Water and nitrogen footprint assessment of integrated agronomic practice management in a summer maize cropping system

The footprints of water and nitrogen(WF and NF)provide a comprehensive overview of the type and quantity of water consumption and reactive nitrogen(Nr)loss in crop production.In this study,a field experiment over two years(2019 and 2020)compared three integrated agronomic practice management(IAPM)systems:An improved management system(T2),a high-yield production system(T3),and an integrated soil-crop management system(ISCM)using a local smallholder farmer’s practice system(T1)as control,to investigate the responses of WF,Nr losses,water use efficiency(WUE),and nitrogen use efficiency(NUE)to IAPM.The results showed that IAPM optimized water distribution and promoted water use by summer maize.The evapotranspiration over the whole maize growth period of IAPM increased,but yield increased more,leading to a significant increase in WUE.The WUE of the T2,T3,and ISCM treatments was significantly greater than in the T1 treatment,in 2019 and 2020respectively,by 19.8-21.5,31.8-40.6,and 34.4-44.6%.The lowest WF was found in the ISCM treatment,which was 31.0%lower than that of the T1 treatment.In addition,the ISCM treatment optimized soil total nitrogen(TN)distribution and significantly increased TN in the cultivated layer.Excessive nitrogen fertilizer was applied in treatment T3,producing the highest maize yield,and resulting in the highest Nr losses.In contrast,the ISCM treatment used a reduced nitrogen fertilizer rate,sacrificing grain yield partly,which reduced Nr losses and eventually led to a significant increase in nitrogen use efficiency and nitrogen recovery.The Nr level in the ISCM treatment was34.8%lower than in the T1 treatment while NUE was significantly higher than in the T1 treatment by 56.8-63.1%in2019 and 2020,respectively.Considering yield,WUE,NUE,WF,and NF together,ISCM should be used as a more sustainable and clean system for sustainable production of summer maize.

Integrated agronomic practice increases maize grain yield and nitrogen use efficiency under various soil fertility conditions

Crop yield potential can be increased through the use of appropriate agronomic practices. Integrated agronomic practice (IAP) is an effective way to increase maize (Zea mays L.) grain yield and nitrogen use efficiency (NUE);however, the physiological processes associated with gains in yield potential obtained from IAP, particularly the different under various soil fertility conditions, remain poorly understood. An IAP strategy including optimal planting density, split fertilizer application, and subsoiling tillage was evaluated over two growing seasons to determine whether the effects of IAP on maize yield and NUE differ under different levels of soil fertility. Compared to farmers' practices (FP), IAP increased maize grain yield in 2013 and 2014 by 25% and 28%, respectively, in low soil fertility (LSF) fields and by 36% and 37%, respectively, in high soil fertility (HSF) fields. The large yield gap was attributed mainly to greater dry matter (DM) and N accumulation with IAP than with FP owing to increased leaf area index (LAI) and DM accumulation rate, which were promoted by greater soil mineral N content (Nmin) and root length. Post-silking DM and N accumulation were also greater with IAP than with FP under HSF conditions, accounting for 60% and 43%, respectively, of total biomass and N accumulation;however, no significant differences were found for post-silking DM and N accumulation between IAP and FP under LSF conditions. Thus, the increase in grain yield with IAP was greater under HSF than under LSF. Because of greater grain yield and N uptake, IAP significantly increased N partial factor productivity, agronomic N efficiency, N recovery efficiency, and physiological efficiency of applied N compared to FP, particularly in the HSF fields. These results indicate that considerable further increases in yield and NUE can be obtained by increasing effective soil N content and maize root length to promote post-silking N and DM accumulation in maize planted at high plant density, especially in fields with low soil fertility.

