秸秆与氮肥配施对辽西旱区土壤酶活性与土壤养分的影响

通过田间试验研究了玉米(Zea mays L.)秸秆与氮肥配施对耕层土壤酶活性及土壤养分的影响。试验设4个秸秆还田量水平,2个施氮量水平。结果表明:在秸秆配施氮肥条件下,耕层土壤中性磷酸酶、脲酶、转化酶和过氧化氢酶活性以及有机质和全氮质量分数均表现为随着玉米秸秆还田量的增加而提高,而硝态氮(3NO-N)和铵态氮(+4NH-N)质量分数则表现为随着玉米秸秆还田量的增加而减少,4种土壤酶活性与土壤有机质和全氮质量分数均呈显著正相关,与土壤硝态氮和铵态氮质量分数则呈显著负相关。玉米秸秆还田量9 000 kg.hm-2配施氮肥量420 kg.hm-2是辽西风沙半干旱区效果较好的技术措施。

低浓度苯系物在新疆干旱区土壤中的吸附行为研究

采集新疆干旱区石化废水库附近区域土壤,以苯、甲苯、乙苯、二甲苯(间、对二甲苯)等典型苯系物为研究对象,系统研究低浓度苯系物在干旱区土壤上的吸附行为,分析土壤有机质含量,溶液p H、溶液含盐量、温度对苯系物吸附的影响。结果显示土壤对低浓度苯系物的吸附16 h达到平衡;吸附等温线经拟合后符合Henry直线型吸附模型;土壤对苯系物的吸附量随着土壤有机质含量的增加而增加,土壤有机质含量与吸附量呈显著正相关(P<0.01,R2≥0.919);溶液p H值对吸附过程无明显作用;随着溶液含盐量增大,土壤对苯系物的吸附量表现为先减小,再稳定;温度升高会抑制土壤对苯系物的吸附作用。

干旱区土壤中西瓜专化型尖孢镰刀菌拮抗菌的筛选及分类

针对宁夏中部干旱带压砂西瓜田长期连作种植所产生的土壤退化、土壤养分含量降低、土壤真菌性病害增加、西瓜减产、品质下降等问题,从患病的西瓜植株上分离出致病菌-尖孢镰刀菌西瓜专化型(Fusarium oxysporum f.sp.niveum),从宁夏环香山地区压砂瓜集中连片种植区采集健康土壤中分离筛选对西瓜枯萎病致病菌有抑菌效果的拮抗菌株,并对拮抗菌株的防病效果以及分类鉴定进行了研究。通过采用平板稀释法筛选出对目标靶具有拮抗作用的拮抗细菌。通过初筛选取8株对目标靶具有拮抗作用的细菌进一步进行复筛试验。经过数据分析,G-1的抑菌率最大,且与其他处理间存在显著性差异,筛选出对目标靶拮抗最强的拮抗菌为G-1。根据形态学观察、细菌生理生化鉴定和16 S r DNA序列的同源性分析,确定拮抗菌株G-1为萎缩芽孢杆菌(Bacillus atrophaeus)。

干旱区土壤自养微生物研究进展

微生物自养固碳是维持干旱区土壤微生物群落结构及异养活动的重要过程,并影响地表生物结皮的演替及生态功能。近年来,土壤微生物组学的广泛应用,拓展了蓝细菌及真核藻类土壤自养微生物功能群研究,揭示了非蓝细菌类原核微生物向土壤输入有机质的可能。基于此,本文综述了干旱区土壤蓝细菌及藻类的分布及功能特征,并总结了环境因子的调控作用,重点总结了近几年对非蓝细菌自养微生物功能群及其生态功能的探索,最后对干旱区土壤自养微生物功能群研究的发展进行了总结与展望,以期为深入理解干旱区土壤微生物群落的形成及发展机理提供理论基础,并为良好生物结皮的构建提供科学依据。

干旱区绿洲土壤中Cd,Pb,Zn形态分布与芹菜有效性

以干旱区绿洲耕层土壤为研究对象,通过盆栽试验,利用Tessier连续提取法研究了原状土以及外源可溶性重金属Cd,Pb,Zn加入土壤后重金属形态分布,分析了土壤中重金属不同化学形态与芹菜有效性之间的关系。结果表明:原状土壤中Cd主要以铁锰氧化态和碳酸盐结合态形式存在,Pb和Zn主要以残渣态形式存在;随着重金属负荷的增大,三种重金属各形态质量分数均有不同程度的提高,Cd以可交换态和碳酸盐结合态为主要赋存形态,Pb和Zn均以碳酸盐结合态和铁锰氧化态为主要赋存形态。实验土壤中,对芹菜Cd吸收量贡献最大的分别为可交换态和碳酸盐结合态,对Pb吸收量贡献最大的分别是碳酸盐结合态和铁锰氧化态,对Zn吸收量贡献最大的分别是碳酸盐结合态和可交换态。

