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  • 黄土高原丘陵区典型植物群落土壤粒径分布特征

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2022-08-09 合作期刊: 《干旱区地理》

    摘要:为探究黄土高原丘陵区不同植物群落的土壤粒径分布特征。选取草地、山杏纯林、油松纯林和油松山杏混交林0~200 cm土壤为研究对象,采用激光衍射技术测定土壤样品粒度组成,计算土壤粒度参数与分形维数,绘制粒度频率曲线。结果表明:(1)研究区土壤属粉壤土,粉粒含量约占总体的56.58%~71.67%,砂粒约占21.37%~38.71%,黏粒约占3.55%~6.96%。(2)各植物群落内土壤粒度组成随土层深度增加分布较为均一,粒径分布整体分选性均较差,呈极正偏度,峰态尖窄,粒度频率曲线为双峰型,曲线波峰一致。不同植物群落土壤粒径分布差异主要集中在土壤表层0~20 cm(P<0.05)。(3)草地、山杏纯林、油松纯林和油松山杏混交林0~200 cm土壤平均分形维数分别为2.63、2.60、2.61、2.58。分形维数与黏粒含量具有极显著正相关关系(P<0.05),其中,草地土壤分形维数与黏粒的相关性最强。总体来看,黄土高原丘陵区草地土壤粒径分布特征显著优于人工林,本研究结果可为黄土高原的生态重建工作提供理论依据。

  • 不同初始盐分浓度下土壤盐结皮的形成过程 及其对蒸发的影响机理

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2022-08-08 合作期刊: 《干旱区地理》

    摘要:土壤盐结皮对土壤水文过程具有重要影响,初始盐分浓度(Initial salt concentration, ISC)的差异会对盐结皮的形成过程产生不同程度的影响,从而导致土壤蒸发的差异。但目前不同ISC下盐结皮形成过程对土壤蒸发的影响机理尚不明确。因此,通过试验模拟与理论分析相结合,动态监测及分析不同ISC下砂土的盐结皮形成、蒸发、土壤表面温度动态变化过程,以期阐明不同ISC下盐结皮形成过程及其对土壤蒸发的影响机理。结果表明:ISC越高,盐结皮在土壤表面出现的时间越早,覆盖率越大,且在同样光照强度和光照时间条件下土表温度增幅越小,蒸发量也越小;对数函数能较好地拟合不同ISC与累积蒸发量之间的关系(R2>0.90);随着ISC的增加,盐结皮对土壤蒸发抑制效率从24.14%(10 g·L-1)增大到71.99%(250 g·L-1)。ISC会显著影响盐结皮形成的过程,并通过影响土表温度的变化进而导致土壤蒸发出现巨大差异。

  • 农业元宇宙:关键技术、应用情景、挑战与展望

    分类: 农、林、牧、渔 >> 农业基础学科 提交时间: 2022-07-19 合作期刊: 《智慧农业(中英文)》

    摘要:元宇宙这一新兴概念受到了产学研各界的广泛关注。农业与元宇宙的结合将极大的推动农业信息化和智能化发展,为农业智能化转型长级提供新功能。为深入了解元宇宙在农业领域的应用研究进展,本文首先介绍了元宇宙的概念和关键技术,分析了行关键技术的原理,特点及其在元宇宙中发挥的功能。接着讨论农业元宇宙的在农业领域的作用,并阐述了国内外农业元宇宙在农业数字孪生与平行农业、虚拟农场、农业教学系统和农产品追溯系统领域的研究进展。最后总结了农业元宇宙面临的挑战并展望了农业元宇宙未来的发展方向本文可为农业元宇宙的应用研究提供指导作用。

  • Spatiotemporal variation and correlation of soil enzyme activities and soil physicochemical properties in canopy gaps of the Tianshan Mountains, Northwest China

    分类: 农、林、牧、渔 >> 林学 提交时间: 2022-07-18 合作期刊: 《干旱区科学》

    摘要:

    The study of the heterogeneity of soil enzyme activities at different sampling locations in canopy gaps will help understand the influence mechanism of canopy gaps on soil ecological processes. In this paper, we analyzed the spatiotemporal variation of soil enzyme activities and soil physicochemical properties at different sampling locations (closed canopy, expanded edge, canopy edge, gap center) in different sampling time (December, February, April, June, August, and October) on the northern slope of the Tianshan Mountains, Northwest China. The results showed that soil catalase, cellulase, sucrase, and acid phosphatase activities were relatively high from June to October and low from December to April, and most of soil enzyme activities were higher at closed canopy than at gap center. Soil urease activity was high during December–February. The soil temperature reached the highest value during June–August and was relatively high at gap center in October, December, and February. Soil water content was significantly higher in December and April than in other months. Soil bulk density was higher at gap center than at closed canopy in December. Soil pH and soil electrical conductivity in most months were higher at closed canopy than at gap center. Soil organic carbon, soil total nitrogen, and soil total phosphorus were generally higher at gap center than at closed canopy. Furthermore, sampling time played a leading role in the dynamic change of soil enzyme activity. The key factors affecting soil enzyme activity were soil temperature and soil water content, which were governed by canopy gaps. These results provide important support for further understanding the influence mechanism of forest ecosystem management and conservation on the Tianshan Mountains.

  • Characteristics of root pullout resistance of Caragana korshinskii Kom. in the loess area of northeastern Qinghai-Tibet Plateau, China

    分类: 农、林、牧、渔 >> 农业基础学科 提交时间: 2022-07-18 合作期刊: 《干旱区科学》

    摘要:

    Roots exert pullout resistance under pullout force, allowing plants to resist uprooting. However, the pullout resistance characteristics of taproot-type shrub species of different ages remain unclear. In this study, in order to improve our knowledge of pullout resistance characteristics of taproot systems of shrub species, we selected the shrub species Caragana korshinskii Kom. in different growth periods as the research plant and conducted in situ root pullout test. The relationships among the maximum pullout resistance, peak root displacement, shrub growth period, and aboveground growth indices (plant height and plant crown breadth) were analyzed, as well as the mechanical process of uprooting. Pullout resistance of 4–15 year-old C. korshinskii ranged from 2.49 (±0.25) to 14.71 (±4.96) kN, and the peak displacement ranged from 11.77 (±8.61) to 26.50 (±16.09) cm. The maximum pullout resistance and the peak displacement of roots increased as a power function (R2=0.9038) and a linear function (R2=0.8242) with increasing age, respectively. The maximum pullout resistance and the peak displacement increased with increasing plant height; however, this relationship was not significant. The maximum pullout resistance increased exponentially (R2=0.5522) as the crown breadth increased. There was no significant relationship between the peak displacement and crown breadth. The pullout resistance and displacement curve were divided into three stages: the initial nonlinear growth, linear growth, and nonlinear stages. Two modes of failure of a single root occurred when the roots were subjected to vertical loading forces: the synchronous breakage mode and the periderm preferential breakage mode. These findings provide a foundation for further investigation of the soil reinforcement and slope protection mechanisms of this shrub species in the loess area of northeastern Qinghai-Tibet Plateau, China.

  • Effects of the growing-maize canopy and irrigation characteristics on the ability to funnel sprinkler water

    分类: 农、林、牧、渔 >> 农业基础学科 提交时间: 2022-07-18 合作期刊: 《干旱区科学》

    摘要:

    Stemflow is vital for supplying water, fertilizer, and other crop essentials during sprinkler irrigation. Exploring the spatial and temporal variations of crop stemflow and its influencing factors will be essential to preventing soil water and nutrient ion's migration to deeper layers, developing, and optimizing effective sprinkler irrigation schedules. Based on the two-year experimental data, we analyzed the variation patterns (stemflow amount, depth, rate, and funneling ratio) of maize stemflow during the growing season, and clarified its vertical distribution pattern. Meanwhile, effects of sprinkler irrigation and maize morphological parameters on stemflow were investigated. The results showed that stemflow increased gradually as maize plant grew. Specifically, stemflow was small at the pre-jointing stage and reached the maximum at the late filling stage. The upper canopy generated more stemflow than the lower canopy until the flare opening stage. After the tasseling stage, the middle canopy generated more stemflow than the other positions. Variation in canopy closure at different positions was the main factor contributing to the above difference. As sprinkler intensity increased, stemflow also increased. However, the effect of droplet size on stemflow was inconsistent. Specifically, when sprinkler intensity was less than or equal to 10 mm/h, stemflow was generated with increasing droplet size. In contrast, if sprinkler intensity was greater than or equal to 20 mm/h, stemflow tended to decreased with increasing droplet size. Compared with other morphological parameters, canopy closure significantly affected the generation of stemflow. Funneling ratio was not significantly affected by plant morphology. Based on the results of different sprinkler intensities, we developed stemflow depth versus canopy closure and stemflow rate versus canopy closure power function regression models with a high predictive accuracy. The research findings will contribute to the understanding of the processes of stemflow involving the hydro-geochemical cycle of agro-ecosystems and the implementation of cropland management practices.