Genome-Wide Association Study of Nitrogen Use Efficiency and Agronomic Traits in Upland Rice

Genome-wide association study(GWAS)was performed for 16 agronomic traits including nitrogen use efficiency(NUE)and yield-related components using a panel of 190 mainly japonica rice varieties and a set of 38390 single nucleotide polymorphism(SNP)markers.This panel was evaluated under rainfed upland conditions in Madagascar in two consecutive cropping seasons with two contrasted nitrogen input levels.Using another set of five grain traits,we identified previously known genes(GW5,GS3,Awn1 and Glabrous1),thus validating the pertinence and accuracy of our datasets for GWAS.A total of 369 significant associations were detected between SNPs and agronomic traits,gathered into 46 distinct haplotype groups and 28 isolated markers.Few association signals were identified for the complex quantitative trait NUE,however,larger number of quantitative trait loci(QTLs)were detected for its component traits,with 10 and 2 association signals for nitrogen utilization efficiency and nitrogen uptake efficiency,respectively.Several detected association signals co-localized with genes involved in nitrogen transport or nitrogen remobilization within 100 kb.The present study thus confirmed the potential of GWAS to identify candidate genes and new loci associated with agronomic traits.However,because of the quantitative and complex nature of NUE-related traits,GWAS might have not captured a large number of QTLs with limited effects.

Nitrogen recovery and agronomic efficiency of forages with nitrogen fertilization under flooded condition

The cow-calf (Bos taurus) industry in subtropical United States and other parts of the world that depends almost totally on grazed pastures is facing several production constraints like changing climatic conditions and increasing cost of fertilizers, especially nitrogen (N). Particularly little is known about the response of forage species to the combined effect of water-logging and the addition of N. A two-year greenhouse study was conducted in 2008 and 2009 to determine i) the effect of flooding duration on N recovery and agronomic efficiency of bahiagrass (Paspalum notatum Fluegge) compared with two flooding tolerant forages, limpograss (Hemarthria altissima Poir), and maidencane (Panicum hematomon Schult) and ii) if N fertilization could mitigate the negative effect of flooding. Nitrogen recovery and agronomic efficiency varied significantly (P ≤ 0.001) among forage species. Averaged across levels of N, N recovery of bahiagrass and limpograss was reduced by about 41% and 56%, respectively after 84 d of continued flooding while N recovery of maidencane was slightly increase by about 5% between 0 and 84 d of flooding. Agronomic efficiencies of bahiagrass (41% to 26%) and limpograss (44% to 31%) were reduced by flooding while agronomic efficiency of maidencane was increased from 24% (no flooding) to 46% at 84 d of continued flooding. However, N recovery and agronomic efficiency of three forage species was positively affected by N fertilization. The overall N recovery of bahiagrass, limpograss, and maidencane ranged from 44% to 59%. Nitrogen fertilization could improve N recovery and agronomic efficiency of forage species under waterlogged condition.

Nitrogen Use Efficiency as Affected by Phosphorus and Potassium in Long-Term Rice and Wheat Experiments

Improving nitrogen use efficiency （NUE） and decreasing N loss are critical to sustainable agriculture. The objective of this research was to investigate the effect of various fertilization regimes on yield, NUE, N agronomic efficiency （NAE） and N loss in long-term （16- or 24-yr） experiments carried out at three rice-wheat rotation sites （Chongqing, Suining and Wuchang） in subtropical China. Three treatments were examined： sole chemical N, N＋phosphorus （NP）, and NP＋potassium （NPK） fertilizations. Grain yields at three sites were significantly increased by 9.3-81.6% （rice） and 54.5-93.8% （wheat） under NP compared with N alone, 1.7-9.8% （rice） and 0-17.6% （wheat） with NPK compared with NP. Compared to NP, NUE significantly increased for wheat at Chongqing （9.3%） and Wuchang （11.8%）, but not at Suining, China. No changes in NUE were observed in rice between NP and NPK at all three sites. The rice-wheat rotation＇s NAE was 3.3 kg kg1 higher under NPK than under NP at Chongqing, while NAE was similar for NP and NPK at Suining and Wuchang. We estimated that an uptake increase of 1.0 kg N hal would increase 40 kg rice and 30 kg wheat ha-1. Nitrogen loss/input ratios were -60, -40 or -30% under N, NP or NPK at three sites, indicating significant decrease of N loss by P or PK additions. We attribute part of the increase in NUE soil N accumulation which significantly increased by 25-55 kg ha-1 yr1 under NPK at three sites, whereas by 35 kg ha-1 yr-1 under NP at Chongqing only. This paper illustrates that apply P and K to wheat, and reduce K application to rice is an effective nutrient management strategy for both the NUE improvement and N losses reduction in China.

