Evaluation of Pathway of Nitrogen Loss in Winter Wheat and Summer Maize Rotation System

The nitrogen loss pathway in winter wheat and summer maize rotation system was studied based on field experimental data. The results showed that nitrogen recovery rate was significantly decreased with nitrogen fertilization rate increased, while residual rate and losses rate had an increasing trend. Accumulated ammonia volatilization loss in winter wheat and summer maize rotation was 12. 8(N0), 22.0(N120), 33. 0(N240) and 64. 5 kg N ha-1 (N360) respectively and rate of ammonia volatilization loss was 3.8, 4.2 and 7.2% respectively while urea was mixed with 0 -10 cm soil or spread before irrigation. Denitrification loss with acetylene-soil core incubation method in winter wheat was lower than 1 kg N ha-1 and rate of denitrification loss was 0. 21 - 0. 26% or trace. Denitrification loss in summer maize was 1 - 14 kg N ha-1 and rate of denitrification loss was 1-5%. The total gaseous loss in winter wheat and summer maize rotation system was less than 10%, and the main nitrogen fertilizer loss way was leaching below 0 - 100 cm soil profile and accumulated in deeper soil.

Identifying the critical phosphorus balance for optimizing phosphorus input and regulating soil phosphorus effectiveness in a typical winter wheat-summer maize rotation system in North China

Phosphorus(P)is a nonrenewable resource and a critical element for plant growth that plays an important role in improving crop yield.Excessive P fertilizer application is widespread in agricultural production,which not only wastes phosphate resources but also causes P accumulation and groundwater pollution.Here,we hypothesized that the apparent P balance of a crop system could be used as an indicator for identifying the critical P input in order to obtain a high yield with high phosphorus use efficiency(PUE).A 12-year field experiment with P fertilization rates of 0,45,90,135,180,and 225 kg P_(2)O_(5)ha^(-1)was conducted to determine the crop yield,PUE,and soil Olsen-P value response to P balance,and to optimize the P input.Annual yield stagnation occurred when the P fertilizer application exceeded a certain level,and high yield and PUE levels were achieved with annual P fertilizer application rates of 90-135 kg P_(2)O_(5)ha^(-1).A critical P balance range of 2.15-4.45 kg P ha^(-1)was recommended to achieve optimum yield with minimal environmental risk.The critical P input range estimated from the P balance was 95.7-101 kg P_(2)O_(5)ha^(-1),which improved relative yield(>90%)and PUE(90.0-94.9%).In addition,the P input-output balance helps in assessing future changes in Olsen-P values,which increased by 4.07 mg kg^(-1)of P for every 100 kg of P surplus.Overall,the P balance can be used as a critical indicator for P management in agriculture,providing a robust reference for limiting P excess and developing a more productive,efficient and environmentally friendly P fertilizer management strategy.

Effects of saline irrigation on soil salt accumulation and grain yield in the winter wheat-summer maize double cropping system in the low plain of North China

In the dominant winter wheat （WW）-summer maize （SM） double cropping system in the low plain located in the North China, limited access to fresh water, especially during dry season, constitutes a major obstacle to realize high crop productivity. Using the vast water resources of the saline upper aquifer for irrigation during WW jointing stage, may help to bridge the peak of dry season and relieve the tight water situation in the region. A field experiment was conducted during 2009-2012 to investigate the effects of saline irrigation during WW jointing stage on soil salt accumulation and productivity of WW and SM. The experiment treatments comprised no irrigation （T1）, fresh water irrigation （T2）, slightly saline water irrigation （T3：2.8 dS m-l）, and strongly saline water irrigation （T4：8.2 dS m-1） at WW jointing stage. With regard to WW yields and aggregated annual WW-SM yields, clear benefits of saline water irrigation （T3 ＆ T4） compared to no irrigation （T1）, as well as insignificant yield losses compared to fresh water irrigation （T2） occurred in all three experiment years. However, the increased soil salinity in eady SM season in consequence of saline irrigation exerted a negative effect on SM photosynthesis and final yield in two of three experiment years. To avoid the negative aftereffects of saline irrigation, sufficient fresh water irrigation during SM sowing phase （i.e., increase from 60 to 90 mm） is recommended to guarantee good growth conditions during the sensitive early growing period of SM. The risk of long-term accumulation of salts as a result of saline irrigation during the peak of dry season is considered low, due to deep leaching of salts during regularly occurring wet years, as demonstrated in the 2012 experiment year. Thus, applying saline water irrigation at jointing stage of WW and fresh water at sowing of SM is most promising to realize high yield and fresh irrigation water saving.

