切沟对沟岸地土壤水分的影响

In order to preliminarily look at rules for soil moisture changes in the bank of the gully and to provide some recommendations for vegetative restoration in gully bank regions in the Loess Plateau, changes of soil moisture with depth and distance to the gully edge and their dynamic changes with time were observed to study the soil water characteristics in the bank of the gully. The results showed that soil water content increased with increasing distance from the gully edge, whereas for the same time period, the closer the distance to the gully wall, the greater the water loss; and that the influential distance of side evaporation decreased as depth increased.     

天然载体控释氮肥研究初探

The Wangdonggou Watershed on the Loess Plateau in China was selected as the study area to develop a model for soil erosion assessments. Using the data collected at 20 sampling sites all tentatively selected indicators were assessed against their corresponding erosion intensity through a correlation analysis. Eight highly correlated indicators were then chosen for the soil erosion assessment. In addition, threshold limits to delineate the class size for these indicators and weights to rank them were determined. Next, a grading model incorporating the selected indicators class rating and their associated weights was developed and verified by an on site evaluation of the soil erosion intensity in the study area. Results of the verification showed that the overall accuracy of the indicator system for assessing soil erosion in the Loess Plateau gully regions could reach 85%.     

黄土高原沟壑区土壤侵蚀评价指标体系——以中国王东沟流域为例

The Wangdonggou Watershed on the Loess Plateau in China was selected as the study area to develop a model for soil erosion assessments. Using the data collected at 20 sampling sites all tentatively selected indicators were assessed against their corresponding erosion intensity through a correlation analysis. Eight highly correlated indicators were then chosen for the soil erosion assessment. In addition, threshold limits to delineate the class size for these indicators and weights to rank them were determined. Next, a grading model incorporating the selected indicators class rating and their associated weights was developed and verified by an on site evaluation of the soil erosion intensity in the study area. Results of the verification showed that the overall accuracy of the indicator system for assessing soil erosion in the Loess Plateau gully regions could reach 85%.     

加速土壤侵蚀对养分流失的影响

Soil erosion and nutrient losses on newly-deforested lands in the Ziwuling Region on the Loess Plateau of China were monitored to quantitatively evaluate the effects of accelerated soil erosion, caused by deforestation, on organic matter, nitrogen and phosphorus losses. Eight natural runoff plots were established on the loessial hill slopes representing different erosion patterns of dominant erosion processes including sheet, rill and shallow gully （similar to ephemeral gully）. Sediment samples were collected after each erosive rainfall event. Results showed that soil nutrients losses increased with an increase of erosion intensity. Linear relations between the losses of organic matter, total N, NH4-N, and available P and erosion intensity were found. Nutrient content per unit amount of eroded sediment decreased from the sheet to the shallow gully erosion zones, whereas total nutrient loss increased. Compared with topsoil, nutrients in eroded sediment were enriched, especially available P and NH4-N. The intensity of soil nutrient losses was also closely related to soil erosion intensity and pattern with the most severe soil erosion and nutrient loss occurring in the shallow gully channels on loessial hill slopes. These research findings will help to improve the understanding of the relation between accelerated erosion process after deforestation and soil quality degradation and to design better eco-environmental rehabilitation schemes for the Loess Plateau.     

Effect of vegetation changes on soil erosion on the loess plateau

Vegetation is one of the key factors affecting soil erosion on the Loess Plateau. The effects of vegetation destruction and vegetation restoration on soil erosion were quantified using data from long-term field runoff plots established on the eastern slope of the Ziwuling secondary forest region, China and a field survey. The results showed that before the secondary vegetation restoration period （before about 1866-1872）, soil erosion in the Ziwuling region of the Loess Plateau was similar to the current erosion conditions in neighboring regions, where the soil erosion rate now is 8 000 to 10 000 t km^-2 year^-1. After the secondary vegetation restoration, soil erosion was very low; influences of rainfall and slope gradient on soil erosion were small; the vegetation effect on soil erosion was predominant; shallow gully and gully erosion ceased; and sediment deposition occurred in shallow gully and gully channels. In modern times when human activities destroyed secondary forests, soil erosion increased markedly, and erosion rates in the deforested lands reached 10 000 to 24000 t km^-2 year^-1, which was 797 to 1682 times greater than those in the forested land prior to deforestation. Rainfall intensity and landform greatly affected the soil erosion process after deforestation. These results showed that accelerated erosion caused by vegetation destruction played a key role in soil degradation and eco-environmental deterioration in deforested regions.     

