干旱沙漠区小麦田水肥管理效率模拟

干旱沙漠区小麦田水肥管理效率模拟试验研究结果表明,在干旱沙漠区30cm厚的黄河灌淤沙地中进一步降低灌溉标准至田间持水量的40%以下是可能的,更低的灌溉标准将有利于提高小麦的水分利用效率,并降低渗漏损失率.在目前施有效氮、磷、钾总量＜800kg/hm2的水平下,施肥差异不会导致水分渗漏、蒸发和小麦对水分利用比例的差异,但小麦籽粒产量随施肥量的增加而增加.0.12kg/m3的高肥水指数(有效氮、磷、钾施用总量/灌水总量)可获得近5500kg/hm2小麦籽粒产量和约0.74kg/m3的水分生产率.     

Negative and positive effects of topsoil biological crusts on water availability along a rainfall gradient in a sandy arid area

Drylands are regarded as highly sensitive to climatic changes. A positive relationship between rainfall and environmental factors (water availability for plants, productivity, species diversity, etc.) is often assumed for areas with an annual rainfall of 100–300 mm. This assumption disregards the fact that a climatic change in arid and semi-arid areas is not limited to climatic factors. This change is often accompanied by a parallel change in surface properties. The alteration of surface properties may have opposite effects on the water regime and ecosystem characteristics. Data on rainfall, runoff, soil moisture regime, and vegetation cover were collected at five monitoring sites in a sandy area along the Israeli–Egyptian border, where average annual rainfall varies from 86 to 160 mm. Data obtained show a decrease in water availability for perennial plants with increasing annual rainfall, clearly expressed by a lower survival of perennial plants in the wetter area. Results obtained cast doubt of the prevailing idea regarding the positive relationship between average annual rainfall and ecosystem characteristics. The findings are attributed to the decisive role played by the non-uniform properties of the topsoil biological crusts along the rainfall gradient considered. Under wetter conditions a thick topsoil biological crust develops. This crust is able to absorb large rain amounts, limiting thus the depth of rainwater infiltration and water availability for the perennial vegetation. A better water regime was found in the drier area, where a thin crust allows deeper water infiltration and water concentration by surface runoff. The process described may be regarded as a desertification process with increasing annual rainfall.     

荒漠区生物土壤结皮对土壤酶活性的影响

在干旱的沙漠生态系统中,生物土壤结皮对于沙丘的固定和土壤生物的维持起着相当重要的作用。土壤酶活性能敏感地指示土壤的恢复程度,是衡量沙区生态恢复与健康的重要生物学属性,而目前关于生物土壤结皮与土壤酶活性的关系研究很少。为探明生物土壤结皮对土壤酶活性的影响,以腾格里沙漠东南缘的人工植被固沙区生物土壤结皮覆盖的沙丘土壤为研究对象,根据固沙时间的不同将样地分为4个不同的区进行采样(57、49、32和22 a固沙区),以流沙区(0 a)和红卫天然植被区(100 a)为对照。研究表明:人工植被固沙区的藻-地衣结皮和藓类结皮均可显著提高土壤碱性磷酸酶、蛋白酶和纤维素酶的活性(p0.05);结皮类型显著影响土壤酶的活性,发育晚期的藓类结皮下土壤碱性磷酸酶、蛋白酶和纤维素酶的活性显著高于发育早期的藻-地衣结皮下土壤酶的活性(p0.05);固沙年限显著影响土壤碱性磷酸酶、蛋白酶和纤维素酶的活性,且与这三种土壤酶活性均存在显著的线性正相关关系(p0.05);目前,生物土壤结皮可显著提高0~20 cm土层碱性磷酸酶、蛋白酶和纤维素酶的活性(p0.05),且这种影响随土层的增加而减弱。而且,生物土壤结皮下土壤碱性磷酸酶、蛋白酶和纤维素酶的活性表现明显的季节变化,表现为夏季秋季春季和冬季。腾格里沙漠东南缘的人工植被固沙区生物土壤结皮的存在与演替提高了土壤酶的活性,生物土壤结皮有利于该区土壤及其相应生态系统的恢复。     

