农牧交错带不同农田耕作模式土壤风蚀的风洞实验研究

在农牧交错带——内蒙古自治区太仆寺旗采集的土壤样品的风洞实验研究结果表明:耕作模式的不同导致土壤风蚀状况的差异。在深松、翻耕、翻耕碾碎、小麦茬10 cm、荞麦茬10 cm、胡麻茬10 cm与无残茬等7种耕作模式的风洞实验中,翻耕碾碎风蚀速率均值最大,达到124.8 g m-2 min-1,胡麻茬最小,为15.14 g m-2 min-1,前者是后者风蚀速率的8.24倍。7种耕作模式风蚀速率均值的大小顺序为:翻耕碾碎>无残茬>深松>荞麦茬>翻耕>小麦茬>胡麻茬。结合对不同耕作模式土壤风蚀速率与风速关系的进一步分析可定量揭示出:翻耕碾碎、无残茬模式防风蚀效果最差,胡麻茬、小麦茬、翻耕模式防风蚀效果最好,深松、荞麦茬防风蚀效果居中。本文结论对农牧交错带旱作农业增强农田防风抗蚀能力有借鉴意义。     

民勤绿洲区撂荒农耕地抗风蚀效果

通过风洞试验,在5个风速下对民勤绿洲区5种不同撂荒年限农耕地的土壤风蚀速率、0—20cm风沙流结构进行了模拟观测研究。结果表明:农耕地撂荒20年后土壤风蚀速率明显增加,撂荒30,40年土壤风蚀速率是其他处理的2.40～4.97倍。不同撂荒年限土壤风蚀速率均随风速的增大呈指数函数递增,但在撂荒30,40年条件下递增较快。风速为14m/s是民勤绿洲农田土壤风蚀加剧的转折点,当风速>14m/s时,农耕地撂荒20年后的土壤风蚀速率明显高于撂荒20年内。0—20cm内,农耕地撂荒20年内和撂荒20年后输沙率与高度分别呈负线性和负指数关系,农耕地撂荒20年内0—4cm输沙量和输沙量百分比(Q0—4/Q0—20)均低于撂荒30,40年。随着撂荒年限的延长,农田表层不可蚀性颗粒(粒径≥1mm的团聚体及粗砂砾)的含量明显降低,且土壤风蚀速率随不可蚀性颗粒含量的增加呈非线性降低趋势。因此,增强民勤荒漠绿洲区撂荒农耕地抗风蚀能力需适当减少撂荒年限。     

新疆策勒县新开垦农田地表蚀积变化

用插钎法结合气象数据对新疆维吾尔自治区策勒县开垦年限分别为2和1a农田地表进行风蚀风积观测,结果表明,沿主风向,防护林带前后0—3H(树高)内表现为风积,林前风积量明显大于林后风积量,防护林带之间中部主要以风蚀为主。红枣幼苗旁种植的冬小麦在一定程度上能有效地抵御红枣根部风蚀。未开垦的植被盖度3个不同的下垫面内,植被盖度和高度越大,其阻沙积沙能力越强。由于新开垦未种植裸荒地地表疏松无植被覆盖,表现出同阶段内最大的地表风蚀量。新开垦农田地表蚀积变化不仅与植被覆盖度、防护林结构、风速大小与风向紧密相关外,还与地表的微地形有关。     

土壤凝结剂沙障防风固沙实验研究

 在7m/s、15m/s和20m/s的实验风速下,对不同浓度土壤凝结剂处理的沙障模型进行风洞吹蚀实验。实验结果表明:抗风蚀强度以40%浓度处理最强,20%最弱,但30%浓度防风蚀效果较为实用。在乌兰布和沙漠东北缘绿洲边缘的流动沙丘,采用较为适用的30%浓度的土壤凝结剂进行1m×1m,1.5m×1.5m,2m×2m等3种不同规格沙障喷洒实验,通过对风速、粗糙度、风沙流结构特征值,以及沙障的蚀积状况进行调查,其结果表明,各种规格的沙障中,1m×1m的沙障性能最好,1.5m×15m次之,2m×2m最差。沙丘不同部位沙障的抗蚀力不同,迎风坡受损程度和风蚀率最高。     

