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.

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.

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.

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).

Effects of reducing and postponing controlled-release urea application on soil nitrogen regulation and maize grain yield

Controlled-release urea(CRU-N)fertilizer application is a solution to improve the utilization rate of nitrogen(N),reduces economic costs and improves crop yields.It is significant to study the effects of release CRU-N reduction and the combined application of conventional urea on soil N control and the large-scale maize planting system.In this study,the effects of controlled-release nitrogen fertilizer reduction and postponement on soil nitrogen components,enzyme activities,and yields were investigated.Seven treatments were set up in this study,including no N fertilizer(CK),100%conventional urea(U),100%controlled-release urea(S),30%controlled-release urea(SU_(3/7)),50%controlled-release urea(SU_(5/5)),70%controlled-release urea(SU_(7/3))and Sodium Salt of Polyaspartic Acid(PASP)-N.The results showed that mixed CRU-N and urea increased yields and net benefits compared with conventional urea at the same application rate of N,and reduced N loss.The application of CRU-N at 70%for maize represented the best overall effects.Compared with U treatment,soil ammonium nitrogen(NH_(4)-N),soil nitrate-nitrogen(NO_(3)-N),and microbial biomass nitrogen(SMB-N)of CRU-N at 70%(SU_(7/3))increased by 35.00%,15.53%,and 25.04%.However,soil nitrate reductase(S-NR)and urease(S-UA)were the best in SU_(5/5) and significantly higher than other treatments.The applications of CRU-N would effectively increase soil N;CRU-N in 50%proportion can promote the maize root growth and improve the efficient utilization of N by soil microorganisms.Like the yields(9186.61 kg/hm^(2)),expertly in the proportion of 70%CRU-N(SU_(7/3))plays a vital role in a wheat-maize rotation system,which can potentially be used to improve the yields,nitrogen use efficiency,and net benefit with low N losses.In conclusion,using CRU-N fertilize effectively improves soil nitrogen,and various ratios of CRU-N can ensure the continuous release the nutrients during the growing period.And among the different proportions of CRU-N,it is optimal in SU_(7/3).

控释尿素不同施用条件下冬小麦产量和氮素利用效应

采用田间试验方法研究了控释尿素不同施用条件对冬小麦产量、氮素利用和经济效益的影响。试验共设7个处理,即CK(空白处理,不施氮肥)、100%PU10/0(普通尿素全量基施,N 240 kg·hm-2)、100%PU6/4(60%的普通尿素基施、40%的普通尿素于拔节期追施,N 240 kg·hm-2)、80%PU6/4(60%的普通尿素基施、40%的普通尿素于拔节期追施,N 192 kg·hm-2)、100%CRU(全量树脂包膜控释尿素基施,N 240 kg·hm-2)、80%CRU(80%树脂包膜控释尿素基施,N 192 kg·hm-2)和40%CRU+40%PU(40%树脂包膜控释尿素+40%的普通尿素基施,N 192 kg·hm-2)。结果表明,无论是产量效应还是氮素利用效应,树脂包膜控释尿素(CRU)处理总体优于普通尿素(PU)处理,尤其树脂包膜控释尿素和普通尿素配施(40%CRU+40%PU)效果最佳,以7 709 kg·hm-2的产量、36.44%的氮肥吸收利用率、15 946元·hm-2的相对净收入达到处理间最高水平。该处理在减少氮素投入量的情况下,不仅促进了冬小麦增产,而且显著提高了肥料的利用率,拥有较高的产投比。因此,树脂包膜控释尿素和普通尿素的配施处理(40%CRU+40%PU)是本试验条件下最优的氮肥处理。

树脂膜控释尿素及普通尿素配施对强筋小麦产量、品质和氮肥利用率的影响

为给小麦高产优质栽培中控释尿素的合理应用提供理论依据,以控释期90d的树脂膜控释尿素为材料,通过田间小区试验,研究了树脂膜控释尿素及普通尿素配施对强筋小麦产量、品质及氮肥利用率的影响。结果表明,与普通尿素(PU)全部底施相比,树脂膜控释尿素及普通尿素配施抑制剂处理均能显著提高小麦产量和氮肥利用率,增幅分别达5.6%～12.6%和32.4%～137.3%。与分次施用普通尿素相比,树脂膜控释尿素及普通尿素配施抑制剂处理使籽粒产量增加1.5%～8.2%;等氮量施用树脂膜控释尿素处理显著提高了籽粒蛋白质含量、沉降值及湿面筋含量;等氮量施用树脂膜控释尿素及普通尿素配施抑制剂处理显著提高了氮肥利用率,增幅达13.9%～42.6%。小麦籽粒产量、品质、土壤无机氮与氮肥利用率皆以树脂膜控释尿素70%+普通尿素30%处理最高,其中产量和氮肥利用率与其他施氮处理差异显著。