Effects of nitrogen fertilization strategies on nitrogen use efficiency in physiology, recovery, and agronomy and redistribution of dry matter accumulation and nitrogen accumulation in two typical rice cultivars in Zhejiang, China

Field experiments were conducted in farmers’ rice fields in 2001 and 2002 to study the effects of nitrogen (N) man-agement strategies on N use efficiency in recovery (RE), agronomy (AE) and physiology (PE) and redistribution of dry matter accumulation (DMA) and nitrogen accumulation (NA) in two typical rice cultivars in Jinhua, Zhejiang Province. This study aimed mainly at identifying the possible causes of poor fertilizer N use efficiency (NUE) of rice in Zhejiang by comparing farmers’ fertilizer practice (FFP) with advanced site-specific nutrient management (SSNM) and real-time N management (RTNM). The results showed that compared to FFP, SSNM and RTNM reduced DMA and NA before panicle initiation and increased DMA and NA at post-flowering. There is no significant difference between SSNM and FFP in post-flowering dry matter redistribution (post-DMR) and post-flowering nitrogen redistribution (post-NR). These results suggest that high input rate of fertilizer N and improper fertilizer N timing are the main factors causing low NUE of irrigated rice in the farmer’s routine practice of Zhejiang. With SSNM, about 15% of the current total N input in direct-seeding early rice and 45% in single rice could be reduced without yield loss in Zhejiang, China.

Effect of Nitrogen Regimes on Grain Yield,Nitrogen Utilization,Radiation Use Efficiency,and Sheath Blight Disease Intensity in Super Hybrid Rice

Poor nitrogen use efficiency in rice production is a critical issue in China. Site-specific N managements （SSNM） such as real-time N management （RTNM） and fixed-time adjustable-dose N management （FTNM） improve fertilizer-N use efficiency of irrigated rice. This study was aimed to compare the different nitrogen （N） rates and application methods （FFP, SSNM, and RTNM methods） under with- and without-fungicide application conditions on grain yield, yield components, solar radiation use efficiency （RUE）, agronomic-nitrogen use efficiency （AEN）, and sheath blight disease intensity. Field experiments were carried out at Liuyang County, Hunan Province, China, during 2006 and 2007. A super hybrid rice Liangyou 293 （LY293） was used as experimental material. The results showed that RTNM and SSNM have great potential for improving agronomic-nitrogen use efficiency without sacrificing the grain yield. There were significant differences in light interception rate, sheath blight disease incidence （DI） and the disease index （ShBI）, and total dry matter among the different nitrogen management methods. The radiation use efficiency was increased in a certain level of applied N. But, the harvest index （HI） decreased with the increase in applied N. There is a quadratic curve relationship between grain yield and applied N rates. With the same N fertilizer rate, different fertilizer-N application methods affected the RUE and grain yield. The fungicide application not only improved the canopy light interception rate, RUE, grain filling, and harvest index, but also reduced the degree of sheath blight disease. The treatment of RTNM under the SPAD threshold value 40 obtained the highest yield. While the treatment of SSNM led to the highest nitrogen agronomic efficiency and higher rice yield, and decreased the infestation of sheath blight disease dramatically as well. Nitrogen application regimes and diseases control in rice caused obvious effects on light interception rate, RUE, and HI. Optimal N rate is helpful to get higher light interception rate, RUE, and HI. Disease control with fungicide application decreased and delayed the negative effects of the high N on rice yield formation. SSNM and RTNM under the proper SPAD threshold value obtained high-yield with high efficiency and could alleviate environmental pollution in rice production.

