渭干河灌区潜水蒸发规律实验分析

依据渭干河灌区潜水蒸发实验场观测资料 ,分析了潜水蒸发随埋深、土质及气象条件下的变化规律 ,对潜水蒸发量进行了公式拟合。结果表明 ,对于壤土类 ,幂函数型和清华公式拟合较好。对于砾石和细砂 ,阿氏公式和清华公式拟合较好。研究结果在生产应用中有一定的实用价值。     

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

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.     

塔里木沙漠公路防护林土壤盐结皮化学特征及其对土壤蒸发的影响

盐结皮是广泛分布于塔里木沙漠公路防护林土壤表层的一个特殊层次,目前对其化学特征及其对土壤蒸发的影响尚无系统研究。文中对塔克拉玛干沙漠腹地不同定植年限防护林土壤盐结皮有机质含量、全盐量、八大离子含量和pH值进行了分析,并进行了盐结皮抑制土壤蒸发试验,结果表明:土壤盐结皮有机质含量随着防护林定植年限的增加而增加;全盐量、各离子含量、pH值均随着防护林定植年限的增加而逐渐降低。其中,全盐量均远高于流沙地;各离子含量与流沙地相比有不同程度的增加,Cl-、Na+和SO24-增加量最为明显,Mg2+、K+、Ca2+和HCO-3次之,CO23-含量极微且基本没有变化,pH值均呈碱性,定植11年防护林盐结皮pH值甚至低于流沙地;盐结皮可以有效的抑制土壤水分的蒸发。     

不同留茬覆盖模式对土壤蒸发和表层土壤含水量的影响

秸秆覆盖模式可显著影响土壤蒸发量和土壤含水量。本研究根据小麦机械收获的特点,设置不同的小麦留茬高度和覆盖量,研究了不同留茬高度和覆盖量组合对冬小麦收获后土壤表层含水量和土壤蒸发量的影响。试验结果显示冬小麦留茬高度0~35 cm对表层土壤含水量和土壤蒸发影响较小,而覆盖会明显改善土壤含水量和降低土壤蒸发量。当留茬高度为0~15 cm、田间剩余秸秆覆盖量为0.348~0.470 kg/m2时,试验期间(31 d)土壤累积蒸发量较无覆盖减少了16%~51%。考虑机收特点,建议小麦留茬高度为5~15 cm,其余残留碎杆覆盖在土壤表面,以减少土壤蒸发和提高水分利用效率。     

基于HYDRUS-1D的不同质地土壤入渗过程数值模拟

基于HYDRUS-1D软件,对不同土质(淤泥、粉砂壤土、砂质粘壤土)的灌溉方案进行了系统的数值实验,模拟灌溉结束时及灌溉结束24 h之后的土壤剖面含水量和土壤湿润锋的变化情况。结果表明:在不产生径流的情况下,灌溉结束24 h后土壤的含水量分布和湿润深度只与土壤种类和灌溉量有关,与灌溉速度无关;对透水性较好的土质,灌溉水分重分布明显,以粉砂壤土灌溉速率0.7 cm·h~(-1)和灌溉时间3 h为例,灌溉结束时和灌溉24 h后土壤湿润深度分别为9.2 cm和20.6 cm,有55.3%的灌溉水参加了水分重分布;土壤湿润深度与灌溉量之间存在线性关系,拟合直线的斜率介于5.15(淤泥)和5.95(砂质黏壤土)之间。     

干旱区潜水蒸发埋深及土质关系实验分析

潜水蒸发量是水资源分析评价中推算陆面总蒸发量的重要因素之一，尤其在缺乏资料地区更为重要。本文根据阜北农场地下水科研站多年积累的资料，在前人研究潜水蒸发的基础上，说明本地区潜水蒸发埋深与不同土质的关系及潜水蒸发量年内之间的变化规律。     

宁夏中部干旱带微咸水灌溉对砂土混合覆盖下土壤水盐运移的影响

通过实地布设微型蒸渗仪模拟研究了低(2.5 L)、中(3.7 L)、高(5.0 L)微咸水灌溉量对0%、20%、40%、60%、80%、100%砂土混合比的土壤水盐运移规律及动态分布。结果显示:在相同灌溉量条件下,当砂土混合比为20%～100%时,累计蒸发量减小幅度可达42.22%～83.07%,表层含水率减小幅度为0.91%～28.91%,而深层含水率减小幅度仅为-2.14%～19.25%,增大砂土混合比对减少累计蒸发量有明显促进作用且增加了深层土壤含水率,可提高农业效能;与之对应的深层土壤盐分累计增加,盐分含量增幅为8.41%～31.9%,且比值越大,峰值出现的时间可能越早,位置越往土层深处推移。表明在宁夏中部干旱带采用砂土混合覆盖可有效减少土壤水分蒸发,抑制盐分表聚,减弱微咸水灌溉对土壤产生的次生危害。     