  • Assessment of drought and its impact on winter wheat yield in the Chinese Loess Plateau

    分类: 农、林、牧、渔 >> 农业基础学科 提交时间: 2022-07-18 合作期刊: 《干旱区科学》

    摘要:

    Drought has pronounced and immediate impacts on agricultural production, especially in semi-arid and arid rainfed agricultural regions. Quantification of drought and its impact on crop yield is essential to agricultural water resource management and food security. We investigated drought and its impact on winter wheat (Triticum aestivum L.) yield in the Chinese Loess Plateau from 2001 to 2015. Specifically, we performed a varimax rotated principal component analysis on drought severity index (DSI) separately for four winter wheat growth periods: pre-sowing growth period (PG), early growth period (EG), middle growth period (MG), and late growth period (LG), resulting in three major subregional DSI dynamics for each growth period. The county-level projections of these major dynamics were then used to evaluate the growth period-specific impacts of DSI on winter wheat yields by using multiple linear regression analysis. Our results showed that the growth period-specific subregions had different major DSI dynamics. During PG, the northwestern area exhibited a rapid wetting trend, while small areas in the south showed a slight drying trend. The remaining subregions fluctuated between dryness and wetness. During EG, the northeastern and western areas exhibited a mild wetting trend. The remaining subregions did not display clear wetting or drying trends. During MG, the eastern and southwestern areas showed slight drying and wetting trends, respectively. The subregions scattered in the north and south had a significant wetting trend. During LG, large areas in the east and west exhibited wetting trends, whereas small parts in south-central area had a slight drying trend. Most counties in the north showed significant and slight wetting trends during PG, EG, and LG, whereas a few southwestern counties exhibited significant drying trends during PG and MG. Our analysis identified close and positive relationships between yields and DSI during LG, and revealed that almost all of the counties were vulnerable to drought. Similar but less strong relationships existed for MG, in which northeastern and eastern counties were more drought-vulnerable than other counties. In contrast, a few drought-sensitive counties were mainly located in the southwestern and eastern areas during PG, and in the northeastern corner of the study region during EG. Overall, our study dissociated growth period-specific and spatial location-specific impacts of drought on winter wheat yield, and might contribute to a better understanding of monitoring and early warning of yield loss.

  • 湿地土壤气体排放对水位变化响应的持续性动态特征

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2022-06-08 合作期刊: 《干旱区地理》

    摘要:

    为探索湿地水位变化与土壤气体排放之间的关系,对黄河中游芦苇湿地进行了半注水和满注水样地处理后的动态监测,对比了7 d水位变化过程中土壤气体排放差异。结果表明:注水造成了土壤CO2排放速率的显著差异;随土壤温度上升,H2O、CO2、H2S排放速率都有上升趋势(满注水样地的H2O除外);半注水和满注水造成的影响,H2O排放速率表现为趋同-异步-消失的特征,在注水前期(63.73 h)半注水和满注水差异基本一致,后期差异较大,直至125.64 h后注水的影响才消失,总体分别造成H2O排放总量76.3%和31.3%的增加;CO2排放速率表现为异步-趋同的特征,注水初期环境的改变造成CO2排放的一致减少,37.69~68.66 h二者出现明显差异,68.66~125.64 h水位虽然恢复,但差异仍然存在,注水分别造成CO2排放总量50.1%和43.2%的减少;H2S排放速率表现为无变化-异步-无变化的特征,总体造成H2S排放总量42.3%和32.3%的增加。研究追踪了水位上升后土壤H2O、CO2和H2S排放速率变化的动态过程,其影响具有异步性和持续性的特点,CO2排放速率表现出较长的响应周期。研究结果对于河流湿地生态功能研究具有重要意义,湿地土壤气体排放对水位变化的响应滞后意味着对湿地生态功能的重要影响,其波动过程需要更长时段的精准研究。