氮水平对苦荞生长发育及氮素吸收利用的影响

为提高西北干旱地区的苦荞产量、减少氮肥施用及提高氮肥利用效率,以适宜西北地区种植的川荞2号(CQ2)和晋荞2号(JQ2)为材料,设置4个施氮水平(0、60、120和180 kg·hm^(-2)),研究氮对苦荞生长、产量及氮素利用的影响。结果表明,随施氮量的增加,苦荞氮肥偏生产力和农学利用效率显著降低,SPAD值、干物质积累量、氮素积累量和每吨籽粒氮需要量逐步增加,而农艺指标、产量及其构成、氮肥表观利用率和氮收获指数均呈先升后降趋势,均以120 kg·hm^(-2)施氮量最高。60、120和180 kg·hm^(-2)施氮量处理下,JQ2的株粒数、有效株数和产量较CQ2平均增加6.2%、6.1%和18.2%,且其氮素吸收利用和收获指数更高,表现出更强的增产性和氮素利用能力。相关性和聚类分析发现,施氮对苦荞各指标的影响可被明显区分,苦荞的氮肥农学利用效率、氮肥偏生产力和氮收获指数与苦荞产量及构成呈极显著正相关。综合考虑氮素吸收利用效率及成本与产量因素,西北干旱地区苦荞氮施用量以120 kg·hm^(-2)为宜,品种以JQ2较为适宜。本研究结果对苦荞的高效生产及生态环境的保护具有重要的理论与实际意义。

高粱杂交种氮高效利用综合评价

为从华北、东北高粱主产区筛选出适应当地生态条件、氮利用效率更高的优质高产高粱品种,以20份国内主推高粱品种为试验材料,采用裂区试验设计,研究供试品种在不同地点的氮肥农学效率和氮肥偏生产力表现。本研究旨在筛选出适宜当地生产的氮高效高粱品种。研究结果表明:基于粱氮素农学利用率和偏生产力,将20个高粱品种分为氮高效型、氮中效型和氮低效型3类,与氮中效型和低效型品种相比,氮高效型品种具有较高的产量。聚类分析表明,在东阳地区试验中,‘晋杂34’、‘辽糯11’、‘吉杂124’、‘晋早5564’和‘金糯粮5’在2年均为氮高效型品种,其中以‘晋杂34’表现最好。在哈尔滨地区试验中,‘龙杂22’、‘龙杂25’、‘沈杂5号’、‘冀酿3号’、‘凤杂4’、‘吉杂124’、‘吉杂127’、‘辽杂37’、‘晋早5564’、‘通杂108’和‘赤杂107’在2年均为氮高效型品种,其中以‘龙杂25’表现最好。因此,东阳地区较为适宜种植的氮高效品种为‘晋杂34’,哈尔滨地区较为适宜种植的氮高效品种为‘龙杂25’。