干旱区绿洲土壤中重金属的形态分布及生物有效性研究

测定了Cd、Pb、Zn和Ni等重金属在不同处理土壤中的全量和各赋存形态,以及它们在盆栽试验油菜(Brassica cole)中的质量分数,并利用Pearson相关系数分析了该区土壤-油菜体系的生物有效性。结果表明,供试绿洲土壤原状土中,Cd、Pb、Zn和Ni均以稳定的残渣态形式存在;而在处理土壤中,重金属被钝化的量有限,Cd的存在形式主要以碳酸盐态为主,Pb、Zn和Ni则主要以铁锰氧化态为主。根据相关性分析,油菜根部和叶部的Ni质量分数均与土壤中Ni的各非残渣态分布系数有相关性,表明当土壤中Ni以非残渣态存在时,活动性Ni的质量分数较高,其被生物吸收利用的可能性也较大;油菜根部的Zn质量分数与土壤中Zn的碳酸盐结合态分布系数显著的正相关性;油菜各部位Cd和Pb的质量分数与土壤中Cd和Pb的各形态分布系数之间无显著相关关系。

绿洲干旱区土壤COS和CS_2交换通量影响因素的研究

文中通过静态箱采样,利用Turbo Matrix 100型热解析仪与气相色谱联用法,分析了环境因子,如水分、温度、光照和玉米秸秆添加等对绿洲干旱区土壤羰基硫(COS)和二硫化碳(CS_2)交换通量的影响。结果表明:干旱土壤COS和CS_2的平均通量分别为1.17、3.28pmol·m^(-2)·s^(-1),淹水土壤COS和CS_2的平均通量分别为-11.11、-3.41pmol·m^(-2)·s^(-1),干旱土壤作为COS和CS_2的源,淹水土壤则为其汇,且淹水土壤交换强度高于干旱土壤。与淹水土壤相比,玉米秸秆的添加使得COS和CS_2的交换强度分别提高了34.2%和149.27%。同时测得COS具有明显的日变化规律,干旱土壤总交换量基本平衡,表现为微弱的释放,淹水土壤总体表现为较强的吸收。CS_2则表现不明显。水分和温度虽然与交换通量之间没有显著相关性,但对交换方向和强度有重要影响。对以上过程的讨论提示我们非生物产生和消耗过程存在的可能性。

黑河流域土壤退化研究

在黑河流域干旱土纲中采集5个典型土壤剖面以研究该地区干旱土壤的演化。同时，为了了解土壤养分含量、土壤干旱化和土壤盐化的变化趋势，测定了高台县两北盐池地区主要盐土类型各剖面中的盐分含量和流域内主要土类中水分含量的分布。结果表明，干旱区内陆河流域土壤的退化主要表现为干旱化、盐渍化和土壤肥力的退化。在流域内干旱化随流域上中下游降水量和干燥度的变化而变化，土壤随距河流的距离及地下水位的高低而变化。流域内土壤从潜育土向雏形土、干旱雏形土和干旱土的方向变化。盐渍化与土壤水分含量和地下水位有关，并与水分的蒸发有密切的关系。在一定范围内，距水源越远，盐分含量一般越高。土壤肥力的退化表现为土壤有机质含量降低，阳离子代换量降低等理化性质的退化，这一退化过程是其它过程的综合反映。质地的退化虽受风沙化的影响，但与土壤的形成母质有一定的关系。

鹤岗地区土壤耕作模式探讨

总结鹤岗地区土壤耕作模式,包括平原易旱区土壤耕作模式、冷凉低湿易涝区土壤耕作模式、丘陵漫岗土壤耕作模式、水稻田土壤耕作模式,以提高鹤岗地区农业发展水平。

干旱区绿洲土壤外源Cd、Pb的形态分布及再分配

以干旱区绿洲土壤为研究对象,采用Tessier连续提取技术对外源Cd和Pb的形态分布与再分配进行了研究。结果表明:在盆栽试验完成后,Cd和Pb主要以碳酸盐结合态和铁锰氧化态存在。Cd的全量是影响其可交换态、碳酸盐结合态和铁锰氧化态含量的主要因素,而有机物结合态和残渣态受其它因素的影响也较大。Pb的全量是其各种形态含量的主要影响因素。随着Cd和Pb添加量的增加,其土壤总的再分配系数呈增加趋势,结合强度系数则相反,表明Cd和Pb各形态间的稳定性下降。随着时间的推移,二者各形态会继续发生变化,但这一过程缓慢。因此,土壤重金属污染具有长期性。