  • 南疆盆地亏缺灌溉和覆膜对油莎豆 生物量及产量的影响

    分类: 农、林、牧、渔 >> 农、林、牧、渔业科学其他学科 提交时间: 2022-06-02 合作期刊: 《干旱区研究》

    摘要:

    研究南疆盆地油莎豆(Cyperus esculentus)滴灌覆膜的效果和最适宜的灌溉制度,为构建南疆盆地油莎豆节水高产管理栽培模式提供参考。通过1 a的试验,在覆膜(M)和不覆膜(NM)条件下,设置3种水分处理水平,即:CK 处理(对照,以当地常用灌溉量 5316.45 m3 ·hm-2 )、T1 处理(灌溉量为 3431.40 m3 ·hm-2)和 T2 处理(灌溉量为4133.85 m3·hm-2 ),灌溉频率为6~10 d,研究覆膜和水分控制对油莎豆生长、品质、产量和水分利用效率的影响。结果表明:(1)油莎豆的密度受水处理的影响显著(P0.05),而根冠比受水处理影响不显著(P0.05)。(2)覆膜处理的草粗脂肪、可溶性淀粉、可溶性糖含量比未覆膜平均提高58.82%3.35%17.20%,覆膜处理块茎的粗脂肪含量、可溶性淀粉、可溶性糖含量均高于未覆膜的,分别增加了7.48%2.56%2.55%,且水处理间差异不显著(P0.05),但是均在T2处理达到最大。(3)产量和水分利用效率随灌溉量增加呈先增加后降低的趋势,其中覆膜条件下,
    T2理的草和块茎的产量最大,分别为 3974.55 kg·hm-25253.85 kg·hm-2,较 CK 处理分别显著增加 6.45%36.95%P0.05),较未覆膜条件下,
    T2CK平均产量显著增加29.41%34.76%P0.05),水分利用效率也在T2处理达到最大值,其中覆膜处理下,草和块茎在T2处理的水分利用效率较CK显著提高38.63%34.33%P0.05);与T2(覆膜)处理相比,未覆膜条件下CKT2处理的草和块茎的水分利用效率分别显著提高38.91%34.33%P0.05),覆膜处理对草的水分利用效率差异不显著(P0.05),但是对块茎的水分利用效率差异显著(P0.05)。因此,在覆膜条件下,灌溉定额为133.85 m3· hm-2T2)时,不仅提高了油莎豆的品质和产量,也提高了水分利用效率,节约水资源。

  • 氮肥后移对花铃期水分亏缺棉花产量的补偿效应研究

    分类: 农、林、牧、渔 >> 农、林、牧、渔业科学其他学科 提交时间: 2022-06-02 合作期刊: 《干旱区研究》

    摘要:

    花铃期是棉花产量形成最关键的时期,为探究氮肥后移对花铃期水分亏缺棉花产量的补偿效应,以新路45号为供试材料,采用裂区试验设计,主区设定2个花铃期滴灌量:常规灌溉量2410 m3·hm-2 W1)为对照、亏缺灌溉量1668 m3·hm-2 W2);副区为3种花铃期施肥比例:N1(花期肥:铃期肥为33)、N2(花期肥:铃期肥为24)、N3(花期肥:铃期肥为42)进行探究。结果表明:(1)相同氮肥条件下,水分亏缺较正常灌溉处理的叶面积指数(LAI)、净光合速率(Pn)显著降低;(2)根据干物质积累Logistic模型,干物质最大积累速率(Vm)出现时间、干物质进入快速积累期时间拐点(t1)均有所提前、干物质快速积累持续时间(?t)有所延长,生殖器官干物质积累量及占比显著降低;(3)水分亏缺处理的单株铃数、单铃重较正常灌溉平均降低了11.7%45.6%,籽棉产量平均降低了17.3%,耗水量、氮肥偏生产力平均降低了35.49%15.97%,水分利用效率平均增加了16.77%。与正常灌溉相比,花铃期水分亏缺条件下,氮肥后移(N2)较N1N3处理的棉花LAIPn都有所增加,且表现为:N2>N1>N3;(4)氮肥后移(N2)处理下的干物质累积量、?tVm表现最优,干物质快速积累期特征值(GT)最为协调,棉花营养生长向生殖生长的转移率最高,为68.25%;(5)与N1N3处理相比,氮肥后移(N2)处理的棉花单株铃数、单铃重分别增加了10.40%16.02%8.41%11.61%,籽棉产量分别增加了7.32%13.88%,耗水量、水分利用效率、氮肥偏生产力均表现为:N2N1>N3。综上所述,氮肥后移通过提高棉花花期LAIPn、减缓盛铃后期的LAIPn的下降幅度,增加地上部分干物质积累量并提高了生殖器官所占比例,调控产量及其构成要素,以减轻水分胁迫对产量的影响。

