绿洲化对土壤养分及化学计量特征的影响

为了阐明绿洲化过程中土壤养分含量及土壤碳氮磷生态化学计量值的动态变化特征,以乌兰布和沙漠东北部绿洲为研究对象,通过24 a的定位监测,分析了土壤有机碳（SOC）、全氮（TN）、全磷（TP）、碱解氮（AN）、速效磷（AP）及土壤C,N,P生态化学计量的动态变化特征。结果表明:（1）研究区土壤总体贫瘠,养分含量整体水平不高。但是随着绿洲建设时间的延长,土壤养分含量呈显著的线性增加趋势。（2）绿洲化过程中,土壤C:N,C:P,N:P,AN:AP的变化趋势总体上呈现先增大后减小的趋势,但是达到最大值的时间各不相同。（3）土壤C,N,P元素化学计量值与C,N,P元素之间的最优拟合关系显示C:N,C:P主要受SOC影响,N:P主要受N影响,表明SOC和N含量决定了研究区土壤中C,N,P化学计量特征的变化过程。     

黄土丘陵沟壑区退耕地人工柠条林土壤养分特征及其空间变异

应用时空互代方法,以柠条林为例,对黄土丘陵沟壑区不同利用年限人工林土壤养分特征、空间变异及其演变进行了系统的研究。结果表明,该区人工林土壤肥力处于较低水平;人工林表层土壤养分中速效磷和速效钾的空间变异性较大;各环境因子对土壤养分有一定的影响,海拔、坡度和坡向等环境因子与人工林地土壤养分间呈负相关关系,坡位和地形与人工林地土壤养分间呈正相关关系。随着利用年限的增加,人工林土壤养分各指标含量均增加,与利用年限有显著的相关性。有机质、全氮、有效氮和速效磷的增加量不明显,全磷含量保持相对稳定的水平,速效钾经过多年积累有明显的增加。从土壤养分指数模型可以算出该区的人工林土壤有机质、全氮、有效氮约需35a能达到中上等养分水平,速效钾则约需27a才能达到中上等养分水平。     

不同土地利用方式对干热河谷地区土壤可蚀性的影响

以四川宁南县金沙江下游的河谷地带为研究区域,选择相同海拔下7种主要的土地利用方式为研究对象,通过室内测试分析,并运用统计和相关分析等方法,研究不同土地利用方式下的土壤可蚀性变异特征。结果表明：在干热河谷区,天然植被水桐树林破坏改为其它土地利用方式后,土壤有机质、全氮、全磷和碱解氮含量显著降低,速效磷和容重没有显著变化,速效钾有一定程度升高,不同利用方式对其影响作用不同,但总体来说改造为合欢林和撂荒草地对土壤理化属性的影响相对较少。相对于天然水桐林,其它土地利用方式土壤可蚀性明显增加,其大小依次为：花椒地〈撂荒地〈草地〈新银合欢地〈桑地〈甘蔗地。相比较而言,无论是天然林地还是人工经济林地,其土壤可蚀性都处于较低的水平;受人为活动影响强烈的农业用地,其土壤可蚀性水平一般较高。说明该地区农业耕作措施可导致土壤对侵蚀营力分离和搬运作用敏感性增强,抗蚀性能较低,更加容易遭受侵蚀,因此在金沙江干热河谷区,从水土保持角度出发,应该尽可能地减少人为活动对土地的干扰,提高土地抵抗侵蚀的能力。     

土壤速效氮、磷、钾含量空间变异特征及其影响因子

利用地统计学和GIS相结合的方法,探讨了双流县土壤速效氮、磷、钾含量空间变异特征及其影响因子。结果表明:1) 土壤速效氮和速效钾含量具有强烈的空间相关性,相关距离分别达38754 m和56187 m,结构性因子是影响其空间变异的主要因子;土壤速效磷含量具有中等空间相关性,相关距离为24210 m,其空间变异受结构性因子和随机性因子共同影响。2) 土壤速效氮含量主要由北向南逐渐降低;速效磷含量主要在东北向西南及东南向西北方向上逐渐降低,而速效钾含量主要由东南向西北逐渐降低。3) 土壤速效氮含量在不同土壤类型及地形地貌间呈极显著差异;土壤速效磷含量在不同成土母质及地形地貌间呈显著或极显著差异;土壤速效钾含量在不同成土母质间呈极显著差异。土壤速效氮、磷、钾含量高值区单位面积化肥施用量明显高于低值区。     