干旱区绿洲土壤中Ni在芹菜中的富集迁移

以干旱区绿洲土壤为供试土壤,采用盆栽试验研究外源Ni污染对芹菜生长的影响及在芹菜中的富集迁移。结果表明:外源Ni的添加在低质量分数下能够促进芹菜的生长,达到一定临界值后,则出现明显的毒害作用;随着土壤中Ni的添加质量分数的增加,芹菜体内的Ni含量也随之增加。统计分析表明对芹菜根部和地上部吸收累积Ni贡献最大的均为铁锰氧化态和碳酸盐结合态;芹菜通过根系吸收的Ni主要存在于根系组织中,根部富集能力明显大于地上部,外源Ni的添加明显抑制了其在芹菜体内的迁移能力。

世界干旱土:分布与潜力

干旱土与干旱区土壤并非完全等同的两个地理概念,但对荒漠区的定义和分布范围作一了解还是有益的。对四家不同的组织和个人在干旱水分状况中所用的指标,即联合国教科文组织在其“干旱区研究”计划中用到的指标、“土壤系统分类”中用的指标、Newhall—Van Wambeke所用的指标以及联合国粮农组织在“农业生态区”规划中所用的指标进行了对比。干早区的土壤,无论是干旱土还是非干旱土,都有一些共同的特殊的表面特性,本文对这些性质作了描述和命名。对干旱区以外出现的干旱土进行了解释,对干旱土在世界上分布作了估计,还对干旱土的诊断特性作了简要的说明。对干旱区的干旱土和非干旱土在雨灌作物、灌溉农业、集水、草场管理及旅游业等方面的潜力作了讨论。最后对现行干旱土分类中某些指标的作用提出了一些看法。

The runoff characteristics and harmonic analysis of the soil moisture dynamics in Robinia pseudoacacia stand

Robinia pseudoacacia stands act as a typical ecological protection forest in hilly semi-arid area of China. Two fields of surface runoff were separately set up in R. pseudoacacia stand and its clearcut area in the western Liaoning Province (1850-12225 E, 4024-4234 N) for measuring the characteristics of runoff and sediment as well as soil moisture dynamics. Contractive analysis of the two land types showed that there existed a significant difference in volumes of runoff and sediment between the sites of R. pseudoacacia stand and its clearcut area. The runoff volume and sediment volume in clearcut area were much bigger than those in R. pseudoacacia stand, with an increase amount of 40%-177% for runoff and 180%-400% for sediment. Hydrograph of surface runoff of typical rainfall showed that the peak value of runoff in R. pseudoacacia stand was decreased by 1.0-2.5?0-3m3s-1 compared with that in its clearcut area, and the occurring time of peak value of runoff in R. pseudoacacia stand was 10-20 min later than that in its clearcut area. Harmonic analysis of soil moisture dynamics indicated that the soil moisture in R. pseudoacacia stand was 2.3 % higher than that in clearcut area, and the soil moisture both in R. pseudoacacia stand and its clearcut area could be divided into dry season and humid season and varied periodically with annual rainfall precipitation. It was concluded that R. pseudoacacia stand plays a very important role in storing water, increasing soil moisture, and reducing surface runoff and soil erosion.

Soil Organic Carbon,Carbon Fractions and Nutrients as Affected by Land Use in Semi-Arid Region of Loess Plateau of China