  • 科技革命、颠覆性技术与智慧农业

    分类: 农、林、牧、渔 >> 农业基础学科 提交时间: 2022-05-23 合作期刊: 《智慧农业(中英文)》

    摘要:

    本文首先阐述了科技革命的概念与满足条件,提出并分析了内生及外生农业颠覆性技术及其差异,特别是提出了跨界技术的概念并论证了其对农业科技进步的外生影响。然后分析了作为跨界技术的集大成者——智慧农业技术的特点,智慧农业对传统农业生产技术与生产方式的替代以及智慧农业与农村经济转型的关系。在此基础上讨论了中国智慧农业发展所面临的问题。最后有针对性地提出了促进颠覆性技术创新和智慧农业发展的政策建议,包括加强关键颠覆性核心技术研发、改革现有的农业高等教育体系、推动跨界技术的农业产业化研发以及在高标准农田及规模化养殖场实施智慧农业生产等。

  • 基于通径分析的低营养水体环境中芽孢杆菌生长与氮转化影响因素研究

    分类: 农、林、牧、渔 >> 水产学 提交时间: 2022-05-18

    摘要:

    [目的] 芽孢杆菌在养殖水体等低营养水环境中氮的转化治理方面具有较高的应用价值,但受很多因素的影响,其中又数菌株特性和环境条件较为重要,然而目前对这两种因素的综合研究尚少,基于通径分析的低营养水体环境中芽孢杆菌生长与氮转化影响因素进行分析研究。

    [方法] 为此,选取2株芽孢杆菌NT9和YB3作为研究对象,通过平板法测定其水解酶活性和抑菌活性等特性,然后模拟配置了4种低营养水体环境,并应用通径分析方法研究菌株特性和环境条件对芽孢杆菌生长和氮转化作用的影响,如直接效应、间接效应和综合效应等。

    [结果] 结果显示,菌株NT9为枯草芽孢杆菌(Bacullis subtilis),与蜡样芽孢杆菌(B. cereus)YB3不同,具有较强的蛋白酶、淀粉酶活性以及抑菌活性,而纤维素酶活性较弱。同时又与菌株YB3相似,在低营养条件下菌株NT9也仅具有有机氮和氨氮降解作用,其中氨氮降解率可达89.3%。通径分析显示,模型的决定系数为0.55-0.95,其它主要的适配度指标也均符合判定标准。菌株的纤维素酶活性(cel)对大多数环境中菌株的生长(gro)以及有机氮、氨氮的降解(dtan)均具有显著的直接促进效应(P<0.001)。水体起始的菌量(iod)、有机氮含量(ion)、氨氮含量(itann)以及时间阶段(stage)等环境因素对grodtan也具有显著的直接影响(P<0.05),但仅限于某些特定的环境。菌株活性与环境因素之间也具有交互作用(P<0.05),对grodtan产生间接效应,增强或抵消直接效应,使某些因素表现出显著的总效应(P<0.05),但也导致其它因素的总效应不显著(P>0.05)。grodtan在某些环境中相互之间也具有直接的促进效应(P<0.001),并且也相互间接影响。研究表明,菌株特性和环境因素的综合作用对低营养水体中芽孢杆菌的生长和氮转化作用具有重要影响,但是在不同的环境中作用的方式不同。

    [结论] 因此,在实际应用中,可能需要结合菌株特性和环境条件拟定具体方案,如菌株、氮源的投加量和投加方式等,以达到更好的使用效果。

  • 淡化条件下生物絮团技术对凡纳滨对虾生长与水质的影响

    分类: 农、林、牧、渔 >> 水产学 提交时间: 2022-05-18

    摘要:

    [目的]为研究淡化条件下生物絮团技术对凡纳滨对虾成虾养殖的影响。

    [方法]在5‰盐度条件下,应用200L水体进行普通养殖(对照组)与生物絮团养殖(BFT组),放养密度90尾/m3,并测定两种养殖方式对虾生长指标与水质指标,以及分析养殖经济效益和污染物减排效果。

