中条山北麓韩阳段冲沟发育及其新构造意义

基于数字高程模型数据(DEM),运用河长坡降指标(SL)、河流Hack剖面、面积高度积分值(HI)及盆地流域形态因子(BS)分析方法对山西省中条山北麓韩阳段6条冲沟地貌发育进行了量化分析。结果表明:中条山北麓韩阳段流域处于地貌演化的壮年期阶段,断层活动性自西南至东北方向呈现先增强后降低的趋势。野外发现盘底村和三新村沟口东岸阶地发育明显而西岸发育相对较弱的一致性规律,说明沟谷东侧山地抬升较强烈、西侧抬升较弱,从而验证韩阳段自西南向东北方向新构造活动性呈现逐渐增强的趋势。     

黄土旱塬区平衡施肥下不同土壤耕作模式的蓄水纳墒及作物增产增收效应研究

【目的】黄土旱塬半湿润易旱区是典型的雨养农业区,多数一年一熟或两年一熟制,冬小麦和春玉米是该区主要的粮食作物,平衡施肥是主要的施肥方式。多年研究和生产实践证明,建立与不同作物轮作方式相配套的土壤轮耕技术体系,可以为作物生长发育创造良好的土、 肥、 水、 气、 热的土壤环境条件,保持农田生态健康发展,促进作物增产增收。本文在当地平衡施肥条件下,通过多年耕作模式定位试验,研究在平衡施肥条件下,不同土壤耕作模式对休闲期和作物生育期0200 cm土层蓄水纳墒状况、 作物产量及其经济效益的影响,为黄土旱塬半湿润易旱区建立在一定肥力水平下与作物轮作体系相配套的土壤轮耕模式提供理论依据。【方法】选择位于黄土旱塬半湿润易旱区腹地的陕西省合阳县甘井镇一年一熟旱作冬小麦春玉米轮作田为试验区,采用免耕、 深松和翻耕3种土壤耕作方法组成4种土壤轮耕模式,即: 翻耕免耕翻耕免耕(RT1); 深松翻耕深松翻耕(RT2); 免耕深松免耕深松(RT3); 免耕翻耕深松免耕(RT4); 以连年翻耕(CK1)、 连年深松(CK2)和连年免耕(CK3)为对照,通过连续4年(2007~2011年)定位试验,研究平衡施肥条件下的7种土壤耕作模式对冬小麦春玉米轮作田0200 cm土层土壤贮水量、 土壤水分含量、 作物籽粒产量、 水分利用效率(WUE)和经济效益的影响。【结果】 1)在土壤休闲期,RT3模式下0200 cm土层土壤贮水量最高,其次是RT2。与对照组相比,4种轮耕模式0200 cm土层土壤贮水量均高于CK1; RT3显著高于CK3,但与CK2差异不显著。0200 cm土层土壤剖面含水量,亦以RT3模式最高。2)在冬小麦生育期,0200 cm土层土壤贮水量和土壤含水量,RT3和CK2模式的较高。3)在春玉米生育期,0200 cm土层土壤贮水量和土壤含水量RT3和CK3较高。4)不同耕作模式的作物籽粒产量、 水分利用效率(WUE)和经济效益,以RT2和CK2模式最高。四年平均结果RT2处理较CK1、 CK2和CK3处理增产10.2%、 3.6%和17.1%,增收23.6%(P0.05)、 6.8%(P0.05)和28.3%(P0.05),提高WUE 9.7%(P0.05)、 4.3%和18.6%(P0.05)。【结论】年际间轮流进行深松和翻耕(RT2)处理,虽然其在土壤蓄水保墒效应方面略低于年际间轮流进行免耕和深松(RT3)和连年深松(CK2)处理,但可获得最佳增产增收效果和最高水分利用效率; 连年深松能够增加水分入渗,保护土壤,增加蓄水能力,但产量和经济效益不如RT2处理,也是该区比较适宜的耕作方法。根据实际状况,在平衡施肥条件下的一年一熟作物轮作区,应推荐深松翻耕的轮耕或连年深松的耕作模式。     

