The main physical properties of planosol in maize(Zea mays L.) cultivation under different long-term reduced tillage practices in the Baltic region

The impact of sustainable reduced tillage （RT） on the physical properties of soil is well documented worldwide; however, there is no precise information about the influence of long-term RT or no-till （NT） on the soils at the boundary for grain maize-growing in the semi-humid subarctic climate conditions of the Baltic states, especially on the formation of a hard- ened upper soil layer （10-15 cm in depth） --＂loosening hardpan＂. This study was carried out at the Research Station of Aleksandras Stulginskis University, Lithuania from 2009-2012. The investigations were based on a long-term （since 1988） field experiment. The aim of the investigation was to ascertain the influence of reduced primary tillage on the main soil＇s physical properties. This study examined soils that were deep ploughing （DP）, shallow ploughing （SP）, deep cultivation （DC）, shallow cultivation （SC）, and no-till （NT）. Reducing the tillage intensity to NT had no significant effect on the structural soil＇s composition; however, the stability of the structure of the 〉1 and 〉0.25 mm-size fractions was significantly higher in the non-reversibly tilled （DC, SC） and NT plots. The penetration resistance of the DP soils was less after primary tillage and wintering, and became similar to the NT plots at the end of the maize growth season. After primary tillage and wintering, the soil moisture content in the upper soil layer （0-5 cm depth） of the NT plots was 17-49 and 16-18% higher than that in the DP. Long-term reduction of primary tillage up to NT generally had no significant effect on the moisture content and soil bulk density of the 0-10 and 10-20 cm layers. The results showed that long-term RT stabilized the physical quality of soil. Less soil penetration resistance was established in the DP plots compared to both RT and NT, however, indicators of the formation of a uniform ＂loosening hardpan＂ layer were not found. It is summarized that long-term RT or NT systems stabilize, or may increase, the physical quality of soil in crop cultivation with low inter-row coverage potential （maize）, and could be applied in semi-humid subarctic climate conditions as a good option to prevent soil degradation.

Corn and Soybean Rotation under Reduced Tillage Management: Impacts on Soil Properties, Yield, and Net Return

A 4-yr field study was conducted from 2007 to 2010 at Stoneville, MS to examine the effects of rotating corn and soybean under reduced tillage conditions on soil properties, yields, and net return. The six rotation systems were continuous corn (CCCC), continuous soybean (SSSS), corn-soybean (CSCS), soybean-corn (SCSC), soybean-soybean-cornsoybean (SSCS), and soybean-soybean-soybean-corn (SSSC). Field preparation consisted of disking, subsoiling, disking, and bedding in the fall of 2005. After the fall of 2006, the raised beds were refurbished each fall after harvest with no additional tillage operations to maintain as reduced tillage system. The surface 5 cm soil from continuous soybean had higher pH than continuous corn in all four years. Unlike pH, total carbon and total nitrogen were higher in continuous corn compared to continuous soybean. Delta 15N tended to be higher in continuous corn compared to continuous soybean. Fatty acid methyl ester (FAME) indicated minor changes in soil microbial community in relation to cropping sequence, however there was a significant shift in rhizosphere community depending on crop. Corn yield increased every year following rotation with soybean by 16%, 31%, and 15% in 2008, 2009, and 2010, respectively, compared to continuous corn. As a result, net returns were higher in rotated corn compared with continuous corn. This study demonstrated that alternating between corn and soybean is a sustainable practice with increased net returns in corn.

