Effects of desertification on soil and crop growth properties in Horqin sandy cropland of Inner Mongolia, north China

Wind erosion and accumulated sand are recognized as the primary forms of cropland desertification in the arid and semiarid region, Inner Mongolia. However, there is a lack of knowledge on the effects of wind erosion and accumulated sand on soil properties and crop growth properties in this region. A field experiment was conducted from 2001 to 2002 on desertified cropland with gradients of wind erosion and accumulated sand to investigate changes in soil and crop growth properties resulting from desertification in the Horqin sandy land. Results indicated that the soil environment degraded significantly and crop growth and biomass were seriously restrained by wind erosion. In the severely eroded cropland, soil clay, organic matter, total N and P, available N and P, average soil moisture decreased by 59.6%, 71.2%, 67.4%, 31.4%, 64.5%, 38.8% and 51.8%, respectively. Erosion increased soil pH from 8.66 to 8.92; delayed plant life cycle by 6 days, decreased plant height and diameter by 15.5% and 29.1%, and decreased above and below ground biomass and seed yield by 87.3%, 47.9% and 96.5%, respectively. Effects of a little accumulated sand were fewer on soil properties and crop growth and seed yield compared to wind erosion, severe accumulated sand effects on the cropland remain to be studied further. The results of correlation analysis showed that crop biomass and seed production were significantly correlated to organic matter, total N, pH and soil moisture under circumstance of worsened soil environment. In the windy and sandy region in Inner Mongolia, some measures to control cropland erosion should be introduced including construction of windbreak, stubble cultivation, increased organic fertilizer and spring irrigation.     

Wind erosion and sand accumulation effects on soil properties in Horqin Sandy Farmland,Inner Mongolia

Rain-fed agriculture is widespread in Inner Mongolia, northern China, where wind erosion of farmland is very common because of sandy soil and dry, windy weather. However, very little is known about the effects of wind erosion on soil physical and chemical properties in this region. A field experiment was conducted in sandy farmland, where erosional and depositional gradients were established to evaluate the effects of wind erosion and leeward sand accumulation on soil texture, nutrient content, soil water, and soil temperature. The research showed that long term wind erosion could result in significant soil coarseness, infertility and dryness. Severe erosion reduced clay by 59.6%, organic C by 71.2%, total N by 67.4%, total P by 31.4%, available N by 64.5%, available P by 38.8%, and average soil water content by 51.8%, compared with non-eroded farmland in the study region. The sand fraction (particles > 0.05 mm), pH and ground-surface temperature increased by 6.2%, 3.7%, and 2.2 °C, respectively. Accumulated sand also caused a decrease in nutrients and soil water content. Under severe sand accumulation, clay was reduced by 2.0%, organic C by 19.3%, total N by 21.7%, total P by 13.7%, available N by 52.5%, and average soil water content by 26.6%. The sand fraction, pH, available P, and ground-surface temperature increased by 0.2%, 0.9%, 5.8% and 2.8 °C, respectively.     

内蒙古降水量分布及其对马铃薯灌溉需水量的影响

马铃薯是内蒙古的优势作物,其生长和产量主要受水分条件的制约.研究内蒙古降水量分布和马铃薯需水规律,可为马铃薯生产合理布局、合理用水以实现稳产提供依据.利用内蒙古1961-2010年46个气象站点的逐日气象资料计算分析了内蒙古马铃薯生育期有效降水量及分布、马铃薯生育期蒸散量和不同年型下马铃薯的灌溉需水量.结果表明:内蒙古马铃薯生育期有效降水量为25～ 240mm,时空分布不均匀,地区间差异大;马铃薯生育期蒸散量为300～700mm,400mm等值线从呼伦贝尔北部开始,穿过锡林郭勒盟的北部,向东到兴安盟.内蒙古地区马铃薯灌溉需水量由东到西有逐渐增大趋势,需水量等值线呈经向分布.1500m3/hm2等值线在内蒙古东北部,等值线以东的呼伦贝尔市、兴安盟的北部地区有效降水基本能满足马铃薯需求,正常年无需灌溉,适合马铃薯大面积种植;内蒙古西部和北部降水资源不足以支撑马铃薯生产,不适合马铃薯种植.歉水年降水量少、蒸散量大,马铃薯灌溉量比平水年平均增加40.4％.     