推荐施肥量下控释肥替代普通尿素提高高粱产量和氮肥生产力

【目的】高粱生产中氮肥施用不合理,氮肥利用效率低,研究适宜重庆地区高粱种植的控释氮肥减施比例,在减少氮肥用量的同时,确保高粱稳产高产,提高肥料利用效率。【方法】田间定位试验于2021、2022年在重庆永川进行,供试高粱品种为晋渝糯3号和金糯粱1号。设置6个处理,分别为不施氮肥(CK);习惯尿素施肥量(U,N 180 kg/hm^(2));尿素推荐施用量(U1,减N 20%,N 144 kg/hm^(2));控释氮肥减施氮量20%(C1,N144 kg/hm^(2));控释氮肥减施氮量30%(C2,N 126 kg/hm^(2));控释氮肥减施氮量40%(C3,N 108 kg/hm^(2))。在高粱开花期和成熟期,调查干物质积累量和转运量,成熟期调查植株和籽粒氮素含量、生物量、产量及产量构成因素。【结果】开花期和成熟期高粱干物质积累量均以C1和U1处理最高,C1处理成熟期干物质积累量又显著高于U1。C1处理叶片花前干物质转运量显著高于U。花后干物质积累量C1处理显著高于其他处理,U1和C2处理显著高于U处理。C1处理晋渝糯3号和金糯粱1号花后干物质积累量对籽粒的贡献率较U分别显著提高了11.54%和12.41%。C1处理的高粱产量最高(晋渝糯3号6611 kg/hm^(2),金糯粱1号5690 kg/hm^(2)),较其他施氮处理显著提高了5.40%~18.66%;其次为C2和U1处理,二者的产量均显著高于U和C3处理。各施氮处理的氮肥生理利用率(NPE)差异不显著;减氮处理间氮肥农学利用率(NAE)无显著差异,氮肥偏生产力(NPFP)差异显著,其NAE和NPFP均显著高于习惯施氮处理U;控释肥各减氮处理的NPFP显著高于普通氮肥推荐量处理U1。C1处理较U处理大幅提高了NAE、NPFP和氮肥利用率(NUE),晋渝糯3号分别提高了58.54%、39.61%和59.28%,金糯粱1号分别提高了80.97%、48.30%和63.08%;与U1处理相比,晋渝糯3号的NPFP、NUE分别提高了5.38%和22.19%,金糯粱1号分别提高了5.82%和4.42%。【结论】推荐施氮量下,用控释肥替代普通氮肥增加了高粱开花期和成熟期干物质积累量,提高了叶片花前干物质转运量和花后干物质积累量及其对籽粒的贡献率,提升了高粱产量和氮肥利用效率,可作为西南地区高粱生产的推荐氮肥施用方式。

氮素水平对雪茄烟苗期干物质积累及氮素营养的影响

【目的】探明氮营养水平对雪茄烟幼苗生长及氮素吸收利用的影响,为提升雪茄烟产质量提供依据。【方法】以2个雪茄烟品种(云雪38、云雪39)为供试材料,采用营养液培养法,比较缺氮(N_(0))、正常供氮(210 mg/L,N_(1))、超量供氮(420 mg/L,N_(2))对雪茄烟幼苗生长状况、干物质积累及氮素吸收利用的影响。【结果】缺氮和超量供氮烟苗均表现出典型症状,正常供氮处理在生长指标及长势长相方面均明显优于其他处理;正常供氮干物质积累量均不同程度高于缺氮和超量供氮处理,且云雪39干物质积累速率整体上均高于云雪38;超量供氮烟苗总氮积累量高于其他处理,且云雪39总氮积累量整体高于云雪38;正常供氮处理烟苗氮利用效率均显著高于超量供氮处理,且云雪39较云雪38对施氮量的响应更敏感。【结论】缺氮和超量供氮条件下,烟苗干物质积累及氮积累均受到不同程度抑制,正常供氮水平(210 mg/L)有效促进烟苗生长发育、干物质积累及氮素利用效率,不同雪茄烟品种对氮素供应水平的响应存在差异。

沼液不同施用量对水芹生长发育与田面水氮素排放的影响

【目的】探明沼液不同施用量对水芹生长发育与田面水氮素排放的影响,筛选适宜的沼液量与化肥配比,为化肥减量和沼液的资源化利用提供参考。【方法】以宜兴实心芹为研究对象,采用盆栽试验,研究不施肥(CK)、常规施肥(N_(0))、沼液50%替代化肥(N_(50))和沼液100%替代化肥(N_(100))对水芹生长发育、田面水总氮和铵态氮浓度及氮素利用率的影响。【结果】不同施肥处理水芹的生长状况、营养品质、田面水的总氮和铵态氮浓度及氮素利用率不同。沼液50%替代化肥处理可显著提高水芹茎鲜重、叶鲜重、地上部鲜重和株高,分别为46.68 g/Pot、16.20 g/Pot、64.23 g/Pot和49.53 cm;增加茎部和叶部的总叶绿素、类胡萝卜素、维生素C含量,分别为0.21 mg/g FW、0.03 mg/g FW、2.61 mg/100g FW和2.02 mg/g FW、0.31 mg/g FW、28.08 mg/100g FW;硝酸盐含量较常规施肥处理分别显著降低30.52%和48.77%;同时降低了水芹田面水总氮和铵态氮浓度,经2次追肥后分别在11 d和23 d达峰值,为113.14 mg/L和38.49 mg/L;氮肥偏生产力和农学效率均达最大,分别为53.53 kg/kg和12.37 kg/kg。【结论】采用沼液50%替代化肥施用有利于促进水芹生长,提高营养品质,同时降低由降雨等引发的氮素排放风险,可在水芹种植上推广应用。