    [结果]结果显示,经过63d的养殖,BFT组对虾成活率(100%)和生产力(1.32 kg/m3)显著高于对照组(P<0.05),同时的对虾平均体重(13.20±1.64 g)、特定生长速率(4.26±0.20%/d)和饵料系数(1.09±0.14)等也均优于对照(P>0.05)。

    [结论]研究表明,淡化条件下采用BFT养殖凡纳滨对虾能够保持良好的水质,提高成活率,促进生长,降低饵料系数。

  • 芽孢杆菌特性对养殖水体氮转化作用的影响

    分类: 农、林、牧、渔 >> 水产学 提交时间: 2022-05-17

    摘要:

    [目的]研究养殖条件下菌株特性及水体环境对芽孢杆菌氮转化作用的影响。

    [方法] 测定了2株芽孢杆菌NT9和YB3的水解酶活性、抑菌活性和生长能力等特性,并对模拟养殖过程中的氮转化作用进行了通径分析。

    [结果] 结果显示,菌株NT9属于枯草芽孢杆菌(Bacullis subtilis),在低营养条件下也具有氨氮转化功能,去除率达89.3%,与菌株YB3相比,具有较强的蛋白酶、淀粉酶活性以及抑菌活性,但是生长能力较差。在模拟养殖水体中,2株菌对硝酸氮、亚硝酸氮、溶解氧、pH、碱度等水质条件影响不大,均能够促进有机氮降解,但氨氮转化效果较差,导致水体氨氮显著积累(P< 0.05)。通径分析显示,水体总菌量(cfu)是促进有机氮降解的主要因素,通径系数(直接作用)0.550(P< 0.01),菌株的纤维素酶活性(cel)和生长能力(gro)等都通过cfu对有机氮降解产生较大的间接作用;而微生物的生长增殖活动(总菌增量,dcfu)则是促进氨氮转化的主要因素,通径系数为-0.112(P< 0.01)。

    [结论] 研究表明,2株芽孢杆菌在养殖条件下均能够促进饲料蛋白的降解,但是氨氮转化效果不明显,根据通径分析结果,可以通过促进芽孢杆菌生长,对同步转化氨氮进行研究。

  • Effects of mixed-based biochar on water infiltration and evaporation in aeolian sand soil

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2022-05-09 合作期刊: 《干旱区科学》

    摘要:

    Abstract: Aeolian sandy soil in mining areas exhibits intense evaporation and poor water retention capacity. This study was designed to find a suitable biochar application method to improve soil water infiltration and minimize soil water evaporation for aeolian sand soil. Using the indoor soil column method, we studied the effects of three application patterns (A (0–20 cm was a mixed sample of mixed-based biochar and soil), B (0–10 cm was a mixed sample of mixed-based biochar and soil and 10–20 cm was soil), and C (0–10 cm was soil and 10–20 cm was a mixed sample of mixed-based biochar and soil)), four application amounts (0% (control, CK), 1%, 2%, and 4% of mixed-based biochar in dry soil), and two particle sizes (0.05–0.25 mm (S1) and <0.05 mm (S2)) of mixed-based biochar on water infiltration and evaporation of aeolian sandy soil. We separately used five infiltration models (the Philip, Kostiakov, Horton, USDA-NRCS (United States Department of Agriculture-Natural Resources Conservation Service), and Kostiakov-Lewis models) to fit cumulative infiltration and time. Compared with CK, the application of mixed-based biochar significantly reduced cumulative soil water infiltration. Under application patterns A, B, and C, the higher the application amount and the finer the particle size were, the lower the migration speed of the wetting front. With the same application amount, cumulative soil water infiltration under application pattern A was the lowest. Taking infiltration for 10 min as an example, the reductions of cumulative soil water infiltration under the treatments of A2%(S2), A4%(S1), A4%(S2), A1%(S1), C2%(S1), and B1%(S1) were higher than 30%, which met the requirements of loess soil hydraulic parameters suitable for plant growth. The five infiltration models well fitted the effects of the treatments of application pattern C and S1 particle size (R2>0.980), but the R2 values of the Horton model exceeded 0.990 for all treatments (except for the treatment B2%(S2)). Compared with CK, all other treatments reduced cumulative soil water infiltration, except for B4%(S2). With the same application amount, cumulative soil water evaporation difference between application patterns A and B was small. Treatments of application pattern C and S1 particle size caused a larger reduction in cumulative soil water evaporation. The reductions in cumulative soil water evaporation under the treatments of C4%(S1), C4%(S2), C2%(S1), and C2%(S2) were over 15.00%. Therefore, applying 2% of mixed-based biochar with S1 particle size to the underlying layer (10–20 cm) could improve soil water infiltration while minimizing soil water evaporation. Moreover, application pattern was the main factor affecting soil water infiltration and evaporation. Further, there were interactions among the three influencing factors in the infiltration process (application amount×particle size with the most important interaction), while there were no interactions among them in the evaporation process. The results of this study could contribute to the rational application of mixed-based biochar in aeolian sandy soil and the resource utilization of urban and agricultural wastes in mining areas.