不同土壤条件下节水灌溉对棉花产量和灌溉水生产力的影响

在黑河中游边缘绿洲通过田间试验研究不同土壤条件下节水灌溉对棉花产量及灌溉水生产力(Irrigation Water Productivity,IWP)的影响,为区域农业土壤的合理利用和制定不同土壤的灌溉对策提供依据。田间试验涉及不同肥力和粒级组成梯度的5种土壤(砂土S1、S2;壤砂土S3和砂壤土S4、S5三个质地类型),设三个灌溉水平:常规充分灌溉(I1)、减量10.5%节水灌溉(I2)和减量21.0%节水灌溉(I3)。结果表明,与充分灌溉相比,减量10.5%和21.0%的节水灌溉,在棉花不同生育期的地上单株生物量和叶面积及收获时的茎干生物量有所降低,但籽棉产量增加了11.6%和11.2%。在减量10.5%和21.0%的节水灌溉下棉花IWP分别为0.51 kg m-3和0.57 kg m-3,较传统灌溉(0.41 kg m-3)提高24.4%和39.0%。不同质地土壤棉花生物量、产量及棉花IWP有显著差异。棉花IWP随土壤黏粉粒和有机质含量的增加而增加,但在黏粉粒和有机质含量最高的土壤出现下降,呈多项式关系。土壤质地与灌溉量对棉花霜前花率、生物量及产量有显著的交互效应。有机质和黏粉粒含量最高的砂壤土S5在充分灌溉下营养生长过旺、吐絮期延后,导致霜前花率降低、籽棉产量和IWP降低。节水灌溉可显著提升棉花IWP,在水资源紧缺的边缘绿洲区,对新垦的砂质土壤种植耗水量较低的棉花、并进行节水灌溉管理,是实现区域节水和合理土地利用的适宜选择。     

内蒙古东部地区盐渍土资源概况及改良利用

阐述内蒙古东部区盐渍土的类型与　分布，总结与适宜于该地区农牧业生产实际的改良利用途径，诸如水利、农业、生物及化学　改良等措施．     

内蒙古东部区粮食产量对气候变化的响应

利用内蒙古东部产粮区25个气象站建站至2005年气象资料与粮豆和主要作物产量资料,分析了作物生长季水热演变规律,及区域作物产量对气候变化的响应。结果表明:(1)近50a该区域水热匹配格局发生变化,特别是近20a暖干化趋势明显;(2)降水是影响该地区粮食生产的关键气象因子,春、夏季降水量的匮乏和生长季高温是粮食生产的主要限制因素;(3)各作物的第一敏感因子不同。小麦和谷子为降水,玉米为夏季高温,马铃薯产量对7-8月温差和4-5月降水反应敏感。(4)据模型推算,当生长季平均最高气温或温差增加1℃时,有可能使玉米气象产量减少102～192kg/hm2,大豆减产87kg/hm2,马铃薯增产55.5kg/hm2。因此,气候暖干化倾向有可能造成该区域农业产量呈下降趋势。研究结果可为有关部门制定应对气候变化策略提供参考。     

太行山前平原近40年降水的变化趋 势及其对作物生产的影响

降水是作物生产的主要限制因素,在干旱半干旱地区尤为重要。通过对太行山山前平原近46年降水量资料分析表明,太行山山前平原降水量在以每年5.1mm速度下降,其中夏玉米季下降比较严重。而冬小麦季的灌溉需水量是夏玉米季的2倍。田间试验结果表明,旱作条件下作物产量与降水量关系密切,而非充分灌溉条件下作物产量的变异性不大,今后应提倡合理灌溉。     