甘肃河西冬小麦保护性耕作对土壤风蚀影响的风洞试验研究

土壤风蚀是指松散的土壤物质被风吹起、搬运和堆积的过程以及地表物质受到风吹起的颗粒的磨蚀过程,其实质是在风力的作用下,表层土壤中的细颗粒和营养物质的吹蚀、搬运与沉积的过程。我国受土壤风蚀及土地沙漠化影响的面积占国土总面积的1/2以上,主要分布于北方干旱、半干旱地区。甘肃河西走廊是我国荒漠化最严重的地带之一,该地区春小麦种植长期采用铧式犁翻耕是导致该地区农田土壤风蚀的主要原因。通过室内风洞试验揭示了冬小麦保护性耕作措施条件下风蚀量、起动风速、风速廓线、地表粗糙度的差异及相关关系。结果表明,各个处理风蚀量、起动风速均高于对照处理,风蚀量与风速存在幂函数关系,16 m s-1风速是土壤风蚀程度由轻变重的一个转折点;在距土样表面5~50 mm范围内,随着高度的递增免耕秸秆覆盖(NTS)、免耕不覆盖(NT)处理较秸秆翻压(TIS)、传统耕作(T)处理风速增加缓慢,每个处理高度(H)与风速(V)遵循指数函数。NT、NTS处理与对照(SWT)的粗糙度K的差异在0.01水平上达到了极显著,TIS处理与对照(SWT)在0.05水平上差异显著,而T处理与对照(SWT)差异不显著。风蚀率(Q)与地表粗糙度(K)之间存在显著负相关关系。起动风速与地表粗糙度存在显著负相关关系。     

民勤绿洲不同耕作方式农田表层土壤风蚀规律的风洞模拟研究

[目的]比较分析不同耕作方式下农田表层土壤防风蚀机理和效果,为区域社会经济和生态环境建设提供科学依据。[方法]利用室内风洞及相关配套设备对甘肃民勤绿洲区的免耕、少耕、秋翻和深松农田表层土壤进行风蚀测试,计算风蚀速率及输沙率,研究其风沙运动规律,分析各种耕作农田表层土壤防风蚀情况。[结果]耕作措施对土壤风蚀速率的影响与风速大小相关,风速较小时,不同耕作方式对风速的影响差异不显著,而当风速大于14 m/s后不同耕作农田表层土壤风蚀速率开始出现较明显差异;少耕、秋翻、深松等耕作方式对农田表层土壤风蚀速率和输沙率的影响差异不明显;免耕耕作方式下农田表层土壤风蚀速率和输沙率最低,风速越高,差距越大;风速、耕作以及两者交互作用对农田表层土壤风蚀速率和输沙率有极显著影响。[结论]免耕耕作能有效抵抗农田表层土壤的风蚀,大幅度减少输沙率,表现出极佳的抗风蚀效果。     

河西绿洲灌区春小麦留茬免耕的防风蚀效应研究

通过风洞模拟试验,对不同留茬高度(20 cm和40 cm)和不同留茬方式(立秆留茬和留茬收后压倒)下的土壤风蚀量和不同处理在25～250 mm高度内的风速廓线进行定量测定,并分析土壤风蚀速率与风速的关系.结果表明,高立秆留茬免耕处理在吹蚀风速20m˙s-1以下时对土壤的防风蚀作用存在显著影响.立秆留茬40 cm的风蚀速率比传统耕作降低87.84%,比相同留茬量的压倒留茬处理降低5.89%,表现为最小风蚀速率,且对吹蚀风速的减弱作用最强,防风蚀效果最好.进一步研究表明,传统耕作的土壤风蚀速率(Q)与风速(V)呈幂函数关系,而免耕处理的土壤风蚀速率(Q)与风速(V)遵循二次函数关系.     

