黄土坡耕地地表微地形空间变异性研究

以黄土高原普遍采用的人工锄耕、人工掏挖和等高耕作等管理措施的坡耕地为研究对象,利用半方差方法分析了不同耕作措施下坡面相对高程空间变异结构特征,以期为开展数值模拟坡面微地形的研究提供理论支持.结果表明:不同耕作措施下坡面相对高程具有较强的空间相关性,依次为等高耕作＜人工掏挖＜人工锄耕;人工锄耕与人工掏挖坡面具有自相似性特...     

基于M-DEM黄土人工锄耕坡面微地形特征研究

黄土人工锄耕坡面微地形是地表径流和土壤侵蚀过程的重要影响因素。文中在1.0 mm/min雨强的人工模拟降雨试验条件下,采用微地形激光扫描测量方法获取5°人工锄耕坡面微地形相对高程,并进行拟合模型参数验证,进而构建了能反映真实地表情况的高精度M-DEM,并在ArcGIS中对其特征参量进行量化研究。结果表明:黄土人工锄耕坡面微地形起伏较小,整体属于凸形斜坡;虽在某些区域容易形成地表径流,但径流变化比较平缓,不容易形成较大的水流;微地形水系分维能较好地反映复杂微地形特征。论文可为在微地形层面进一步揭示黄土耕作坡面土壤侵蚀机理研究提供数据支持和方法参考。     

植被变化与水沙响应关系研究——以延河流域为例

以延河流域为研究对象,利用TM影像和降雨、径流泥沙数据,基于统计学和RS/GIS技术方法,分析了流域植被与水沙之间的响应关系及自然恢复植被的减水减沙效益.结果表明:2003-2005年与80年代相比,降雨增加导致径流量、输沙量增加8.1％、47.5％;人类活动导致径流量、输沙量减少23.4％、55.6％;人工林草植被减少径流量、泥沙量为0.228亿m3、543.478万t,自然恢复植被减少径流量、泥沙量为0.121亿m3、152.970万t;人工林草植被的减水、减沙效益占人类活动贡献的46.94％、30.64％,而自然恢复植被的减水、减沙效益占24.97％、8.62％.植被在水土保持中的作用日益突出,自然恢复植被减水减沙比重增大,“封育”措施在流域治理中具有重要意义.     

盐渍化灌区耕地-荒地-沙地水盐分布及盐分累积特征

以河套灌区不同利用类型土地为研究对象，旨在探究耕地、荒地、沙地土壤水分变异及土壤积盐特征与盐分离子对土壤积盐量的影响。结果表明：耕地、荒地、沙地土壤水分分布不均，含水率变异系数随土层深度加深而减小，沙地表层变异性较大，变异系数为104.5%；耕地积盐主要集中在春季和秋季收获期,春汇后土壤脱盐约2.1 t·hm^-2，灌水间歇期毛管作用下土壤积盐约0.76 t·hm^-2；荒地70%盐分聚积在表层，春汇后最多可积聚39.85 t·hm^-2；耕地积盐量与荒地积盐量呈显著负相关关系，与沙地积盐量呈显著正相关关系,相关系数分别为-0.249、0.712；HCO^-₃、Na⁺在耕、荒地间随水移动性较强，耕、沙地间SO^2-₄、Mg²⁺随水移动性较强。主成分分析表明影响耕地积盐量主要是SO^2-₄和Cl^-,影响荒地和沙地积盐量主要是Na⁺和Cl^-。采用逐步回归分析方法建立耕、荒、沙地1.2 m深土壤积盐回归预测模型。     

PAM与SAP交并施用对旱区坡耕地氮素淋溶的影响

通过在旱区坡耕地上模拟降雨试验，研究在降雨强度40 mm·h^-1和历时为3 h的条件下，7种线性水溶性高分子聚合物（PAM）和新型节水保水材料（SAP）交并施用方式对径流和氮素淋溶的影响。结果表明：与对照处理（不施用PAM和SAP）相比较，施加PAM和SAP有效减少了径流量和氮素淋溶量，减少的地表径流量达93.29%，相应地降低水中总氮淋溶量达25.58%，保水作用SAP强于PAM；同时，减少的土壤侵蚀量达91.85%，相应地降低泥沙中总氮淋溶量达37.96%；由降雨后土壤剖面养分分布可知，0~15 cm深度土壤的含氮量比对照组高50.24%。说明施加PAM和SAP增加了根系层的持水和保肥能力，降低了土壤养分随水的深层渗漏，且保土作用PAM强于SAP。在坡耕地施加PAM和SAP不但可以减少水土流失，而且能降低土壤氮素的流失，防止肥料对地下水的污染。     