Improved crop protection and biodiversity of the agroecosystem by reduced tillage in rice paddy ffelds in southern China

Agricultural sustainability has benefited from the broad adoption of conservation agriculture(CA)practices for decades,in which the reduction of mechanical disturbances to soil(also known as reduced tillage,RT)is one of the most essential principles for CA implementation.Many studies have recommended the advantages of CA practices in the promotion of biodiversity,but the integrated impacts on crop productivity and biodiversity remain unclear.Since CA has been applied in rice production in the subtropical area of southern China for several years,the effects of CA,particularly the RT methods,need to be evaluated for the local and long-term adoption.In this study,we established an integrated network to illustrate how the reduction of tillage intensity influenced organisms including invertebrates(such as rice pests and their predators),pathogens and weeds,and then led to an impact on rice yield.The two-year study demonstrated that major rice pests,such as rice planthoppers,stem borers and apple snails,were effectively controlled by RT practice.Similarly,the occurrence of common diseases declined with less tillage.Compared to the conventional tillage(CT)treatment,the density of weeds in paddy fields deceased significantly in the RT treatment.In addition,the diversity and richness of pest predators increased remarkably in paddy fields where either reduced or no tillage was applied,which highlighted the significance of a CA strategy for the promotion of biodiversity in the agroecosystem.More importantly,the rice yield gradually increased after the two-year reduction of tillage.Taken together,our results suggest that the reduction of tillage intensity is beneficial for the protection of rice crops from various pests,and facilitates the sustainability of the agroecosystem and rice yield,which provides a solid basis and novel insights for the establishment of sustainable agroecosystems by CA-related practices in rice production in southern China.

Potential Effect of Conservation Tillage on Sustainable Land Use: A Review of Global Long-Term Studies

Although understood differently in different parts of the world, conservation tillage usually includes leaving crop residues on the soil surface to reduce tillage. Through a global review of long-term conservation tillage research, this paper discusses the long-term effect of conservation tillage on sustainable land use, nutrient availability and crop yield response. Research has shown several potential benefits associated with conservation tillage, such as potential carbon sequestration, nutrient availability, and yield response. This research would provide a better perspective of the role of soil conservation tillage and hold promise in promoting application of practical technologies for dryland farming systems in China.

Genotype×tillage interaction and the performance of winter bread wheat genotypes in temperate and cold dryland conditions

Growing concerns for food security and the alleviation of hunger necessitate knowledge-based crop management technologies for sustainable crop production.In this study,13 winter bread wheat genotypes(old,relatively old,modern,and breeding lines)were evaluated under three different tillage systems,i.e.,conventional tillage(CT,full tillage with residue removed),reduced tillage(RT,chisel tillage with residue retained)and no-tillage(NT,no-tillage with residue retained on the soil surface)in farmer’s fields under rainfed conditions using strip-plot arrangements in a randomized complete block design with three replications in the west of Iran(Kamyaran and Hosseinabad locations)over two cropping seasons(2018–2019 and 2019–2020).The main objectives were to investigate the effects of tillage systems and growing conditions on the agronomic characteristics,grain yield and stability performance of rainfed winter bread wheat genotypes.Significant(P<0.01)genotype×tillage system interaction effects on grain yield and agronomic traits suggested that the genotypes responded differently to the different tillage systems.The number of grains per spike and plant height were positively(P<0.0)associated with grain yield under the NT system,so they may be considered as targeted traits for future wheat breeding.Using statistical models,the modern cultivars(“Sadra”and“Baran”)were identified as high yielding and showed yield stability across the different tillage systems.As per each tillage system,genotype“Sadra”followed by“Zargana-6//Dari 1-7 Sabalan”exhibited higher adaption to CT;while cultivars“Jam”and“Azar2”showed better performance under the RT system;and cultivars“Varan”and“Baran”tended to have better performance expression in the NT condition.The increased grain yields achieved in combination with lower costs and greater profits from conservation agriculture suggest that adapted cultivar and NT systems should be evaluated and promoted more widely to farmers in the west of Iran as an attractive package of crop management technologies.In conclusion,variations in the performance of genotypes and the significant genotype×tillage system interaction effects on grain yield and some agronomic traits assessed in this study suggest that the development and selection of cultivars adapted to the NT system should be considered and included in the strategies and objectives of winter wheat breeding programs for the temperate and cold dryland conditions of Iran.