生物土壤结皮对荒漠区土壤微生物生物量的影响

为探明生物土壤结皮对土壤微生物生物量碳和氮的影响,以腾格里沙漠东南缘的人工植被固沙区生物土壤结皮覆盖的沙丘土壤为研究对象,根据固沙时间的不同将样地分为4个不同的区进行采样(55、47、30和20 a固沙区),以流沙区(0 a)和天然植被区(100 a)为对照。研究表明:人工植被固沙区的藻-地衣结皮和藓类结皮均可显著提高土壤微生物生物量碳(SMBC)和氮(SMBN)含量(p0.05),且固沙年限与SMBC和SMBN含量存在显著的正相关关系(p0.05);结皮类型显著影响土壤微生物生物量,藓类结皮下SMBC和SMBN含量显著高于藻-地衣结皮下SMBC和SMBN含量(p0.05);此外,生物土壤结皮可显著提高0~20 cm土层SMBC和SMBN含量(p0.05),且这种影响随土层的增加而减弱。而且,生物土壤结皮下SMBC和SMBN含量表现明显的季节变化,表现为夏季春季秋季。水热因子是决定土壤微生物生物量季节变化的主要因子,而生物土壤结皮通过调节土壤温度和湿度而影响土壤微生物生物量的季节变化。     

黄土区坡耕地土壤结皮对入渗的影响

黄土高原地区,坡面土壤水分是生态建设的关键问题。以黄土高原坡耕地人为管理方式为背景,在室内人工模拟降雨条件下采用等高耕作和人工掏挖两种措施,并且设计直线坡作为对照,研究不同耕作措施下土壤结皮的形成特征,同时从降雨-入渗的角度研究两种类型结皮(结构结皮和沉积结皮)对坡面土壤水分入渗的影响。研究结果表明:土壤结皮阻碍坡面土壤水分入渗,结皮坡面产流时间早,且土壤累积入渗量明显低于无结皮坡面;采用Kostiakov模型、Horton模型、蒋定生模型对坡面土壤水分入渗过程进行优化模拟的结果表明蒋定生模型适用于描述本研究坡面土壤水分入渗的特征;耕作措施造成的微地形对土壤结皮的类型有很大影响,在洼地径流携带泥沙堆积形成沉积结皮,地势较高处降雨雨滴直接打击形成结构结皮。研究两种类型结皮发现,沉积结皮相对于结构结皮密度高且孔隙度低,并且两种类型结皮对坡面土壤水分入渗的影响存在差异,沉积结皮平均减渗效应为37.13%,结构结皮平均减渗效应为19.79%,因此,沉积结皮更大程度影响坡面土壤水分入渗。     

Feasibility of cyanobacterial inoculation for biological soil crusts formation in desert area

Practical testing of the feasibility of cyanobacterial inoculation to speed up the recovery of biological soil crusts in the field was conducted in this experiment. Results showed that cyanobacterial and algal cover climbed up to 48.5% and a total of 14 cyanobacterial and algal species were identified at the termination of inoculation experiment; biological crusts' thickness, compressive and chlorophyll a content increased with inoculation time among 3 years; moss species appeared in the second year; cyanobacterial inoculation increased organic carbon and total nitrogen of the soil; total salt, calcium carbonate and electrical conductivity in the soil also increased after inoculation. Diverse vascular plant communities composed of 10 and 9 species are established by cyanobacterial inoculation on the windward and leeward surface of the dunes, respectively, after 3 years. The Simpson index for the above two communities are 0.842 and 0.852, while the Shannon-Weiner index are 2.097 and 2.053, respectively. In conclusion, we suggest that cyanobacterial inoculation would be a suitable and effective technique to recover biological soil crusts, and may further restore the ecological system.     

Differential hydrological response of biological topsoil crusts along a rainfall gradient in a sandy arid area: Northern Negev desert,Israel

Drylands are regarded as highly sensitive to climatic change. The putative positive relationship between average annual rainfall and runoff, assumed for areas between 100 and 300 mm ignores the fact that climatic change in drylands is not limited to climatic factors alone, but is often accompanied by a parallel change in surface properties. Data on rainfall, runoff and soil moisture regime were collected at five monitoring sites in a sandy area, along a rainfall gradient from 86 to 160 mm. Despite the uniform sandy substratum the frequency and magnitude of runoff declined with increasing annual rainfall. Under wetter conditions a thick topsoil biological crust develops. This crust is able to absorb and retain large rain amounts, limiting the depth to which water can penetrate, and therefore water availability for the perennial vegetation. In the drier area, the thin crust can absorb only limited rain amounts, resulting in surface runoff and deeper water infiltration at run-on areas. Our findings demonstrate the important role played by different types of biological soil crusts along the rainfall gradient considered, and question the generally held belief that higher rainfall necessarily leads to deeper water infiltration in sandy arid areas; and higher water availability for the perennial vegetation.     