Water consumption in summer maize and winter wheat cropping system based on SEBAL model in Huang-Huai-Hai Plain, China

Crop consumptive water use is recognized as a key element to understand regional water management performance. This study documents an attempt to apply a regional evapotranspiration model（SEBAL） and crop information for assessment of regional crop（summer maize and winter wheat） actual evapotranspiration（ET a） in Huang-Huai-Hai（3H） Plain, China. The average seasonal ET a of summer maize and winter wheat were 354.8 and 521.5 mm respectively in 3H Plain. A high-ET a belt of summer maize occurs in piedmont plain, while a low ET a area was found in the hill-irrigable land and dry land area. For winter wheat, a high-ET a area was located in the middle part of 3H Plain, including low plain-hydropenia irrigable land and dry land, hill-irrigable land and dry land, and basin-irrigable land and dry land. Spatial analysis demonstrated a linear relationship between crop ET a, normalized difference vegetation index（NDVI）, and the land surface temperature（LST）. A stronger relationship between ET a and NDVI was found in the metaphase and last phase than other crop growing phase, as indicated by higher correlation coefficient values. Additionally, higher correlation coefficients were detected between ET a and LST than that between ET a and NDVI, and this significant relationship ran through the entire crop growing season. ET a in the summer maize growing season showed a significant relationship with longitude, while ET a in the winter wheat growing season showed a significant relationship with latitude. The results of this study will serve as baseline information for water resources management of 3H Plain.

Effects of mulches on water use in a winter wheat/summer maize rotation system in Loess Plateau, China

Limited water resources often result in reduced crop yield and low water productivity（WP）. In northwestern China, crop production is generally dependent on precipitation. Therefore, a variety of agricultural rainwater harvesting（ARH） techniques have been used for conserving soil moisture, ameliorating soil environment, increasing crop yield, and improving water use efficiency. A two-year（2013–2015） field experiment was conducted under a typical sub-humid drought-prone climate in Yangling（108°24′E, 34°20′N; 521 m a.s.l.）, Shaanxi Province, China, to explore the effects of mulching（same for summer maize and winter wheat） on soil moisture, soil temperature, crop water consumption, and crop yield with a winter wheat/summer maize rotation. Crops were planted in a ridge-furrow pattern and the treatments consisted of a transparent film mulch over the ridges（M1）, a crop straw mulch in the furrows（M2）, a transparent film mulch over the ridges and a crop straw mulch in the furrows（M3）, a black film mulch over the ridges and a crop straw mulch in the furrows（M4）, and a control with no mulch（CK）. Results showed that M4 was the best treatment for improving soil water storage and content, and decreasing crop water consumption during the summer maize and winter wheat rotation. In both maize and wheat seasons, M1 had a higher soil temperature than M2 and CK, and M3 had a higher soil temperature than M4. In the maize seasons, M4 had the highest yield, WP, and precipitation productivity（PP）, with the average values for these parameters increasing by 30.9%, 39.0%, and 31.0%, respectively, compared to those in CK. In the wheat seasons, however, M3 had the highest yield, WP, and PP, with the average values for these parameters being 23.7%, 26.7%, and 23.8% higher, respectively, than those in CK. Annual yield（maize and wheat yields combined） and WP did not differ significantly between M3 and M4. These results suggested that M3 and M4 may thus be the optimal ARH practices for the production of winter wheat and summer maize, respectively, in arid and semi-arid areas.

Study on Soil Denitrification in Wheat-Maize Rotation System

Soil denitrification was studied in wheat-maize rotation cropping system on an aquic cambisol. Results showed that the N loss amount by denitrification ranged from 4.7 to 9.7 kg per hectare with different levels of nitrogen application and the key stage for denitification was during summer maize-growth-period, especially within 1-2 weeks after fertilizer nitrogen was applied. Similar trend was found between soil N2O production/emission dynamic and denitrification dynamic in the rotation system, which may indicate that mainly N2O is produced in nitrification process.