  • Impact of rainfed and irrigated agriculture systems on soil carbon stock under different climate scenarios in the semi-arid region of Brazil

    分类: 农、林、牧、渔 >> 农业基础学科 提交时间: 2022-05-09 合作期刊: 《干旱区科学》

    摘要:

    Abstract: Understanding the dynamics of soil organic carbon (SOC) is of fundamental importance in land use and management, whether in the current researches or in future scenarios of agriculture systems considering climate change. In order to evaluate SOC stock of the three districts (Delmiro Gouveia, Pariconha, and Inhapi districts) in the semi-arid region of Brazil in rainfed and irrigated agriculture systems under different climate scenarios using the Century model, we obtained RCP4.5 and RCP8.5 climate scenarios derived from the Eta Regional Climate Model (Eta-HadGEM2-ES and Eta-MIROC5) from the National Institute for Space Research, and then input the data of bulk density, pH, soil texture, maximum temperature, minimum temperature, and rainfall into the soil and climate files of the Century model. The results of this study showed that the Eta-HadGEM2-ES model was effective in estimating air temperature in the future period. In rainfed agriculture system, SOC stock under the baseline scenario was lower than that under RCP4.5 and RCP8.5 climate scenarios, while in irrigated agriculture system, SOC stock in the almost all climate scenarios (RCP4.5 and RCP8.5) and models (Eta-HadGEM2-ES and Eta-MIROC5) will increase by 2100. The results of this study will help producers in the semi-arid region of Brazil adopt specific agriculture systems aimed at mitigating greenhouse gas emissions.

  • Soil carbon mineralization as affected by water content and nitrogen rate after ryegrass incorporated into soil

    分类: 农、林、牧、渔 >> 农艺学 提交时间: 2022-05-08

    摘要:

    Planting cover crop has been suggested as a way of increasing soil organic carbon in agricultural land. Ryegrass (Lolium multiflorum L.), as a cover crop, could improve soil fertility and lower soil CO2 emission. However, effects of soil water content and nitrogen on soil carbon mineralization after ryegrass incorporation are not fully understood. The present study was to investigate the effect of soil water content and nitrogen rate on soil carbon mineralization after ryegrass incorporated into upland red soil (Ferralsols). A laboratory experiment was established, including soil water contents [15% (W1), 30% (W2), 45% (W3)] and nitrogen rates [0 (N1), 60 mg/kg(N2), 120 mg/kg(N3)]. The results showed that the highest soil carbon mineralization accumulation was observed in W3N3. Nitrogen application inhibited carbon mineralization rate and accumulation in the late stage of ryegrass incorporation at W1, but increased carbon mineralization rate and accumulation at W2. With increasing soil water content, nitrogen application could improve soil carbon mineralization at the early stage of ryegrass incorporation. In conclusion, soil nitrogen and water content could regulate soil carbon mineralization. Considering to reduce the soil CO2 emissions, rational nitrogen application should be taken seriously during cover crop (ryegrass) incorporated into the upland red soil.