西北干旱荒漠区典型露天煤矿不同下垫面风沙流特征

为揭示西北干旱荒漠区露天煤矿风蚀特征,选取该区域内具备代表性的典型露天矿区,对其不同场地下垫面进行分析,通过野外实地监测,分析了矿区不同下垫面风沙流特征。研究结果显示：随高度增加,块石植被低覆盖干燥（RLd）下垫面风沙流输沙量垂向特征表现为先依次递减后增加,其余下垫面则总体表现为随高度增加而减少;0.2 m为风沙流的主要输移层,砾石覆盖度、植被覆盖度与地表湿润度的增加,会有效降低风沙流水平通量。近地表土壤结构受大型机械循环作业活动变的疏松、风蚀物质粒径减小,同时因自身地表干燥,研究区近地表土壤风蚀可蚀性增加;水平通量在风季时期因人为干扰作用,沙尘加快了运移。在车工机械的影响下,矿内生产活跃区下垫面风沙流空间结构特征较其他下垫面出现向高层偏移的现象,主要开采区域风蚀程度严重,且人为干扰程度越强,偏移现象越明显。矿区周边沙地下垫面水平通量较大,地表可风蚀性质较强,受研究区盛行风及人为采矿导致地表凹陷等因素影响,该区域是矿区大粒径风蚀物质的主要来源地。因地表湿润度与植被覆盖度的增加,部分下垫面风沙流结构最优关系式为指数函数的形式,表现为随高度增加输沙量变化较急剧,其余下垫面风沙流结构最优关系式函数类型为幂函数。矿内主要开采活跃区下垫面的输移物质主要为极细粉沙,且主要粒径组风蚀物影响范围超过1.5 m,是造成露天矿区能见度下降的主要原因。研究成果可为西北干旱荒漠区露天矿区沙害防治提供理论依据和科技支撑。     

西北旱区石羊河流域作物耗水点面尺度转化方法的研究

基于DEM与GIS空间分析功能研究了石羊河流域主要农作物春小麦需水量ET_c的时空分异规律。根据8个气象站近50年气象资料,应用1998年FAO推荐的Penman-Monteith公式计算参考作物蒸发蒸腾量ET₀,由收集到的春小麦需水量试验资料获得多年平均作物系数K_c。近50年来流域上游的古浪、天祝春小麦全生育期ET_c呈微弱的增加趋势,中游的凉州区表现出极显著的减少趋势,其他站减少趋势不显著。确立了ET_c与海拔高度、纬度、坡向的多元回归关系,借助Arcview3.3、ArcGIS9.0与Visual Basic6.0软件实现了春小麦ET_c的空间尺度转换,并分析了石羊河流域25%、50%、75%三个不同水文年春小麦ET_c的空间变异情况。石羊河流域春小麦ET_c由山区向绿洲平原递增,多年平均值为270～591 mm。估计值与计算值相差在11.1%以内。     

沙漠地区麦田土壤养分运动特征

研究了干旱沙漠地区新垦沙地和耕种20年左右的灌淤土可溶性养分运动特征.结果表明,在小麦1个生长周期内土壤养分发生较大的衰减,表层养分呈梯级下降趋势,其明显吻合于灌溉周期;以灌溉导致养分淋溶造成土壤养分下降为主,以作物吸收利用造成土壤养分下降为辅.土壤下层存在养分截留层,当总灌水量由649mm(59mm/次)增至1998mm(111mm/次)时作物吸收利用养分量分别降低42%(沙土)和50%(灌淤土),土壤养分总消耗量分别减少40%(沙土)和49%(灌淤土).当灌水量太大时,许多土壤养分被水运移至土壤深层,致使作物难以吸收到这些养分.     