东北黑土地土壤风蚀风洞模拟试验研究

东北黑土区耕地土壤疏松,抗侵蚀能力弱,在大风天气下易产生土壤风蚀.针对东北黑土区突泉县农田黑土风蚀过程中主导因子对风沙流结构及风蚀量的影响特征进行风洞模拟试验.研究表明:黑土风沙流风速廓线呈对数函数分布,风沙流中土壤颗粒运动对风速的影响主要集中在80 mm高度以内,黑土风沙流断面风蚀物含量随高度增加呈指数递减趋势;随风速增大黑土风沙流高度呈对数递增;黑土土壤风蚀量随风速增大呈指数递增趋势.得出黑土风蚀的临界表层土壤(2 cm深度内土壤)含水量为7％,表层土壤含水量大于7％的地表难以发生风力侵蚀;风蚀量与土壤表层含水量在临界土壤含水量范围内符合对数分布;黑土土壤风蚀强度随风速增大呈幂函数递增.     

施用PAM防治松散土风蚀的机理及其抵御风沙流能力研究

采用室内风洞试验方法,研究了内蒙古西部干旱半干旱地区荒漠沙地松散土风蚀规律、风沙流对风蚀量的影响和施用PAM防治松散土壤风蚀的机理及其抗风沙流的能力。风沙流对风蚀量的影响试验,采用试样接续放置的方法,前一试样为后一试样提供风沙流;施用PAM试样抗风沙流的能力试验,采用PAM使用量为1g/m2,2 g/m2和4 g/m2等3个处理水平和0,17.6%,36.4%,7.7%等4个吹角水平。试验结果表明,相同的风速条件下风沙流对土壤的侵蚀程度比净风侵蚀程度高得多,侵蚀量显著不同;PAM用量为1 g/m2时,在7~8m/s风速的风沙流作用下只能经历5~10 min的吹蚀试样即破坏;PAM用量为2 g/m2时可以抵御8~10 m/s风速的风沙流历时30 min的吹蚀;PAM用量达4 g/m2时,可以抵御10 m/s风速的风沙流历时30 min的吹蚀试样仍未破坏,几乎可以防止自然界99%的各级风速所引起的土壤风蚀。从经济方面考虑,推荐PAM用量为2g/m2可以防止自然界中大部分风力(约97%~99%)造成的风蚀,经济上是可行的。经PAM处理的试样破坏过程和切片分析得出,在松散土表面喷施PAM之所以能够有效地防止风蚀,最根本的原因是施用PAM溶液后松散土表面可形成较厚的结皮。     

科尔沁沙地不同风沙土的风蚀特征

通过风洞实验，研究了科尔沁沙地两种典型风沙土的风蚀特征。流动沙丘土样和农田土样的风蚀率随风速的增加均呈幂函数关系增长。风干的农田土样在风速3．7m／s时开始出现风蚀现象，但流沙土样的临界起沙风速是4．3m／s。在低风速段．农田土样的风蚀率大于流沙土样，但当风速增加到大约5．7m／s以上时，流沙土样的风蚀率开始大于农田土样，并且差值随风速的增加而加大。两种土样的风蚀率随土样含水率的增加呈负幂函数关系迅速减小。但流沙土样风蚀率的减小要比农田土样更迅速。流沙土样的临界起沙风速随含水量的增加呈线性关系增长，而农田土样的临界起沙风速随含水量的增加呈二次幂函数关系增长。两种风沙土在风蚀特征方面的差异，主要是由质地不同引起的。增加土壤含水量，是本地区风季减小风蚀的有效方法。     