内蒙古河套灌区地下水合理利用的方案分析

内蒙古河套灌区地下水位浅,合理利用地下水可以减少灌区引黄水量,保证黄河下游用水。根据灌区实际情况,制定了灌区地下水利用原则,提出了地下水插花开采形式,并计算了开采条件下的地下水补给量,分析了引黄水量、地下水开采量及地下水位的关系,在“三亩补一亩”的开采条件下,地下水开采量以1 100～1 500 m³/hm²为宜。地下水合理开采可缓解灌区水资源紧张局面,对河套灌区水资源可持续开发利用具有重要意义。     

茬口和灌水对小麦产量及水分利用效率的影响

为高效利用水分资源以及不同茬口冬小麦栽培提供合理的灌水制度,在山西临汾采用小区试验设计方法研究了茬口和灌水对小麦产量及水分利用效率的影响.结果表明:各茬口3个灌水处理的小麦平均产量以玉米茬口＞油葵茬口＞休闲茬口＞大豆茬口,水分利用效率则为油葵茬口＞玉米茬口＞大豆茬口＞休闲茬口;各茬口均随灌水量的增加产量和水分利用效率提高,大豆茬口的灌浆水、其他3个茬口的拔节水分别较拔节水、灌浆水更有利于提高小麦产量和水分利用效率.同时明确了不同灌水处理条件下,各茬口在不同生育时段贮水和耗水的动态特征.     

Influences of nitrogen treatments and irrigation methods on soil chemical properties

Abstract

Changes in soil chemical properties were investigated in conjunction with an ongoing study of fertility and irrigation relationships of cotton. Four irrigation methods and five nitrogen fertilization rates were the primary focus of the study. The four irrigation regimes studied were: high frequency center pivot, low frequency center pivot, furrow irrigated, and unirrigated. Nitrogen rates were 0, 30, 60, 90, and 120 lb N/A. Soil samples were collected from each plot in 6‐in‐ increments to a depth of 24 in. in 1982 and again in 1986 after four years of continuous cotton production. The soil samples were analyzed for pH, organic matter (OM), P, K, electrical conductivity (EC), and NO₃ ^‐‐N. All background soil characteristics were found to vary with depth with the exception of NO₃ ^‐‐N. The follow‐up sampling and testing in 1986 showed significant differences in soil properties as a function of irrigation, N‐fertilization, depth, and their interactions. Nitrates were accumulated in the 18 to 24‐in. depth under high (120 lb N/A) fertilization, and in the 0 to 6‐in. depth under the four lower treatments (0, 30, 60, and 90 lb N/A). Soil pH was highest in the furrow and high frequency center pivot irrigated regimes and lowest in the unirrigated regime. Soil pH also decreased with depth. Electrical conductivity of the soil was highest in the high frequency regime and not significantly different among the other three irrigation methods. The 0M content of the soil was greatest in the high frequency regime but not significantly different in the low frequency, furrow, or unirrigated blocks. Soil 0M was found to decrease with depth through 18 in. in all cases. The P and K status of the soil was not changed as a result of the N fertilization or irrigation treatments.     

咸水灌溉下土壤水盐动态和作物生长研究进展

我国淡水资源短缺且分布不均, 供求矛盾突出, 合理开发利用咸水资源、增辟灌溉水源将成为解决水资源危机的重要途径之一。本文从以下几个方面对国内外咸水资源灌溉利用的研究进展进行了综述, 以期为咸水安全灌溉提供指导。(1)咸水灌溉对土壤水盐运移的影响, 主要包括咸水灌溉后不同土层土壤水盐分布规律、不同灌溉水矿化度对土壤水盐运移的影响、灌溉方式对土壤盐分积累的作用; (2)咸水灌溉对作物生长的影响, 主要包括咸水灌溉与作物产量、品质的关系; (3)咸水灌溉对作物生理变化的影响及其作用机理, 主要包括咸水灌溉对植株脯氨酸含量、抗氧化酶活性、丙二醛含量、叶绿素含量及光合作用的影响。     