Severe drought strongly reduces water use and its recovery ability of mature Mongolian Scots pine (Pinus sylvestris var. mongolica Litv.) in a semi-arid sandy environment of northern China

Trees growing in a semi-arid sandy environment are often exposed to drought conditions due to seasonal variations in precipitation, low soil water retention and deep groundwater level. However, adaptability and plasticity of individuals to the changing drought conditions greatly vary among tree species. In this study, we estimated water use (T_s) of Mongolian Scots pine (MSP; Pinus sylvestris var. mongolica Litv.) based on sap flux density measurements over four successive years (2013-2016) that exhibited significant fluctuations in precipitation in a semi-arid sandy environment of northern China. The results showed that fluctuations in daily T_s synchronously varied with dry-wet cycles of soil moisture over the study period. The daily ratio of water use to reference evapotranspiration (T_s/ET₀) on sunny days in each year showed a negative linear relationship with the severity of drought in the upper soil layer (0-1 m; P<0.01). The decrease in Ts induced by erratic drought during the growing season recovered due to precipitation. However, this recovery ability failed under prolonged and severe droughts. The T_s/ET₀ ratio significantly declined with the progressive reduction in the groundwater level (g_w) over the study period (P<0.01). We concluded that the upper soil layer contributed the most to the T_s of MSP during the growing season. The severity and duration of droughts in this layer greatly reduced T_s. Nevertheless, g_w determined whether the T_s could completely recover after the alleviation of long-term soil drought. These results provide practical information for optimizing MSP management to stop ongoing degradation in the semi-arid sandy environments.     

风速和秸秆覆盖对土壤水分蒸发影响的模拟试验研究

通过室内模拟试验方法,研究了不同风速(静风、0.5、1.5m/s)和秸秆覆盖量(0、4 120、8240kg/hm2)对土壤水分蒸发的影响.结果表明:(1)土壤水分蒸发受风速和秸秆覆盖的明显影响,当土壤含水量大于田间持水量的70%、覆盖量一定时(0、4120 kg/hm2)时,风速0 m/8与1.5 m/s之间的土壤日...     

生物结皮发育对地表蒸发过程影响机理研究

生物结皮的形成与发育显著改变了土壤地表特征及下伏土壤性质,对地表蒸发过程产生深远影响.但目前已有研究对生物结皮存地表蒸发过程中的作用仍存在很大争议.文中通过覆盖结皮和模拟降水的方法对土壤蒸发过程进行研究,以期初步揭示生物结皮发育影响地表蒸发过程的机理.结果表明:生物结皮主要通过结皮层对降水的截留和阻碍扩散作用及对下伏土...     

覆膜开孔条件下盐渍土壤的潜水蒸发及水盐运移特性

为研究地下水浅埋区不同覆膜开孔率盐碱土的潜水蒸发和水盐运动情况,在室内进行了土柱蒸发模拟试验(地下水埋深50 cm)。结果表明,与不覆膜相比,覆膜可显著降低潜水蒸发强度、减少潜水累积蒸发量,同时也有效减少了盐分在土表的积累量。蒸发结束时,开孔率分别为3.24%、9.97%和20.27%的潜水累积蒸发量与裸土相比分别减少了79.87%、74.19%和77.93%,土层深度5 cm范围内土壤电导率分别降低了36.93%、34.41%和35.16%,即覆膜开孔率 的差异对盐分累积的影响小于对潜水蒸发的影响。三种处理中,9.97%开孔率的土表积盐量和潜水蒸发量均相对较大。随着蒸发历时的增加,不同处理土壤含水量剖面的变化相对较小,但潜水蒸发强度却有所降低,这与蒸发过程中盐壳形成后反过来又抑制了潜水蒸发有关。其次,覆膜阻滞不同盐离子表聚的效果不同,其中Cl^-表聚作用受开孔率影响较大,而Na⁺和SO₄^2-表聚作用受开孔率影响不大。     

新疆平原非灌区自然植被生态耗水量的计算

本文以新疆平原非灌区为研究区域,该区域自然植被主要依靠汲取浅层地下水来满足其对水分的需求。通过TM卫星影像处理、水文地质调查手段查明了研究区域内各流域的包气带岩性、浅层地下水埋深和自然植被分布面积及覆盖率,应用GIS技术划定计算单元,利用典型地下水均衡试验场潜水蒸发蒸腾试验资料确定各计算单元的潜水蒸发系数和植被系数,进而计算出现状条件下研究区域自然植被生态耗水量为63.7762×108m3/a。     