西北干旱区生态用地概念及其功能分类研究

阐明了西北干旱区生态用地概念与定义 ,并依据功能将其划分为人工型与自然型两大类。其中人工型生态用地包括农业绿洲型和城镇绿洲型 ,自然型生态用地包括自然保护区型、山区水源涵养林型、天然绿洲型、湿地型、荒漠植被型和夹荒地型 ,分析了每种类型生态用地服务于主体生态系统的功能。并指出该区近期生态用地的研究重点应集中于生态用地资源评价 ,掌握其数量、质量及其空间分布规律 ;确定生态用地在西北干旱区以及区内不同流域中所占合理比例 ;定量化研究生态用地与生态用水间的关系。     

干旱荒漠区土地利用变化对地表温度的影响

该文以Landsat TM 遥感影像为主要数据源,获取了宁夏中卫市沙坡头区1992年和2007年的土地利用信息;利用单窗算法反演了对应时期该区域的地表温度（LST）;据此分析了土地利用变化与地表温度变化之间的关系。结果显示：1）不同利用方式的土地的LST有显著差异,流动沙地的LST最高,其次是固沙用地、草原化荒漠等;2）过去15 a间,研究区内最为明显的土地利用变化方向是“草原化荒漠转变为农田”和“流动沙地转变为固沙用地”;3）“草原化荒漠转变为可灌溉农田”会导致LST明显下降,“草原化荒漠转变为压砂田”     

亏缺灌溉对中国西北干旱区棉花生长、水分利用特征和产量的影响

Water shortage is a key constraint to sustainable agricultural production in Xinjiang, Northwest China. To enhance the use efficiency of valuable irrigation water resources, a 2-year experiment(2010–2011) was conducted to quantify the response of cotton(Gossypium hirsutum L.) growth and yield to different degrees of deficit irrigation(DI) regimes; to determine the effects of DI on the characteristics of water use for cotton, seasonal water use, available soil water in the root zone, soil water depletion, evapotranspiration(ET)-based water use efficiency and irrigation-based water use efficiency, and to determine the best DI regime for optimal water-saving and yield output. The plots were irrigated at 100%(100ET), 85%(85ET), 70%(70ET), 55%(55ET) and 45%(45ET) of the regional ET of cotton in northern Xinjiang. The effect of DI irrigation on water use characteristics was evaluated by analyzing available soil water and soil water depletion in the root zone along with water use efficiencies of cotton. The study showed that the growth, water use characteristics and yield of cotton varied with irrigation regime. Seasonal ET and seed cotton yield were linearly correlated with irrigation amount. The second-order polynomial equation best approximated water-yield relationship of cotton in the study area.Cotton yield response factor was 0.65, suggesting limited water conditions were suitable for cotton cultivation. Economic evaluation of DI treatments confirmed that the yield loss was less than 10% under 70 ET and 85 ET, which was acceptable for greater sustainability.The results suggested that proper DI schemes were necessary for sustainable cotton production in the region. While irrigation at 85 ET was safe for high cotton yield, irrigation at 70 ET was a viable alternative under limited irrigation water availability.     

降雨对荒漠草原生物土壤结皮化学计量的影响

生物土壤结皮是干旱地区地表景观的基本组成部分,对生物地球化学循环具有重要影响。在中国北方荒漠化地区,生物土壤结皮化学计量在很大程度上是未知的,特别是降雨如何影响荒漠草原生物土壤结皮化学计量仍然不确定。该研究以自然降雨为对照,通过使用遮雨棚和喷灌系统控制降水输入,开展增水和减水处理野外控制性试验,研究降雨量对荒漠草原生物土壤结皮化学计量的影响。试验结果表明：1）减水处理增加了结皮层C∶N、C∶P和N∶P的比率,增水处理增加了结皮层下垫面C∶N、C∶P和N∶P比率;2）减水处理增大了结皮层与下垫面之间C含量的差异,同时减小了N和P含量的差异,增水处理增大了结皮层与下垫面之间N和P含量的差异,减水处理有利于结皮层C的积累,而增水后结皮层中磷的有效性降低;3）适宜的土壤水分条件促进了结皮层及下垫面土壤微生物生物量碳（Soil Microbial Biomass Carbon,SMBC）和土壤微生物生物量氮（Soil Microbial Biomass Nitrogen,SMBN）的积累,而过高的降雨量导致土壤养分损失,不利于SMBC和SMBN的积累。相对干旱的土壤环境有利于结皮层土壤C、N的富集,为土壤微生物呼吸提供较多的营养物质,有利于SMBC和SMBN的积累。总之,在中国北方荒漠化地区,生物土壤结皮和下垫面的C∶N∶P化学计量对降雨量有不同的响应。     

