冀西北坝上地区土地利用方式对土壤化学性质的影响

为了解不同土地利用方式对冀西北坝上地区土壤化学性质的影响,对该地区4种土地利用方式(围封林地、围封采伐地、未围封林地和耕地)下的土壤化学性质进行了分析.结果 表明:耕地的pH在7.5～8.5之间,明显高于其他3种土地利用方式(在6.5～7.5之间)(P＜0.05);耕地土壤的有机质、全氮、全磷、全钾及速效氮、磷、钾都明显高于3种林地(P＜0.05);2种封育林地表层土壤(0～10 cm)各养分含量明显高于未封育林地(P＜0.05),但深层土壤差异不明显.土地利用方式对土壤养分的垂直分布有显著影响,耕地土壤养分,除速效磷外,均表现为先下降后上升的趋势,养分含量变化曲线呈"V"型;3种林地土壤养分随土层深度的增加而降低,拐点均在10～20 cm土层,养分含量变化曲线呈"L"型.由以上结果得出结论,土地利用方式对土壤养分含量及其空间分布具有明显影响,耕地因为人工施肥的原因各养分含量明显高于林地,但土壤有明显的盐碱化趋势;封育可明显提高林地表层土壤养分含量,但对深层土壤影响较小.     

塞罕坝地区云杉人工林土壤养分的研究

研究了塞罕坝地区云杉人工林土壤有机质、pH、全磷、全氮、全钾、速效磷、速效钾和碱解氮的含量在不同地势（沟底、坡面和曼甸）和不同土层深度条件下的差异。结果表明,0～10 cm深度土壤各类养分在坡面地势的含量显著高于沟底和曼甸,其中有机质、全磷、速效磷和碱解氮含量平均相差50.7%、34.8%、37.4%和46.3%,沟底的速效钾和碱解氮显著高于曼甸;10～20 cm深度土壤有机质含量、全磷含量、全钾含量、速效磷含量和碱解氮含量存在显著差异,以上元素在坡面地势的含量比沟底和曼甸平均高出46.7%、34.2%、22.7%、27.3%和63.8%,但沟底和曼甸中各类元素的差异不显著;20～40 cm深度土壤有机质、速效磷和碱解氮含量存在显著差异,坡面的含量明显高于沟底和曼甸,但沟底和曼甸中各类元素的差异不显著。相同地势条件下,各类土壤养分元素均呈现出地表高于地下的现象,其中0～10 cm深度土壤有机质、全氮、全钾和碱解氮含量分别比20～40 cm深度土壤高出65.2%、53.2%、80.3%和64.8%,pH在不同土壤深度间无明显差异。研究结果为塞罕坝云杉人工林经营提供了理论依据。     

渭北高原苹果根区土壤养分变化及对果树再植植株生长的影响

对渭北高原地区苹果园距树干横向水平0～200 cm、纵向垂直0～80 cm土层深度范围内的果树根区空间土壤养分的盈亏变化进行了研究,并结合盆栽试验,分析了不同根区土壤对苹果再植植株的影响。结果表明: 在水平方向上,随距树干距离的增加,土壤养分含量呈增高趋势;垂直方向上,除水溶性Ca、Mg外,其他养分随土层加深呈下降趋势。果园根区土壤速效P、水溶性Ca、水溶性Mg、有效Zn、有效Mn有亏缺现象,N/P、K/P、Ca/P、Ca/Mg、Ca/Mn、Ca/Zn存在养分比例失调。果园土壤的盆栽幼树株高、新梢长度、粗度、叶面积和根活力较生茬土壤的分别减少44.93%、34.46%、23.88%、49.48%和11.40%,表现明显的重茬障碍症状,土层愈深的土壤,症状愈重,距树干愈远的土壤,症状愈轻。果园土壤中Zn元素亏缺和Ca/Zn比例失调可能是造成渭北高原苹果再植病害发生的重要原因之一。距树干横向水平100～200 cm、纵向垂直0～40 cm土层土壤养分含量较高,盆栽幼树再植病害较轻,是老果园更新再植应选择的栽植区域。     