电厂灰水排放对周边土壤化学组分的影响机理

以灞桥电厂灰水为研究对象,分析了电厂灰水排放对周围土壤化学成分的影响。结果表明:黄土比亚砂土对灰水的碱性具有较好的缓冲能力;亚砂土和黄土的主要阳离子(K+、Na+、Ca2+、Mg2+)溶出/沉积存在明显的区别,其中亚砂土的主要阳离子均呈溶出状态,使可溶性物质溶失,亚砂土的渗透性得到提高,增加了地下水水质恶化的风险性;黄土中Na+、Mg2+表现为溶出,而K+、Ca2+则呈现沉积状态;灰水长期排放,易使物质在土壤中沉积,阻塞孔隙,降低土壤导水率,将对土壤的结构产生不良影响。造成黄土与亚砂土主要阳离子溶出/沉积的主要原因,是土-水系统中物质溶解/沉淀和阳离子交换作用综合作用的结果。     

秸秆覆盖条件下冬小麦棵间蒸发规律研究

在大田条件下,研究分析多覆盖(覆盖量6 000 kg/hm2),少覆盖(覆盖量3 000 kg/hm2)和不覆盖处理对冬小麦棵间蒸发的影响,结果表明:冬小麦逐日棵间蒸发表现为10月中旬、3月下旬和6月上旬较大,多覆盖、少覆盖和对照三个处理逐日变化量和逐日累计量有相同变化趋势;三个处理日均棵间最大蒸发量均出现在灌浆～成熟期、最小值出现在越冬～返青期;覆盖处理对对照抑制率都是在播种～分集期最大,越冬～返青期最小;覆盖处理中,多覆盖抑蒸效果最好.     

不同麦秸覆盖量对夏玉米田棵间土壤蒸发和地温的影响

采用微型蒸渗仪(Micro-lysimeter)和曲管地温表观测了不同麦秸覆盖量下夏玉米田的棵间土壤蒸发和土壤温度,试验设置5个处理(秸秆覆盖量分别为0(对照)、1 500、4 500、7 500、10 500 kg/hm2),分析了不同秸秆覆盖量下夏玉米田棵间土壤蒸发和土壤温度的动态变化规律.结果表明,麦秸覆盖夏玉米田有效抑制了棵间土壤蒸发,平抑了地温的变化幅度;夏玉米生育期内,4种覆盖处理(由高覆盖量至低覆盖量)棵间土壤蒸发比对照依次减少了63.51%、60.98%、52.94%、34.07%,0～20 cm的地温平均日变幅比对照分别降低了3.14℃、2.93℃、2.32℃、2.02℃.麦秸覆盖处理的抑蒸稳温效应,促进了夏玉米生长,提高了夏玉米的产量和水分利用效率.     

库尔勒地区不同下垫面潜水蒸发昼夜变化特性研究

为研究新疆地区的潜水蒸发特性,开展了裸地(埋深1.0 m、1.5 m和2.0 m)、覆膜无作物(开孔率0.78%、2.4%和5.0%)以及种植棉花(埋深1.0 m、1.5 m和2.0 m)等三种下垫面条件的潜水蒸发试验,分别研究了昼夜、日间及夜间变化动态。研究表明,有作物比无作物潜水蒸发系数大,且随埋深的增加,两者潜水蒸发系数差异性减弱;三种下垫面条件共9种处理均表现为潜水夜间蒸发补给量大于白天蒸发补给量,且地下水埋深越大,裸地夜间潜水消耗与白天潜水消耗的比值有所降低,棉花地则是呈增加趋势,这与棉花蒸腾强度的昼夜变化不同有关。进一步分析表明,无作物种植时,潜水蒸发的日变化波动幅度较大,潜水蒸发主要消耗时段为2∶00~10∶00和18∶00~22∶00;有作物种植时,潜水蒸发的日变化较为稳定,其无明显主要消耗时段,只是在昼夜交替时(20∶00左右)发生较大幅度变化;白天尤其是午后,因强烈的太阳辐射使得土壤输水能力不能满足大气蒸发需求而导致毛管断裂,潜水蒸发量明显降低,平均降低0.66mm.h-1;夜间土壤的输水能力大于蒸发能力而使毛管恢复连通,从而促使潜水蒸发有所增强,平均增加0.26mm.h-1。     