气候变暖对西北干旱区农业热量资源变化的影响

气候变暖将改变农业气候资源尤其是热量资源的时空分布。本文通过分析西北干旱区67个气象站点的气象数据,研究了西北干旱区近50年气温、积温、霜冻的变化特征与规律。结果表明,西北干旱区气温呈上升趋势,上升幅度为0.33℃.10a 1,高于全国平均水平,其中北疆增温幅度大于其他地区。年内变化上,冬季增温幅度最大。近50年,西北干旱区≥0℃、≥10℃积温变化率分别为67.8℃.10a 1和68.8℃.10a 1,≥0℃和≥10℃积温持续的时间也呈增加趋势,其中≥0℃积温持续天数的增加主要是由于结束日期的推迟引起的,而≥10℃积温天数的增加主要是因为初始日期的提前。研究区无霜期呈增加趋势,主要表现为初霜日的延迟和终霜日的提前,其趋势分别可达2 d.10a 1和1.4 d.10a 1,前者贡献略大。西北干旱区初霜出现日期的年际波动小于终霜日,终霜出现日期晚于≥10℃积温开始日期约10 d,且气温变暖的趋势并没有引起这一状况的改变,而多数站点≥10℃积温结束日期早于初霜开始日期。     

秸秆覆盖及播种方式对马铃薯耗水特性和产量的影响

为明确西北旱作雨养农业区不同秸秆带状覆盖种植模式下马铃薯耗水规律、水分利用效率及产量的变化规律,以地膜覆盖和露地种植(CK)为对照,设置4种秸秆带状覆盖模式(①种植带和覆盖带各40 cm、单行播种,②种植带和覆盖带各40cm、双行播种,③种植带和覆盖带各50cm、单行播种,④种植带和覆盖带各50 cm、双行播种),研究不同秸秆带状覆盖模式对旱地马铃薯耗水特性和产量的影响。结果表明:秸秆带状覆盖处理与CK相比,马铃薯薯块产量和水分利用效率平均分别显著提高34.0%、21.5%,分别平均较地膜覆盖显著降低31.3%、25.0%;其中40 cm覆盖种植结构产量和水分利用效率较50 cm覆盖种植结构分别明显提高4.5%和6.8%,双行播种较单行播种增产4.4%,二者水分利用效率无明显差异。秸秆带状覆盖条件下,播种—现蕾阶段的耗水量、耗水强度及耗水模系数平均较CK显著降低14.5%、15.2%、15.4%,平均较地膜覆盖显著增加20.9%、19.0%、31.5%;与CK相比,现蕾—块茎膨大阶段耗水量、耗水强度及耗水模系数无显著性差异,相比于地膜覆盖,则分别平均显著减少20.7%、22.2%、13.9%;块茎膨大—成熟阶段分别平均较CK显著提高51.7%、52.4%、50.0%。同时,相比于CK,单薯重、商品薯率分别显著提高17.3%、31.8%,单株结薯数和小薯率降低7.5%、17.6%。可见,秸秆带状覆盖栽培可通过降低现蕾前的耗水和增加块茎膨大后的耗水,一定程度上缓解马铃薯植株后期对水分的需求,延长块茎膨大后植株光合作用,提高有机物的积累量,从而提高薯块产量和水分利用效率。而秸秆带状覆盖中,单行种植以种植带∶覆盖带=40 cm︰40 cm最好,双行种植以种植带︰覆盖带=50 cm︰50 cm较适宜。     

Influence of relative surface age on hydraulic properties and infiltration on soils associated with desert pavements

Av horizons found in desert pavement environments are known to evolve pedogenically over geologic time. This study was conducted to determine whether increased pedogenic development of the Av (vesicular) horizon over relative time impacts the hydraulic properties of individual soil peds and the mechanism of infiltration as inferred by dye patterns. We examined peds from the Av horizons associated with desert pavements that mantled three different alluvial deposits with different relative surface ages (Qf5 (∼ 10 ka), Qf3 (∼ 50–100 ka), and Qf2 (∼ 10–50 ka)) and included an additional surface (Qf6 (∼ 4 ka)) for the dye studies. We hypothesized that increases in the development of the Av over time would lead to a more structured soil surface with greater potential flow between soil peds and lower hydraulic conductivity of the soil peds themselves. Results showed that average K_s and α of the Qf5 peds were significantly greater than estimated for the Qf2 and Qf3 peds. Although K_s was greater for the Qf5 peds, the steady-state infiltration rate was equal for the Qf3, Qf2, and Qf5 surfaces, perhaps indicating a reduction in matrix flow through soil peds and an increase in interped flow between soil peds.     