利用PAM防治松散扰动沙土风蚀效果的风洞试验研究

翻耕农地和建设工地的扰动松散土是沙尘的重要来源。防止扰动土风蚀是保护生态环境的重要内容。该研究通过室内风洞模拟试验，研究了PAM对于提高松散扰动土起动风速、防止风蚀的效果。试验分别采用0°、10°、20°、30°不同的吹角，地表处理为：喷施PAM（用量分别为0.5，1，2，4 g/m²）、喷施清水和未加处理的自然松散扰动（沙）土。试验结果表明：通过表面喷洒PAM溶液可以显著地提高松散扰动土的起动风速，达到控制风蚀的目的；仅喷洒清水处理也可以在一定程度上提高沙尘的起动风速，但其效果甚微；如果松散(沙)土喷施PAM的表面不被扰动（无裂纹），用于松散土风蚀防治时PAM用量控制在1 g/m²以上就可以有效防止风蚀发生，试样经受风速为14 m/s左右的大风、历时30 min而未产生风蚀。     

用气象数据估算固定和半固定沙地的起沙速率

Taibus County, Inner Mongolia, China, lies in a farming-pastoral ecotone, where severe wind erosion and various aeolian sand hazards are prevalent and fixed and semi-fixed sand dunes occur frequently. This study was conducted to investigate the relationships between sand transportation rate and wind speed for the fixed and semi-fixed sand dunes based on field measurements. The annual quantity of soil erosion by wind was estimated using meteorological wind data. The results indicated that the sand transportation rate in Taibus County in 2000 was 57.38 kg cm-1 year-1 for the semi-fixed dunes and 4.56 kg cm-1 year-1 for the fixed dunes. The total duration of erosive winds covered 12.5% of the time of the year, and spring posed the highest potential of sand transportation. Wind with low speed (≤17 m s-1) and high frequency plays a dominant role in sand transportation, while strong wind (≥17 m s-1) with low frequency significantly enhanced the sand transportation. Erosive wind speed, directions, and frequency were three crucial dynamic factors influencing sand hazards in the farming-pastoral ecotone. The dominant factors intensifying sand and dust storms in Taibus County might be related to the favorable wind condition in combination with the durable drought, which led to land desertification and vegetation degradation.     

Effect of particle-size distribution on wind erosion rate and soil erodibility

Wind erosion is a serious problem, especially in arid and semi-arid regions. This study was conducted to assess the effects of wind speed as well as soil particle-size distribution on erosion rate (ER) using a wind tunnel. For this purpose, two clay loam soil samples (C2 and C10) in addition to a sandy clay loam (S2) were exposed to different wind velocities of 2, 9 and 18 m s^?1. The result showed that erosion rate increased significantly with increasing wind speeds. In addition, a critical diameter of 0.84 mm for soil particles was supported; for larger particles the changes in erosion rate were negligible. Furthermore, soil erodibility (K) was determined, which for S2, C2 and C10 was 57.73, 10.27 and 1.43, respectively. To predict soil erodibility, a power relationship as K = 3.382 MWD^?1.732 (R ² = 0.99) was established. The results indicated with increasing wind speed, the sensitivity of S2 remained constant, whereas C2 and C10 resisted wind speed. The finding of this research indicates the importance of particle-size distribution on wind erosion rate as well as soil erodibility.     

延怀盆地不同土地利用类型土壤风蚀物特征

研究延怀盆地典型土地利用类型地表土壤风蚀物分布特征,可为了解该区域风蚀过程、改善生态环境提供数据支撑。以怀来县为研究对象,采用野外监测和室内分析相结合的方法,分析了葡萄、果桑、欧李、玉米免耕、玉米翻耕5种土地利用类型在冬季休耕期(上年11月—次年2月)和春季备耕期(3—5月)风蚀物质量、粒径及碳氮含量随高度的变化特征。结果表明:(1)欧李与玉米翻耕地土壤风蚀物质量分数垂向分布遵循幂函数递减规律; 果桑、葡萄与玉米免耕地土壤风蚀物质量分数在监测高度范围内随高度增加无规律性变化。(2)春季备耕期5种土地利用类型输沙通量均高于冬季休耕期。(3)冬季休耕期5种土地利用类型风蚀物的粒径范围集中分布在500～2 μm; 春季休耕期5种土地利用类型风蚀物的粒径范围集中分布在250～2 μm。(4)5种土地利用类型冬季休耕期风蚀物碳氮含量高于春季备耕期。风蚀物质量、碳氮含量及粒径的垂直分布受土地利用类型和人为活动的影响,其中人为活动对输沙通量影响较大,因此在该区域土壤风蚀防治过程中可以采用构建防风草篱、合理调整土地利用布局的方式,达到降低近地表风速、拦截风沙的作用。     