不同有机肥用量对京郊设施西瓜产量及土壤硝态氮含量累积的影响

过量施用有机肥会导致土壤养分流失、病虫害多发,甚至出现农作物根系吸水困难,发生烧根、僵苗等现象。为研究有机肥的合理用量、降低有机肥使用对环境的负面影响,本试验以北京郊区设施西瓜为研究对象,共设置了5个鸡粪用量处理(0、37500、75000、112500、150000 kg/hm^2),分析了不同鸡粪用量对西瓜产量和土壤硝态氮累积量及有机氮利用效率的影响。结果表明,随着有机肥施用量的增加,西瓜产量呈先增加后下降的趋势,当鸡粪用量为75000 kg/hm^2时,西瓜单产及总产量均最高,其吸氮总量、水分利用效率和有机氮利用率也最高,而土壤硝态氮累积量最低。各处理不同土层硝态氮含量和累积量均随土壤深度的增加呈现递减趋势。因此,鸡粪施用量为75000 kg/hm^2相对合理,可以在该地区及周边推广应用。     

Functional and structural landscape indicators of intensification,resilience and resistance in agroecosystems in southern Argentina based on remotely sensed data

There is increasing interest in developing criteria to evaluate the environmental implications of intensive agricultural land use. This implies discriminating between nature and man-made effects upon structural and functional attributes of agroecosystems. Adequate indicators of these combined effects should be cost efficient yet compatible with the core of ecological theory on biodiversity, spatial organization and ecosystem stability. We developed resistance-resilience metrics of plant growth to evaluate the intensity of agricultural use in a temperate irrigated basin in southern Argentina. The metrics are based on an analysis of the components of a temporal series of vegetation indices computed at a low resolution from available globally remote sensed reflectance imagery. We related the developed metrics to the properties of the soils and plant canopies observed at field scale and high-resolution imagery of the basin. Soil depth, soil erosion status and land fragmentation account for large fractions of the variance of the distribution of functional groups of the plant canopies and are also correlated with smaller scale attributes of land vegetation cover. Resistance-resilience indicators constitute a cost-efficient and adequate approach to evaluate the degree of intensification of land agricultural use.     

氮肥施用量对温室彩椒产量及土壤硝酸盐含量的影响

在日光温室水肥一体化栽培条件下,研究了5个氮肥施用水平对土壤硝酸盐含量、彩椒产量及经济效益的影响。结果表明:不同氮肥施用水平下,0～20cm土壤硝酸盐含量均高于20～100cm土层;随着氮肥施用量的增加,0～20、20～40、40～60、60～80、80～100cm各土层土壤硝酸盐含量及0～100cm土壤硝酸盐累积量均呈升高趋势。15kg·(667m2)-1施氮水平(中等氮肥)下,日光温室彩椒产量、经济效益及其单位氮素增收均为最高。     

Ownership and soil quality as sources of agricultural land fragmentation in highly fragmented ownership patterns

The relation between landscape structure and its drivers is a central issue in studies of landscape ecology. However, agricultural land fragmentation is dealt with in only a few such studies. We have investigated the effects of ownership and soil quality on agricultural land fragmentation in the highly fragmented ownership patterns that characterize some of the transition countries of Central and Eastern Europe. Using patch-scale spatial data generated from GIS, Minimal Adequate Models, based on ANOVA, were performed to test for the effects of ownership and soil quality patterns on arable land and grassland fragmentation across 483 study areas. The results show that there are important differences in the predictors of fragmentation between arable land and grassland. Grassland fragmentation was found to be associated particularly with ownership fragmentation, whereas arable land fragmentation tended to be driven mainly by soil conditions. A higher proportion of public ownership supports the more frequent appearance of larger patches. We found a significantly positive relationship between natural soil fertility and arable land fragmentation, while there was a strongly negative relationship between natural soil fertility and grassland fragmentation. Soil quality diversity was observed to be the most important driver affecting arable land fragmentation, but only a non-significant driver of grassland fragmentation. The study provides arguments for intervention aimed at reducing the huge differences between the levels of land-ownership and the land-use fragmentation.     