Distribution of soil water-stable aggrega-tes and organic carbon content affected by tillage systems:a meta-analysis

A better understanding of soil carbon(C)distribution within aggregate fractions is essential to evaluating the potential of no-till for sustaining productivity and protecting the environment.A meta-analysis on 744 comparisons from 34 studies was conducted to determine the effects of three different tillage treatments(conventional mouldbould ploughing tillage(CT),reduced tillage(RT)and no tillage(NT))on water-stable aggregate size distribution,soil C concentration in aggregate fractions.The meta-analysis indicates that compared with CT treatment,NT/RT significantly(P<0.05)increases macro-aggregate above 20 cm by 20.9%-82.2%(>2.00 mm)and 5.9%-19.1%(0.25-2.00 mm),whereas NT/RT significantly reduces micro-aggregate and silt clay fractions above 20 cm.NT/RT significantly(P<0.05)increases the SOC in macro-aggregate(>0.25 mm)and micro-aggregate(<0.25 mm)size classes above 20 cm soil depth compared with CT.The results suggest that soil sampling depth should be considered to evaluate the influence of tillage systems on the distribution of soil aggregate,and the content of aggregate-associated C content.

Effects of Five Years Adoption of No-Tillage Systems for Vegetables Crops in Soil Organic Matter Contents

Vegetables productions systems are done normally with intense soil tillage causing a strong decline of soil quality. Use of conservation systems can be an alternative to recover this quality. In order to evaluate the effects of such systems on soil organic matter, an experiment has been conducted in randomized blocks design and factorial scheme 3 × 2: three soil management systems (no-tillage;reduced tillage and conventional tillage) and two cover crops (maize single;and intercropping maize with gray velvet bean—Stizolobium niveum);and repeated measures over time. Soil samples were collected before the implementation of the experiment and at the end of each crop cycle until the fifth crop cycle. Carbon associated with humic substances is also determined in 0 - 5 cm, 5 - 10 cm and 10 - 30 cm at the end of the last crop cycle. The SOM content was higher in RT (48.34 g·kg-1) than in the CT (39.48 g·kg-1) at the end of the fifth crop cycle. SOM content in NT (44.92 g·kg-1) was statistically equal to RT and CT, during the same period. In 0 - 5 cm, carbon contents associated to the humic substances present the same behavior of SOM contents in 0 - 10 cm. Probably these results are associated with the capacity of each system to improve superficial contents of SOM stable fractions. It follows that the conservation systems used are alternatives to the cultivation vegetables in order to improve soil organic matter contents.

RT-3DE联合BNP对HFNEF的临床诊断价值

目的:运用实时三维超声心动图(RT-3DE)对射血分数正常心力衰竭患者(heart failure with reduced ejection fraction,HFNEF)的舒张功能不全分级来探究与血清脑钠肽(BNP)浓度水平的关系。方法:选取射血分数正常心力衰竭患者65例。同期体检中心健康人65例为对照组。根据《2016 ASE/EACVI指南与标准》对舒张功能不全分级,运用超声心动图测量舒张功能相关指标参数;分别测定两组患者的血BNP浓度水平;将两组患者舒张功能不全分级与血BNP浓度水平比较,并作相关性分析。结果:随着舒张功能不全分级程度加重,实验组血BNP浓度水平明显高于对照组(P<0.05);且舒张功能障碍分级的等级与血BNP浓度水平呈正相关(r=0.338,P<0.05)。结论:应用RT-3DE对舒张功能不全分级与血BNP的结合,可提高超声心动图对HFNEF诊断的准确性。

基于LabVIEW RT的仪器资源共享方案的设计及实现

利用成熟商用的PXI平台硬件环境搭建基于LabVIEW RT实时操作系统的仪器资源共享方案,解决装备研发、生产测试中仪器资源紧张问题。该方案能够通过实时操作系统进行仪器资源集中管控和按需分配,提高仪器使用效率。采用该方案部署仪器资源共享工位,能够满足装备研发、生产测试需求,节约仪器资源,大幅降低仪器使用成本。

Tillage and crop management impacts on soil loss and crop yields in northwestern Ethiopia