水盐梯度对滨海湿地土壤养分指标和酶活性的影响

[目的]研究海水入侵对滨海湿地土壤性质的影响,为分析水盐梯度对土壤养分指标和酶活性的影响机制提供依据。[方法]采集胶州湾滨海湿地表层土壤并设计室内模拟试验,测定不同水盐梯度上的土壤养分指标和酶活性。[结果]盐分和水分对土壤pH值和容重(BD)的影响显著;土壤有机质(TOM)、氨氮(NH_4~+-N)、速效磷(AP)、速效钾(AK)、蔗糖酶(SA)、脲酶(UA)、碱性磷酸酶(APA)均随水梯度的增加表现为先升高后降低的趋势,在30%水梯度时达到最高值;土壤TOM,AP,AK,SA,UA,APA均随盐梯度的增加而降低,NH_4~+-N随盐梯度的增加而增加。土壤SA与TOM,AP,AK存在显著正相关关系;APA与TOM,AP,AK,BD显著正相关;UA与pH值,BD显著正相关,与NH_4~+-N具有一定的相关性。[结论]在一定范围内,土壤中水分过高或过低、盐分增加均会对土壤养分含量和酶活性产生抑制作用;土壤养分和酶活性之间存在密切的相关关系。     

基于GIS和丰缺指标法的区域施肥管理体系的构建

  【目的】  采用GIS定位和养分丰缺指标相结合的方法,研究西辽河平原耕地土壤碱解氮、有效磷、速效钾的空间分布特点,建立直观、精准的推荐施肥系统。  【方法】  西辽河平原包括科尔沁区、开鲁县、奈曼旗、科尔沁左翼后旗、科尔沁左翼中旗。以该区域的15421个土壤测试数据和143个玉米“3414试验”数据为基础,运用GIS方法计算耕地土壤碱解氮、有效磷、速效钾的空间插值结果,结合土壤丰缺指标,将西辽河平原耕地土壤碱解氮、有效磷、速效钾养分分区,确定不同土壤氮磷钾养分组合下的施肥量,并制作玉米氮磷钾分区施肥图。  【结果】  西辽河平原耕地土壤养分空间分布不均,大部分土壤碱解氮含量较低,有效磷、速效钾含量中等。耕地土壤有效氮、磷、钾养分含量呈低氮–中磷–中钾 (碱解氮 ≤ 69.5 mg/kg、有效磷4.18～10.40 mg/kg、速效钾90.3～152.5 mg/kg)、中氮–中磷–中钾 (碱解氮69.5～107.9 mg/kg、有效磷4.18～10.40 mg/kg、速效钾90.3～152.5 mg/kg)、中氮–中磷–高钾 (碱解氮69.5～107.9 mg/kg、有效磷4.18～10.40 mg/kg、速效钾 > 152.5 mg/kg) 的面积占比分别为42.4%、14.1%、13.5%。土壤碱解氮、有效磷、速效钾含量 (x) 与经济最佳施肥量 (y) 之间存在较好的对数关系,氮施肥模型y = –102.5ln(x) + 617.22,磷施肥模型y = –36.11ln(x) + 174.1,钾施肥模型为y = –25.89ln(x) + 180.96。不同土壤养分组合种植玉米所需的经济最佳N–P₂O₅–K₂O用量 (kg/hm2) 组合分别为202–110–58、168–107–57、164–102–47。  【结论】  土壤碱解氮、有效磷、速效钾含量与相对产量存在较好的对数函数关系。西辽河灌区土壤有效氮磷钾丰缺指标的划分以75%和85%作为相对产量的分级区间较为合适。在土壤有效氮磷钾养分大数据的支撑下,采用GIS和丰缺指标法相结合的方法,可以准确快捷地构建区域施肥管理体系。     

典型喀斯特峰丛洼地坡面土壤养分空间变异性研究

采用线形取样,利用地统计学方法研究了典型喀斯特峰丛洼地坡面土壤养分的空间变异特征.结果表明:有机碳、全氮、碱解氮和速效钾具有相似的空间变异结构,其变程变化在212～251 m之间,与坡面不同土地利用方式的空间范围相当.全磷和全钾的变异尺度较小,为141.2 m和120.6m.受部分耕地施用磷肥影响,速效磷的变异尺度最小,仅为85.1 m.除pH值外,土壤各养分均表现为强烈的空间相关性.有机碳、全氮、碱解氮等养分的空间分布表现出随着海拔高度增加而增大的特征,人类的耕作管理和峰丛洼地特殊的水文地质过程是影响土壤养分空间变异的主要因素.     