基于Landsat 8影像提取豫中地区冬小麦和夏玉米分布信息的最佳时相选择

遥感技术对大尺度农业实时监测提供了一个理想的手段,遥感影像植被分类的最佳时相对作物种植面积遥感监测非常重要。本文选取2020年至2021年的6景Landsat 8影像,覆盖了夏玉米从乳熟到收获、冬小麦从越冬到成熟的生育期,以此分析不同时相的冬小麦-夏玉米与其他地类在光谱特征和NDVI上的差异,通过决策树的方法提取豫中地区冬小麦-夏玉米的空间分布情况。结果表明,冬小麦-夏玉米在不同生长发育时期,提取到的面积比有所不同,对于夏玉米而言,乳熟时期的提取效果要优于之后的时期,其在2020年8月26日的总体精度最高,为83.60%,Kappa系数为0.72,分类质量很好;对于冬小麦而言,最佳识别时期则处于冬小麦的越冬期,其在2021年1月1日的总体精度最高,为92.36%,Kappa系数为0.81,信息提取效果很好。除了作物自身生长过程的覆盖度变化,分类精度随成像时间而改变。多时相信息提取也发现,受到天气等环境条件限制,夏玉米和冬小麦的种植区域不完全重叠,山区冬季不适合冬小麦种植从而没有与夏玉米出现重叠分布。本研究有助于我们从宏观上对作物分布及生长状况作出及时有效的判断,对农业监测,特别是对轮作农田的信息管理和作物物候、种植面积等研究具有广阔的应用前景。

Significant reduction of ammonia emissions while increasing crop yields using the 4R nutrient stewardship in an intensive cropping system

Ammonia (NH_3) emissions should be mitigated to improve environmental quality.Croplands are one of the largest NH_3sources,they must be managed properly to reduce their emissions while achieving the target yields.Herein,we report the NH_3 emissions,crop yield and changes in soil fertility in a long-term trial with various fertilization regimes,to explore whether NH_3 emissions can be significantly reduced using the 4R nutrient stewardship (4Rs),and its interaction with the organic amendments (i.e.,manure and straw) in a wheat–maize rotation.Implementing the 4Rs significantly reduced NH_3 emissions to 6 kg N ha~(–1) yr~(–1) and the emission factor to 1.72%,without compromising grain yield (12.37 Mg ha~(–1) yr~(–1))and soil fertility (soil organic carbon of 7.58 g kg~(–1)) compared to the conventional chemical N management.When using the 4R plus manure,NH_3 emissions (7 kg N ha~(–1) yr~(–1)) and the emission factor (1.74%) were as low as 4Rs,and grain yield and soil organic carbon increased to 14.79 Mg ha~(–1) yr~(–1) and 10.09 g kg~(–1),respectively.Partial manure substitution not only significantly reduced NH_3 emissions but also increased crop yields and improved soil fertility,compared to conventional chemical N management.Straw return exerted a minor effect on NH_3 emissions.These results highlight that 4R plus manure,which couples nitrogen and carbon management can help achieve both high yields and low environmental costs.

冬小麦-夏玉米轮作田沟金针虫垂直活动特征

基于河北固城农业气象国家野外科学观测研究站2019—2020年、2021—2022年冬小麦-夏玉米轮作田沟金针虫在土壤中分层调查数据,引入虫口重量指标,结合虫口密度指标,揭示沟金针虫在冬小麦-夏玉米轮作田为害-休眠动态变化,讨论沟金针虫在土壤中垂直活动特征、气象条件与其相关性以及对冬小麦产量影响。结果表明:沟金针虫在冬小麦-夏玉米轮作田存在3个为害期和3个休眠期,且交替出现。3个为害期出现在冬小麦返青-拔节期、夏玉米幼苗期、冬小麦秋苗期,3个休眠期出现在冬小麦越冬期、冬小麦成熟-收获期、夏玉米灌浆-成熟期,3个为害期中以冬小麦返青-拔节期最为严重。冬季偏暖及春季回暖早,沟金针虫表现出晚下早上特征,使得沟金针虫冬季休眠期缩短而为害活动期延长;土壤温度、湿度以及食源关系共同影响沟金针虫为害、休眠以及取食活动,其为害适宜土壤重量含水率约为15%~18%,适宜土壤温度为14~18℃。分析沟金针虫为害与冬小麦减产率可知,虫口密度每增加10 m^(-2)或虫口重量每增加1.0 g·m^(-2),可导致减产率增加5.1%。

