秸秆颗粒不同量还田对设施土壤酶活性的影响

设施土壤长期存在碳输入不足的问题,秸秆颗粒是实现外源碳大量输入的重要途径之一。采用盆栽试验方式,设置粉碎秸秆、秸秆颗粒两种秸秆类型,4种秸秆还田量水平(干土重的1%、2%、3%、4%),以无秸秆还田为对照(CK),研究秸秆颗粒不同量还田对设施土壤碳氮循环相关酶活性的影响。结果表明:(1)秸秆颗粒与粉碎秸秆还田均对纤维素酶、β-葡糖苷酶、α-葡糖苷酶、脲酶、亮氨酸氨基肽酶、乙酰氨基葡萄糖苷酶、谷氨酰胺合成酶、酸性磷酸酶的活性有正效应,但对酚氧化酶活性具有负效应。对过氧化氢酶活性表现为少量秸秆还田时是正效应,高量秸秆还田时是负效应;(2)秸秆颗粒与粉碎秸秆处理的土壤酶活性均随还田量的增加呈先增加后降低变化,秸秆颗粒与粉碎秸秆处理的差异主要与还田量水平相关。还田量超过2%达到一定水平后,对酶活性的影响均出现正效应降低的效果。高量还田条件下在3%还田量水平以上时,秸秆颗粒更利于改善土壤碳氮循环相关酶活性;(3)秸秆颗粒大量还田可显著增加土壤养分含量;(4)土壤养分含量与土壤酶活性显著相关,是土壤酶活性变化的主控因子;(5)秸秆颗粒的适宜还田量为3%~4%,而粉碎秸秆的适宜还田量不宜超过2%。总之,秸秆颗粒在3%~4%的高还田量水平下可显著提升土壤养分含量和土壤酶活性,是有效改善碳氮失衡设施土壤的高量碳肥输入方式。

秸秆还田配施氮肥对东北春玉米光合性能和产量的影响

秸秆还田配施氮肥是解决旱作农田"耕层变浅"、"土壤紧实"、"有效耕层土壤减少"问题的重要措施之一,在旱作农业生产中具有重要意义。为探明秸秆深翻还田配施氮肥对东北春玉米光合性能和产量的影响,本研究于2014—2015年在辽宁铁岭设置S0F0(秸秆0 kg hm^(–2)+纯NPK 0 kg hm^(–2))、SN0(秸秆9000 kg hm^(–2)+纯N 0 kg hm^(–2)+纯P 112.5 kg hm^(–2)+纯K 90 kg hm^(–2))、SN1(秸秆9000 kg hm^(–2)+纯N 112.5 kg hm^(–2)+纯P 112.5 kg hm^(–2)+纯K 90 kg hm^(–2))、S0N2(秸秆0 kg hm^(–2)+纯N 225 kg hm^(–2)+纯P 112.5 kg hm^(–2)+纯K 90 kg hm^(–2),当地传统种植方式,CK)、SN2(秸秆9000kg hm^(–2)+纯N 225 kg hm^(–2)+纯P 112.5 kg hm^(–2)+纯K 90 kg hm^(–2))、SN3(秸秆9000 kg hm^(–2)+纯N 337.5 kg hm^(–2)+纯P 112.5kg hm^(–2)+纯K 90 kg hm^(–2))6个处理开展了研究。结果表明,秸秆还田配施氮肥对春玉米籽粒产量和生物产量影响显著,秸秆还田9000 kg hm^(–2)和配施氮肥225 kg hm^(–2)处理的籽粒产量最高,比秸秆不还田和施氮量225 kg hm^(–2)处理(CK)2年平均增产6.33%,增产的主要原因是百粒重和行粒数的显著提高和秃尖的显著降低;玉米籽粒产量并未随着施氮量的增加而持续增加;相同施氮量条件下,秸秆还田比秸秆不还田2年平均群体生物产量增加2.95%。秸秆还田配施氮肥能够增加春玉米株高、茎粗、叶面积,提高叶绿素含量和光合作用,相同施氮量条件下,秸秆还田比秸秆不还田处理2年平均灌浆期叶面积增加2.71%,光合速率提高4.80%。综合分析认为,秸秆还田9000 kg hm^(–2)和配施氮肥225kg hm^(–2)是辽北棕壤区春玉米生产比较理想的还田和施肥模式,在该区域农业发展中具有一定的应用价值。