Soil Phosphorus Variability: Scale-dependence in an Urbanizing Agricultural Landscape

We examine the hypothesis that human activity changes patterns of variance in soil P (Bray-1) concentrations across several spatial scales. We measured soil P concentrations and variability for each of four different land uses at three distinct levels of analysis. Land uses were remnant prairie, lawns, corn fields of cash grain farms, and corn fields of dairies in Dane County, Wisconsin (USA). For each land use type, levels of analysis were sites (an agricultural field, residential lawn or prairie, ranging in size from 100 m² to approximately 20 ha), 10-m plots within a site, and points within the 10-m diameter plot. The rank of mean soil P concentrations was cash grain > dairy > lawn > prairie. For all land use types, most of the variance was accounted for by site-to-site variation. Among-site variance was higher for human-dominated sites (0.55, 0.15, 0.14 [log (mg/kg)]² for cash grain, dairy, and lawn sites, respectively) than it was for prairies (0.07 [log (mg/kg)]²). However, prairies had the highest among-plot variation (0.04 [log (mg/kg)]²) compared to other sites (0.01, 0.002, and 0.01 [log (mg/kg)]² for cash grain, dairy, and lawn sites, respectively). The results indicate that in this watershed, human activity has increased the mean soil P and variance of soil P, and shifted the scale of variance to larger spatial extents. Human impacts on landscape pattern extend to soil properties that affect nutrient flow and eutrophication of surface waters. Because soil P turns over slowly, the legacy of altered soil P patterns may affect freshwaters for centuries.     

毛乌素沙地不同林型下土壤肥力综合评价

土壤理化性质是评估林下土壤肥力重要指标;土壤肥力差异影响植被分布、演替轨迹等;探究土壤肥力质量,以期为鄂尔多斯地区毛乌素沙地人工造林树种选择、科学经营森林等提供参考。以鄂尔多斯地区毛乌素沙地杨柴(Hedysarum mongolicum)、藏锦鸡儿(Caragana tibetica)、沙地柏(Sabina vulgaris)、柠条锦鸡儿(Caragana korshinskii)、沙柳(Salix linearistipularis)5种典型林型下土壤为研究对象,选取土壤pH、有机质、全氮、全磷、全钾、铵态氮、速效磷、速效钾含量等指标作为评价土壤肥力因子,基于隶属度函数法对数据标准化,确定各项指标隶属度值,采用主成分分析法确定各指标权重,结合隶属度值及权重值,应用综合评价法对不同林型下土壤进行综合肥力评价,利用内梅罗指数法和综合评价法得出结论辅助验证。结果表明:1)研究区土壤pH变化范围为7.31~10.46,均值为8.35。2)7项因子对不同研究区综合土壤肥力贡献率依次为全钾(0.177)>速效磷(0.148)>铵态氮(0.138)>速效钾(0.134)>有机质(0.127)>全磷(0.099)>全氮(0.057)。3)不同林型下土壤应用综合评价法和内梅罗指数法确定土壤综合肥力质量变化趋势一致,依次为杨柴林>藏锦鸡儿林>沙地柏林>柠条锦鸡儿林>沙柳林。研究区土壤整体属于碱性土壤;土壤中全钾含量较高,对林地土壤肥力贡献率最高;土壤全氮、全磷含量较低,是林地土壤肥力主要限制因子;杨柴林林下土壤肥力较高,相较其它林分立地条件较好。     

A GIS-based index for relating landscape characteristics to potential nitrogen leaching to wetlands

We developed a spatially-explicit, quantitative Nitrogen Leaching Index to assess the potential for non-point source subsurface nitrogen pollution to wetlands. The index was based on the leaching potential of the watershed soils, the amount of nitrogen available for leaching, and the spatial position of nitrogen sources in the watershed. A raster or cell-based geographic information system (GIS) was used to estimate the necessary data inputs for calculating the index, such as soil hydrologic group, land use/soil type combination, groundwater residence time, and location of septic systems. The Total and Average Watershed Nitrogen Leaching Index (TWNLI and AWNLI) were calculated by summing and averaging, respectively, individual cell contributions over a watershed.Analysis of nine wetland watersheds in central New York state, USA, with mixed forest and agricultural land uses illustrated the use of the index for identifying and ranking wetlands with potential nitrogen pollution. Results showed that the spatial characteristics of a watershed potentially can effect subsurface nitrogen delivery to groundwater-dominated wetlands. The use of an index based on watershed soils, topography, and land use may be useful for assessing potential nitrogen pollution to wetlands at a regional scale.     