Key soil nutrient requirements for different yield levels in North China

ABSTRACT

Soil chemical properties are closely related to crop production levels. Understanding the relationships between soil nutrients and different yield levels is important for improving the efficiency of fertilization management programs. The objectives of this study were to understand the key soil nutrient requirements for different crop yield levels using 10 experimental wheat-maize rotation sites and to optimize fertilization applications in North China. The results found significant differences between the soil chemical properties among the study sites, with average contents in the range of 10.07–14.72 g/kg for soil organic carbon (SOC), 0.38–1.29 g/kg for total nitrogen (TN), 56.43–89.77 mg/kg for available nitrogen (AN), 17.36–48.54 mg/kg for available phosphorus (AP), 79.4–184.5 mg/kg for available potassium (AK), 0.78–5.97 mg/kg for soil Cu, and 0.75–2.20 mg/kg for soil Zn. The soil pH values were 6.46–8.19. Significant correlations (p < 0.05) were found between high-level yields and higher contents of SOC, TN, AN, and AP when a suitable soil pH were present. The higher levels of soil SOC and TN were important for maintaining high-level yields in these regions. Soil AN and pH are two key limitations that could significantly (p < 0.05) improve medium-level yields. Although some soil indicators, including SOC, TN, AN, AP, soil pH, soil Zn, and Cu could significantly influence low-level yields, soil amendments with C, N, and available P and having a suitable soil pH were especially important for improving low-level yields. These results could be used to improve conventional methods of fertilization management and increase the efficiency of fertilizer use in North China.     

哈尔滨市辖区黑土速效养分空间异质性分析

研究在哈尔滨市所辖黑土区的6个市县进行,共采集表层(0～20cm)黑土土样411个,测定了全部样点的有机质、全氮的养分含量,同时测定了部分样点的碱解氮、速效磷、速效钾的养分含量,利用地统计学中协同克立格分析方法并结合经典统计学和GIS技术分析碱解氮、有效磷、速效钾养分空间异质性。分析表明有效磷空间分布符合指数模型,碱解氮、速效钾符合高斯模型,其块金值与基台值之比分别为50.0%、39.7%、6.3%,有效磷和碱解氮为中等程度空间相关水平,速效钾为强度空间相关水平;与克里格对比,应用协克里格插值绘制的三种速效养分空间分布图精度显著提高,为协克里格方法在土壤养分空间异质性分析上的应用提供了实践依据。     

黄土丘陵区刺槐人工林土壤养分特征及演变

为了探明黄土丘陵沟壑区人工林土壤养分状况及其演变规律,应用时空互代的方法,以刺槐林为代表,对该区不同利用年限的人工林土壤养分特征及其时空变化等进行了系统研究。结果表明,黄土丘陵区人工林土壤肥力处于低水平;人工林表层土壤养分中有机质和速效磷的空间变异性较大;坡度、坡向、坡位等环境因子对土壤养分有一定的影响。随利用年限的增加,人工林土壤全氮,有机质、碱解氮、速效钾含量及土壤养分指数均增加,与利用年限有极显著的相关性,其变化趋势符合y=axb模型。全氮,有机质和碱解氮随利用年限的增加量不显著,而速效钾每经过10年就有显著增加,全磷和速效磷含量则保持相对衡定的水平。黄土丘陵区人工林地土壤有机质、全氮、碱解氮、速效钾及养分指数年增长率分别约为0.20g.kg、0.01g.kg、0.69mg.kg、2.27mg.kg和0.04。该区人工林地土壤有机质、全氮、碱解氮及养分指数约需50年、速效钾约需30年可达到中上等养分水平。     