Cropland (CP),native grassland (NG) and two shrub land treatments which were converted from cropland in 1985:seabuckthorn (Hippophae rhamnoides L.) (ST),and branchytamarisk (Tamarix ramosissima) (BT) were investigated to evaluate effects of land use conversion on soil organic carbon (SOC) and soil nutrients in the semi-arid region of the Loess Plateau of China.Total organic carbon (TOC),light fraction organic carbon (LFOC),heavy fraction organic carbon (HFOC),total N (TN),nitrate nitrogen (NO 3-N) and nitrite nitrogen (NO 2-N),ammonium nitrogen (NH + 4-N),total P,and available P (AP) were measured.The results showed that SOC in NG,ST and BT were 12.7%,27.7% and 34.8% higher than that of the cropland,respectively.LFOC,light fraction (LF) dry matter,ratio of TOC to TN (C/N) and the ratio of TOC to AP (C/P) were higher in the shrub land or native grassland than in the cropland.Cropland had the highest TN,the sum of NO 3-N and NO 2-N,TP and AP due to the use of chemical fertilizers.TOC significantly correlated with LFOC,HFOC and C/N.LFOC significantly correlated with dry matter of the LF and C/N.TN,the sum of NO 3-N and NO 2-N and AP were significantly negatively correlated with TOC and LFOC.Therefore,land use conversion from cropland to shrub land,or maybe grassland,contributed to SOC sequestration and improved soil nutrients stabilization.

Effects of Land Use Change on Ecosystem Services in Arid Area Ecological Migration

Ecological migration is the process of increasing the population density in the immigration area and transferring the ecological pressure from emigration area to immigration area. This process may result in significant changes in land use and land cover in the area of immigration and have an important effect on ecosystem services. Therefore, scientifically revealing the effects and differentiation mechanisms of ecological migration on ecosystem services is becoming an important issue related to the implementation of the national ecological migration strategy in China. This study employed the Hongsibu District as a typical example of ecological migration. Hongsibu District is located in the central Ningxia steppe and desert steppe areas. Remote sensing data covering five periods from the period before ecological migration in 1995 and after migration in 2000, 2005, 2010, and 2015 was used to measure the value of ecosystem services(ESV). A geographical detector model and the value of ecosystem services model were used to diagnose the dynamic mechanism of the effects of land use change on ecosystem services. The results showed that: 1) The development of large-scale ecological resettlement has caused the area of cultivated land and urbanized land area to increase significantly in the area of immigration, while the grass area decreased significantly. 2) The overall value of the Hongsibu ecosystem services increased in a form of a ‘V'. Among them, during the period of 1995–2005, the overall ESV decreased and had an annual rate of change of-0.67%. During the period of development 2005–2015, the ESV increased steadily, with an annual rate of change of 0.79%. 3) The proportion and total ESV in soil formation and protection, waste treatment, and biodiversity conservation of the Hongsibu District decreased from 57.61% in 1995 to 56.17% in 2015, indicating that the region's ecological regulation function slightly decreased. 4) The ESV in the Hongsibu District, showed a low distribution pattern of ecosystem services increasing from northeast to southwest, and the capacity of three townships, Hongsibu, Taiyangshan, and Liuquan, to provide ecosystem services gradually declined over time. The ecological service function of Xinzhuangji Township and Dahe Township gradually improved. 5) The sensitivity index of the ESV of each land use type was less than 1, indicating that the environment lacks flexibility in providing a strong ESV index in Hongsibu, which shows that the research results are reliable and believable. 6) During the study period, the decisive force of the change of land use on ecosystem services in Hongsibu District was: grassland(0.9934), climate regulation(0.9413), soil formation and protection(0.9321) and waste treatment(0.9241).

Downward Movement and Leaching of NO_3^--N fromNitrogen-Fertilized Corn on Dryland Soil

Field lysimeter method was employed to investigate the downward movement and leaching of N applied to summer corn (Zea may L.) on dryland soil in Beiling. A N-fertilizer (120 kg N hm-2) and a control treatment were arranged for the study. Soil solution was collected at depths of 20, 40, 60, 120 and 170 cm,while leachate was collected at the bottom (200 cm) of the lysimeter. The results showed that the downward movement of NO3-N in soil profile was greatly affected by rainfall pattern. The peak of leached NO3-N from both treatments coincided with the peak of the rainfall. In addition, leached NO3-N from both treatments and rainfall were significantly correlated (P<0.05). The amount of leached NO3-N was not great in the N-fertilizer treatment. The results also suggested that N fertilization could cause NO3-N contamination of groundwater during the rainy season.