耕作制度对胡麻土壤酶活性的影响

采用“轮作、休闲、连作、间作、休闲1年-种植”5种耕作模式，结合通径分析，研究不同耕作制度对胡麻土壤酶活性变化特征的影响，以及土壤养分对土壤酶的影响效应。结果表明：（1）胡麻枞形期，研究区表土层4种土壤酶活性各处理间无显著差异（P＜0.05）,说明不同耕作制度在胡麻生长前期对土壤酶影响不明显；盛花期，蔗糖酶活性T1、T2、T3和T4分别较T5提高44.6%、53.3%、61.9%和34.9%，脲酶活性T5、T1和T2分别较T4提高266.0%、157.0%和140.0%，碱性磷酸酶活性T3较T2提高54.0%；硕果期，过氧化氢酶活性T2 和T3分别为1.41 mL·g^-1·h^-1和1.51 mL·g^-4·h^-1，显著高于T1、T4和T5；（2）胡麻盛花期，亚土层土壤脲酶活性T2和T5分别为1.74 mg·g^-1·d^-1和1.70 mg·g^-1·d^-1，显著高于T1、T3和T4；过氧化氢酶活性T1较T5提高212.0%，碱性磷酸酶活性T5较T4提高了21.6%；（3）蔗糖酶与碱性磷酸酶间显著负相关，与脲酶间正相关，其余酶为负相关；（4）耕层不同土壤酶活性受土壤养分因子影响的多重效应不同，pH、全磷含量能够促进蔗糖酶、过氧化氢酶活性提高，有机质、pH含量促进碱性磷酸酶活性提高；亚土层不同土壤酶活性受土壤因子影响的多重效应增加，主要为限制因子，且限制因子数要远大于表土层。     

北方寒区日光温室冬季基质袋培番茄蒸腾量模拟

北方寒区日光温室冬季生产基本无通风，为了探寻室内弱光、高湿、低温及低风速环境下的番茄蒸腾量模拟模型，基于Penman-Monteith（P-M）方程及适应此特定环境的边界层空气动力学阻力、气孔平均阻力、土壤热通量等参数模拟了温室长季节栽培番茄（Lycopersicon esculentum Mill）单株的蒸腾速率并进行了试验验证，揭示了蒸腾速率与净辐射、饱和水汽压差的日变化规律，确定了蒸腾速率与植株上方净辐射的定量关系，检验了土壤热通量取值对蒸腾速率的影响。结果显示：2017-12-11—2018-01-03室内太阳总辐射最大值367 W·m^-2、夜晚及阴天相对湿度接近100%、室内风速接近0 m·s^-1的情况下，单株植株边界层空气动力学阻力变化范围晴天为147~438 s·m^-1，阴天为 211~365 s·m^-1；气孔平均阻力晴天69~1 506 s·m^-1，阴天132~1 151 s·m^-1；P-M方程模拟的单株番茄逐时蒸腾速率在晴天、阴天中午的平均值分别为0.06、0.02 mm·h^-1，模拟值与实测值比较，平均相对误差约为10%。研究还表明，单株番茄上方净辐射量的43.5%通过蒸腾作用转化为潜热；试验环境下，土壤热通量的取值变化对蒸腾速率影响不大。研究确定的蒸腾速率估算模型可为北方寒区冬季日光温室基质袋培番茄蒸腾量估算以及水分管理提供参考。     