湘中南土地整理后烟田土壤肥力指标评价及空间变异特征

掌握土地整理区土壤养分特征已成为烟田快速培肥和提升土壤质量的首要问题。采用GIS与地统计学相结合的方法,评价了土地整理后烟田土壤养分等肥力指标的适宜性等级状况及其空间变异特征。结果表明:研究区土壤偏酸,有机质、碱解氮含量普遍缺乏,存在较大面积的缺钾现象;各肥力指标均属于中等变异,变异系数大小顺序依次为有效磷 > 速效钾 > 碱解氮 > 有机质 > 全氮 > 全磷 > 全钾 > pH值。有机质和速效钾的变异函数比较符合指数模型,全钾、碱解氮用高斯模型拟合效果好,而pH值、全磷、全氮和有效磷则以球状模型拟合效果最佳。肥力指标的块金系数[C₀/（C₀+C）]中,土壤有机质、全钾、碱解氮分别为0.903,0.998,0.823,空间相关性较弱;而pH值、全氮、全磷和有效磷的块金系数[C₀/（C₀+C）]变化范围为0.501~0.724,具有中等空间相关性;各肥力指标空间变程为99~1 003 m,最大和最小值分别为全钾和碱解氮;各肥力指标表现出不同的空间分布特征,其中,pH值呈斑块状,碱解氮及全钾呈条带状,全磷整体上呈从北至南含量增加的梯度分布格局。     

Rhizosphere soil enzymatic and microbial activities in bamboo forests in southeastern China

Bamboo has been introduced to coastal sandy areas in southeastern China to protect and restore coastal ecosystems. An understanding of the chemistries and enzymatic and microbial activities in the soils of these bamboo forests will aid our understanding of how bamboo plantations can improve soil fertility and will provide scientific evidence for policy makers for encouraging the planting of bamboo in other coastal areas. We investigated the physical and chemical properties of the rhizosphere soil [soil moisture content (SMC), pH, and contents of soil organic matter (SOM), total nitrogen (TN), available nitrogen (AN), total phosphorus (TP), available phosphorus (AP), total potassium (TK) and available potassium (AK)], enzymatic activities (sucrase, protease, urease and catalase) and microbial properties (counts of bacteria, fungi and actinomycetes) in five bamboo forests. The bamboo forests had significantly higher levels of SOM, TN, AN, TP, AP, TK, and AK and lower pH relative to a control soil sample from an area devoid of plants. Soil enzymatic activities and microbial communities were considerably higher in the bamboo forests than in the soil from the barren land. The chemical contents, enzymatic activities and microbial counts of the soil and the litter and root biomasses were higher in forests with the bamboo species Dendrocalamopsis oldhami and Pseudosasa amabilis than in forests with the other three species (Acidosasa edulis, Dendrocalamopsis vario-striata, and Dendrocalamopsis beecheyana var. pubescens), which suggests that these two species could adapt to sandy soil and grow well in a hostile environment. These results indicate that planting bamboo may help to both enrich soil fertility and increase the diversity of tree species in coastal ecosystems. The difference between aboveground and belowground biomass may have been responsible for these changes in soil properties.     

Influence of land use change on soil nutrients in an intensive agricultural region of North China

The pressures of development and major shifts in land use have increased the need to assess the impact of land use change on soil nutrients. This study was conducted in an area with intensive agricultural land use in north China to assess effects of land use change on soil organic carbon (SOC), total nitrogen (TN), available phosphorus (AP) and available potassium (AK). Soil samples were collected from rainfed land, irrigated land, virgin grassland and vegetable land in 1980 and 1999. SOC, TN and AP were higher in 1999 than in 1980, and the increases followed the following order: vegetable land > irrigated land > rainfed land, except for AK. Soil nutrient contents were increased when land uses underwent the following changes (except for AK): virgin grassland → rainfed land → irrigated farmland → vegetable land. The SOC, TN and AP fluxes (rate of change in C, N, P and K as kg(ha y)⁻¹) in the transition systems from rainfed land to vegetable land were 518.46, 69 and 3.9 kg(ha y)⁻¹, respectively, which were considerably higher than the transition systems from rainfed land to irrigated land. The SOC, TN and AP fluxes in the transition systems from virgin grassland to irrigated land were 297.83, 56.3, 2.1 kg(ha y)⁻¹, respectively, which were higher than the transition systems from virgin grassland to rainfed land. The study shows that land use intensification can increase soil nutrient contents if accompanied by increased fertilizer application.     