A New Assessment of Soil Loss Due to Wind Erosion in European Agricultural Soils Using a Quantitative Spatially Distributed Modelling Approach

Field measurements and observations have shown that wind erosion is a threat for numerous arable lands in the European Union (EU). Wind erosion affects both the semi‐arid areas of the Mediterranean region as well as the temperate climate areas of the northern European countries. Yet, there is still a lack of knowledge, which limits the understanding about where, when and how heavily wind erosion is affecting European arable lands. Currently, the challenge is to integrate the insights gained by recent pan‐European assessments, local measurements, observations and field‐scale model exercises into a new generation of regional‐scale wind erosion models. This is an important step to make the complex matter of wind erosion dynamics more tangible for decision‐makers and to support further research on a field‐scale level. A geographic information system version of the Revised Wind Erosion Equation was developed to (i) move a step forward into the large‐scale wind erosion modelling; (ii) evaluate the soil loss potential due to wind erosion in the arable land of the EU; and (iii) provide a tool useful to support field‐based observations of wind erosion. The model was designed to predict the daily soil loss potential at a ca. 1 km² spatial resolution. The average annual soil loss predicted by geographic information system Revised Wind Erosion Equation in the EU arable land totalled 0·53 Mg ha⁻¹ y⁻¹, with the second quantile and the fourth quantile equal to 0·3 and 1·9 Mg ha⁻¹ y⁻¹, respectively. The cross‐validation shows a high consistency with local measurements reported in literature. © 2016 The Authors. Land Degradation and Development published by John Wiley & Sons, Ltd.     

Effectiveness of Fly Ash and Polyacrylamide as a Sand-Fixing Agent for Wind Erosion Control

Searching for an effective and economical sand stabilization measure has an important significance in wind erosion control. Wind tunnel experiments were conducted to evaluate the sand-fixing effect of fly ash (FA) at three different application rates (10, 20, and 30?% (w/w) soil). The additional effect of polyacrylamide (PAM) was also studied under two different application rates (0.05 and 0.1?% (w/w) soil) on the basis of the optimum FA usage. The results indicated that the utilization of FA increased the threshold wind speed of the treated soil significantly, which was further increased by the addition of PAM. The soil treated with 20?% FA could most effectively withstand the pure wind with a wind speed of 8?m?s^?1 for 10?min, while only the slightest wind erosion occurred after exposure to the sand-carrying wind with a wind speed of 8?m?s^?1 for 10?min. However, moderate wind erosion occurred after exposure to both the pure wind and the sand-carrying wind with a wind speed of 14?m?s^?1 for 10?min, respectively, and there was a decline in the wind erosion rate with the increase of FA application rate. The soil treated with 20?% FA and 0.05 or 0.1?% PAM could effectively withstand the pure wind with a wind speed of 14?m?s^?1 for 30?min, while only the slightest wind erosion occurred after exposure to the sand-carrying wind with a wind speed of 14?m?s^?1 for 30?min. The combination of a 20?% FA and 0.05?% PAM application rate is recommended to give effective and economical wind erosion protection.     