缓释尿素减施对冬小麦产量和氮素利用效率的影响

为优化旱地小麦高效施氮管理，实现高效生产目标，通过2 a（2019—2020年度和2020—2021年度）田间试验，设不施肥（CK）、不施氮（T1）、300 kg·hm^-2尿素N（T2，常规施氮处理）、300 kg·hm^-2缓释尿素N（T3）、195 kg·hm^-2缓释尿素N（T4）和90 kg·hm^-2缓释尿素N（T5）6个处理，分析不同缓释尿素减施量对农田土壤硝态氮分布及累积、氮素吸收与转运、冬小麦产量和氮素利用效率的影响。结果表明，缓释尿素减施处理（T4和T5）显著降低收获期0~200 cm土层的土壤NO^-₃-N累积量，同时提高0~40 cm土层NO^-₃-N占比。施用缓释尿素显著提高冬小麦氮素转运量和花后氮素吸收量，T3处理较当地常规施氮处理分别提高12.9%和13.6%。氮素转运对籽粒的贡献率随缓释尿素减施比例的增加呈先增后降的变化趋势，T4处理最大，较其他施氮处理提高0.2%~50.0%。施用缓释尿素可不同程度地改善冬小麦产量构成因素和提高产量；T4处理两年产量分别为8 434、9 060 kg·hm^-2，2019—2020年度较T2和T3处理分别提高19.7%和13.9%，2020—2021年度分别提高17.3%和10.4%，其经济效益2019—2020年度较T2和T3处理分别提高33.3%和34.0%，2020—2021年度分别提高26.8%和23.2%。缓释尿素减施显著降低氮素表观损失，提高了氮素利用效率和氮肥偏生产力。通过拟合分析发现，缓释尿素施用量为208.7 kg·hm^-2时，两年产量分别为8 054、8 806 kg·hm^-2，净效益分别为6 890、8 475 CNY·hm^-2，NHI分别为78.2%和78.9%，可实现西北旱区冬小麦高产高效。     

农业生产活动对黄土高原丘陵沟壑区坡地土壤水分动态的影响

通过在坡度为20°耕地和荒草坡面对降水、土壤水密集观测,结合模拟降雨实验,从降雨入渗、蒸散发等过程分析讨论了影响黄土高原丘陵沟壑区坡地土壤水分动态的主要因素。结果表明:1)降雨入渗量△S主要受控于雨强和降雨量,坡耕地的入渗量随着雨强增加而衰减的速度快于荒坡,坡耕地有利于中等雨强大雨的下渗,雨强增大时两坡面的降雨转化率逐渐接近,且植被的再分配作用凸显,甚至使短历时暴雨时坡耕地的入渗速度低于荒坡,长历时的大、暴雨或连续降雨利于深层入渗,坡面耕作或在裸地上种植冰草后降雨转化率增约50%;2)7月～10月上旬为土壤水补给期,土壤水分在枯水年及平水年处于负平衡,在丰水年获得补给,最终以蒸散发消耗;3)荒地主要耗水层在20cm,耕地土壤水分活跃层及作物主要耗水层延伸至30cm。总体上,农作物增大蒸散发量、增加土壤水分利用深度,农业生产活动对减少降雨径流、增加土壤水资源量、强化水分小循环有重要作用。     

甘肃陇西中药材种植区土壤有机质分布特征

通过采集和分析甘肃省陇西县17个乡镇200个中药材种植区的土壤有机质含量数据,对陇西县中药材主产区的土壤有机质水平及储量空间分布格局进行研究。结果表明：县域各乡镇土壤有机质密度水平在27.03×10³~65.87×10³ kg·hm^-2范围之间，变异系数在19.30%~51.78%之间，属中等变异强度。陇西县土壤有机质含量的分布表现出自西向东逐渐减少的变化规律，并且局部地区具有聚集效应。土壤有机质密度随土壤深度增加呈现先上升后下降的整体趋势，其中表层0~10 cm的土壤有机质密度水平最低，为10.76×10³ kg·hm^-2，10~30 cm土层最高，为18.93×10³ kg·hm^-2。土壤有机质空间分布受到纬度、坡度、海拔、坡向的影响，纬度、海拔的影响程度最大。土壤有机质密度与降雨量、蒸发量、气温、相对湿度4个气象因子之间存在显著相关性，其中与降雨量、相对湿度之间呈显著、极显著负相关，与气温和蒸发量之间呈显著、极显著正相关。     

Effects of structural and depositional crusts on soil erosion on the Loess Plateau of China

Conventional tillage practices used on the Loess Plateau lead to different soil surface micro-topography which results in forming two types of soil crusts. The objective of this study was to explore the formation position, properties and erosion characteristics of structural crusts and depositional crusts under the influences of the microtopography in the rainfall experiments. Two simulated rainstorms were applied in the experiments. The first rainfall event was used for soil crust formation, then the following simulated rainfall storms at 40 mm h^?1, 60 mm h^?1, and 80 mm h^?1 rates were applied to the soil boxes set to a 17.6% (10°) slope under three tillage types (contour tillage, artificial digging, and straight slope conditions) to investigate the resulting runoff discharge rate and sediment yield on crusted soil surface. Results show that: (1) structural crusts formed on the mounds, and depositional crusts formed in the depressions after the first rainfall events; structural crusts exhibit a lower thickness, bulk density, higher porosity and shear strength than depositional crusts; (2) structural crusts increased the runoff yield less and decreased the sediment yield more than depositional crusts; and (3) the runoff yield was significantly greater, and the sediment yield was lower on the crusted soil surface than that on the uncrusted soil surface, regardless of the effect of the tillage treatments.     