Fertilizer location modifies root zone salinity,root morphology,and water‐stress resistance of tree seedlings according to the watering regime in a dryland reforestation

There is a direct relationship between soil nutrient concentration in localized zones and root proliferation and elongation under well‐watered conditions. However, in field studies under semiarid conditions this relationship can change due to higher salt accumulation and soil dryness that affect root growth, water stress resistance, and seedling survival. We assessed the effect of different locations of fertilizer placement in the soil profile and water availability on root zone salinity, root development and ecophysiological responses of Quillaja saponaria Mol. after outplanting. A single dose (6 g L^?1) of controlled‐release nitrogen fertilizer (CRF_N) was placed at 0 cm (top layer), 15 cm (middle layer), or 30 cm (bottom layer) depth in the containers in a greenhouse, in addition to an unfertilized treatment (control). After 6 months, seedlings were transplanted to the field and subjected to weekly watering regimes (2 L plant^?1 and unwatered). Morphological and ecophysiological parameters were periodically measured on seedlings, as well as soil electrical conductivity (EC). After 1 year, the shoot : root ratio of unwatered seedlings decreased as a function of CRF_N placement depth, which was attributed to lower shoot growth and not to greater root growth. The root morphology of the bottom layer treatment was negatively affected by high EC in unwatered seedlings. Greater total root length and root volume of the middle layer treatment was found only when well‐watered; however, this did not contribute to improve physiological responses against water stress. The lowest EC and the highest photochemical efficiency, net photosynthesis, and stomatal conductance were shown by unfertilized seedlings, independent of water availability. Our findings suggest that varying depth of CRF_N placement does not contribute significantly to improve root growth under water restriction. Water supplements, independently of the CRF_N location in the substrate, contribute to decrease root zone salinity, and consequently, improve root volume growth.     

不同降水年型旱地小麦覆盖对产量及水分利用效率的影响

【目的】明确旱地麦田休闲期覆盖的蓄水增产效果和生育期覆盖播种的节水增产效果,探索旱地小麦不同降水年型休闲期覆盖和生育期覆盖的保水技术新途径。【方法】于2011-2014年在山西闻喜县开展大田试验,以休闲期覆盖渗水地膜与不覆盖为主区,以生育期膜际条播、条播为副区,研究覆盖对旱地麦田3 m内土壤水分、小麦产量构成、水分利用效率和节水增产效率的影响。【结果】休闲期覆盖较不覆盖处理提高了播种期0-300 cm土层土壤蓄水量,丰水年达40-41 mm,平水年达55-58 mm,欠水年达70 mm,且欠水年更有利于蓄积土壤水分于深层,显著提高了不同降水年型休闲期土壤蓄水效率,达到20%以上,其覆盖的蓄水效果可延续至孕穗期,且生育期配套膜际条播效果更佳。休闲期覆盖较不覆盖处理显著提高小麦穗数、产量和水分利用效率,产量提高20%以上,水分利用效率提高15%以上,且生育期配套膜际条播小麦穗粒数、千粒重也显著提高。结果还表明,休闲期覆盖处理小麦播种期土壤水分每多蓄1 mm,丰水年小麦可增产21-27 kg·hm^-2,平水年可增产16-18 kg·hm^-2,欠水年可增产13-24 kg·hm^-2,且休闲期覆盖条件下,生育期膜际条播播种对产量的提升有较大的调控作用。生育期地膜覆盖保水后,旱地麦田节水、增产效果提高,单位粮食生产节水量提高10%以上,消耗1 mm土壤水分产量提高11%以上。【结论】旱地小麦休闲期覆盖有利于蓄积休闲期降雨,改善底墒,尤其欠水年蓄水效果更佳,有利于提高小麦花前土壤水分,促进有效穗数的形成,提高产量,且生育期膜际条播播种效果更佳。底墒充足时,生育期膜际条播播种有利于提高旱地麦田的节水增产效果,而欠水年底墒不足时,会导致水分浪费和减产。     