内蒙古气候变化及其对主要农作物的影响

了解气候变化对内蒙古种植业结构的影响,是有效制定应对措施和政策的重要依据。本文以全区4个主要产粮区为代表,利用近50a的气候资料和近27a作物生育期资料,分析了当地气候变化特征及其对主要作物物候期和种植面积的影响。结果表明：近50a来,内蒙古主要农业区温度明显升高,≥10℃积温增加了350-570℃.d,河套灌区和大兴安岭东麓地区增温幅度大于阴山北部丘陵区和科尔沁地区。东西部地区的降水量变化差别较大,科尔沁和大兴安岭东麓地区生长季降水量减少了44.0mm和55.0mm,河套灌区和阴山北部丘陵区则增加了10.4mm和2.4mm。玉米春季物候期提前,秋季物候期推后,物候期延长了10-20d,大兴安岭东麓延长最为明显;春小麦和大豆则由于温度升高加快了发育进程,表现为全生育期缩短;马铃薯全生育期变化不明显,但可收期普遍延迟。玉米、马铃薯种植面积扩大,春小麦种植面积减小,玉米种植界限向北延伸等与气候变暖的关系密切。     

内蒙古沙漠化土地中不同土地类型土壤表面可蚀性颗粒对比研究

土壤粒度分布对土壤风蚀具有直接的影响作用,研究不同土地类型的粒度特征及其可蚀性粒度状况对于了解不同尺度上土壤特性的空间异质性和土壤侵蚀、土壤利用变化对土壤的影响程度和尺度具有重要的参考价值。就内蒙古境内四个沙化地区的典型土地类型的粒度特征进行了比较研究,认为不同土地类型沙化土地间表土的粒度性质存在显著差异,移动沙丘最为粗化且分选较好,峰值较大,其次为各类沙丘,各地以耕地或草地最为细化,分选较差,峰值平缓。表现出风蚀沙化的阶段性。就可蚀性粒径而言,总体上,各地以固定沙丘、耕地的颗粒物可能释放较少,而退化草原、移动沙丘、半固定沙丘等土地类型颗粒物可能释放较多。就起尘粒径而言,各地的起尘颗粒以耕地和地带性草原植被的含量最大,其次为退化草原,而各类沙丘含量较小。说明合理利用草场资源和保护性耕作的重要性。     

内蒙古1981-2010年干湿气候类型和净第一性生产力演变

为了更好服务于内蒙古地区生态建设,提供地区大气候背景的演变过程。运用徐文铎湿润指数划分了内蒙古地区的干湿气候类型,研究结果表明:1981—2010年内蒙古半干旱区、干旱区+极干旱区面积、亚湿润区+湿润区面积分别为343 090,388 035,411 819 km²;2001—2010年半干旱区+干旱区+极干旱区面积是20世纪90年代面积的1.3倍;半湿润区+湿润区面积减少了0.5倍,地区生态环境质量进一步下降。干湿气候类型与历年降水量分布图对比显示,干旱区和极干旱区面积与200 mm降水量分布线对应;湿润区在东北地区与400 mm分布线接近;分布最广的半干旱区受温度和降水综合影响较多,与雨量带分布无明显关系。1981—2010年,温度呈显著增加趋势,降水量下降趋势属正常气候波动。地区净第一性生产力（NPP）与降水量的相关系数达到显著水平,相关系数为0.930 0,而与温度的相关系数只有-0.270 0。年代际NPP在2001—2010年下降明显,从西北到东南阶梯式降低,受影响较大的地区主要分布在呼伦贝尔市西部的典型草原和温性草甸草原,赤峰市和通辽市也下降明显;总趋势是东部区下降明显,西部区波动变化,整体下降明显。     