Sulcotrione soil persistence and mobility in summer maize and winter wheat crops

Sulcotrione soil persistence in spring maize ( Zea mays L.) crops grown on a sandy loam soil was greater at pH 5·5 and 6·0 (soil half-life T _1/2≈58 days) than at pH 7·1 ( T _1/2 = 44 days). Sulcotrione was also applied as recommended on a summer maize crop at the five- to six-leaf growth stage, grown on a sandy loam soil. Sulcotrione soil half-life was 44 days, and the herbicide remained mainly in the 0- to 5-cm surface soil layer during the cropping period, in spite of the high water solubility and the heavy rains at the end of August; lower sulcotrione concentrations (10–18% of the total during the 2-month period after sulcotrione application) were detected in the 5- to 10-cm surface soil layer. The herbicide was applied pre-emergence to winter wheat ( Triticum aestivum L.) at four sites that differed in their soil texture and composition: loamy sand, sandy loam, loam and clay loam. Persistence was greater in the soils containing more organic matter. In soils having similar organic matter contents, persistence was lower in the soil containing more sand relative to loam and clay. During the winter crops, sulcotrione moved down to the 10- to 15-cm soil layer, in spite of the fact that the rains were lower in winter than in summer. Sulcotrione most generally was not detected in the 15–20 cm soil layer of the maize and winter wheat crops.     

农田灌溉模式下塔里木河流域地下水水位的变化分析——以塔里木河上游为例

根据1997、2000年的监测资料,分析了塔里木河上游地下水水位的时空变化,反映了不同的土地利用方式对地下水水位的影响。在农田灌溉模式下,在垂直河道方向上地下水水位的变化受到塔里木河干流水位、农田灌溉和潜水蒸发的影响。沿河道的横切方向上地下水位的变化与距河道距离成正相关,但具有明显的滞后反应,其滞后时间随垂直河道的距离增加而增加。干流水位明显影响地下水的范围为3.5km。农田灌水使地下水水位在3、11月份明显抬升,也在7月份时对地下水水位产生影响,使其抬升。潜水蒸发量随地下水水位的升高而增加,使地下水水位变化趋于缓和。     

GSPAC water movement in extremely dry area

Under an extremely arid condition,a PVC greenhouse was built on the top of Mogao Grottoes in gobi area.The results of 235-day constant extraction of condensed water on the greenhouse film and soil water content showed that 2.1 g/(m2·d) groundwater moved up and exported into the soil,and a phreatic water evaporation existed in the extreme dry area where the groundwater is buried deeper than 200 m.After a prolonged export,the soil water content in the greenhouse was not lower but obviously higher than the original control ones.According to the monitored parameters including relative humidity and absolute humidity of soil,and temperature outside and inside the greenhouse,it was found that there is the available condition and mechanism for the upward movement of groundwater,and also it can be sure that the exported water was not from the soil and atmosphere outside the greenhouse.Phreatic water,an important source for soil water,interacts with atmosphere moisture via soil respiration.Soil salinity also has important effects on soil water movement and spatial-temporal heterogeneity.The extremely dry climate,terrestrial heat and change of upper soil temperature are the fundamental driving forces of water transportation and phreatic water evaporation in the Groundwater-Soil-Plant-Atmosphere Continuum(GSPAC) system.     

生物炭对塿土持水能力的影响

通过连续6年定位试验,探究较长时间施用生物炭对土壤保水作用的影响,以期为塿土区水土保持和土壤改良提供理论参考。田间试验于2011年开始,设4个生物炭施用梯度：对照,不施生物炭（B0）;5 t·hm^-2（B5）;10 t·hm^-2（B10）;20 t·hm^-2（B20）。在2017年测定了土壤含水量、土壤基础理化性质和水分累积蒸发量等。结果表明：生物炭能够显著减小土壤容重、增加土壤孔隙度、饱和含水量和田间持水量,且随着生物炭施入量的增加,各指标变化幅度也增大,B20与B0处理相比,土壤容重减少了8.28%,毛管孔隙度增加了20.17%,饱和含水量与田间持水量分别增加了22.17%和14.86%;生物炭显著增加了土壤团聚体稳定性,B20与B0处理相比,土壤水稳性团聚体含量增加了19.00%,团聚体破坏率和不稳定团粒指数分别降低了11.34%和9.61%;生物炭还可有效抑制土壤水分的蒸发,B10和B20处理的土壤累积蒸发量分别比B0处理减少了7.45%和10.18%。结合逐步回归分析与通径分析发现,生物炭对土壤结构的改良是其促进土壤持水能力的主要原因。土壤孔隙度和有机碳含量是影响土壤饱和含水量的主要因子,影响土壤毛管持水量的主要因子为有机碳含量和土壤毛管孔隙度,而毛管孔隙度与水稳性团聚体含量则解释了绝大部分土壤田间持水量的变化。研究表明生物炭施用可以显著改良土壤结构,提升塿土持水性能,增加干旱半干旱地区土壤的蓄水保墒能力。