Lack of appropriate agronomic practices is one of the major causes for soil erosion and low yields in teff(Eragrostis tef[Zucc.])production in Ethiopia.A 3-yr study was conducted at the Aba Gerima watershed in northwestern Ethiopia,to investigate the effects of two tillage practices(reduced tillage[RT]and conventional tillage[CT]),two planting methods(row planting[RP]and broadcast planting[BP]),and two compaction options(with[+T]and without[-T]trampling)on soil loss and teff yields in a split-split plot arrangement.Sediment concentration ranged from 0.01 to 5.37 g L^(-1)(mean,0.25 g L^(-1))in our study.Accordingly,the estimated total(August-October)soil loss ranged from 0.2 to 0.5 t ha^(-1)(mean,0.3 t ha^(-1)).The sediment concentration and total soil loss were significantly influenced(P<0.05)by tillage,planting methods,and trampling only in the third monitoring year.RT reduced soil loss by 19% relative to that of CT,whereas RP resulted in a 13%reduction in soil loss over BP.The-T plots showed a 15%reduction in soil loss as compared to+T plots.Results revealed significant increase in soil total carbon and nitrogen in RT and-T.Less soil loss and greater teff grain yield were obtained in plots with improved agronomic practices(RT and RP)compared to conventional ones(CT and BP).Based on our findings we conclude that the use of RT,RP,and-T practices can effectively minimize soil loss without any crop yield penalty.

少免耕土壤结构与导水能力的季节变化及其水保效果

通过对黑土坡耕地免耕、少耕与传统耕作土壤物理性状全生育期观测，比较研究土壤结构和导水性状季节变化差异及其与水土流失的关系。结果表明，表层0～20 cm土壤，免耕土壤容重全生育期维持在1.20～1.30 g cm^-3，变化小，大于0.25 mm的水稳性团聚体含量（WR0.25）和平均重量直径（MWD）高于传统耕作，初始和稳定入渗速率均高于少耕和传统耕作，土壤含水量分别较少耕和传统耕作高4.7和4.4个百分点，较传统耕作分别减少地表径流和土壤流失量86%和100%；少耕除夏季各项性状均介于免耕和传统耕作之间，夏季垄沟深松后，垄沟土壤容重显著降低，较免耕和传统耕作降低0.15 g cm^-3以上，提高土壤初始入渗速率30%以上，较传统耕作减少水和土壤流失量20%和40%。传统耕作土壤容重，垄台由播种时的0.91 g cm^-3增加至收获时的1.23 g cm^-3，垄沟一直维持在1.30 g cm^-3左右，WR0.25、MWD、土壤稳定入渗速率、含水量均较低，全生育期10%的雨水流失，土壤流失量615 t km^-2 a^-1。免耕土壤结构稳定，蓄水保水最佳，为效果显著的水土保持耕作措施，少耕也有一定的保水保土作用；免耕和少耕均能够改善土壤物理性状。

保护性耕作对农田生态系统净碳释放量的影响

以华北平原小麦-玉米两熟地区保护性耕作5年田间定位试验为基础,利用West提出的净碳释放方程对翻耕、少耕和免耕3种耕作方式下农田各项投入造成的碳释放和土壤碳累积进行比较。结果表明:在翻耕、少耕、免耕3个处理下,5年间各项农田投入造成的碳释放分别为312.60、295.4和280.52kg.km-2.a-1,表层30cm土壤的碳储量分别为30.59、32.76和31.61Mg.km-2,农田净碳释放量分别为312.60、-138.59和-76.52kg.km-2.a-1;与翻耕地比较,免耕和少耕地的相对净碳释放量为-236.08和-451.19kg.km-2.a-1;免耕地农田投入的碳减排量(32.08kg.km-2.a-1)为土壤碳增汇量(204.00kg.km-2.a-1)的15.73%,少耕地农田投入的碳减排量(17.19kg.km-2.a-1)为土壤碳增汇量(434.00kg.km-2.a-1)的3.96%。少耕地对减少大气CO2的贡献大于免耕地。