河套灌区土壤盐分对化肥氮素转化过程的影响研究

土壤盐渍化严重影响土壤养分利用与生产力提升,为阐明土壤盐渍化对河套灌区农田土壤肥料氮素转化关键过程的影响。以内蒙古河套灌区不同含盐量土壤为试验材料,通过室内恒温培养试验,分析了不同盐分梯度下土壤中氮素转化的水解和硝化过程。试验共设置了低盐(EC_5:1=1.46 dS/m)、中盐(EC_5:1=2.19 dS/m)、高盐(EC_5:1=3.43 dS/m)3种盐分梯度,分别施用尿素和磷酸二铵两种化学氮肥。研究结果表明:①土壤盐分升高抑制了尿素的水解作用,高盐处理尿素的净水解量较中盐和低盐处理分别降低19.4%和27.1%,而土壤盐分在中盐时对磷酸二铵的水解表现出促进效应,中盐处理磷酸二铵净水解量较低盐、高盐处理分别提高33.6%和4.3%。②土壤高盐分会抑制硝化反应的开始,高盐处理相较低盐、中盐处理推迟3 d左右;土壤盐分升高对两种氮肥净硝化量的影响均表现为先促进后抑制的作用,中盐处理尿素的净硝化量,较低盐、高盐处理分别提高了8.6%和9.1%,中盐处理磷酸二铵的净硝化量,较低盐、高盐处理分别提高了19.1%和5.1%。③在等...     

施氮和灌溉管理下作物产量和土壤生化性质

氮和水对作物生长非常重要,研究施氮和灌溉管理下作物产量、土壤性质以及它们的关系对我国农业科学有重要意义。本文以中国科学院封丘农业生态试验站为平台,研究了施氮(每季施氮150 kg·hm?2、190 kg·hm?2、230 kg·hm?2、270 kg·hm?2,以不施氮为对照)和灌溉(灌溉量达到0~20 cm、0~40 cm、0~60 cm土壤的田间持水量,以雨养为对照)管理下小麦-玉米轮作系统作物产量和土壤生化性质,以及它们之间的关系。研究结果表明,150~270 kg·hm?2施氮量对2008年、2009年玉米产量和2009年、2010年小麦产量无显著影响;灌溉对2010年玉米产量无显著影响,而2008年、2009年玉米产量随灌溉量增大而增加。尽管2008—2011年小麦产量随灌溉量变化趋势不一致,但与雨养相比灌溉提升了小麦产量。施氮在不同程度上提升了土壤全氮和速效氮含量、脱氢酶和脲酶活性、微生物生物量碳、基本呼吸和硝化势,稍微降低了土壤pH并大幅降低了速效磷含量(降幅48.7%~51.6%);灌溉提升了土壤全氮含量和脱氢酶活性,降低了全钾含量、脲酶活性、基本呼吸、硝化势。多元回归分析显示,某些土壤生化性质(全氮、溶解性有机碳、速效磷含量及微生物生物量碳氮、呼吸熵、硝化势)与2009年、2010年玉米产量很好地线性拟合。综上,土壤生化性质因施氮和灌溉发生不同程度的分异,因施氮和灌溉而分异的土壤生化性质能部分地鉴定作物产量。本研究方法可为产量主导因子的筛选及产量估算模型的建立提供一定参考依据。     

内蒙古典型草原区退耕方式对植物群落特征与土壤特性的影响

退耕后不恰当的植被建设会严重影响植物群落演替及土壤性质.本文以内蒙古太仆寺旗境内典型草原为研究区,以天然草地为对照,研究退耕后自然恢复与人工种草2种退耕方式对植物群落特征及土壤性状的影响,揭示不同退耕方式的生态恢复效应.通过样方法调查不同退耕方式草地的盖度、生物量和多样性特征,并对土壤密度、机械组成及养分含量等进行了室内测定分析.结果表明:1)植物群落多样性、盖度、地上及地下生物量均表现为人工种草＜自然恢复＜天然草地,且相比于人工种草,自然恢复草地的物种组成与天然草地更为相似;2)不同退耕方式影响下土壤性质的差异主要集中在表层0～10 cm;3)在表层0～ 10 cm,土壤密度及砂粒含量表现为人工种草＞自然恢复＞天然草地,而土壤黏粒、有机质(SOM)及全氮(TN)含量则表现为人工种草＜自然恢复＜天然草地.以上结果说明,在内蒙太仆寺旗退耕后采用自然恢复方式比人工种草更有助于改善土壤理化性质、建立稳定的植被系统.经过12年的恢复,退耕草地(人工种草与自然恢复草地)仍未恢复到天然草地的水平.     