播期调整对华北北部冬小麦、夏玉米产量和品质的影响

【目的】基于田间分期播种试验,研究华北北部冬小麦、夏玉米播期调整,其生长发育、光合生理特性、籽粒灌浆和产量形成及品质对气候变暖的不同响应,为华北平原农业生产采取措施应对气候变化提供科学依据。【方法】采用分期播种方法,于2017—2023年在华北北部的河北固城农业气象国家野外科学观测研究站开展冬小麦和夏玉米的大田分期(早播10 d、正常播期、晚播10 d、晚播20 d)播种试验,获取冬小麦和夏玉米的生育进程、地上干物质累积和分配、叶片光合特性、籽粒灌浆速率以及产量农艺性状和籽粒营养成分等资料。【结果】冬小麦全生育期随播期推迟而缩短,主要原因在于冬前幼苗期缩短;夏玉米全生育期与播期呈抛物线关系,播期每推迟10 d,幼苗期缩短1.3 d,花粒期和籽粒形成-灌浆期分别延长1.5和1.6 d。冬小麦、夏玉米籽粒灌浆过程对播期调整的响应完全不同,冬小麦籽粒灌浆特征在播期间反应并不敏感,夏玉米籽粒灌浆速率在播期间差异较小,但籽粒形成期、灌浆结束日期和峰值日期因播期推迟顺次延后,且灌浆持续日数因播期每推迟10 d,灌浆持续日数缩短4 d。北方麦区在秋暖和冬暖背景下,冬小麦播种期界限延宽,播期对产量的影响明显减弱,播期推迟配套增加播种量,产量不减且会小幅增产;夏玉米产量随播期推迟明显递减,理论产量播期每推迟10 d递减率1381.50 kg·hm^(-2),但冬小麦和夏玉米晚播20 d产量都凸显跳跃变小。播期每推迟10 d,冬小麦籽粒分配率递增1.67%,夏玉米则递减1.57%,冬小麦收获指数提高0.017,而夏玉米降低0.016。冬小麦和夏玉米叶片光合速率(Pn)对播期的响应亦不同,冬小麦播期间的Pn较为相近,而夏玉米播期每推迟10 d Pn递减率1.21μmol·m^(-2)·s-1。播期调整对华北北部冬小麦、夏玉米籽粒品质不会产生明显影响。【结论】气候变暖背景下我国北方冬小麦延迟播种,延宽适宜播种期是适应气候变暖的积极有效措施,华北平原夏玉米适期早播可避免高温热害影响,有助于稳产增产。

西北旱塬免耕的产量效应受降水特征和施肥显著影响

【目的】在冬小麦-夏春玉米轮作体系,研究不同降水年型条件下西北雨养农业区耕作与施肥对作物产量的影响,为西北旱塬作物高产稳产提供理论依据。【方法】基于2005年甘肃陇东旱塬设置的土壤耕作与培肥长期定位试验(3年冬小麦—1年春玉米),主处理为传统耕作和免耕,副处理为不施肥(CK)、单施氮肥(N)、单施磷肥(P)、单施农家肥(M)、氮磷配施(NP)和氮磷配施农家肥(NPM)。结合对冬小麦和玉米产量的分析,探究不同耕作与施肥处理下作物产量在不同降水年型的差异机制。【结果】降水年型、耕作和施肥方式显著影响冬小麦和玉米产量。无论何种降水年型或耕作方式,配施有机肥的NPM处理作物产量(冬小麦3441 kg/hm^(2),春玉米8991 kg/hm^(2))均显著高于其他施肥处理,并且NPM处理对作物的增产效果在丰水年型更为明显。在丰水年型,相对于传统耕作,免耕处理的作物产量无明显差异,但在干旱及平水年型下,免耕冬小麦平均产量分别下降了15.6%和25.7%,玉米平均产量分别下降了17.9%和4.6%;与传统耕作相比,免耕处理下的冬小麦和玉米水分利用效率在干旱年型分别下降了6.7%和17.0%,冬小麦水分利用效率在平水年型下降了24.0%。免耕处理下土壤有机质、全氮、全钾、速效氮、速效磷和速效钾含量显著高于传统耕作。【结论】在西北半干旱雨养农业区,干旱及平水年型免耕虽然提高了土壤养分含量,但降低了作物水分利用效率,这是导致作物产量降低的主要原因。因此,需要根据降水情况选择耕作方式,提高西北黄土旱塬作物产量的稳定性。