Effects of climate factors and soil properties on soil nutrients and elemental stoichiometry across the Huang–Huai–Hai River Basin,China

Purpose

Soil nutrients, elemental stoichiometry, and their associated environmental control play important roles in nutrient cycling. The objectives of this study were (1) to investigate soil nutrients and elemental stoichiometry, especially potassium and its associative elemental stoichiometry with other nutrients under different land uses in terrestrial ecosystems; (2) to discuss the impacts of climate factors, soil texture, and soil physicochemical properties; and (3) to identify the key factors on soil nutrient levels and elemental stoichiometry.

Materials and methods

Soil data, including pH, bulk density (BD), cation exchange capacity (CEC), volumetric water content (VMC), clay, silt and sand contents, total carbon (TC), nitrogen (TN), phosphorous (TP) and potassium (TK), available nitrogen (AN), phosphorus (AP), potassium (AK), and soil organic matter (SOM) under different land-use types, were collected, and their elemental stoichiometry ratios were calculated. Climate data including temperature, precipitation, relative humidity, wind speed, and evapotranspiration were collected. The least significant difference test and one-way analysis of variance were applied to investigate the variability of soil nutrients and elemental stoichiometry among land-use types; the ordinary least squares method and the general linear model were used to illustrate the correlations between soil nutrients, elemental stoichiometry, and soil properties or climate factors and to identify the key influencing factors.

Results and discussion

Woodlands had the highest SOM, TN, AN, and AK contents, followed by grasslands, croplands, and shrublands, while the TP and TK contents only varied slightly among land-use types. SOM, TN, AN, N/P, and N/K were strongly negatively correlated to soil pH (p <?0.05) and were strongly positively correlated to soil CEC (p <?0.05). For soil texture, only C/N was moderately negatively correlated to silt content but moderately positively correlated to sand content (p <?0.05). For climate factors, SOM, TN, AN, N/P, and N/K were significantly negatively correlated to evapotranspiration and temperature (p <?0.05), and the correlations were usually moderate. Soil pH explained most of the total variation in soil nutrients, and climate factors explained 5.64–28.16% of soil nutrients and elemental stoichiometry (except for AP (0.0%) and TK (68.35%)).

Conclusions

The results suggest that climate factors and soil properties both affect soil nutrients and elemental stoichiometry, and soil properties generally contribute more than climate factors to soil nutrient levels. The findings will help to improve our knowledge of nutrient flux responses to climate change while also assisting in developing management measures related to soil nutrients under conditions of climate change.

     

衡阳紫色土丘陵坡地不同植被恢复阶段土壤酶活性特征研究

本文以典型的衡阳紫色土丘陵坡地不同植被恢复阶段为研究对象,采用空间代替时间序列方法,选用立地条件基本相似的草坡阶段（Grassplot, GT）、 灌草阶段（Frutex and grassplot,FG）、 灌丛阶段（Frutex, FX）和乔灌阶段（Arbor and frutex, AF）,通过调查取样和实验分析,对不同植被恢复阶段的土壤酶、 养分与微生物及其相关性进行了研究。结果表明, 1）随着恢复阶段的演替,脲酶、 多酚氧化酶、 蔗糖酶与过氧化氢酶的活性显著增加,在每个恢复阶段,脲酶、 多酚氧化酶、 蔗糖酶与过氧化氢酶活性随着土层的加深而逐渐减弱,脲酶与多酚氧化酶、 蔗糖酶与过氧化氢酶活性呈显著正相关关系,蔗糖酶与脲酶和多酚氧化酶呈极显著正相关。 2）随着恢复阶段的演替,土壤养分的时空变化与土壤酶活性的变化趋势基本一致,土壤有机碳、 全氮与碱解氮含量呈上升趋势,土壤pH随植被恢复和演替而降低,随土壤深度的增加而上升,与土壤酶活性的变化趋势相反;脲酶与有机碳、 全氮、 碱解氮呈极显著正相关,与pH呈显著负相关,多酚氧化酶与有机碳、 碱解氮呈极显著正相关,与全氮、 速效磷、 速效钾呈显著正相关,与pH呈显著负相关,蔗糖酶活性与有机碳、 全氮、 碱解氮、 速效磷、 速效钾呈显著正相关。 3）不同恢复阶段土壤细菌数量最多,真菌数量和放线菌数量与细菌数量的变化趋势各不相同;细菌平均数量为AF＞FX＞FG＞GT,真菌数量为 FG＞GT＞FX＞AF,放线菌数量为 GT＞FX＞FG＞AF。4）主成分分析揭示脲酶与多酚氧化酶可作为衡阳紫色土丘陵坡地土壤质量评价的指标。研究结果将丰富该地区植物生态学与恢复生态学的内容,为衡阳紫色土丘陵坡地生态系统的恢复与重建提供了重要依据。     