子午岭植被自然恢复过程中土壤有机碳密度的时空变化

To probe the processes and mechanisms of soil organic carbon （SOC） changes during forest recovery, a 150-year chronosequence study on SOC was conducted for various vegetation succession stages at the Ziwuling area, in the central part of the Loess Plateau, China. Results showed that during the 150 years of local vegetation rehabilitation SOC increased significantly （P 〈 0.05） over time in the initial period of 55-59 years, but slightly decreased afterwards. Average SOC densities for the 0-100 cm layer of farmland, grassland, shrubland and forest were 4.46, 5.05, 9.95, and 7.49 kg C m^-3, respectively. The decrease in SOC from 60 to 150 years of abandonment implied that the soil carbon pool was a sink for CO2 before the shrubland stage and became a source in the later period. This change resulted from the spatially varied composition and structure of the vegetation. Vegetation recovery had a maximum effect on the surface （0-20 cm） SOC pool. It was concluded that vegetation recovery on the Loess Plateau could result in significantly increased sequestration of atmospheric CO2 in soil and vegetation, which was ecologically important for mitigating the increase of atmospheric concentration of CO2 and for ameliorating the local eco-environment.     

黄土丘陵小流域蒸散发和水分平衡对植被恢复的影响

Evapotranspiration, soil moisture balance and the dynamics in a gully catchment of the Loess Plateau in China were determined with 6 land use treatments including natural grassland, shrubs （Caragana rnicrophylla）, two woodlands （Prunus armeniaca var. ansu and Pinus tabulaeformis）, cultivated fallow, and farmland （Triticum aestiuum L.） in order to obtain a better understanding of soil moisture balance principles and to improve vegetation restoration efficiency for ecological rebuilding on the plateau. Average runoff from cultivated fallow was very high, reaching 10.3% of the seasonal rainfall. Evapotranspiration under T. aestivurn was not significantly different from natural grasslands. Compared with natural grass, evapotranspiration was significantly greater （P 〈 0.05） in 2002 and there was an increase in soil moisture depleted in the 1-3 m soil under P. armeniaca, P. tabulaeformis and C. microphylla. During the two years of the study the average soil moisture （0-100 cm soil profile） of T. aestivurn was generally the highest, with P. armeniaca, P. tabulaeformis and C. rnicrophylla usually the lowest. Thus, according to the soil moisture balance principle for this area the planned reforestation project was not ecologically reasonable. Reducing human disturbance and restoration with grass could be more effective.     

西藏高原土壤侵蚀敏感性空间分布

The Tibet Plateau, occupying the main part of Qinghai-Tibet Plateau and having an average altitude of 4 500 m, has geomorphological features that are unique in the world, with soil erosion being one of the main ecological problems. Thus the main objectives of the present research were to set up an efficient and simple way of evaluating spatial distribution of soil erosion sensitivity in the Tibet Plateau as well as the responses of soil erosion to changes of natural environmental conditions, and to indicate key regions where soil erosion should be preferentially controlled. Based on the Universal Soil Loss Equation （USLE）, the study applied geographic information system （GIS） technology to develop a methodological reference framework, from which soil erosion sensitivity could be evaluated. The impact of precipitation, soil, topography and vegetation on soil erosion was divided into classes of extreme sensitivity, high sensitivity, medium sensitivity, low sensitivity and no sensitivity. With the aid of GIS, the resultant map from overlaying various factors showed that soil erosion sensitivity had great discrepancy in different parts of the region. In the southeastern part of the Tibet Plateau there were mainly three classes of sensitivity, namely, extreme, high and medium sensitivity. However, the other two classes; low and no sensitivity, were dominant in the northwestern part.     