保护性耕作对大豆生长发育及土壤微生物多样性影响

明确保护性耕作对作物生长发育和土壤微生物群落的影响对于土壤管理具有重要意义。在中国科学院海伦长期定位区设置了免耕(NR)、少耕(RT)和旋松(ROT)3个耕作处理,研究了保护性耕作下大豆生长发育和产量情况,同时采用荧光定量PCR(Real-time PCR)和变性梯度凝胶电泳(DGGE)方法分析了土壤微生物多样性变化。研究结果显示:在苗期免耕和少耕对大豆生长具有一定的抑制作用,同时加重根腐病病害,但在成熟期免耕和少耕大豆生长优势明显,产量显著增加,其中少耕最高,比旋松增产3.9%,达到2 507.3 kg.hm-2。3种耕作方式对土壤细菌数量影响不大,真菌数量是免耕>少耕>旋松(P<0.05),其中免耕菌落数(CFU)和基因组DNA质量分别比旋松增加31.9%和13.3%,旋松和少耕的细菌/真菌比值要明显高于免耕。DGGE电泳分析表明,免耕和少耕对土壤细菌多样性增加不明显,但可以显著提高真菌多样性。主成分分析得出少耕和旋松细菌群落具有较高的相似性,而真菌群落结构3种耕作方式差异明显。

耕作方式对长期免耕农田土壤微生物生物量碳的影响

以华北冬小麦-夏玉米两熟区长期免耕土壤为研究对象,研究不同耕作方式(免耕、翻耕和旋耕)对长期免耕土壤微生物生物量碳(SMBC)的影响,为制定合理的轮耕制度提供依据。试验结果表明:长期免耕土壤进行耕作处理后SMBC的时空分布和稳定性产生显著变化。不同耕作处理SMBC含量在0～5 cm和5～10 cm土层变化明显,小麦起身期含量最低,收获期最高;深层SMBC变化不明显。免耕处理SMBC随土壤层次明显降低,且各土壤层次SMBC差异达显著(P<0.05)水平;翻耕、旋耕处理0～5 cm和5～10 cm土层间SMBC无明显差异,其他层次间差异显著(P<0.05)。从生育期平均值看,0～5 cm土层免耕处理SMBC含量较高,翻耕和旋耕处理则分别比免耕降低6.7%、6.1%;与免耕相比,5～10 cm土层SMBC翻耕、旋耕处理分别增加30.2%和20.7%(P<0.01),10～20 cm土层SMBC翻耕、旋耕处理比免耕增加48.1%(P<0.01)和10.5%(P<0.05)。在冬小麦生育期内,0～20 cm土层SMBC稳定性表现为翻耕>旋耕>免耕,20～30 cm土层SMBC稳定性表现为免耕>翻耕>旋耕。

土壤旋切振动减阻的有限元分析

提出了一种对旋耕机具施加振动载荷进行压实土壤切削减阻的方法。对板结土壤参数进行土壤三轴测试试验,结合LS-DYNA的MAT147材料模型,测试土壤材料模型参数,并建立了南方丘陵地带板结土壤本构模型及土壤振动旋切过程的有限元数值模型。通过三维数值模拟和计算,分析了外加激励的振型、频率及振幅等因素对土壤切削阻力的影响及变化规律,并得到实现最优减阻效果的各项参数组合。研究结果表明,采用振动旋耕机具进行土壤作业过程中,选择合适振动频率、幅值以及振动类型的外加刀具振动能实现土壤耕作减阻,有效降低机具的土壤切削功率。