控释尿素养分速测及在田间土壤中氮素释放率研究

介绍了一种树脂包膜尿素工厂在线质检的养分速测方法,即,100℃快速浸提对二甲氨基苯甲醛分光光度法,建立了该方法与缓释肥料国家标准(GB/T23348-2009)中规定的25℃静水浸提凯氏定氮法测定结果之间的相关关系,验证了该速测方法预测计算肥料养分释放期的可行性;将控释尿素施用于田间土壤,实时监测土壤的温湿度状况,对比了控释尿素在25℃水与田间土壤中的氮素累积释放趋势。结果表明:(1)100℃浸提对二甲氨基苯甲醛分光光度法可以准确的预测树脂包膜尿素在25℃下的养分释放率和养分释放期。应用此法测定预测样品S1和S2的养分释放期的误差分别只有0.10d和1.75d,相对误差不超过2.3%。(2)控释尿素S1、S3分别在25℃水中与田间耕层土壤(75%相对含水量)中的氮素释放趋势基本一致。25℃静水与耕层土壤的温差(<5℃)较小,不足以引起肥料在两介质中氮素累积释放率的显著差异。

缓释尿素对马铃薯产量和肥料利用效率的影响

为明确缓释尿素在马铃薯上的施用效果,2009—2011年在马铃薯主产区武川县和察右中旗进行了马铃薯施用缓释尿素试验研究。结果表明,马铃薯施用氮肥均有显著的增产效果,施用缓释尿素比普通尿素增产5.7%~12.7%,平均为7.4%,以普通尿素配合缓释尿素基施产量最高。施用缓释尿素较普通尿素马铃薯的商品率提高2个百分点,单株块茎数增加0.2~0.6个,块茎单重增加6.5~7.2 g。施用缓释尿素氮肥的农学效率提高7.5~8.8 kg/kg,氮素（N）利用率提高11.4~15.9个百分点,可以显著提高氮肥施肥肥效,减少氮素损失。一次性基施缓释尿素75%施氮量与100%普通尿素基施效果相当,说明施用缓释尿素可以减少施氮量25%而基本不减产。

β-环糊精控释尿素对大白菜产质量与氮肥利用率的影响

为研究不同配比环糊精控释尿素对大白菜产量、品质和氮肥利用率的影响,用自行研制的β-环糊精控释尿素进行田间试验。结果表明,与尿素习惯用量相比,在尿素用量减半的情况下,环糊精控释尿素能显著提高大白菜产量、品质和氮肥利用率,效果最佳的环糊精与尿素配比为1∶1,在尿素用量相同的情况下,该处理可增产61.7%,硝酸盐含量降低8.1%,VC含量增加4.7%,还原性糖含量增加16.2%,氮肥当季利用率提高35.1%。

施氮深度和水分胁迫对藜麦幼苗生理及产量的影响

为了探讨藜麦应对施肥深度和水分胁迫的响应,该文以藜麦(Chenopodium quinoa)为材料,在盆栽条件下,设置3种施氮处理[D1(控释尿素施在0~8 cm深度)、D2(控释尿素施在8~16 cm深度)、D3(控释尿素施在16~24 cm深度)]和3种水分处理[W1(正常供水)、W2(中度干旱)、W3(重度干旱)],分析施氮深度和水分胁迫对藜麦幼苗生理及产量的影响。结果表明:(1)相同水分条件下,随着施肥深度的增加,藜麦生长指标(株高、茎粗、叶面积、地上部生物量、主根长、根系表面积、根系体积)、生理指标[超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性、过氧化氢酶(CAT)活性、可溶性糖含量、可溶性蛋白含量、叶绿素总量]和产量指标呈先升高后降低趋势。D2处理(适当的深施氮肥)均高于D1处理(浅层施氮)和D3处理(底层施氮)。(2)相同施氮深度条件下,随着干旱胁迫程度的增加,藜麦生长指标和产量指标呈逐渐降低的趋势,生理指标均呈先升高后降低的趋势。说明藜麦幼苗对水分需求明显,可通过增加抗氧化酶活性和渗透调节物质适应一定程度的干旱,生产实践中应注意苗期水分的供应,以促进生育后期产量的形成。综上可知,适宜的水氮管理(D2W1)可以促进藜麦的生长及生理特性,增强藜麦的抗旱能力,提高藜麦的产量。该研究结果为进一步研究藜麦的水肥管理、高产栽培提供参考。

Reducing nitrogen fertilization of intensive kiwifruit orchards decreases nitrate accumulation in soil without compromising crop production