内蒙古沙漠化土地中不同土地类型土壤表面可蚀性颗粒对比研究

土壤粒度分布对土壤风蚀具有直接的影响作用,研究不同土地类型的粒度特征及其可蚀性粒度状况对了解不同尺度上土壤特性的空间异质性和土壤侵蚀、土壤利用变化对土壤的影响程度和尺度具有重要的参考价值.就内蒙古境内4个沙化地区典型土地类型的粒度特征进行比较研究,认为不同土地类型沙化土地间表土的粒度性质存在显著差异,移动沙丘最为粗化且分选较好,峰值较大,其次为各类沙丘,各地以耕地或草地最为细化,分选较差,峰值平缓,表现出风蚀沙化的阶段性.就可蚀性粒径而言,各地以固定沙丘、耕地的颗粒物可能释放较少,而退化草原、移动沙丘、半固定沙丘等土地类型颗粒物可能释放较多.就起尘粒径而言,各地的起尘颗粒以耕地和地带性草原植被的含量最大,其次为退化草原,而各类沙丘含量较小.说明合理利用草场资源和保护性耕作的重要性.     

Spatial variability in soil heat flux at three Inner Mongolia steppe ecosystems

Closing the energy budget at flux measurement sites is problematic, even when the fetch extends over flat, homogeneous surfaces with low vegetation cover. We used the residual energy balance and ordinary least square (OLS) linear regression methods to quantify spatial variability in soil heat flux contributing to energy balance closure (EBC), by deploying a mobile energy system within the footprints of three Eddy-covariance towers located in the steppe of Inner Mongolia, China. The EBC at the study sites had a daily average residual of 8–19 W m⁻² with OLS slopes of 0.83–0.96. The EBC was better achieved at the wet site than at the dry site. The spatial variability in soil heat flux was 48 W m⁻² (13% of R_n) during the day and 15 W m⁻² (34%) at night, with an average of 29 W m⁻² (24%) across the three sites. A 9% OLS slope difference due to this variability was recorded from our eight plot measurements. A large amount of missing energy (110 W m⁻² at peak) could occur with decreasing OLS slope of 23% across the three grassland sites when soil heat flux is not taken into account. In particular, heat storage in the top soil layer not only influenced the magnitude of EBC, but also adjusted soil heat flux to match the ‘truth schedule’. Heat storage in the top soil layer comprised half of the soil heat flux when the heat flux plate was deployed at a depth of 30 mm. If this part of heat storage was neglected, the residual of EBC would increase as large as 60 W m⁻² with OLS slope decreasing 9%. Comparing them with the multiple-location soil heat flux measurements, the single-location measurements from near the Eddy-covariance towers obtained a slightly better EBC with the OLS slope increasing by 4%.     

土壤厚度对天然草地植被盖度和生物量的影响

土壤厚度是土壤肥力存在和植物生长的重要物质基础.本文调查了内蒙古东部地区多伦、锡林浩特和巴林左旗3个长期保护天然草地的土壤厚度和植被盖度等植物生长状况.结果表明,天然草地植被盖度、地上生物量和高度随土壤厚度的增加而增大.当土壤厚度小于20 cm时,植被盖度和地上生物量随土壤厚度的降低急剧减小,当土壤厚度小于10 cm时,植被类型为非地带性植被,盖度小于30%,地上生物量小于150 g/m2;当土壤厚度大于20 cm后,植被盖度一般大于80%,地上生物量接近或大于200 g/m2,而且土壤厚度大于20 cm后植被盖度和地上生物量随土壤厚度的继续增大变化平缓.研究区地带性天然草地植被正常生长的最低土壤厚度为20 cm左右.