施用生物炭和秸秆还田对农田温室气体排放及增温潜势的影响

【目的】农业生态系统增温潜势是影响全球气候变化的重要部分。本研究通过田间试验明确施用生物炭和秸秆还田对农田增温潜势的影响,以期为减缓气候变化和农业废弃物资源化利用提供理论依据。【方法】在山东省桓台县农业生态系统试验站的冬小麦-夏玉米轮作农田中开展了3年田间定位试验,试验共设置4个处理:①对照(CK);②施用生物炭9.0t·hm^(-2)·a^(-1)(C);③全量秸秆还田(S);④秸秆还田配施9.0 t·hm^(-2)·a^(-1)生物炭(CS)。4个处理均施等量的氮磷钾化肥,其中氮肥为尿素,用量为200 kg·hm^(-2)·a^(-1),磷肥为过磷酸钙,用量为55 kg·hm^(-2)·a^(-1),钾肥为硫酸钾,用量为40 kg·hm^(-2)·a^(-1)。采用静态暗箱-气相色谱法测定各处理温室气体(CO_(2)、N_(2)O和CH_4)的排放通量并计算净全球增温潜势(NGWP)和温室气体排放强度(GHGI),分析连续施用生物炭和秸秆还田对农田温室气体排放及增温潜势的影响。【结果】(1)综合3年的温室气体排放情况,与CK处理相比,S和CS处理的年平均生态呼吸排放量(Re)分别增加了47.8%和67.9%(P<0.05);C处理的年平均N_(2)O累积排放量降低了20.3%(P<0.05),而S和CS处理的N_(2)O年平均累积排放量分别增加了23.6%和41.4%(P<0.05)。(2)与CK处理相比,C、S和CS处理的土壤有机碳年平均变化量(ΔSOC)均有显著增加,其中CS处理增幅最大,增加了150.6%(P<0.05)。与第1年相比,C、S和CS处理第3年的ΔSOC均有显著增加(P<0.05),分别增加了21.7%、20.8%和17.8%。各处理的NGWP和GHGI均存在显著差异,与CK相比,C、S和CS处理的年平均NGWP分别降低了163.5%、171.7%和273.0%(P<0.05),与第1年相比,C、S和CS处理第3年的NGWP均有显著降低(P<0.05),分别降低了73.4%、58.8%和54.7%。与CK相比,C、S和CS处理的年平均GHGI分别降低了236.2%、253.3%和388.9%(P<0.05),C、S和CS处理第3年的GHGI较第1年分别降低了126.3%、98.2%和108.6%(P<0.05)。就产量而言,C、S和CS处理的作物产量保持相对稳定,有轻微增长,但与CK相比无显著差异。【结论】与单施化肥相比,在施化肥的基础上添加生物炭、秸秆还田、秸秆还田配施生物炭的措施均能够在不影响作物产量的前提下抑制增温潜势,其中秸秆还田配施生物炭能够最大程度地降低农田增温潜势,因此秸秆还田配施生物炭是增加农田固碳、缓解气候变化的一项有效措施。

华北平原冬小麦-夏玉米农田生态系统土壤自养和异养呼吸模型构建

土壤呼吸是陆地生态系统碳循环的重要过程,准确估算土壤呼吸对估算陆地生态系统碳源汇具有重要意义。通过在华北平原典型农田内开展土壤呼吸及其组分的原位观测实验,构建了适用于华北平原冬小麦-夏玉米轮种制农田生态系统的半经验半机理土壤异养呼吸和土壤自养呼吸模型。结果表明,冬小麦-夏玉米农田土壤异养呼吸模型可表达为土壤温度和土壤水分的函数,其中,土壤温度对土壤异养呼吸的影响适合用Arrhenius方程描述,而土壤水分的影响适合用对称的倒抛物线描述。验证表明,该模型的R^(2)和RMSE分别为0.68和0.52μmol m^(-2)s^(-1)。土壤自养呼吸模型包括维持呼吸和生长呼吸两个模块,其中,维持呼吸表达为土壤温度和叶面积指数的函数,其形式分别为Van′t Hoff指数方程和米氏方程;生长呼吸表达为总初级生产力与维持呼吸之差的线性函数。冬小麦季和夏玉米季土壤自养呼吸模型的结构相同,但是两种作物的模型参数差异较大。验证表明,冬小麦季土壤自养呼吸模型的R2和RMSE分别为0.64和0.50μmol m^(-2)s^(-1),夏玉米季土壤自养呼吸模型的R2和RMSE分别为0.67和0.37μmol m^(-2)s^(-1)。相比于不区分土壤异养呼吸和土壤自养呼吸的土壤总呼吸模型,本研究构建的土壤异养呼吸和土壤自养呼吸模型能够更加准确地模拟土壤呼吸的季节变化和年际变化过程,可为华北平原冬小麦-夏玉米轮种制农田生态系统的土壤呼吸估算提供方法依据。