Soil surface roughness change and its effect on runoff and erosion on the Loess Plateau of China

As an important parameter in the soil erosion model, soil surface roughness（SSR） is used to quantitatively describe the micro-relief on agricultural land. SSR has been extensively studied both experimentally and theoretically; however, no studies have focused on understanding SSR on the Loess Plateau of China. This study investigated changes in SSR for three different tillage practices on the Loess Plateau of China and the effects of SSR on runoff and erosion yield during simulated rainfall. The tillage practices used were zero tillage（ZT）, shallow hoeing（SH） and contour ploughing（CP）. Two rainfall intensities were applied, and three stages of water erosion processes（splash erosion（I）, sheet erosion（II） and rill erosion（III）） were analyzed for each rainfall intensity. The chain method was used to measure changes in SSR both initially and after each stage of rainfall. A splash board was used to measure the splash erosion at stage I. Runoff and sediment data were collected continuously at 2-min intervals during rainfall erosion stages II and III. We found that SSR of the tilled surfaces ranged from 1.0% to 21.9% under the three tillage practices, and the order of the initial SSR for the three treatments was ZT〈SH〈CP. For the ZT treatment, SSR increased slightly from stage I to III, whereas for the SH and CP treatments, SSR decreased by 44.5% and 61.5% after the three water erosion stages, respectively, and the greatest reduction in SSR occurred in stage I. Regression analysis showed that the changes in SSR with increasing cumulative rainfall could be described by a power function（R2〉0.49） for the ZT, SH and CP treatments. The runoff initiation time was longer in the SH and CP treatments than in the ZT treatment. There were no significant differences in the total runoff yields among the ZT, SH and CP treatments. Sediment loss was significantly smaller（P〈0.05） in the SH and CP treatments than in the ZT treatment.     

黄土区土质道路径流水动力学参数的灰色关联度分析

黄土区土质道路路面侵蚀是该地区土壤侵蚀中的重要形式之一,为了探讨其土壤剥蚀率与径流水动力学参数的相关关系,以便为该地区道路土壤侵蚀预报模型的建立提供帮助,采用室内人工降雨及放水冲刷实验、灰色关联度分析方法研究了裸露土质路和植草土质路的径流水动力学参数与土壤剥蚀率间的关系,结果表明:1)在15°坡度、不同雨强条件下,可根据径流量或水流功率计算土壤剥蚀率;2)在2mm.min-1雨强、不同坡度条件下,可根据水流功率或坡度计算土壤剥蚀率;3)在降雨加放水冲刷试验条件下,裸露土质路的土壤剥蚀率可通过径流水深或径流流速计算得出,而植草土质路的土壤剥蚀率可通过过水断面单位能量或径流量计算得出。因此,在无汇水条件时,根据径流水流功率计算土壤剥蚀率较为合理;在有汇水条件时,采用径流量计算土壤剥蚀率较为合理。     

薄土坡耕地石坎反坡水平阶水沙调控效果

为研究石坎反坡水平阶对于薄土坡耕地的水沙调控效果,设置了两个标准天然降雨径流小区（措施小区和对照小区）分别对次降雨径流和泥沙进行了观测,结果表明：石坎反坡水平阶措施能够有效地调控坡耕地地表径流,年均径流削减率为22.5%,且在短历时、大雨强降雨条件下的调控效果好于长历时、小雨强降雨;该措施对于坡耕地泥沙调控效果显著且稳定,年均泥沙削减率95.5%,措施小区的坡面产沙量随降雨特征值变化的波动幅度远远小于对照小区;石坎反坡水平阶措施通过减少坡面侵蚀,间接提高了坡耕地作物产量,春玉米年均增产6.2%。     

Effect of soil management on soil erosion on sloping farmland during crop growth stages under a large-scale rainfall simulation experiment