秸秆一次性深埋还田量对亚表层土壤肥力质量的影响

【目的】在以小麦–玉米轮作制为主的黄淮海北部地区,由于长期实施浅旋耕,亚表层土壤结构紧实、有机质匮乏,本研究通过分析不同倍量的粉碎秸秆深埋还田对亚表层土壤肥力的影响,为该地区选择适宜的秸秆还田方式进行亚表层培肥提供理论依据。【方法】本试验在微区土池中进行,设置低(6000 kg/hm^2,T1)、中(12000 kg/hm^2,T2)、高(18000 kg/hm^2,T3) 3种不同量粉碎秸秆的一次性深埋还田试验,并与常规旋耕下的秸秆不还田处理(CK)进行对比,研究2013-2016年深埋还田条件下不同用量秸秆对土壤蓄水量、紧实度、有机碳、全氮、速效氮磷钾含量及作物根系生物量、籽粒产量等指标的影响,并运用主成分分析法评估秸秆增量深还对亚表层土壤肥力质量的影响。【结果】1) 0-40 cm土壤蓄水量随秸秆用量增加而提高,其中T3、T2处理下土壤蓄水量在冬小麦季平均分别提高了50.94%(P <0.05)和59.77%(P <0.05),夏玉米季增幅低于冬小麦季,这表明增加秸秆用量更有利于干旱季土壤水分的保蓄;增加秸秆用量能降低亚表层土壤紧实度高达60%,且能调节土壤pH使之趋于中性;2)中、高量秸秆深埋还田显著提高了亚表层土壤养分含量,如T2、T3处理下有机碳含量显著提高7%~20%(P <0.05),全氮含量显著提高7%~18%(P <0.05),速效养分含量显著提升10%~30%(P <0.05),并增加了亚表层土壤C/N及养分库容;3)主成分分析表明,T3处理的土壤肥力质量略优于T2处理,而以T1处理最差,一次性秸秆增量深还能够长时间维持较高的土壤肥力;4)中、高量秸秆深埋还田可提高冬小麦及夏玉米籽粒产量及其根系生物量,以T2处理冬小麦、夏玉米3年平均籽粒产量最高,增幅分别为7.02%和5.11%(P <0.05),T2、T3处理冬小麦根系生物量平均提高21.9%和16.0%(P <0.05),提高夏玉米根系生物量18.4%和19.5%(P <0.05),然而对秸秆生物量的提高不显著,且T2处理在还田前期对作物生物量的提升作用优于T3处理。【结论】秸秆深埋还田可显著改善亚表层土壤结构,增加土壤养分库容,并提高根系生物量及籽粒产量。12000~18000 kg/hm^2秸秆一次性深埋还田可显著提高亚表层土壤肥力质量,是该地区培肥土壤的有效措施。