Excessive nitrogen （N） fertilization of high value horticultural crops is a common problem that not only increases the cost to farmers, but also negatively affects crop growth and the environment. A three-year field experiment was conducted in an intensive kiwifruit orchard in Shaanxi Province, China to compare the effects of reduced N fertilization applied as urea （U）, and controlled release urea （CRU） on the N nutrition of kiwi vines, fruit yield and quality, and nitrate-N accumulation in the soil profile. The three treatments included a conventional N application rate （CF-U, 900 kg N ha-1 yr-1 as urea）, two reduced N fertilization treatments where the amount of N fertilizer applied as U and CRU was reduced by 25％ in 2013 and 2014, and by 45％ in 2015. The 25 and 45％ reduced N treatments had no adverse effects on the N concentrations in leaves and pruning branches and the fruit yield and quality of kiwi vines. However, they significantly enhanced the partial factor productivity of applied N （PFPN） and the economic benefits, and reduced nitrate accumulation in the 0-200 cm soil profile. The same benefits of reduced N fertilization were observed for both the U and CRU treatments, but the CRU treatment had the added benefit of decreasing the loss of nitrate through leaching. We concluded that the current level of N fertilization in kiwi orchards is very excessive, and reducing the N fertilizer rate by 25-45％ could not only guarantee fruit yield, but also reduce N accumulation and loss.

向日葵施用缓释尿素的效果及氮磷钾施肥效应研究

为了掌握向日葵施肥效应及施用缓释尿素的效果,在巴彦淖尔市五原县和赤峰市开展了食用向日葵田间肥料试验。研究结果表明,向日葵施用氮磷钾化肥均有增产效果,增产效果为氮肥>钾肥>磷肥。向日葵施用缓释尿素具有显著的增产效果,在河套灌区向日葵基施缓释尿素比普通尿素基施配合追施增产0.7个百分点,在燕山丘陵旱作区施用缓释尿素比普通尿素基施配合追施增产5.8%,同时施用缓释尿素氮素的农学效率有所增加。向日葵施用氮肥的农学效率平均为1.89 kg/kg;施用磷肥(P2O5)的农学效率平均为2.20 kg/kg;施用钾肥(K_2O)的农学效率平均为4.00 kg/kg。采用缓释尿素一次施用可以代替普通尿素基施加追施,而且缓释尿素一次施用的肥料利用率显著提高。缓释尿素一次施用向日葵的茎粗、盘径、单盘结实数、结实率、千粒重和籽仁率都有所增加。

Comparative effects of nitrogen application on growth and nitrogen use in a winter wheat/summer maize rotation system

The application of fertilizer in agricultural production has become universally common for achieving high crop yields and economic benefits, but it has potential impacts on food safety, energy crisis and environmental pollution. Optimal management of fertilization is thus necessary for maintaining sustainable agriculture. Two-year（2013–2015） field experiment was conducted, in Yangling（108°24′E, 34°20′N, and 521 m a.s.l.）, Shaanxi Province, China, to explore the effects of different nitrogen（N） applications on biomass accumulation, crop N uptake, nitrate N（NO_3~–-N） distribution, yield, and N use with a winter wheat/summer maize rotation system. The N applications consisted of conventional urea（U）（at 80（U80）, 160（U160）, and 240（U240） kg N ha^（–1）; 40% applied as a basal fertilizer and 60% top-dressed at jointing stage） and controlled-release urea（CRU）（at 60（C60）, 120（C120）, 180（C180）, and 240（C240） kg N ha~（^（–1））; all applied as a basal fertilizer） with no N application as a control（CK）. The continuous release of N from CRU matched well with the N demands of crop throughout entire growing stages. Soil NO_3~–-N content varied less and peaked shallower in CRU than that in urea treatments. The differences, however, were smaller in winter wheat than that in summer maize seasons. The average yield of summer maize was the highest in C120 in CRU treatments and in U160 in urea treatments, and apparent N use efficiency（NUE） and N agronomic efficiency（NAE） were higher in C120 than in U160 by averages of 22.67 and 41.91%, respectively. The average yield of winter wheat was the highest in C180 in CRU treatments and in U240 in urea treatments with C180 increasing NUE and NAE by averages of 14.89 and 35.62% over U240, respectively. The annual yields under the two N fertilizers were the highest in C120 and U160. The results suggested that CRU as a basal fertilizer once could be a promising alternative of urea as split application in semiarid areas.

旱地马铃薯氮磷钾肥效应及缓释尿素的效果

在内蒙古阴山北麓进行的旱作马铃薯施肥试验,结果表明：旱作马铃薯施用氮磷钾肥均有显著的增产效果,氮肥〉磷肥〉钾肥。缓释尿素与普通尿素配合施用增产效果更佳,单株结薯数、单薯重和商品率都有所提高。研究明确了旱作马铃薯施用氮磷钾肥的养分利用率分别为33.0%、16.5%和41.2%。缓释尿素与普通尿素配合施用氮素利用率提高4.4~4.8个百分点,缓释尿素与普通尿素配合施用促进了磷钾肥的养分利用率。