不同水肥模式对机插稻产量形成和氮肥吸收利用的影响

为阐明机插稻返青活棵-分蘖期不同水肥管理方式对其产量形成和氮肥吸收利用的影响,并提出机插稻返青活棵-分蘖期适宜的水肥管理模式,于2022年以南粳9108和南粳5718为供试品种,在返青活棵-分蘖期设置不同水肥管理方式(水稻返青活棵期多次水分灌排与分蘖期增施氮肥(T1)、水稻返青活棵期多次水分灌排与分蘖期不增施氮肥(T2)、水稻返青活棵期减少灌水不排水且分蘖期不增施氮肥(T3)),对比分析不同水肥管理方式下水稻产量形成和氮肥吸收利用的差异。结果表明,返青活棵-分蘖期不同水肥管理方式对机插稻产量和氮肥吸收利用影响显著。相较于T2处理,T1和T3处理显著增加了水稻产量和氮素积累量,产量分别提高8.2%~9.5%和13.3%~13.7%,成熟期氮素积累量分别提高7.0%~8.8%和12.8%~15.2%(p<0.05)。相较于T1处理,T3处理水稻拔节期茎蘖数降低11.4%~11.9%,茎蘖成穗率显著提高11.3%~12.4%,拔节期叶面积指数和干生物量分别显著降低8.2%~9.3%和6.3%~8.6%,抽穗期-成熟期光合势和群体生长率无显著差异。在产量及其构成因素方面,T1和T3处理间无显著差异(p>0.05)。在氮素吸收利用方面,T1和T3处理在氮素积累量方面无显著差异,但T3处理氮肥农学利用率和氮肥回收利用率较T1分别显著增加20.1%~22.2%和22.7%~23.0%(p<0.05)。综上所述,在分蘖期不增施氮肥的基础上,通过返青活棵期减少灌水和不排水的方式可以实现机插稻产量和氮肥利用率的同步提升。

基于APSIM的内蒙古突泉春玉米水氮管理措施

水分和氮肥是制约旱地农业生产的重要因素。基于2013—2022年内蒙古自治区突泉春玉米发育期、单产和田间管理数据,对农业生产系统模型(agricultural production system simulator,APSIM)调参验证;基于验证后的模型,结合1981—2022年突泉气象数据,设计不同水分亏缺程度下水氮管理情景,以春玉米单产、水氮用量和效率为指标,提出春玉米最优水氮管理措施,并分析不同降水年型下春玉米适宜灌溉量和施氮量。结果表明:APSIM对春玉米出苗-开花日数、出苗-成熟日数和单产模拟值与实测值的归一化均方根误差分别为1.3%、1.2%和2.8%,APSIM可定量模拟春玉米发育期和单产。综合春玉米单产、灌溉量、施氮量、水分生产力和氮肥农学效率,最优管理措施为0~100 cm土壤剖面深度下水分亏缺程度为60%时补充灌溉,灌溉量为171.0 mm,施氮量为197.8 kg·hm^(-2)。当春玉米生长季降水量为200~400、401~600 mm和601~800 mm时,适宜的灌溉量分别为233.0~283.5、110.5~148.4 mm和125.0~155.0 mm,施氮量分别为176.9~219.3、218.3~241.5 kg·hm^(-2)和211.8~249.9 kg·hm^(-2)。