Soil erosion on farmland is a critical environmental issue and the main source of sediment in the Yellow River, China. Thus, great efforts have been made to reduce runoff and soil loss by restoring vegetation on abandoned farmland. However, few studies have investigated runoff and soil loss from sloping farmland during crop growth season. The objective of this study was to investigate the effects of soil management on runoff and soil loss on sloping farmland during crop growth season. We tested different soybean growth stages (i.e., seedling stage (R1), initial blossoming stage (R2), full flowering stage (R3), pod bearing stage (R4), and initial filling stage (R5)) and soil management practice (one plot applied hoeing tillage (HT) before each rainfall event, whereas the other received no treatment (NH)) by applying simulated rainfall at an intensity of 80 mm/h. Results showed that runoff and soil loss both decreased and infiltration amount increased in successive soybean growth stages under both treatments. Compared with NH plot, there was less runoff and higher infiltration amount from HT plot. However, soil loss from HT plot was larger than that from NH plot in R1-R3, but lower in R4 and R5. In the early growth stages, hoeing tillage was effective for reducing runoff and enhancing rainfall infiltration. By contrast, hoeing tillage enhanced soil and water conservation during the late growth stages. The total soil loss from HT plot (509.0 g/m²) was 11.1% higher than that from NH plot (457.9 g/m²) in R1-R5. However, the infiltration amount from HT plot (313.9 mm) was 18.4% higher than that from NH plot (265.0 mm) and the total runoff volume from HT plot was 49.7% less than that from NH plot. These results indicated that crop vegetation can also act as a type of vegetation cover and play an important role on sloping farmland. Thus, adopting rational soil management in crop planting on sloping farmland can effectively reduce runoff and soil loss, as well as maximize rainwater infiltration during crop growth period.     

京津水源区坡耕地土壤侵蚀特征分析

坡耕地是保障粮食安全与经济发展的重要资源.本文利用承德市南山径流场资料对不同坡长下径流深、含沙量及侵蚀量进行对比分析,结果显示:坡长和降雨强度都对土壤侵蚀有影响,随着坡长变化,导致土壤侵蚀量变化的两个主导因素不断变换.雨强小于0.25 mm/min时,坡面土壤侵蚀模数随坡长的增加而增大;雨强大于0.25mm/min时,随坡长的增加先增大后减小,最大侵蚀量总是出现在22 m坡长范围内.径流深均值与侵蚀量增量随坡长变化趋势一致,含沙量均值变化与雨强关系密切.所以治理京津水源区坡耕地水土流失,应在22 m坡长以内采取等高植物篱等措施,既可降低工程投入,又减少坡面土壤流失,提高土地生产力.     

耕作模式和播种方式对旱地小麦产量形成的影响

于2015—2017年在山西省闻喜旱地小麦试验示范基地开展大田试验,以耕作模式为主区,设休闲期深翻和免耕两种模式,以播种方式为副区,设探墒沟播、膜际条播和常规条播3种方式,研究旱地小麦土壤水分、产量形成和经济效益的差异。结果表明：休闲期深翻显著提高旱地小麦播前0～300 cm土壤蓄水效益,达46.97%～240.44%;提高旱地小麦生育时期土壤耗水量,达6.48%～13.07%;提高穗数、穗粒数、千粒重和产量,分别达3.32%～7.22%、3.67%～6.53%、1.11%～3.61%、10.23%～13.16%。探墒沟播和膜际条播较常规条播显著提高了旱地小麦茎蘖成穗率,达5.99%～16.87%,显著提高穗长0.8～1.7 cm,提高可孕小穗数1～3个;提高了穗数、穗粒数,分别达5.28%～15.75%和1.51%～11.25%,此外,休闲期深翻后采用探墒沟播较膜际条播减少投入1 200元·hm^-2,主要是旋耕机械投入、地膜和回收地膜人工投入,增加经济效益622～754元·hm^-2。休闲期深翻后采用探墒沟播较常规条播减少投入300元·hm<...     

聚丙烯酸钠对黄土坡面产流产沙的影响研究

通过野外模拟降雨试验,研究了施用SP对黄土坡面产流、产沙的影响,并对实验数据进行数学模拟,建立了SP施用量与产流、产沙强度间的关系模型.结果表明:SP施用量与产流时间、平均产流强度呈二次函数相关关系,与产沙强度呈线性负相关关系.SP用量在0～2.42 g/m\+2之间时,能够延缓坡面产流,用量为1.21 g/m\+2时延缓产流效果最明显;用量介于0～3.31 g/m2之间时,能够增加土壤入渗,减少坡面产流量,用量1.65 g/m2的增渗减流效果最佳;施用SP后,能够减少坡面输沙强度,且用量越大,减沙效果越明显.SP可影响坡面产流过程,用量1.8 g/m2时,能够减小产流初期径流强度增幅,用量为3.6 g/m2时,其产流过程线与对照极接近,而施用量增加到5.4 g/m2时,产流强度明显增大.SP对坡面产沙过程的影响表现为:随施用量增大,产沙强度峰值呈逐步减小的变化趋势.