旱地组合型微垄全膜不同覆盖时期对土壤水分及胡麻生长的影响

春夏干旱是榆中县旱作区胡麻产量的主要限制因素。进一步减少旱地冬春季土壤水分的无效蒸发、提高土壤含水量,为胡麻前期生长创造良好的土壤条件是实现该区胡麻高产稳产的必须步骤。2011—2012年连续两年在地处甘肃省中部半干旱雨养农业区的榆中县石头沟旱作农业示范点进行了组合型微垄全膜覆盖不同覆膜时期对旱地胡麻生长影响的试验。本试验设组合型微垄全膜秋覆盖垄侧栽培、组合型微垄全膜播种前覆盖垄侧栽培和露地穴播三个处理,分别对其土壤水分、经济性状、生育期、产量结果进行分析。结果表明,旱地胡麻组合型微垄全膜秋覆盖垄侧栽培可明显减少冬春季土壤水分的无效蒸发,增加土壤水分含量,0~60 cm的土壤平均含水量,分别比旱地胡麻微垄全膜播种前覆盖垄侧栽培和旱地胡麻露地穴播栽培高31.9 g·kg-1和45.3 g·kg-1;胡麻的经济性状明显改善,株高分别比旱地胡麻微垄全膜播种前覆盖垄侧栽培和旱地胡麻露地穴播栽培高3.8 cm和14.7 cm、单株蒴果数分别增加8.5个和11.5个、蒴果粒数分别增加0.6个和1.65个、千粒重分别提高0.05 g和0.31g。旱地胡麻组合型微垄全膜秋季覆盖垄侧栽培比胡麻露地栽培增产1 471.2 kg·hm-2,增幅129.54%,比旱地胡麻微垄全膜播种前覆盖垄侧栽培增产378.22 kg·hm-2,增幅17.41%,增产效果十分明显。     

Diversity in weed seed production and the soil seed bank: Contrasting responses between two agroecosystems

This study was carried out to compare the diversity in seed production and the soil seed bank in a dryland and an irrigated agroecosystem in the dry tropics. Both agroecosystems showed a comparable number of species, but only 25% and 38% similarity during the winter and rainy cropping seasons, respectively. In the irrigated agroecosystem, the amount of seed production diversity was almost double in the winter season, compared to the rainy season. The weed seedbank diversity was low but was sensitive to cropping practices and seasons in both agroecosystems. A considerably smaller soil seedbank size in the irrigated agroecosystem (cf. dryland) was related to lowered weed seed production. The dryland agroecosystem showed a greater accumulation of the seeds of broad‐leaved weeds, whereas the irrigated agroecosystem accumulated more seeds of the grasses or sedges. About three‐fourths of the seeds during the winter season were accounted for by Anagallis arvensis and Chenopodium album in the dryland agroecosystem and by C. album and Melilotus indica in the irrigated agroecosystem. However, during the rainy season, Ammannia baccifera, Echinochloa colona and Cyperus rotundus dominated in both agroecosystems. The changes in the weed seed bank and its diversity are mainly attributed to differences in water management, which tends to reduce species diversity, especially at a lower depth, but leads to the dominance of some potentially noxious weeds (e.g. Phalaris minor and M. indica). Approximately double the soil seedbank size and a greater diversity at a lower depth might indicate an adaptive mechanism in the storage of weed seeds in the dryland agroecosystem.     

Human induced dryland degradation in Ordos Plateau,China, revealed by multilevel statistical modeling of normalized difference vegetation index and rainfall time-series