陇海铁路郑州—圃田段铁路旁土壤重金属污染

The pollution status and horizontal distribution of heavy metals (Ni, Pb, Cr, Zn, Cu, and Cd) in the soil on railroad side along the Zhengzhou-Putian section of Longxi-Haizhou Railroad were studied by collecting soil samples along a sampling section perpendicular to the railroad at the distances of 0, 10, 20, 30, 50, 100, 200, 300, and 500 m from the railroad edge. The concentrations of heavy metals in the sampling soils were higher than those of the control site. The concentrations of Pb, Zn, and Cd were found to be the highest in the soils at the railroad edge, and then decreased with increasing distance from the railroad. The highest concentrations of Ni, Cr, and Cu in soils were located at about 10-30 m from the railroad. Compared with the single factor pollution index (SFPI) of heavy metals calculated for the control site, the average SFPI from the sampling sites decreased in the order of Cr > Cd > Pb > Zn > Ni > Cu. There were notable negative correlations between the integral pollution index (IPI) of soil heavy metals at all sampling sites and the distances from the railroad. According to three IPIs calculated from the background values of heavy metals in och-aquic Cambisols, the heavy metal concentrations in the control soil, and the 2nd levels for soil heavy metals in GB15618-1995, the study area could be divided, based on the distances from the railroad, into four pollution zones: heavy pollution zone (0-10 m), medium pollution zone (10-50 m), slight pollution zone (50-100 m), and warning zone (100-500 m), respectively.     

Land use effects on the dynamics of soil C, N and microbes in the water-wind erosion crisscross region of the northern Loess Plateau, China

The water-wind erosion crisscross region of the northern Loess Plateau in China is under constant pressure from severe erosion due to its windy and dry climate and intensive human activities. Identifying sustainable land use patterns is key to maintaining ecosystem sustainability in the area. Our aim was to appraise the impacts of different land use regimes on the dynamics of soil total organic C(TOC), total N(TN), and microbes in a typical watershed in the northern Loess Plateau to identify sui...     

不同施肥条件下氯氰菊酯对土壤酶活性的影响及其降解差异

采用长期定位施肥试验土壤（轻壤质黄潮土），研究不同施肥条件下，氯氰菊酯降解变化和对土壤酶活性的影响。结果表明，不同的施肥处理对土壤中氯氰菊酯的降解行为有显著影响，长期施用氮肥，土壤中速效氮含量升高，对氯氰菊酯降解有抑制作用；施用磷肥则促进降解；施用有机肥在提高土壤有机质含量的同时，虽加速了氯氰菊酯降解，但降解延滞期和残留期有所增加。氯氰菊酯在土壤中的降解遵循一级动力学方程，降解半衰期为10．13d（PK）～14．58d（NK）。土壤中加入氯氰菊酯后，脱氢酶、脲酶活性有所升高，施肥处理不同，升高幅度也不一样．均达显著水平。磷酸酶活性变化在不同施肥处理中，表现不一样。培养26d左右，土壤酶活性大多都能恢复到初始水平。研究土壤中农药残留与施肥、土壤酶活性的关系，对于实现农业可持续发展具有重要意义。     

添加秸秆对土壤矿质氮量、微生物氮量和氮总矿化速率的影响

采用室内恒温培养法,研究了在乌沙土上添加15N标记秸秆后,秸秆15N在矿质氮、微生物氮和土壤不同组分中的分配情况,并应用氮同位素库稀释法测定了秸秆在乌沙土上的氮总矿化速率。结果表明:将秸秆添加到土壤后,微生物氮量显著增加,而土壤矿质氮量在14天时迅速下降。随着秸秆的分解,秸秆15N进入矿质氮库和微生物氮库,矿质15N在第7 d时最高,占到添加秸秆15N的6.7%,微生物15N在第14 d最高,占到添加秸秆15N的18.1%,随后矿质15N和微生物15N量都下降。56 d时,仍有50.8%的秸秆氮没有分解掉,5.4%的秸秆15N进入土壤53μm~2 mm组分,15.5%进入2~53μm组分,14.6%进入小于2μm组分,有13.6%的秸秆氮损失掉。在培养开始时,乌沙土的氮总矿化速率为2.81 mg kg-1d-1,秸秆在乌沙土上的氮总矿化速率分别为2.50 mg kg-1d-1。     

Microbial response to bensulfuron-methyl treatment in soil.