干旱荒漠地区苹果园地膜及秸秆覆盖的农业生态效应研究

试验研究地面覆秸秆、覆膜、覆膜 覆秸秆等节水措施对干旱荒漠地区苹果园土壤水分、温度和肥力等因子的效应及对苹果生长的影响结果表明 ,几种节水措施均有效提高 0～ 6 0cm土层土壤含水量 ,最大增幅出现在 5、6月份 ,与果树需水规律相一致 ,缓解了水分供需矛盾。覆膜、覆膜 覆秸秆处理有明显增温效应 ,覆秸秆则表现前期降温而后期增温的双重效应 ,并增加土壤有机质及速效氮、磷、钾含量 ,提高土壤肥力和改善土壤结构 ,其中覆秸秆处理土壤有机质含量增加 18 7% ,地面覆盖处理土壤容重降低 0 0 19～ 0 133g/cm3 ,1年生枝长增加 16 4 %～39 4 % ,叶面积增大 2 7～ 3 86cm2 ,单产增加 1710～ 2 4 6 0kg/hm2 ,果实可溶性固形物含量提高 0 9%～ 1 2 %。     

Soil surface disturbances in cold deserts: effects on nitrogenase activity in cyanobacterial-lichen soil crusts

Cyanobacterial-lichen soil crusts can be a dominant source of nitrogen for cold-desert ecosystems. Effects of surface disturbance from footprints, bike and vehicle tracks on the nitrogenase activity in these crusts was investigated. Surface disturbances reduced nitrogenase activity by 30–100%. Crusts dominated by the cyanobacterium Microcoleus vaginatus on sandy soils were the most susceptible to disruption; crusts on gypsiferous soils were the least susceptible. Crusts where the soil lichen Collema tenax was present showed less immediate effects; however, nitrogenase activity still declined over time. Levels of nitrogenase activity reduction were affected by the degree of soil disruption and whether sites were dominated by cyanobacteria with or without heterocysts. Consequently, anthropogenic surface disturbances may have serious implications for nitrogen budgets in these ecosystems.     

冬灌对冻融期干旱区荒漠绿洲农田土壤水热状况的影响

冬灌可显著改善土壤水热状况,对缓解"春旱"和促进农作物生长发育具有积极的影响。文章通过探究冻融期干旱荒漠区不同开垦年限的农田土壤水热变化特征,揭示冬灌对土壤水热变化及农田水量平衡的影响,为荒漠绿洲农田水分管理提供理论借鉴。研究选取了黑河中游荒漠绿洲过渡带新垦绿洲农田土壤和老绿洲农田土壤(灌耕风沙土和灌耕灰棕漠土),利用土壤温湿度监测仪(ECH_2O)测定的土壤含水量和土壤温度及模拟土柱测定的渗漏损失量,分析了冻融期土壤水热动态变化过程及冬灌对深层渗漏损失的影响。结果表明:老绿洲农田消融历时(26 d)显著长于新垦绿洲农田(12 d),新垦绿洲农田消融历时短不利于春季土壤水分的保持;且翌年土壤完全融化后,新垦绿洲农田浅层(0～40 cm)贮水量低于老绿洲农田;此外,160 mm的冬灌事件导致新垦绿洲农田深层渗漏量为老绿洲农田的4.1倍。新垦绿洲农田需考虑补充灌溉以保证春播作物正常出苗,老绿洲农田"蓄水保墒"生态效应优于新垦绿洲农田。因此,在干旱区荒漠绿洲过渡带农田水分管理中,需综合考虑深层渗漏和"冻后聚墒"效应,针对土壤质地差异实施动态的冬灌策略以保证灌溉水资源优化利用。