拉萨河流域中下游洪积扇土壤养分评价

  【目的】  洪积扇是拉萨河流域珍贵的土地资源,目前西藏对洪积扇土地资源的管理还相当粗放,过度放牧、不合理开垦等人为活动已导致部分土地资源土壤肥力低下。本研究根据实地调查所得的土壤养分数据,对拉萨河流域中下游洪积扇的土壤养分状况进行综合评价,为其进行合理开发利用奠定基础。  【方法】  选取该区域20个典型洪积扇,分别于2019年和2020年7—8月采集土壤样本,测定土壤有机质(OM)、全氮(TN)、全磷(TP)、全钾(TK)、碱解氮(AN)、有效磷(AP)和速效钾(AK) 7个指标。基于主成分分析确定各养分指标的权重,以全国第二次土壤养分普查养分分级标准为依据,应用物元模型进行土壤养分综合评价。  【结果】  洪积扇土壤OM、TN、TP、TK、AN、AP和AK的含量分别为2.65～314.57 g/kg、0.14～17.55 g/kg、0.04～2.06 g/kg、7.71～25.57 g/kg、7.70～358.56 mg/kg、0.12～342.50 mg/kg和17～1350 mg/kg。在321个样点中,土壤TN和TP含量在Ⅳ级以下的样点分别仅占9.97%和15.89%,而土壤AN和AP含量在Ⅳ级以下的样点分别占46.42%和48.60%,土壤AN和AP含量缺乏;61.99%的样点土壤养分综合评价等级在Ⅳ级以上,土壤养分含量充足。洪积扇草地、灌丛和农田中Ⅳ级以上的样点分别占63.84%、55.77%和60%。土壤TN、OM和AN是影响土壤养分综合水平最主要的指标。土壤养分综合评价结果显示,20个洪积扇中有1个洪积扇为Ⅰ级,土壤养分含量极丰富;分别有9个洪积扇为Ⅲ和Ⅳ级,土壤养分含量较丰富或适中;仅有1个洪积扇为Ⅵ级,土壤养分含量极贫乏。 Ⅲ、Ⅳ和Ⅵ级洪积扇海拔和年平均降雨量逐级显著降低(P<0.05),年平均气温逐级显著升高(P<0.05)。  【结论】  拉萨河流域中下游洪积扇总体呈现出海拔越低,土壤养分水平越低的分布特征。20个洪积扇中,相对于土壤全氮和全磷,土壤有效氮和有效磷含量贫乏或极贫乏的样点数增加了36.45%和32.71%,并且在不同植被类型下均存在这种现象。     

Soil fertility,enzyme activity,and microbial community structure diversity among different soil textures under different land use types in coastal saline soil

Purpose

This investigation assessed the responses of soil fertility, enzyme activity, and microbial community diversity to soil texture and land use type.

Materials and methods

The tested soils included five soil textures (sandy loam, medium loam, heavy loam, light clay, and medium clay soils) with two land use types (uncultivated and paddy soils) in the coastal zone of Zhejiang Province, China.