玉米秸秆颗粒还田对土壤有机碳含量和作物产量的影响

为改进麦玉轮作区秸秆还田方式,推进秸秆资源高效利用,快速提升土壤质量,以秸秆不还田为对照(CK),通过连续3年田间微区试验,研究了等量玉米秸秆粉碎还田(CCSI)和颗粒化还田(GSI)对0～20 cm和20～40 cm土层土壤有机碳(SOC)、可溶性有机碳(DOC)和作物产量的影响。结果表明:与CK相比,GSI和CCSI两种秸秆还田方式均能提高SOC和DOC含量,但主要集中在还田后1.5年内,还田后1.5～3年处理间无显著差异。在秸秆还田处理中,GSI处理能快速提高SOC和DOC含量。在还田当年,GSI处理0～20 cm土层SOC和DOC的平均含量较CCSI处理提高6.59%和3.00%,20～40 cm土层分别提高17.36%和12.65%,且两土层DOC/SOC也显著高于CCSI处理,但随着还田后时间延长,CCSI和GSI处理间差异逐渐缩小,还田后1.5年两者无显著差异。此外,GSI处理利于提高作物产量,且在还田当年增产效应更加突出。与CK和CCSI处理相比,GSI处理还田当年小麦产量分别提高9.80%和10.82%,玉米产量分别提高9.54%和3.45%。进一步分析发现,2013—2016年GSI处理虽然增加了经济投入,但由于具有更高的籽粒产量,最终获得较高的年均净利润,分别比CK和CCSI处理提高10.09%和3.24%。研究表明,秸秆颗粒还田较常规粉碎还田能快速提高SOC和DOC含量,促进当季作物增产,获得较高的经济效益。

河套平原碱蓬种群空间布局特征与土壤微域特征分析

选择河套平原盐碱荒地碱蓬作为研究对象,通过野外观测、采样和室内分析,探讨河套平原碱蓬野生种群的空间分布特征与其土壤微域特征,以及土壤水盐等环境条件对碱蓬群落格局形成的影响。结果表明,河套平原碱蓬野生种群主要呈聚集分布格局。碱蓬群落的盖度与根区土壤水分含量极显著正相关,与根区土壤盐分含量显著负相关,与根区土壤中K^+、Na^+的含量显著负相关,说明河套平原碱蓬群落的分布主要受土壤水分含量和土壤盐分含量的双重影响,各离子中以钾、钠离子影响最为显著。碱蓬群落对降低土壤含盐量有一定作用,对根区土壤中SO_4^(2-)、Na^+降低最多,K^+降低最少,也会降低根区土壤pH值。土壤环境与碱蓬群落相互影响,盐碱程度影响碱蓬群落的盖度,碱蓬作为耐盐碱植物对盐碱地土壤含盐量有良好的降低作用。

施用功能微生物菌剂对重度盐碱地向日葵生长及土壤微生物的影响

为了明确功能微生物菌剂对重度盐碱土壤向日葵农艺性状及微生物群落的影响,采用盆栽试验,研究施用ACCC19743、ACCC19833两种不同微生物菌剂对向日葵农艺性状、叶绿素含量、土壤微生物细菌群落多样性及物种组成等的影响。结果表明:与对照处理相比,施用ACCC19743微生物菌剂的土壤pH显著下降了0.17个单位(P<0.05,下同),而施用两种微生物菌剂对土壤含盐量无显著影响;施用微生物菌剂后向日葵的叶面积、株高、地上部干物质量及SPAD值均有所提高,其中ACCC19743处理分别较对照提高了7.52%、57.67%、46.51%、8.72%,均达到显著水平。在门分类水平上,共检测分类12个菌门,其中变形菌门(Proteobacteria)占有明显优势,相对丰度为54.61%~57.68%,其次为拟杆菌门(Bacteroidetes)和放线菌门(Actinobacteria),而ACCC19743处理有利于增加变形菌门和拟杆菌门的丰度。综上所述,ACCC19743菌剂处理能有效降低土壤pH,增加变形菌门和拟杆菌门相对丰度,提高向日葵叶片中叶绿素含量,促进其生长发育,可推荐在河套灌区重度盐碱地应用。