Nutrient flows and land use change in a rural catchment: a modelling approach

Due largely to unprecedented land-use changes in the Porijõgi River catchment (southern Estonia) losses of nutrients and organic matter have decreased significantly. During the period 1987–1997 abandoned lands increased from 1.7 to 10.5% and arable lands decreased from 41.8 to 23.9%. At the same time, the runoff of total-N, total-P, SO₄ and organic matter (after BOD₅) decreased from 25.9 to 5.1, 0.32 to 0.13, 78 to 48, and 7.4 to 3.5 kg ha^–1 yr^–1, respectively. The most significant decreases occurred in agricultural subcatchments while the changes were insignificant in the forested upper course catchment. A simple empirical model which incorporates land-use pattern, fertilization intensity, soil parameters and water discharge accurately described the variations of total-N and total-P runoff in both the whole catchment and its agricultural subcatchments (R ² varies from 0.95–0.99 for N to 0.49–0.93 for P). In small agricultural subcatchments the rate of fertilization is found the most important factor for nitrogen runoff, whereas in larger mosaic watersheds land use pattern plays the main role. Seven alternative scenarios compiled on the base of the empirical model allow to forecast potential nitrogen and phosphorus losses from the catchment. This information can be used in further landscape and regional planning of the whole region.     

A Factorial Nutritional Study of the Perpetual-Flowering Carnation Grown Under Glass

Two varieties of glasshouse carnations (Improved William Sim and Saugus White) have been grown under 48 different combinations of manurial treatment. The treatments consisted of three levels of nitrogen and two of potash in factorial combination, applied in solution through trickle irrigation equipment to beds of compost (steamed loam with 20% peat and 10% grit) containing two levels each of phosphate, magnesium sulphate and lime (carbonate).

Soil samples were taken periodically for the determination of nitrate, available phosphate and potash, pH and pC. The distribution of nutrients was also studied in irrigated and non-irrigated areas of the beds.

A tip-burn of the leaves of variety Saugus White, attributed tomanganese toxicity from the steamed loam, developed shortly after the plants became established in the beds. Symptoms of nitrogen and potassium deficiencies were observed in the second half of the trial.

The total numbers of blooms of both varieties were increased by 6-9% at the intermediate and high levels of nitrogen as compared with the lowest level of this nutrient (P=0.001). The higher level of phosphate increased the flowering of Improved William Sim by 20%, but was not beneficial to Saugus White. The higher level of potash increased the flowering of Saugus White but somewhat depressed that of Improved William Sim. The main effects of magnesium and lime were not significant, but both factors occurred in significant interactions. Averaged over all combinations of treatments, Saugus White yielded 24% more blooms than Improved William Sim.

Splitting of the calyx was markedly decreased at the higher levels of nitrogen (P=0.001), and increased to a lesser extent by the higher levels of phosphate (P=0.05), potash (P=0.001) and lime (p=0.05). Improved William Sim gave far more split calyces than Saugus White.

The weight of the aerial portions of the plants at the end of the trial was reduced by the higher levels of nitrogen and increased by the higher level of potash. The combination of high phosphate with low potash was particularly unfavourable to variety Saugus White. THE visual symptoms of acute mineral deficiencies of the carnation have been described by Messing (1958). Chan et al. (1958) reported factorial nutritional studies of the carnation (variety Apollo) in relation to nitrogen, phosphorus, potassium and calcium in culture solution. Flower production increased significantly with increasing nitrogen concentration, and also to a lesser extent with potassium concentration, but the effect of phosphorus was relatively small and not significant. Much of the available data relating to glasshouse carnations grown in soil is contained in bulletins and periodicals published for commercial growers in America. Without attempting a comprehensive survey of such data, one notes beneficial responses to nitrogen (Beach and Mussenbrock, 1948; Holley et al., 1951) and potash (Holley, 1953).