  • Variation of soil physical-chemical characteristics in salt-affected soil in the Qarhan Salt Lake, Qaidam Basin

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2022-03-24 合作期刊: 《干旱区科学》

    摘要:

    Soil salinization has adverse effects on the soil physical-chemical characteristics. However, little is known about the changes in soil salt ion concentrations and other soil physical-chemical characteristics within the Qarhan Salt Lake and at different soil depths in the surrounding areas. Here, we selected five sampling sites (S1, S2, S3, S4, and S5) alongside the Qarhan Salt Lake and in the Xidatan segment of the Kunlun Mountains to investigate the relationship among soil salt ion concentrations, soil physical-chemical characteristics, and environmental variables in April 2019. The results indicated that most sites had strongly saline and very strongly saline conditions. The main salt ions present in the soil were Na+, K+, and Cl–. Soil nutrients and soil microbial biomass (SMB) were significantly affected by the salinity (P<0.05). Moreover, soil salt ions (Na+, K+, Ca2+, Mg2+, Cl–, CO32–, SO42–, and HCO3–) were positively correlated with electrical conductivity (EC) and soil water content (SWC), but negatively related to altitude and soil depth. Unlike soil salt ions, soil nutrients and SMB were positively correlated with altitude, but negatively related to EC and SWC. Moreover, soil nutrients and SMB were negatively correlated with soil salt ions. In conclusion, soil nutrients and SMB were mainly influenced by salinity, and were related to altitude, soil depth, and SWC in the areas from the Qarhan Salt Lake to the Xidatan segment. These results imply that the soil quality (mainly evaluated by soil physical-chemical characteristics) is mainly influenced by soil salt ions in the areas surrounding the Qarhan Salt Lake. Our results provide an accurate prediction of how the soil salt ions, soil nutrients, and SMB respond to the changes along a salt gradient. The underlying mechanisms controlling the soil salt ion distribution, soil nutrients, and SMB in an extremely arid desert climate playa should be studied in greater detail in the future.

  • Integrating multiple electromagnetic data to map spatiotemporal variability of soil salinity in Kairouan region, Central Tunisia

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2022-03-15 合作期刊: 《干旱区科学》

    摘要:

    Soil salinization is a major problem affecting soils and threatening agricultural sustainability in arid and semi-arid regions, which makes it necessary to establish an efficient strategy to manage soil salinity and confront economic challenges that arise from it. Saline soil recovery involving drainage of shallow saline groundwater and the removal of soil salts by natural rainfall or by irrigation are good strategies for the reclamation of salty soil. To develop suitable management strategies for salty soil reclamation, it is essential to improve soil salinity assessment process/mechanism and to adopt new approaches and techniques. This study mapped a recovered area of 7200 m2 to assess and verify variations in soil salinity in space and time in Kairouan region in Central Tunisia, taking into account the thickness of soil materials. Two electromagnetic conductivity meters (EM38 and EM31) were used to measure the electrical conductivity of saturated soil-paste extract (ECe) and apparent electrical conductivity (ECa). Multiple linear regression was established between ECe and ECa, and it was revealed that ECa-EM38 is optimal for ECe prediction in the surface soils. Salinity maps demonstrated that the spatial structure of soil salinity in the region of interest was relatively unchanged but varied temporally. Variation in salinity at the soil surface was greater than that at a depth. These findings can not only be used to track soil salinity variations and their significance in the field but also help to identify the spatial and temporal features of soil salinity, thus improving the efficiency of soil management.

  • 努尔苏丹樟子松人工林土壤粒度组成特征研究

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2022-02-11 合作期刊: 《干旱区地理》

    摘要:

    为了揭示努尔苏丹不同林龄樟子松人工林对土壤粒度组成的影响,通过野外采样与室内分析相结合,分析了努尔苏丹周边不同林龄樟子松人工林土壤粒度与分形维数特征,研究了分形维数与土壤特性之间的关系。结果表明:(1)研究区土壤粒度组成以粉粒为主,砂粒次之,黏粒最少, 樟子松人工林的种植能够显著提升土壤表层细颗粒物质含量。不同林龄人工林深层土壤颗粒量差异不显著。种植樟子松人工林对土壤粒度的影响主要在表层区域。(2)土壤分形维数变化在 2.059~2.569之间,在人工林生长过程中分形维数呈现先增大后减小的趋势,并在种植年限为15 a 时达到最大。土壤分形维数与黏粒、粉粒具有正相关性,20 μm粒径是反映研究区人工林土壤分形维数的临界粒径。(3)研究区土壤分形维数与土壤有机质、全氮含量呈极显著正相关关系,土壤分形维数可以用来评价土壤的养分状况。研究结果可以为努尔苏丹人工林建设和生态恢复提供理
    论依据。