减量施肥条件下生物炭与耕作方式对玉米氮吸收及产量的影响

研究采用大区试验,以种植在草甸黑土玉米鑫鑫1号为研究对象,在常规秸秆还田基础上,设置深翻(D)和旋耕(S)两种耕作方式,以常规施肥量F为对照,设置减量20%的减肥处理(F1),在减量施肥基础上设两个生物炭添加水平2500kg·hm^-2(B1)和5000kg·hm^-2(B2),共8个处理,研究减肥条件下,生物炭与耕作方式对玉米氮吸收和产量的影响,为减肥条件下玉米稳产提供科学依据。结果表明,减肥条件下玉米氮素积累和产量因耕作方式和生物炭施用量不同存在差异,深翻提高地上部氮素积累量和产量,较旋耕分别增加6.23%~8.02%,0.16%~6.61%;减肥条件下配施生物炭提高地上部氮素积累量和产量,深翻和旋耕条件下分别较减量施肥处理提高地上部氮素积累量6.24%和7.41%、6.10%和7.31%,提高产量8.95%和9.30%、10.21%和15.88%,且在深翻和旋耕条件下,B2较B1分别增产3.50%和5.14%。综上,在本试验减肥20%条件下,深翻和旋耕两种耕作方式配施高量生物炭(5000kg·hm^-2)有利于提高草甸黑土玉米氮素吸收和产量。

水稻少耕及其生理生态特性研究进展

本研究已探索到，连续１０年２０季在只耙不犁的少耕田撒播水稻与在按传统方法犁耙的全耕田撒播水稻相比，每季的稻谷产量都较高。其原因是少耕撒播稻（以下称少耕稻）的穗粒性状优于全耕撒播稻（以下称全耕稻），而这种优势的产生则在于少耕法能导致耕作层土壤的物理性质和养分，向着有利于根系生长的方向发展，而使少耕稻与全耕稻相比具有较发达与生理活性较强的根系，并进而导致少耕稻在稻苗的长势长相、功能叶的生理活性，以及在延缓功能叶的衰老等方面都优于全耕稻。

华北高寒区多年保护性耕作对农田土壤容重的影响

为了在保护土壤、减抑风蚀的同时,兼顾作物的产量,探索适合华北高寒区的保护性耕作模式,给当地作物生产提供理论依据,在农业部张北野外观测站连续9年不同耕作方式定位研究的基础上,于2007—2009年探讨了免耕、松耕和翻耕对土壤耕层容重的影响。结果表明,3种耕作方式播种期不同耕层土壤容重均以免耕最高,翻耕最低,播前0～10cm、10～20cm土壤容重免耕分别为1.65、1.81g/cm3,翻耕则分别为1.38、1.47g/cm3,收获期土壤容重差异不明显。华北高寒区不同耕作方式对农田耕层土壤容重具有明显的影响,翻耕和松耕可以显著降低耕层土壤容重。受作物根系生长生物力的影响,收获期与播种期相比,免耕及松耕农田耕层土壤容重呈下降趋势,翻耕则无明显变化。

立式旋耕方式下氮肥不同减施水平对小麦品质的影响

为探究立式旋耕(30 cm±5 cm)下氮肥减施对小麦品质的影响,研究了2017—2018、2018—2019年两个小麦生长季立式旋耕下CK(300 kg N·hm^(-2))与减氮10%(RF10)、20%(RF20)、30%(RF30)处理小麦品质变化,测定项目包括籽粒品质和面粉流变特性、拉伸性能等。结果表明:与CK相比,RF10处理小麦籽粒蛋白质含量当季略增,连续减施第二季则显著下降12.2%;RF20、RF30两季均下降,且RF30当季显著下降11.6%,RF20第二季显著下降11.1%。RF10、RF20湿面筋含量与CK比,当季略升,第二季下降;RF30两季均下降,且当季与CK差异显著,降幅为10.8%。氮肥减施后面粉吸水量呈增加趋势,面团形成时间呈缩短趋势;面团稳定时间与CK比均缩短,RF20、RF30与CK差异显著。RF10、RF20面团弱化度较CK均升高,RF30当季显著升高,第二季下降。RF10、RF20面粉能量值当季升高,第二季下降;RF30两季均下降。氮肥减施对籽粒容重、出粉率、拉伸阻力及延伸性等影响规律性不明显。研究表明,减施10%、20%氮肥能实现减肥不降产,对当季小麦品质影响不大,连续减施则影响小麦品质;减施30%氮肥时小麦产量有降低趋势,且品质有所下降。