不同种植密度与氮肥互作对红花产量及品质的影响

为明确引黄灌区红花(Carthamus tinctorius)最佳种植密度和适宜氮肥施用量,本试验选用红花‘甘红1号’为试验材料,采用裂区设计,主区为施氮量,副区为种植密度,设3个施N水平(45、90、135 kg·hm^(-2))和4个种植密度(株行距分别为30 cm×60 cm、25 cm×60 cm、25 cm×50 cm、27 cm×40 cm),研究不同施氮量和种植密度对红花产量品质及氮素吸收利用的影响。结果表明,施氮量和种植密度显著影响红花产量品质及氮素利用,农艺性状、产量性状及氮素积累量随着两者的增加呈先增大后降低的趋势。籽粒产量、羟基红花黄色素A (HSYA)、氮素积累量、氮肥表观利用率和氮肥农学利用率受交互作用影响显著,干花产量对种植密度反应敏感。其中,施氮量90 kg·hm^(-2)、株行距25 cm×50 cm条件下,HSYA含量最高,其余指标在施氮量90 kg·hm^(-2)、株行距25 cm×60 cm条件下趋于最大。综合考虑产量、品质、氮素利用协同提高,在引黄灌区红花种植最佳施氮量为90 kg·hm^(-2),种植密度以株行距25 cm×50 cm或25 cm×60 cm为宜。

功能性缓释掺混肥料对玉米产量及土壤氮含量的影响

根据玉米需肥规律开发了功能性缓释掺混肥,为考察其对玉米生长及土壤氮素含量的影响,开展了田间小区试验。试验共设6个处理,以不施肥(CK1)、普通掺混肥(CK2)处理为对照,调查了玉米生物学性状、产量以及玉米收获后土壤中硝态氮、铵态氮、碱解氮含量等指标。结果表明:在等施肥量条件下,功能性缓释掺混肥处理的玉米产量比CK2处理的增产7.98%,差异显著;在功能性缓释掺混肥施用量减少20%的条件下,不会造成玉米减产;功能性缓释掺混肥处理的氮素农学利用率比CK2处理的提高7.98%~26.82%;在等施肥量条件下,功能性缓释掺混肥处理的0~20 cm土层中硝态氮和碱解氮含量比CK2处理的分别提高了10.34%和17.39%,铵态氮含量降低了14.29%。

不同缓释肥料用量及运筹方式对杂交晚稻农艺性状及产量的影响

为筛选出适合晚稻生产的肥料运筹方式,减少肥料成本、增加经济效益,以籼粳杂交晚稻甬优7850为试验材料,研究不同缓释肥料用量及运筹方式对产量、农艺性状及氮素效率的影响。结果表明,等养分处理下,有机无机缓释肥有利于提高有效穗、每穗粒数,667 m^(2)基肥使用30 kg加适量分蘖肥较常规施肥增产4.80%,氮肥农学效率最高;等成本情况下,缓释肥处理氮素减少,产量仍较常规施肥增加1.53%,且氮肥农学效率明显高于常规施肥。双季晚稻有机无机缓释肥以667 m^(2)基肥用量30 kg、总氮量在10.7~12.0 kg为宜。

Effects of Combined Application of Inorganic Fertilizer and Organic Manures on Nitrogen Use and Recovery Efficiencies of Hybrid Rice (Palethwe-1)

We conducted two field experiments to investigate combined effects of organic and inorganic fertilizers on nitrogen use and recovery efficiencies of hybrid rice (Palethwe-1) during dry and wet seasons, 2015. Four levels of inorganic fertilizer (0%, 50%, 75%, and 100% NPK), based on recommended rates of 150 kg N ha-1, 70 kg P2O5 ha-1, and 120 kg K2O ha-1, were used with cow manure, poultry manure, and vermicompost (5 t·ha-1each) in a split-plot design with three replicates. In both seasons, with 50% NPK, the N uptake level achieved with poultry manure was similar to that obtained with 75% and 100% NPK. The greatest N use, internal, agronomic N use, and recovery efficiencies were obtained with 50% NPK + poultry manure, but were similar to those obtained from cow manure and vermicompost subplots. As the amount of applied N from organic and inorganic fertilizer increased, the N use efficiency and related parameters decreased, due to similar yields among plots with different NPK application levels. Poultry manure resulted in the highest significant correlations between applied N and N accumulation, followed by cow manure and vermicompost, in both seasons. Neither chemical fertilizer nor organic manure alone led to optimum N use and N recovery efficiencies. The combination of 50% inorganic fertilizer (75 kg N ha-1) and poultry manure (5 t·ha-1) enhanced the N uptake, the N use and recovery efficiencies of hybrid rice. Cow manure (5 t·ha-1) in combination with 75% inorganic fertilizer (112.5 kg N ha-1) was an adequate substitute for reduced chemical fertilizer usage. Therefore, this study highlighted combined application of inorganic fertilizers and organic manures had the benefits not only in reducing the need for chemical fertilizers but also in improving N uptake by hybrid rice (Palethwe-1) leading to the better environment.