A laboratory incubation study was conducted to evaluate the effect of bensulfuron-methyl treatment on soil microbial biomass and N-mineralization of a loamy sand soil. The herbicide was applied at 0 (control), 0.01 (field rate), 0.1, and 1.0 microg g(-1), and soil microbial biomass carbon (C(mb)), soil microbial biomass nitrogen (N(mb)), and N-mineralization rate (k) were measured at different times after herbicide treatment. Compared to the untreated soil, C(mb) and N(mb) decreased significantly (p < or = 0.05) within the first 7 days after herbicide treatment at 0.1 and 1.0 microg g(-1), and the impact was greater for N(mb) than for C(mb). Nitrogen mineralization was significantly suppressed during the first 5 days of incubation when the soil was treated with bensulfuron-methyl at 0.1 and 1.0 microg g(-1). The overall impact of bensulfuron-methyl to the soil microbial communities was closely related to the application rate in the range of 0.01-1.0 microg g(-1). This effect, however, was found to be transitory, and significant impact occurred only at high application rates.     

中国南方大棚蔬菜地氮平衡与损失

High rates of fertilizer nitrogen (N) are applied in greenhouse vegetable fields in southeastern China to maximize production;however,the N budgets of such intensive vegetable production remain to be explored.The goal of this study was to determine the annual N balance and loss in a greenhouse vegetable system of annual rotation of tomato,cucumber,and celery at five N (urea) application rates (0,348,522,696,and 870 kg N ha-1 year-1).Total N input to the 0-50 cm soil layer ranged from 531 to 1 053 kg ha-1,and N fertilizer was the main N source,accounting for 66%-83% of the total annual N input.In comparison,irrigation water,wet deposition,and seeds in total accounted for less than 1% of the total N input.The fertilizer N use efficiency was only 18% under the conventional application rate of 870 kg N ha-1 and decreased as the application rate increased from 522 to 870 kg N ha-1.Apparent N losses were 196-201 kg N ha-1,of which 71%-86% was lost by leaching at the application rates of 522-870 kg N ha-1.Thus,leaching was the primary N loss pathway at high N application rates and the amount of N leached was proportional to the N applied during the cucumber season.Moreover,dissolved organic N accounted for 10% of the leached N,whereas NH3 volatilization only contributed 0.1%-0.6% of the apparent N losses under the five N application rates in this greenhouse vegetable system.     

太湖地区水稻最适宜施氮量研究

To determine the optimal amount of nitrogen(N) fertilizer for achieving a sustainable rice production at the Taihu Lake region of China,two-year on-farm field experiments were performed at four sites using various N application rates.The results showed that 22%-30% of the applied N was recovered in crop and 7%-31% in soils at the rates of 100-350 kg N ha 1.Nitrogen losses increased with N application rates,from 44% of the applied fertilizer N at the rate of 100 kg N ha 1 to 69% of the N applied at 350 kg N ha 1.Ammonia volatilization and apparent denitrification were the main pathways of N losses.The N application rate of 300 kg N ha 1,which is commonly used by local farmers in the study region,was found to lead to a significant reduction in economic and environmental efficiency.Considering the cost for mitigating environmental pollution and the maximum net economic income,an application rate of 100-150 kg N ha 1 would be recommended.This recommended N application rate could greatly reduce N loss from 199 kg N ha 1 occurring at the N application rate of 300 kg N ha 1 to 80-110 kg N ha 1,with the rice grain yield still reaching 7 300-8 300 kg DW ha 1 in the meantime.     