Effect of varying soil water stress regimes on nutrient uptake and biomass production in Dalbergia sissoo seedlings in Indian desert

One-year-old seedlings of Dalbergia sissoo from a single provenance were planted in non-weighing lysimeter tanks in July 1998 with a view to provide optimize irrigation parameters in desert areas. Varying water regimes were maintained by re-irrigating the seedlings at 36.2 mm （W1）, 26.5 mm （W2）, 20.2 mm （W3） and 18.1 mm （W4） treatments when the soil water content decreased to 7.56%, 5.79%, 4.44%, 3.23% in the respective treatments. Height, collar diameter, number of leaves and leaf area were highest （p 〈 0.01） for the seedlings irrigated at W1 levek Above-mentioned growth parameters did not differ between W1 and W2 treatments but the seedlings in W2 level had highest biomass per liter of water use （i.e., water use efficiency, WUE）. Irrigation levels of W3 to W5 negatively affected seedling growth, biomass production and nutrient accumulation. Soil water availability below W2 level （i.e., 5.79%） caused an increase in percentage of root biomass to the total biomass of the seedling. However, there was a decrease in percentage of leaf dry biomass in W3 and W4 treatments and in percentage of stem dry biomass in the seedlings of W5 treatment. Seedlings in W5 treatment survived till at soil water potential of-1.96 MPa. Limitation of soil water availability in W3 and W4 treatments affected growth and biomass production of D. sissoo seedlings. W： level was best for growth and biomass production in which water use efficiency was highest. Therefore, better growth and biomass production of D. sissoo seedlings could be obtained by irrigating the seedlings at soil water content of≥5.79% in the loamy sand soil.

Effect of Plant Fiber-Polyacrylamide Blend on Retention and Evaporation Water at Arid and Semi-Arid Soils of Algeria

Soil and water conservation is essential for sustaining food production and for preserving the environment in arid and semi arid lands （ASALs） where conditions for agriculture and other land use systems are often harsh and unpredictable. The ASALs of Algeria are an important source of a variety of non wood forest products like Stipa tenacissima L. plant （esparto grass）. This research was conducted to determine the effects of different low concentration （〈 I%） polyacrylaJnide, Stipa tenacissima L. fiber （esparto grass fibers） and its mixtures with the polymer at water retention in arid and semi arid soil. All samples are characterized by infrared spectroscopy, X-ray Diffractometry, thermal analysis TG DSC and scanning electron micrographs （SEM）. The results showed that polymer blend in soil could improve better soil physical proprieties decreased evaporation and increase water retention in arid soils compared with application of any other blend at the same concentration. The use of Polyacrylamide-Cellulose blend appears to promise for reducing the labor cost of irrigation at arid and semi-arid soils, and offers safe and environmentally friendly inexpensive materials. The importance of Polyacrylamide-Cellulose blends to alleviate poor physical properties and retain water in these arid regions to sustain plant growth.

Simulation of the Bare Soil Surface Energy Balance at the Tongyu Reference Site in Semiarid Area of North China

The performance of a I-D soil model in a semiarid area of North China was investigated using observational data from a cropland station at the Tongyu reference site of the Coordinated Enhanced Observing Period （CEOP） during the non-growing period, when the ground surface was covered with bare soil. Comparisons between simulated and observed soil surface energy balance components as well as soil temperatures and water contents were conducted to validate the soil model. Results show that the soil model could produce good simulations of soil surface temperature, net radiation flux, and sensible heat flux against observed values with the RMSE of 1.54℃, 7.71 W m^-2, and 27.79 W m^-2, respectively. The simulated volumetric soil water content is close to the observed values at various depths with the maximal difference between them being 0.03. Simulated latent heat and ground heat fluxes have relatively larger errors in relative to net radiation and sensible heat flux. In conclusion, the soil model has good capacity to simulate the bare soil surface energy balance at the Tongyu cropland station and needs to be further tested in longer period and at more sites in semiarid areas.

Effects of soil moisture and soil depth on nitrogen mineralization process under Mongolian pine plantations in Zhanggutai sandy land, P. R. China

The rates of soil N mineralization at soil depths of 0-15, 15-30, 30-45 and45-60 cm and moisture regimes were measured at three sand-fixation plantations of Pinus sylvestrisvar. mongolica by laboratory aerobic incubation method. The results showed that average rates ofsoil net N-mineralization across soil depth varied from 1.06 to 7.52 mg · kg^(-1)·month^(-1) atsoil depths from 0 to 60 cm. Statistical analyses indicated that the effects of different soildepths, moistures and their interactions on net N-mineralization rates were significant (P < 0.05).The net N-mineralization rates significantly decreased with increasing soil depths and at depth 0-15cm accounted for 60.52% of that at depth of 0-60 cm. There was no difference in soil netN-mineralization rates between half and fully-saturated water treatments, however these rates weresubstantially higher than that without water treatment (P < 0.05). The factors influencing Nmineralization process have to be studied further in these semiarid pine ecosystems.