Effects of vegetation pattern and of biochar and powdery soil amendments on soil loss by wind in a semi-arid region

Dust emission from wind erosion is a widespread phenomenon in arid and semi-arid areas having considerable implications for ecosystems and human well-being. However, few studies have examined the efficiency of biochar amended to soil on wind erosion control. Aimed at studying the effect of biochar on resistance of soils against wind erosion, a wind tunnel experiment was conducted. We tested (a) soils amended with hard waste walnut wood biochar and soft maize cob biochar, and (b) soils amended with powdery waste wood and powdery maize cob, and compared them with (c) non-treated soil, in their susceptibility to wind erosion and also the additional effect of various patterns of vegetation cover. Amending soil with biochar and powdery material did significantly increase their resilience to wind erosion because of increased soil aggregation. In comparison with the non-treated control, the mass flux of un-vegetated soil reduced from 4.42 to 1.86 g m⁻² s⁻¹ for the waste walnut wood biochar, from 4.28 to 1.50 g m⁻² s⁻¹ for maize cob biochar, from 4.11 to 1.44 g m⁻² s⁻¹ for powdery maize cob and from 3.97 to 1.14 g m⁻² s⁻¹ for powdery waste walnut wood. When combining amendments with vegetation, there was still a substantial improvement, though the soil treatments responded differently in terms of soil loss to different vegetation patterns. A single row vegetation pattern had the highest mass flux, while a zigzag vegetation pattern had the lowest. In conclusion, waste wood or maize cobs, whether applied as biochar or as powdery material, are able to fix soil and reduce wind erosion.     

风蚀作用下农田土壤碳损失的估算

农业生态系统土壤碳库是陆地生态系统碳库的重要组成部分,具有巨大的固碳潜力,成为当前国际研究的热点。风蚀作为土壤侵蚀的形式之一,是在风力作用下对地表物质进行迁移,成为土壤表面碳损失的动力之一。通过野外调查采样、风洞试验,结合青海共和盆地沙沟河流域气象资料,研究沙沟河流域农田土壤碳密度、碳库及在风蚀作用下土壤碳损失量。结果表明,沙沟河流域农田0-20cm土壤碳密度约为47.56t/hm²,碳库约为139.19×10⁴t,年平均土壤碳损失为2.47×10⁴t。分析表明,人为因素对农田土壤碳密度产生一定的影响。风蚀作用成为沙沟河流域土壤碳损失不可忽视的动力之一。     

甘肃秦王川灌区种植豆禾混播牧草的农田生态保育效应

以裸地(CK)、种植小麦(Triticum aestivum)和苜蓿/无芒雀麦(Medicago sativa/Bromus inermis)豆禾混播牧草地为研究对象,通过测定地表植被特征指标、土壤风蚀量及理化性质等指标,探究秦王川灌区农田风蚀规律及种植春小麦和牧草对土壤及养分流失的影响。结果表明:农田表土损失呈秋末冬初流失较多,冬季较少,春季又明显增强的"U"形曲线模式,从9月至翌年6月,出现2个风蚀高峰期(9—11月和3—5月);耕地裸露造成表土年均流失1.7 kg/m~2,即每年被风吹蚀1.3 mm厚表土,土壤有机质损失236.2 kg/hm~2,而种植小麦和牧草后在地表植被(根茬)覆盖作用下表土流失减少20.1%和52.3%,有机质损失减少12.2%和50.7%;由于风蚀季牧草植被(根茬)的盖度、高度和地表生物量均较小麦大,使得牧草地的地表粗糙度和湿度及表土(0—5 cm)含水率较小麦地高,从而造成土壤和有机质流失较小麦地少;相关和回归分析显示,地表植被特征指标与地表粗糙度和土壤含水率间呈显著正相关,而与地表土壤和有机质流失量呈极显著负相关;植被盖度每提高1%,将使表土和有机质流失减少4.1 g/m~2和59.3 mg/m~2,地表生物量每提高1 g/m~2,将使表土和有机质流失减少2.3 g/m~2和34.0 mg/m~2;春季春播小麦地的表土流失量与裸地相同,而种植多年生豆禾混播牧草可显著减少表土流失和有机质损失。综合以上,甘肃灌区农田春季播种农作物易引起土壤退化,而种植多年生豆禾混播牧草可实现农田生态保育,从而提高耕地质量和区域环境质量。