减氮和施生物炭对华北夏玉米-冬小麦田土壤CO2和N2O 排放的影响

2013年6月-2014年6月,在河南省新乡夏玉米-冬小麦试验田设置四种处理即农民常规施肥（F处理,250kg·hm^-2）、减氮20%（LF处理,200kg·hm^-2）、减氮20%+黑炭（LFC）,以不施肥处理为对照（CK）,采用静态箱-气相色谱法,对夏玉米-冬小麦生长季土壤CO_²和N_²O排放通量动态进行测定。结果表明：（1）夏玉米-冬小麦田的土壤CO₂排放通量为21.8～1022.7mg·m^-2·h^-1,土壤CO_²排放通量主要受土壤温度和水分的影响,在夏玉米季受土壤水分的影响更为显著,而在冬小麦季则为5cm土层处的温度对其影响更为突出。减施氮肥20%处理和减氮加生物黑炭共同作用使土壤CO_²累积排放量显著降低,小麦生长季的减排作用尤为显著。（2）施肥和灌溉是影响土壤N_²O排放的最主要因素,施肥期间N2O排放量分别占夏玉米季和冬小麦季累积排放量的73.9%～74.5%和40.5%～43.6%;施肥量主要影响排放峰的强度,灌溉主要影响排放峰出现时间的早晚且会影响不同措施的减排效果。在每季作物250kg·hm^-2施氮水平下减施氮肥20%使夏玉米季和冬小麦季的N₂O累积排放量分别降低15.7%～16.8%和18.1%～18.5%,是高产集约化农田减排N₂O的有效措施。在适宜施氮水平（200kg·hm^-2）下施用生物黑炭,短期内对土壤N₂O排放无显著影响。（3）夏玉米-冬小麦田农民常规施肥水平的N₂O排放系数为0.60%,减氮施肥的N₂O排放系数为0.56%。在华北平原高产集约化农田适当减氮施肥不仅能降低农田土壤温室气体排放,且对作物产量无影响,是适宜的温室气体减排措施。     

不同有机肥对采煤塌陷区土壤氮素矿化动态特征研究

为揭示不同有机肥对煤矿复垦土壤氮素矿化特性的影响,以山西省孝义市水峪煤矿采煤塌陷复垦土壤为研究对象,采用室内好气培养法,研究在40%含水量和30℃培养条件下,施用3种有机肥(鸡粪、猪粪、牛粪)后在0~161天的氮素矿化动态特征,以明确不同有机肥对该矿区复垦土壤氮素矿化特征,从而预估不同有机肥的供氮特性,为合理施用有机肥进行低产农田的培肥改造提供科学依据。结果表明:(1)各处理0~14天铵态氮含量均随培养时间的延长迅速下降,与培养时间呈极显著负相关关系(P<0.01),14~161天土壤铵态氮含量维持在较低水平,培养结束时,各处理铵态氮含量均低于1.31mg/kg。(2)各处理土壤硝态氮含量、累积量及矿质氮累积量变化均呈近似的“S”形曲线递增,表现为0~56天缓慢增加,56~84天迅速增加,84天至培养结束(161天)其含量基本不变。培养结束时不同处理间硝态氮含量、累积量及矿质氮累积量整体上均表现为鸡粪>猪粪>牛粪>空白,且鸡粪较猪粪和牛粪处理间存在显著差异,猪粪和牛粪较空白处理间存在显著差异(P<0.05)。(3)不同施肥处理出现氮素净矿化的时间点不同,其中鸡粪处理在第14天时最早出现净矿化现象,而猪粪和牛粪在培养28天后才出现明显的氮素净矿化。(4)不同施肥处理在培养的不同阶段硝态氮和矿质氮累积速率不同,但整体趋势一致,表现为培养0~84天各处理土壤累积矿化波动较大,56~84天达到峰值,培养84~161天各处理矿化速率平稳下降。总体来看,有机肥的施入能有效促进煤矿复垦土壤氮素矿化,从而提高土壤氮素有效性。其中,施鸡粪较猪粪和牛粪对提高矿区复垦土壤有效氮效果更好。4种处理的氮素矿化效果总体表现为鸡粪>猪粪>牛粪>空白。     