亚表层培肥结合覆膜提高干旱区盐碱地土壤肥力及优势菌群丰度的机理

[目的]针对西北干旱气候条件下表层土壤贫瘠多盐的特点,研究亚表层(10 30 cm)培肥结合地膜覆盖对盐碱地土壤化学性质及微生物区系的影响,为盐碱地合理耕层的构建提供参考。[方法]试验设在内蒙古五原县,以向日葵为供试作物进行田间小区和微区试验。设常规翻耕(CK)、翻耕+地膜覆盖(PM)、施有机肥(106.8 t/hm^2)于亚表层(OM)、亚表层有机培肥+地膜覆盖(OMP)共 4 个处理。测定了春灌前、后以及向日葵收获后,不同耕作措施下土壤剖面的 pH 值、盐分、有机质和速效养分含量以及微生物区系。[结果]春灌前,亚表层培肥处理(OM、OMP)10 30 cm 土层盐分含量比 CK、PM 处理分别增加了 37.1%~52.9%、32.1%~47.2%(P < 0.05),但在春灌后盐分含量无显著差异。地膜覆盖具有很强的抑制返盐效果,OMP 处理效果好于 PM 处理。作物收获后,OMP 处理 0 10 cm 表层返盐率相对 CK、PM 和 OM 处理分别降低了 131%、77.6%和 106%,PM 处理相对 CK 和 OM 处理分别降低了 53.5%和 28.7%(P < 0.05)。与 CK 相比,OM、OMP 处理 10 30 cm 土层 pH 值分别降低了 0.36、0.60 个单位(P < 0.05),有机质、速效氮、速效磷、速效钾分别增加了 100%和 127%、88.7%和 105%、564%和 514%、453%和 400%(P < 0.05);30 40 cm 土层 pH 值分别降低了 0.45、0.44 个单位(P < 0.05),速效磷和速效钾含量显著增加了 517%和 604%、191%和 157%,OMP 处理有机质含量显著增加了 33.6%(P < 0.05)。高通量测序结果表明,OM、OMP 处理显著提升了芽孢杆菌属(Bacillus)、交替赤杆菌属(Altererythrobacter)、降解类固醇杆菌属(Steroidobacter)、链霉菌属(Streptomyces)与诺卡氏菌属(Nocardioides)等优势菌群丰度(P < 0.05),但微生物多样性(Shannon 指数和Simpson 指数)和丰富度(ACE 指数和 Chao1 指数)与 CK、PM 处理差异不显著。相关性分析结果表明,芽孢杆菌属、交替赤杆菌属、降解类固醇杆菌属、链霉菌属与诺卡氏菌属相对含量均与收获后 0 40 cm 有机质与速效养分含量呈极显著正相关,与 pH 值呈极显著负相关(P < 0.01),但与全盐含量无显著相关性。[结论]亚表层培肥结合地表覆膜一方面可有效降低盐分表层集聚,快速增加土壤有机质和速效养分,另一方面可提高土壤优势菌群丰度,增强有机物的矿化分解,是改良西北干旱区盐碱土的有效耕作措施。

河套灌区春灌结合秸秆隔层对盐碱土壤温度的调控效果

【目的】对内蒙古河套灌区向日葵生长季土壤温度进行连续监测,从土壤温度变化的角度对春灌结合秸秆隔层措施进行了科学评价。【方法】田间微区定位试验在内蒙古五原县进行,供试作物为食用向日葵(Helianthus annuus L.),品种为JK601 (2016—2017年)和HT361 (2018年)。以无秸秆隔层+常规春灌量2250m^3/hm^2为对照(CK),其他处理均采用秸秆隔层,灌水量为对照的100%(W100)、90%(W90)、80%(W80)。秸秆隔层一次性布置,之后连续3年,用5TE-传感器测定食葵生育期膜内距地表下10、20、30和40 cm处土壤水分、电导率、温度。在食葵收获期,调查产量和产量构成因素。【结果】与CK相比,W100处理0—40cm土层土壤温度在食葵生育时期均表现出增温效果,但增温幅度随着试验年份的增加而降低,其中在2016年食葵蕾期、花期和成熟期显著增温0.7℃~1.8℃,2017年食葵苗期、蕾期和花期生长阶段显著增温0.6℃~1.7℃(P <0.05),而在2018年两处理间土壤温度无显著差异。W100处理0—40 cm土层土壤温度在食葵苗期和蕾期最高,与W90和W80处理相比,3年平均提高了0.3℃~0.4℃和0.2℃~0.5℃;而在食葵花期和成熟期表现为W80处理的土壤温度最高,与W100和W90处理相比,3年平均提高了0.8℃~1.0℃和0.5℃~1.0℃(P <0.05)。相较于CK处理,W100处理和W90处理均能增加食葵产量。其中,W100处理在3年分别增产34.63%、18.83%和6.57%,W90处理分别增产30.42%、15.91%和0.64%。【结论】综合比较土壤温度调控、节约水资源、作物产量,在当地常规春灌基础上减少10%灌水量结合秸秆隔层处理(W90)是较优方案。秸秆隔层处理对土壤温度的调控效果在前两年较为显著,因此,应考虑每两年进行一次隔层处理,以保证该措施对土壤温度调控的有效性。