氮素形态配比对设施基质栽培番茄产量及品质的影响

采用槽栽方式,以罗拉为试材,设置10个硝态氮、铵态氮、酰胺态氮配比处理,研究不同氮素形态配比对设施基质栽培番茄叶片酶活性、果实品质、产量及氮素农学效率的影响。结果表明:除T5处理外,各氮素形态配比处理的番茄叶片硝酸还原酶(NR)、谷氨酰胺合成酶(GS)活性均高于对照,T1处理NR活性最高为53.26μg·h^(-1)·g^(-1),比对照提高了23.48%。适宜氮素形态配比可以改善番茄果实品质,提高产量及氮素农学效率,其中产量以T5处理最高,达197151.90 kg·hm^(-2),比对照增产25.23%。综合考虑各指标,本试验条件下T5处理,即硝态氮∶铵态氮∶酰胺态氮为1∶3∶5表现较佳,番茄产量最高,果实品质较好。

氮高效甜瓜种质资源的筛选与评价

[目的]挖掘和筛选耐低氮、氮高效的甜瓜种质资源,提高甜瓜的氮效率。[方法]以59个甜瓜品种(系)为供试材料,采用田间试验进行施氮(CK,200 kg/hm^(2))与不施氮(LN,0 kg/hm^(2))处理,对甜瓜成熟期主要农艺性状、产量、氮吸收与利用等相关性状进行分析,研究不同甜瓜品种(系)间产量、氮素积累量及氮素生理利用率间的差异及相关性。[结果]施氮处理下不同甜瓜品种(系)果实纵径、果实横径、果肉厚、果形指数、单瓜重、叶干重、茎干重、果干重、植株干重等主要农艺性状的变异幅度为15.79%~22.96%,不施氮处理不同甜瓜品种(系)主要农艺性状的变异幅度为18.16%~30.93%;施氮处理下不同甜瓜品种(系)叶氮含量、茎氮含量、果氮含量、叶氮积累量、茎氮积累量、果氮积累量、植株氮积累量及氮生理利用率等氮吸收与利用相关性状的变异系数变化幅度为14.69%~26.00%,不施氮处理不同甜瓜品种(系)氮吸收与利用相关性状的变异系数变化幅度为16.40%~39.44%,不施氮处理甜瓜的主要农艺性状、氮吸收与利用相关性状的变异系数明显大于施氮处理,表明不同甜瓜品种(系)在耐低氮方面存在显著的遗传差异性,且氮素供应不足时更容易鉴别不同甜瓜品种(系)的耐低氮能力。相关分析表明,2种施氮水平下,甜瓜产量与果实纵径、果实横径、果实肉厚、果形指数、单瓜重、叶干重、茎干重、果干重、植株干重、叶氮积累量、茎氮积累量、果氮积累量、植株氮积累量均呈显著或极显著正相关。基于2种氮水平下的产量差异将不同甜瓜品种(系)耐低氮能力划分为4类,分别为双高效型、低氮高效型、高氮高效型和双低效型;2种氮水平下,4类氮效率品种间的产量、植株干重、植株氮积累量和氮生理利用率差异均达到极显著水平。[结论]双高效型和低氮高效型甜瓜对氮肥反应不敏感,在氮素供应不足时亦能吸收利用更多的氮素,获得较高的产量,适合低氮条件下种植,属于耐低氮型。