15N标记秸秆在太湖地区水稻土上的氮素矿化特征研究

采用室内恒温培养试验研究了在太湖地区乌栅土和黄泥土上添加15N标记秸秆后,秸秆15N在矿质氮、微生物氮和不同粒径土壤组分中的分配情况,并应用氮同位素库稀释法测定了秸秆在两种土壤上的氮总矿化速率。结果表明:两种土壤添加秸秆后,土壤矿质氮量在7～28 d之间迅速下降,微生物氮在前7 d逐渐升高,随后维持稳定。随着秸秆的分解,秸秆15N进入矿质氮库和微生物氮库,矿质15N在第7天时最高,占添加秸秆15N的9.24%～12.3%,微生物15N在第14天时最高,占添加秸秆15N的21.3%～40.5%,随后矿质15N和微生物15N量均下降。在培养的第7～28天之间,矿质15N和微生物15N出现下降,可能存在秸秆氮的损失。培养56 d时,10.5%～13.3%的秸秆15N进入土壤53μm～2 mm组分,24.5%～26.5%进入2～53μm组分,30%进入<2μm组分,有5.7%～14.9%的秸秆氮损失掉,仍有15.4%～29.1%的秸秆未分解,秸秆在乌栅土上分解的更多,但损失也更多。添加秸秆后0.5 d时,秸秆在乌栅土和黄泥土上的氮总矿化速率分别为1.61 mg kg-1d-1和1.48 mg kg-1d-1;56 d时,秸秆在乌栅土和黄泥土上的氮总矿化速率分别为0.26 mg kg-1 d-1和0.36 mg kg-1 d-1。     

红壤水稻土微生物生物量氮与总氮矿化的关系

通过田间采样并布置室内培育试验,研究了红壤水稻土微生物生物量N和总N的矿化动态及其相互关系。结果表明,红壤水稻土微生物生物量N矿化速率和矿化量随培养时间延长而降低,随水稻土肥力水平提高而增加。12周培养期内,红壤水稻土微生物生物量N的一半以上被矿化,其中约1/2的矿化量出现在前4周;不同熟化程度红壤水稻土的累积矿化N量为73.0～127.8mg/kg,平均矿化速率为6.09～10.7mg/(kg·wk)。用双指数方程和一级动力学方程可以很好地模拟红壤水稻土微生物生物量N和总N的矿化过程。微生物生物量N和总N的矿化过程均可分为快速和缓慢2个阶段,培养的前8周是快速矿化阶段。2个模拟方程参数的比较表明,微生物生物量N矿化量占总N矿化量的比例为10.8%～49.5%,其矿化潜力大,持续矿化时间长,对保证土壤N素的持续供应有积极作用。     

肥际氮素浓度下添加不同碳源对水稻土微生物特性的影响

研究肥际氮素浓度下添加不同碳源后微生物的变化特征,对于了解不同活性碳源对肥际养分浓度下氮素转化和调控作用以及提高氮素利用率等具有重要意义。采集我国亚热带地区典型的水稻土,模拟肥际氮素浓度,设置不同硫铵用量和葡萄糖、纤维素或木质素碳源添加处理,进行室内培养试验,研究了各处理土壤微生物生物量碳氮、矿化及微生物群落功能多样性的变化。结果表明,在培养7天和35天,高氮素用量下与不添加碳源处理相比,添加葡萄糖、纤维素和木质素各处理土壤微生物生物量碳分别增加5.0%～126.8%、17.5%～210.9%和14.7%～210.0%,微生物生物量氮分别增加-5.4%～109.3%、32.0%～173.1%和-14.2%～194.8%(负数表示减少)。而中等和常量氮素条件下添加这3种碳源,土壤微生物生物量碳氮也呈增加趋势。肥际氮素各浓度下添加葡萄糖处理CO2释放量最多,其次是添加纤维素,最后是添加木质素。BIOLOG分析显示,高、中氮素用量下,平均吸光值(AWCD)、Shannon、Simpson和McIntosh指数都较低,添加3种碳源处理后均有提高,而单独添加不同碳源及添加常量氮素和碳源处理,AWCD值和微生物功能多样性指数水平较高。较高的肥际氮素浓度下添加葡萄糖、纤维素或木质素可提高土壤微生物活性。在当前大量施无机氮肥的条件下,注重有机物的配合施用,有利于减小氮素损失的风险。