减氮下不同肥料配施对麦玉复种体系作物氮素积累分配及产量的影响

为探索陕西关中地区冬小麦-夏玉米复种体系氮肥减量增效潜力,构建适宜的作物养分管理体系,于2018-2019年采用田间试验研究了减氮并配施不同肥料对麦玉复种体系作物生长状况、植株氮素积累分配、作物产量以氮素利用效率的影响。试验设置5个处理:常规施氮(225 kg·hm^(-2),N 100);减氮20%(180 kg·hm^(-2),N 80);减氮配施生物炭(180 kg·hm^(-2),生物炭22500 kg·hm^(-2),N 80+BC);减氮配施缓释肥(180 kg·hm^(-2),尿素∶缓释肥=1∶1,N 80+S);减氮配施微生物菌肥(180 kg·hm^(-2),微生物菌肥3600 kg·hm^(-2),N 80+BF)。结果表明:减氮及其配施不同肥料对夏玉米大喇叭口期后株高、干物质和氮素积累没有显著影响;而N 80+BF促进了夏玉米氮素向籽粒中的分配;N 80+BC提高了夏玉米产量和收获指数,且较N 80处理分别显著提高8.3%和20.1%;减氮下三种配施处理均能提高夏玉米氮农学利用率和氮肥偏生产力,且以N 80+BC处理表现最佳,较N 100分别显著提高43.3%和29.0%,较N 80分别显著提高45.8%和8.3%;N 80+BC和N 80+BF还能显著提高夏玉米氮肥表观表观回收率,二者较N 100显著增加18.1%和10.7%,较N 80处理显著增加26.9%和19.0%。与N 80相比,N 80+BF有效提高了冬小麦扬花期和成熟期分蘖数、茎蘖成穗率以及成熟期干物质和氮素积累量,并能显著提高冬小麦穗数和产量,增幅分别为13.7%和16.2%。减氮下3种配施处理均能提高冬小麦氮农学利用率、氮肥偏生产力和氮素利用率,其中氮农学利用率和氮肥偏生产力在N 80+BF处理表现最佳,较N 100分别显著提高了31.2%和28.4%,较N 80分别显著提高了33.7%和16.2%,氮素利用率在N 80+S处理表现最佳。综上所述,减氮及其配施处理中,180 kg·hm^(-2)配施生物炭(22500 kg·hm^(-2))和180 kg·hm^(-2)配施微生物菌肥(3600 kg·hm^(-2))更有利于作物生长,促进氮素积累与分配,提高作物产量和氮素利用效率,实现关中地区麦玉复种体系氮肥管理的“减量增效”。

不同锌源叶面喷施对冬小麦和夏玉米产量及籽粒营养品质的影响

为探明不同锌源叶面肥喷施对小麦和玉米产量、籽粒矿质元素含量及锌、铁生物有效性的影响,对冬小麦-夏玉米轮作体系开展不同叶面肥喷施试验。小麦季设置去离子水(CK1)、尿素(CK2)、尿素+纳米氧化锌(U+ZnO)、尿素+壳聚糖纳米锌(U+ZnCNP)、尿素+普通七水硫酸锌(U+Zn)5种叶面肥处理;玉米季增加尿素与锌铁硒多元混合喷施处理(U+Zn/Fe/Se)。结果表明:各叶面肥喷施处理对小麦和玉米籽粒产量均无显著影响,但对籽粒微量元素含量有显著影响。不同锌源与尿素混合叶面肥对小麦籽粒锌含量强化效果由弱到强依次为U+ZnCNP<U+ZnO<U+Zn。与CK2处理相比,处理U+Zn使小麦籽粒锌含量显著提高77.7%(从22.80 mg·kg^(-1)增加至40.52 mg·kg^(-1))、籽粒植酸与锌(PA/Zn)摩尔比显著下降42.1%,使籽粒锌生物有效性(TAZ)显著提高74.5%。对于玉米,与CK2处理相比,处理U+Zn/Fe/Se使籽粒锌含量提高32.3%(从14.93 mg·kg^(-1)增加至19.60 mg·kg^(-1))、硒含量显著提高12.7倍(从17.66μg·kg^(-1)增加至242.04μg·kg^(-1))、籽粒PA/Zn摩尔比显著下降27.0%,使籽粒TAZ显著提高36.9%,使整个植株或玉米秸秆磷与锌(P/Zn)和磷与铁(P/Fe)摩尔比降低。研究表明,叶面喷施普通七水硫酸锌是提高小麦、玉米籽粒锌含量和生物有效性的最佳形式,其强化小麦籽粒锌效果优于玉米。叶面喷施尿素与锌铁硒混合溶液可同时提高玉米籽粒锌、硒含量及锌、铁生物有效性(籽粒、全株、秸秆),是解决人体或动物微量元素营养缺乏的有效农艺强化措施。