Land degradation causes serious environmental problems in many regions of the world,and although it can be effectively assessed and monitored using a time series of rainfall and a normalized difference vegetation index(NDVI)from remotely-sensed imagery,dividing human-induced land degradation from vegetation dynamics due to climate change is not a trivial task.This paper presented a multilevel statistical modeling of the NDVI-rainfall relationship to detect human-induced land degradation at local and landscape scales in the Ordos Plateau of Inner Mongolia,China,and recognized that anthropogenic activities result in either positive(land restoration and re-vegetation)or negative(degradation)trends.Linear regressions were used to assess the accuracy of the multilevel statistical model.The results show that:(1)land restoration was the dominant process in the Ordos Plateau between 1998 and 2012;(2)the effect of the statistical removal of precipitation revealed areas of human-induced land degradation and improvement,the latter reflecting successful restoration projects and changes in land management in many parts of the Ordos;(3)compared to a simple linear regression,multilevel statistical modeling could be used to analyze the relationship between the NDVI and rainfall and improve the accuracy of detecting the effect of human activities.Additional factors should be included when analyzing the NDVI-rainfall relationship and detecting human-induced loss of vegetation cover in drylands to improve the accuracy of the approach and eliminate some observed non-significant residual trends.     

基于WEPP模型的多级梯田暴雨侵蚀模拟初步研究

针对2013年6—9月份安塞县马家沟多级梯田遭受暴雨侵蚀严重等问题,运用新一代水蚀预报模型WEPP模型对马家沟多级梯田在暴雨条件下的侵蚀情况进行模拟,并将WEPP模型模拟的结果与实测资料进行了对比。结果表明:WEPP 模型能够较好地模拟黄土丘陵区多级梯田在暴雨条件下的径流量以及土壤侵蚀量,随着梯田级数的增加,WEPP模型对径流量与侵蚀量的模拟精度逐渐降低。由于受该区地下水的影响,模拟径流量总体小于采用径流系数法算得的径流量,由于梯田田埂的防蚀作用,模拟土壤侵蚀量总体大于实测侵蚀量。研究为黄土丘陵区梯田防蚀以及梯田修筑提供科学依据及有效方法,为黄土丘陵区多级梯田的暴雨侵蚀预测提供了合理化建议。     

集雨补灌条件下旱塬小麦玉米带田节水灌溉试验研究

对旱塬地区小麦套作玉米带田集雨限量补灌条件下带田产量、水分利用效率、叶日积(LAD)及作物复合群体生长率(CGR)进行了分析研究,认为该区发展小麦玉米带田限量补灌(35mm)的最佳生育时期为小麦抽穗期和玉米抽雄开花期,有条件时灌2水以小麦抽穗期、玉米抽雄开花期和小麦扬花期、玉米吐丝期为宜。这与各处理0～90cm土层水分利用效率的大小表现一致。带田复合群体总LAD、平均CGR灌水与不灌水处理间差别不明显,说明LAD、CGR并非单一水分因素所致,水分条件的改善对此二者的作用仅为其中一个方面,今后的栽培管理中也应重视其它方面如增施有机肥等。     

2009,2010年襄汾旱地冬小麦生产现状分析

为了了解山西省旱地冬小麦生产现状,2009,2010年分别对山西省襄汾县150户和96户农户的旱地冬小麦生产现状进行了调查分析。结果表明:(1)该地区这2年冬小麦生产有90.67%和73.93%的农户产量低于4 000 kg/hm2,仅有9.33%和26.07%的农户产量大于4 000 kg/hm2,平均产量2009年为1 467 kg/hm2,2010年为3 366 kg/hm2,均低于我国平均水平和发达国家水平。(2)2009年氮肥用量平均为118.76 kg/hm2,2010年为146.69 kg/hm2,小于120 kg/hm2的农户分别占25.33%和53.13%,大于120 kg/hm2的农户分别占74.67%和46.87%。(3)2009年磷用量平均为62.78 kg/hm2,2010年为95.40 kg/hm2;2009年钾的平均用量为11.39 kg/hm2,2010年为55.66 kg/hm2。2009年90.00%的农户和2010年53.13%的农户磷肥用量不能满足小麦的需要,钾肥不足更严重。(4)2009年只以种肥方式一次性投入,且几乎都是化肥,有机肥只通过留茬翻压,没有施基肥和追肥。2010年有种肥、基肥和追肥,但只有1户用有机肥。(5)2年灌溉次数分别为52,138次,灌水严重不足,灌溉次数和产量呈正相关。合理施肥和灌溉是山西旱地冬小麦产量上新台阶的唯一途径。