Despite the commercial importance of the carnation as a glasshouse crop, relatively little attention has been given to its nutritional requirements as grown in this country. A series of large-scale factorial nutritional studies was accordingly undertaken, the first of which is now reported.     

内蒙古鄂尔多斯市公园绿地土壤肥力调查与评价

通过土壤样品采集和实验室分析,系统研究鄂尔多斯市公园绿地土壤的化学特性及养分丰缺状况,包括pH值、有机质、全氮、全磷以及有效氮、磷、钾,分析养分因子之间的相关性,评价公园绿地土壤的肥力状况,揭示出鄂尔多斯市公园绿地土壤存在的问题：土壤pH值偏高,其中85.7%的土壤呈强碱性,其余呈碱性;多数土壤有机质、全氮、全磷、碱解氮、有效磷、速效钾含量处于缺乏及以下水平;土壤pH值与有机质、速效钾分别显著和极显著负相关;有机质与其他养分因子之间均极显著相关。     

Agricultural land-use patterns and soil erosion vulnerability of watershed units in Vietnam’s northern highlands

Since the mid eighties, agricultural development and increased population growth in Vietnam’s northern highlands have modified land use patterns and thus, increased the runoff process and soil degradation induced by water erosion. In the last decade, Vietnamese literature has focused on the computation of soil losses over large areas. Most of these spatial and quantitative soil erosion studies do not consider the impact of agricultural land use diversity (spatial heterogeneity), particularly at the watershed scale, and the annual variability of seasonal landscape factors on soil erosion vulnerability and hence, landscape dynamics. We present an integrated approach combining field measurements and observations, GIS and modeling to determine the spatial and temporal dynamics of soil erosion vulnerability according to watershed units and hence, the impact of physical environment components and agricultural land use patterns on landscape evolution. Tables and graphics showing the cropping systems, the periods within a year, and the watershed units that are most vulnerable are presented. The double cultivation cycles for paddy rice fields not only imply two periods of land preparation and establishment that expose the soil surface to raindrop impacts, but also increased soil management practices that decrease the soil’s resistance to detachment. Despite the low levels of soil management practices for the shifting cultivation system, the near absence of soil conservation practices clearly increases their vulnerability. Hence, rainfed cropping systems, mainly soya and cassava, cultivated on sloping lands (hills and mountains) where soil erosion vulnerability is the highest represent the watershed units which are the most prone to soil loss.     

Cultural Variation and Mycorrhizal Status of Blueberry Plants in NW Oregon Commercial Production Fields

ABSTRACT

Ericoid mycorrhizal fungi (EMF) form symbiotic relationships with roots of blueberry plants providing increased access to nutrients from fertilizers and soil. In August of 2001, we sampled 55 fields in Oregon to assess the mycorrhizal status of blueberry plants under production conditions and to determine whether any relationships exist between field characteristics, root distribution, soil characteristics and level of colonization by mycorrhizal fungi. Variation in measured soil characteristics, root type, root distribution and mycorrhizal colonization occurred with cultivar, field age, bed type, rate of nitrogen fertilization, irrigation type, and mulch. Root biomass was lower in the upper 15 cm of soil compared to 15-30 cm depth. Distribution of roots between the two sampled depths varied significantly with field age, nitrogen fertilization rate, and the time of 50% harvest for the different cultivars sampled. Root length was generally greatest in the upper 15 cm of the soil than at the 15-30 cm depth. Root colonization by ericoid mycorrhizal fungi (EMF) ranged from 0.5 to 44% of total root length with higher colonization generally occurring in the upper 15 cm of the soil where the majority of smaller, finer roots were found. Colonization generally increased with increasing plant age. In young plants the highest levels of colonization were found in roots from the upper 15 cm of soil while in older plants the highest levels of colonization were found in roots at the 15-30 cm depth. Colonization of roots by EMF in the upper 15 cm of the soil tended to decrease with increasing N fertilization rate, while root colonization at the 15-30 cm depth was unaffected by rate of N fertilization. Roots on cultivars that fruited early in the season tended to have higher levels of colonization than cultivars that fruited later in the growing season. Root biomass and root length were negatively correlated with soil pH and available Ca in soil, while root colonization by EMF was negatively correlated with ammonium levels in the soil. Differences in soil characteristics, root type and distribution, and mycorrhizal colonization found in this study need to be investigated in terms of production efficiency of blueberry in Oregon.     