Results and discussion

Soil texture had a significant effect on soil pH, electrical conductivity (EC), organic carbon (OC), total nitrogen (TN), available nitrogen (AN), phosphorus (AP) and potassium (AK), catalase and protease activities, total phospholipid fatty acids (PLFAs), bacterial and actinomycetes PLFAs, and microbial diversity (MD). The clay content was significantly positively correlated to soil EC, OC, TN, AN, AP, AK, catalase activity, total PLFAs, bacterial and actinomycetes PLFAs, and MD but significantly negatively associated with soil pH and protease activity. Land use type also had significantly influenced soil pH, EC, OC, TN, AN, AP, AK, catalase, protease and urease activities, total PLFAs, bacterial, actinomycetes, and fungal PLFAs, and MD. The paddy soil had higher OC, TN, AN, AP, catalase, protease and urease activities, total PLFAs, bacterial and actinomycetes PLFAs, and MD but lower soil pH, EC, and AK than the uncultivated soil. The interaction with soil texture and land use type had significantly affected soil pH, EC, OC, TN, AN, AP, AK, catalase and protease activities, total PLFAs, bacterial and actinomycetes PLFAs, and MD.

Conclusions

Soil texture and land use type could be considered important factors in improving soil fertility, enzyme activity, and microbial diversity in coastal saline soils.

     

桂西北典型环境移民迁入区土壤养分特征分析

在桂西北典型环境移民迁入区,分析了5种土地利用方式表层(0-20 cm)土壤有机质(SOM)、全量养分和速效养分的变化特征.结果表明,根据变异系数(Cv)大小,除速效磷(AP)为强变异外Cv＞1.0),其余土壤养分都为中等变异(0.1＜Cv＜1.0).整体而言,移民迁入区SOM、全氮(TN)含量处于较高水平,速效氮(AN)、速效磷(AP)含量处于中等水平,全磷(TP)、速效钾(AK)处于偏低水平,而全钾(TK)处于低水平.土地利用方式是影响土壤养分的主要因素.灌丛和荒草地的SOM,TN,AN处于较高水平,果园和旱地则处于中等水平;次生林SOM处于较高水平,TN处于中等水平,而AN处于偏低水平.除旱地和果园AP含量处于中等水平外,不同利用方式土壤的TP,TK,AP,AK含量处于低或偏低水平.由于采取了较好的水土保持措施,移民后较大规模的土地利用变化没有导致明显的土壤退化,但需要增加磷钾肥的施用量.     

小尺度土壤养分的空间变异及其影响因素探讨—以江苏省无锡市典型城乡交错区为例

以江苏省无锡市城乡交错区为例,在8km2范围内,采集102个土壤表层样,利用地统计学和G IS相结合的方法,研究了土壤全量和速效氮、磷、钾的空间变异特征,并对其影响因素进行了探讨。结果表明土壤养分空间变异程度从大到小依次为:土壤全氮>土壤全磷>土壤速效磷>土壤速效氮>土壤速效钾>土壤全钾。土壤全氮空间变异受到土壤类型的影响,土壤全磷的空间变异与居民点分布有关,土壤全钾空间变异与土壤粘粒关系最密切。土壤全量养分和相应的速效养分具有显著相关关系,在空间分布上,也分别存在不同程度的相似性。同时土壤全磷和土壤速效养分受土地利用影响也较大。研究还表明,城乡交错区土壤氮、磷流失风险增加,需要实施有效措施控制氮、磷肥料的过度施用。     

四川省盐源县植烟土壤氮磷钾空间变异特征及影响因素

利用地统计学和回归分析方法分析四川省盐源县植烟土壤碱解氮、有效磷、速效钾含量空间变异特征以及不同因素对其空间变异的影响,以期为盐源烤烟种植区划、科学施肥和产质量提升提供科学依据。结果表明:1碱解氮、有效磷和速效钾的均值分别为102.84、10.18、148.10 mg/kg,整体处于中等水平,变异系数分别为38.66%、90.08%、60.65%,达到中等变异程度,空间分布不均;2碱解氮、有效磷空间分布符合指数模型,具有中等空间自相关,速效钾符合高斯模型,具有明显空间自相关,空间变异受结构性因素和随机性因素共同影响;3盐源植烟土壤碱解氮、有效磷和速效钾空间变异的主控因素有所不同,碱解氮为坡度和前茬作物,有效磷为土壤类型和前茬作物,速效钾为海拔和坡度,因此植烟区规划和施肥需要综合考虑不同的影响因素。