水氮耦合对地下滴灌冬小麦和夏玉米水氮利用效率影响研究

【目的】探索冬小麦、夏玉米地下滴灌条件下最佳灌水施氮制度。【方法】采用田间试验方法,分别设置4个灌水水平,冬小麦:W1:2580 m^(3)/hm^(2)、W2:2240 m^(3)/hm^(2)、W3:2020 m^(3)/hm^(2)、W4:1560 m^(3)/hm^(2),夏玉米:W1:1306 m^(3)/hm^(2)、W2:1088 m^(3)/hm^(2)、W3:814 m^(3)/hm^(2)、W4:650 m^(3)/hm^(2),2个施氮水平,冬小麦、夏玉米均为:F1:180 kg/hm^(2)、F2:100 kg/hm^(2),研究水氮耦合对冬小麦、夏玉米水氮利用效率及产量影响。【结果】W2F1处理冬小麦产量最大,继续增加灌水量冬小麦产量并未增加,而夏玉米产量随灌水量增加而增加;土壤氮素残留量均表现为F1处理>F2处理,且冬小麦氮素残留量随灌水量增加先减少后增加,W1处理夏玉米氮素残留量最大,冬小麦、夏玉米氮肥偏生产力均与产量变化趋势一致;冬小麦、夏玉米耗水量均随灌水量增加而增加,水分利用效率均随灌水量增加呈先增大后减小趋势。【结论】拟合优化表明,冬小麦的适宜灌水量为214 mm,适宜施氮量100 kg/hm^(2);夏玉米适宜灌水量为103 mm,适宜施氮量100 kg/hm^(2)。

夏玉米施用含锌尿素效应及对后茬小麦的影响

为明确新型肥料含锌尿素在夏玉米上的施用效果及其在冬小麦上的后效,采用田间试验,研究了施用含锌尿素、普通尿素、普通尿素+土施锌肥、普通尿素+喷施锌肥下夏玉米产量、养分吸收积累、土壤养分含量变化及其后效对冬小麦产量的影响。结果表明,普通尿素+喷施锌肥夏玉米产量较高,较不施氮显著增产17.5%,含锌尿素较不施氮显著增产16.7%,较普通尿素显著提高5.6%,与传统施锌无显著差异;含锌尿素地上部氮、锌素积累量较普通尿素分别显著提高9.0%、47.8%;夏玉米收获后含锌尿素处理土壤有效锌含量为1.83 mg·kg^(-1),较普通尿素处理提高88.6%;普通尿素+土施锌肥后茬冬小麦产量较高,较普通尿素显著增产11.9%,施用含锌尿素冬小麦产量较普通尿素提高4.7%,轮作周年产量提高5.2%;夏玉米利润和周年轮作利润分别提高826.2和1490.4元·hm^(-2)。含锌尿素较普通尿素提高了土壤有效锌含量,对后茬冬小麦、周年产量也有一定增产增收效果,夏玉米产量、干物质积累和氮肥利用效率等与传统施锌无显著差异。含锌尿素投入成本较传统施锌(氮肥和锌肥)降低26.1%,含锌尿素较普通尿素提高了产量和效益,具有在夏玉米-冬小麦轮作体系中推广应用的潜力。