Buried straw layer and plastic mulching increase microflora diversity in salinized soil

Salt stress has been increasingly constraining crop productivity in arid lands of the world. In our recent study, salt stress was aleviated and crop productivity was improved remarkably by straw layer burial plus plastic iflm mulching in a saline soil. However, its impact on the microlfora diversity is not wel documented. Field micro-plot experiments were conducted from 2010 to 2011 using four tilage methods： （i） deep tilage with plastic iflm mulching （CK）, （i） straw layer burial at 40 cm （S）, （ii） straw layer burial plus surface soil mulching with straw material （S＋S）, and （iv） plastic iflm mulching plus buried straw layer （P＋S）. Culturable microbes and predominant bacterial communities were studied; based on 16S rDNA, bacterial com-munity structure and abundance were characterized using denaturing gradient gel electrophoresis （DGGE） and polymerase chain reaction （PCR）. Results showed that P＋S was the most favorable for culturable bacteria, actinomyces and fungi and induced the most diverse genera of bacteria compared to other tilage methods. Soil temperature had signiifcant positive correlations with the number of bacteria, actinomyces and fungi （P〈0.01）. However, soil water was poorly correlated with any of the microbes. Salt content had a signiifcant negative correlation with the number of microbers, especialy for bacteria and fungi （P〈0.01）. DGGE analysis showed that the P＋S exhibited the highest diversity of bacteria with 20 visible bands folowed by S＋S, S and CK. Moreover, P＋S had the highest similarity （68%） of bacterial communities with CK. The major bacterial genera in al soil samples wereFirmicutes,Proteobacteria andActinobacteria. Given the considerable increase in microbial growth, the combined use of straw layer burial and plastic iflm mulching could be a practical option for aleviating salt stress effects on soil microbial community and thereby improving crop production in arid saline soils.

Straw layer burial to alleviate salt stress in silty loam soils: Impacts of straw forms

Salt stress can be alleviated by straw layer burial in the soil, but little is known of the appropriate form of the straw layer for optimal regulation of soil water and salinity because of the uncontrollability of field tests. Here, the following four straw forms with compaction thickness of 5 cm buried 40–45 deep were studied: no straw layer(CK), segmented straw(SL, 5 cm in length), straw pellet(SK), and straw powder(SF). The three straw forms(SL, SK and SF) significantly delayed the infiltration of irrigation water down the column profile by 71.20–134.3 h relative to CK and the migration velocity of the wetting front under SF was the slowest. It took longer for the wetting front to transcend SK than SL but shorter for it to reach the bottom of soil column after water crossed the straw layer. Compared with CK, the average volumetric water content in the 0–40 cm soil layer increased by 6.45% under SL, 1.77% under SK and 5.39% under SF. The desalination rates at the 0–40 and 0–100 cm soil layers increased by 5.85 and 3.76% under SL, 6.64 and 1.47% under SK and 5.97 and 4.82% under SF. However, there was no significant difference among straw forms in the 0–40 cm soil layer. Furthermore, the salt leaching efficiency(SLE, g mm^–1 h^–1) above the 40 cm layer under SL was 0.0097, being significantly higher than that under SF(0.0071) by 37.23%. Salt storage under SL, SK and SF in the 40–45 cm layer accounted for 4.50, 16.92 and 7.43% of total storage in the 1-m column profile. Cumulative evaporation under SL and SF decreased significantly by 41.20 and 49.00%, with both treatments having the most significant inhibition of salt accumulation(resalinization rate being 36.06 and 47.15% lower than CK) in the 0–40 cm soil layer. In conclusion, the different forms of straw layers have desalting effects under high irrigation level(446 mm). In particular, SL and SF performed better than SK in promoting deep salt leaching and inhibiting salt accumulation on the soil surface. However, SL was simpler to implement and its SLE was higher. Therefore, the segmented 5 cm straw can be recommended as an optimum physical form for establishing a straw layer for managing saline soils for crop production.