海城市耕地、果园土壤肥力状况

2004年辽宁省土壤肥料总站在海城市采集土壤样品322个，对有机质、全氮、碱解氮、有效磷、速效钾、pH值、有效硫、有效镁、有效硅、有效钙、有效硼、有效钼、有效铁、有效锰、有效铜、有效锌等16项土壤养分指标进行了测试分析。结果表明，海城市土壤有机质含量较低，氮素和钾素含量不足，磷素含量丰富，中量元素除钙素外基本不缺，微量营养元素硼和钼缺乏，其他很丰富。菜田的土壤肥力较高，水稻田和果园次之，旱田土壤肥力最差。旱田和果园的碱解氮、水稻田的速效钾含量偏低。     

皮墨垦区沙地枣园土壤特性分析

为研究沙地枣园的土壤地力培肥和水肥高效利用措施提供基础,对皮墨垦区沙地枣园土壤养分及理化特性进行分析。结果表明:试验区土壤盐渍化程度低,土壤为碱性,土壤结构疏松,田间持水量较小,土壤有机质、全氮、全钾、水解氮、有效磷含量极低,全磷、速效钾、交换性镁含量中等,交换性钙含量高。     

雄安新区化肥使用及氮磷盈余空间分布特征研究

近年来,随着白洋淀内源污染与点源污染逐渐得到控制,农业面源污染逐渐成为制约白洋淀水质改善的重要因素。改善白洋淀生态环境状况,加强农业面源污染防控至关重要。然而,当前对雄安新区农业面源污染的认识尚待提高,尤其需要加强对种植业化肥使用及其氮磷盈余空间分布特征研究。因此,本研究以雄安新区主要种植模式小麦—玉米为研究对象,采用农田养分平衡方法,分析2016年雄安新区小麦—玉米氮、磷养分输入、输出与盈余情况,为雄安新区农业面源污染防控提供科学依据。结果表明：(1)雄安新区农田氮磷养分的输入以化肥为主,输出以籽粒为主,总体化肥氮、磷投入水平为446.82 kg/hm²、84.23 kg/hm²,籽粒输出氮、磷养分水平为312.71 kg/hm²、42.79 kg/hm²;(2)雄安新区小麦—玉米农田氮磷养分均表现为盈余状况,且氮磷养分盈余与氮肥、磷肥投入极显著正相关;(3)雄安新区氮素、磷素盈余强度分别为273.74 kg/hm²、44.99 kg/hm²,不同县市氮...     

Ecosystem-scale spatial heterogeneity of stable isotopes of soil nitrogen in African savannas

Soil ¹⁵N is a natural tracer of nitrogen (N) cycling. Its spatial distribution is a good indicator of processes that are critical to N cycling and of their controlling factors integrated both in time and space. The spatial distribution of soil δ¹⁵N and its underlying drivers at sub-kilometer scales are rarely investigated. This study utilizes two sites (dry vs. wet) from a megatransect in southern Africa encompassing locations with similar soil substrate but different rainfall and vegetation, to explore the effects of soil moisture and vegetation distribution on ecosystem-scale patterns of soil δ¹⁵N. A 300-m long transect was set up at each site and surface soil samples were randomly collected for analyses of δ¹⁵N, %N and nitrate content. At each soil sampling location the presence of grasses, woody plants, Acacia species (potential N fixer) as well as soil moisture levels were recorded. A spatial pattern of soil δ¹⁵N existed at the dry site, but not at the wet site. Woody cover distribution determined the soil δ¹⁵N spatial pattern at ecosystem-scale; however, the two Acacia species did not contribute to the spatial pattern of soil δ¹⁵N. Grass cover was negatively correlated with soil δ¹⁵N at both sites owing to the lower foliar δ¹⁵N values of grasses. Soil moisture did not play a role in the spatial pattern of soil δ¹⁵N at either site. These results suggest that vegetation distribution, directly, and water availability, indirectly, affect the spatial patterns of soil δ¹⁵N through their effects on woody plant and grass distributions.