, followed by the application of N in mixture （urea ＋ organic sources）, while the control plots （no Napplied） ranked in the bottom. Among the six organic sources （three animal manures： poultry, sheepand cattle; three crop residues： onion, berseem and wheat）, application of N in the form of poultrymanure was superior in terms of higher YC and GY. When applying 120 kg/hm2 N source, 75% N fromurea ＋ 25% N from organic source resulted in higher YC and GY in 2011, while applying 50% N fromurea ＋ 50% N from organic sources caused higher YC and GY in 2012. Therefore, the combinedapplication of N sources in the form of urea ＋ organic source can produce good performances in termsof higher YC and GY of rice under rice-wheat cropping system.

Hole fertilization in the root zone facilitates maize yield and nitrogen utilization by mitigating potential N loss and improving mineral N accumulation

Reducing environmental impacts and improving N utilization are critical to ensuring food security in China.Although root-zone fertilization has been considered an effective strategy to improve nitrogen use efficiency (NUE),the effect of controlled-release urea (CRU) applied in conjunction with normal urea in this mode is unclear.Therefore,a 3-year field experiment was conducted using a no-N-added as a control and two fertilization modes (FF,furrow fertilization by manual trenching,i.e.,farmer fertilizer practice;HF:root-zone hole fertilization by point broadcast manually) at 210 kg N ha^(–1) (controlled-release:normal fertilizer=5:5),along with a 1-year in-situ microplot experiment.Maize yield,NUE and N loss were investigated under different fertilization modes.The results showed that compared with FF,HF improved the average yield and N recovery efficiency by 8.5 and 22.3%over three years,respectively.HF had a greater potential for application than FF treatment,which led to increases in dry matter accumulation,total N uptake,SPAD value and LAI.In addition,HF remarkably enhanced the accumulation of ^(15)N derived from fertilizer by 17.2%compared with FF,which in turn reduced the potential loss of^(15)N by 43.8%.HF increased the accumulation of N in the tillage layer of soils at harvest for potential use in the subsequent season relative to FF.Hence,HF could match the N requirement of summer maize,sustain yield,improve NUE and reduce environmental N loss simultaneously.Overall,root-zone hole fertilization with blended CRU and normal urea can represent an effective and promising practice to achieve environmental integrity and food security on the North China Plain,which deserves further application and investigation.

Synthesis of Urea by Ammonolysis of Propylene Carbonate

Studying urea formation by ammonolysis of propylene carbonate in a liquid phase showed that this process is two-stage, and proceeds through preferred formation of 2-hydroxypropyl carbamate, besides, the rate of the first stage is much higher than the rate of the second stage （urea formation）. With the aid of the HPLC and HPLC/MS methods found some other intermediate products and offered consecutive-parallel scheme of the process. The obtained results explain the composition of impurities obtained during the production of the 13C-urea for diagnostic breath tests.

秸秆还田及不同比例控失尿素对华北平原小麦产量及潮土性质影响

为探讨不同控失尿素比例和秸秆还田对华北平原小麦产量及潮土化学性质的影响,本研究以华北潮土区小麦-玉米轮作体系为研究对象,采用裂区试验设计,以秸秆还田为主区,控失尿素比例为副区。秸秆还田模式设秸秆全量还田(S1)、秸秆不还田(S0)2种;控失尿素比例设不施肥(CK)以及控失尿素占总施氮量比例为0、40%、70%和100%(LCU0、LCU40、LCU70、LCU100)5个处理。在作物收割后进行产量测定,并采集0~20 cm耕层土壤进行常规土壤养分含量测定。结果表明:与S0处理相比,S1处理显著提高土壤有机质和速效钾含量。控失尿素显著提高土壤硝态氮含量,其他土壤养分含量无显著变化。秸秆不还田条件下,施用化肥显著降低了土壤pH值。控失尿素比例为70%时土壤养分含量最高。秸秆还田对小麦产量及吸氮量无显著影响,控失尿素对小麦产量及吸氮量增加具有极显著影响。在所有处理中,S1-LCU40处理的籽粒和秸秆产量最高,籽粒产量达7009.26 kg·hm^(-2),秸秆产量达11361.38 kg·hm^(-2)。秸秆还田对土壤氮素依存率具有显著影响,不同比例控失尿素对氮素收获指数具有显著影响,对氮肥表观利用率、土壤氮素依存率具有极显著影响。控失尿素比例为40%或70%时氮素吸收利用指标较优。综上,在华北平原潮土区,秸秆还田与40%控失尿素比例配施可以显著提升土壤供氮能力,提高小麦产量和氮素吸收与利用指标,是较为适宜的管理措施,但其机理及长期效应还需进一步研究。

控失尿素对氮素利用率、土壤硝态氮含量及冬小麦增产效果的影响

为探索控失尿素的施用方法,发现控失尿素在施用中存在的问题,以冬小麦为试验对象,开展了田间小区试验,考察了不同施肥处理和施肥方式对冬小麦产量、氮素利用率和土壤硝态氮含量的影响。结果表明:施氮处理的冬小麦产量高于不施氮处理的,处理间差异极显著;氮素施用量和施肥方式相同时,控失尿素处理的冬小麦产量高于普通尿素处理的,处理间差异极显著;氮素施用量和肥料品种相同而施肥方式不同时,底施+追施的增产效果优于全底施的,处理间差异显著;控失尿素氮素施用量比普通尿素减少20%的条件下,冬小麦产量无显著性差异;与施用普通尿素的处理相比,施用控失尿素的处理不仅氮素利用率高,且均不同程度地降低了土壤中硝态氮的含量。施用控失尿素可以提高冬小麦的产量和氮素利用率,降低土壤中硝态氮的含量。

控释尿素与普通尿素配施对橡胶树叶片和胶乳养分及产量的影响

为了明确控释尿素与普通尿素配施在橡胶树上的应用效果,通过2年田间试验,研究了减氮条件下控释尿素与普通尿素不同比例配施对橡胶树产量、叶片和胶乳矿质养分及土壤氮含量的影响,为橡胶树栽培管理中合理施氮提供技术支撑。结果表明:控释尿素与普通尿素配施可提高橡胶树干胶产量和叶片氮含量,与常规施肥相比,橡胶树干胶产量增幅为16.28%~39.13%(2021年)和7.94%~9.69%(2022年),叶片氮含量增幅为10.54%~19.17%(2021年)和10.24%~21.50%(2022年),控释尿素与普通尿素配施处理叶片氮含量均处于正常值以上。控释尿素与普通尿素配施还能够增加胶园肥穴土壤碱解氮含量,较常规施肥增加了11.27%~80.36%。控释尿素与普通尿素配施比例为50∶50时,橡胶树干胶产量(2022年)、叶片氮含量(2021—2022年)和土壤碱解氮含量(2021—2022年)均显著高于常规施肥。综上所述,在本试验条件下,控释尿素与普通尿素配施比例为50∶50能够获得较高的干胶产量,可改善叶片营养状况,维持土壤氮水平,有利于实现橡胶树施肥管理的绿色协同增效。