The Potential Contribution of Subsurface Drip Irrigation to Water-Saving Agriculture in the Western USA

Water shortages within the western USA are resulting in the adoption of water-saving agricultural practices within this region. Among the many possible methods for saving water in agriculture, the adoption of subsurface drip irrigation （SDI） provides a potential solution to the problem of low water use efficiency. Other advantages of SDI include reduced NO3 leaching compared to surface irrigation, higher yields, a dry soil surface for improved weed control, better crop health, and harvest flexibility for many specialty crops. The use of SDI also allows the virtual elimination of crop water stress, the ability to apply water and nutrients to the most active part of the root zone, protection of drip lines from damage due to cultivation and tillage, and the ability to irrigate with wastewater while preventing human contact. Yet, SDI is used only on a minority of cropland in the arid western USA. Reasons for the limited adoption of SDI include the high initial capital investment required, the need for intensive management, and the urbanization that is rapidly consuming farmland in parts of the western USA. The contributions of SDI to increasing yield, quality, and water use efficiency have been demonstrated. The two major barriers to SDI sustainability in arid regions are economics （i.e., paying for the SDI system）, including the high cost of installation; and salt accumulation, which requires periodic leaching, specialized tillage methods, or transplanting of seedlings rather than direct-seeding. We will review advances in irrigation management with SDI.

Subcellular Cd accumulation characteristic in root cell wall of rice cultivars with different sensitivities to Cd stress in soil

The variations of grain cadmiun（Cd） concentrations, translocation factors（TFs） of Cd from roots to shoots/grains of six rice cultivars, characterized with different Cd-sensitivities in polluted soil were studied, the selected rice cultivars were Xiangzao 17（R1）, Jiayu 211（R2）, Xiangzao 42（R3）, Zhuliangyou 312（R4）, Zhuliangyou 611（R5）, and Jinyou 463（R6）, respectively. The Cd subcellular distribution and Cd binding characteristics on subcellular fractions of rice root cell wall（CW） were further investigated. The results showed that the rice grain Cd contents varied significantly, with a maximum variation of 47.0% among the cultivars, the largest grain Cd content was observed with cultivar R1（Cd-sensitivity cultivar） and the smallest with R5（Cd-tolerance cultivar）. The translocation factors of Cd from roots to shoots（TF_（shoot）） and roots to grains（TF_（grain）） varied greatly among the cultivars. In general, the TFgrain of the cultivars followed the order of R1〉R2〉R3〉R4〉 R6-R5. The Cd concentration（mg kg^（–1） FW） in the fraction of root CW, the fraction of cell wall removing pectin（CW-P） and the fraction of cell wall removing pectin and hemicellulose（CW-P-HC） of the cultivars generally followed the order of CW-P〉CW〉CWP-HC; the ratios of Cd concentration（mg kg–1 FW） in the fraction of CW-P to that of CW were mostly more than 1.10, while the ratios of Cd concentration in the fraction of CW-P-HC to that of CW were mostly less than 0.60, indicating that Cd was mainly stored in the hemicellulose of the root CW. The ratios of Cd of CW-P-HC to CW generally followed the descending order of R1~R2〉R3〉R4〉R5~R6 for the cultivars, which implied that hemicellulose is probably the main subcellular pool for transferring Cd into rice grain, and it restrains the translocation of Cd from shoot to the grain, especially for the Cd-tolerance cultivars（R5 and R6）, the compartmentation of more Cd in hemicellulose in root CW is probably one of the main mechanisms for Cd tolerance of rice cultivars.