秸秆还田和施肥对冬小麦-夏大豆轮作系统培肥与生产效益的影响

为探明秸秆还田和化肥施用对冬小麦-夏大豆轮作系统土壤培肥和生产效益的影响,于2020-2022年在关中平原开展田间定位试验,设置秸秆不还田不施肥(S0F0)、秸秆不还田常规施肥(S0F1)、秸秆还田配合常规施肥(S1F1)和秸秆还田配合减量施肥(S1F0.8)4个处理。利用静态暗箱-气相色谱法监测土壤N_(2)O排放通量,综合分析土壤养分、作物产量和土壤N_(2)O排放,明确秸秆还田配施化肥在土壤培肥、增产减排方面的效应。结果表明,秸秆还田和施肥通过显著提高土壤有机质(SOM)、全氮(TN)、全磷(TP)、硝态氮(NO_(3)^(-)-N)、铵态氮(NH_(4)^(+)-N)、速效磷(AP)含量来促进土壤培肥。与S0F0相比,S1F0.8和S1F1处理提高土壤综合肥力314.24%~317.12%、330.58%~384.98%;S1F0.8和S1F1处理显著提高冬小麦产量80.29%~101.25%、82.50%~107.66%,提高夏大豆产量25.31%~34.72%、36.93%~45.20%;S0F1、S1F0.8、S1F1均显著增加土壤N_(2)O累积排放量和种植系统温室气体排放强度,但S1F0.8较S0F1、S1F1处理显著降低土壤N_(2)O累积排放量和种植系统温室气体排放强度;S1F0.8和S1F1处理提高生产效益75.09%~75.88%、67.54%~114.23%。综上,秸秆还田配合常规施肥(S1F1)是关中平原麦-豆轮作系统土壤培肥的有效方式;但依照国家降低化肥施用量的要求来说,秸秆还田配合减量施肥(S1F0.8)是关中平原麦-豆轮作系统增产、减排、提高收益的推荐方式。

冬小麦-夏玉米周年“四密一稀”浅埋滴灌水肥药一体化绿色生产技术

本研究针对黄淮海冬小麦-夏玉米两熟区面临的出苗质量、播种—出苗期水分供应、灌溉施肥及时性及技术粗放等问题,并就进一步提高光温水肥资源利用效率是实现该区域粮食单产提升和绿色发展的重要途径等,从2018年起开展了一系列创新研究。通过实施冬小麦“四密一稀”条带种植配套卫星导航播种技术、冬小麦-夏玉米周年浅埋滴灌水肥药一体化技术等关键核心技术,结合配套现代化农机与信息技术装备,形成了一套集成的“冬小麦-夏玉米周年‘四密一稀’浅埋滴灌水肥药一体化绿色生产技术”。2010—2023年田间示范表明,该技术有效解决了上述生产难题,达到了小麦玉米周年增产和水肥资源高效利用的目标。与农民传统相比,小麦增产9%~17%,玉米增产12%~14%,周年节水450~750 m^(3)/hm^(2),节肥20%,节约人工成本2250~3000元/hm^(2)。该技术为黄淮海区冬小麦-夏玉米周年绿色高产提供了新的可行性方案。

改进密闭室抽气法以准确定量旱地土壤氨挥发

密闭室抽气法被认为是定量土壤NH_(3)挥发较为可靠的方法,具有灵敏度高且成本低的优点。然而,大部分研究忽略了密闭室抽气法大气进气口NH_(3)浓度,可能会高估土壤NH_(3)挥发量,目前尚缺乏相关定量研究。本研究以华北冬小麦-夏玉米轮作为对象,对比分析了2019——2021年间冬小麦基肥(2次)、追肥(1次)、夏玉米四叶肥(2次)、夏玉米十叶肥(2次)共7次施肥后,改进密闭室抽气法前后测定农田土壤NH_(3)挥发的结果。改进前为包含大气背景NH_(3)的测定方法,为常规测定方法;改进后为扣除大气背景NH_(3)的测定方法,通过在田间加装3套采集距地面2.5 m高度大气的装置实现。结果表明:改进后的NH_(3)挥发通量(以N计)比改进前低0~0.23 kg·hm^(-2)·d^(-1)(0%~100%),平均值为0.06 kg·hm^(-2)·d^(-1)(33%),且37%的样本存在显著性差异(P<0.05,n=931)。改进后的NH_(3)挥发累积量比改进前低0.53~2.66 kg·hm^(2)(3%~53%),平均值为1.15 kg·hm^(-2)(29%),且47%的样本存在显著性差异(P<0.05,n=49)。改进前后NH_(3)挥发量(包括通量和累积量)存在显著差异的样本占比随着NH_(3)挥发量降低而升高。回归分析表明,改进前的NH_(3)挥发累积排放量可以用算式校正得到真实的NH_(3)累积排放量,校正式为y=0.94x-0.78(R2=0.99,P<0.01,n=49),其中y和x分别为校正后和校正前的NH_(3)挥发累积量,该算式可应用于华北土壤-作物体系NH_(3)挥发累积量的校正。综上,利用抽气法定量农田土壤NH_(3)挥发需要扣除大气背景NH_(3)以得到准确的测定结果,对于未扣除大气背景的旱地NH_(3)挥发累积量,可采用校正算式进行校正。