Apple replant disease: the influence of soil phosphorus and other factors on the growth responses of apple seedlings to soil fumigation with chloropicrin

The effects of fumigating field soils before replanting apple are frequently predicted from bioassays where apple seedlings are grown in pots, some containing untreated soil and the others containing chloropicrin-fumigated soil. The results from 418 such bioassays made during eight years are discussed with reference to the effects of certain physical and chemical soil features. Soil phosphorus (P) content and pH had large effects on growth in fumigated (but not untreated) soils; they therefore had large effects on the growth response to soil fumigation. There were no indications of important effects due to soil content of potassium or magnesium or to soil texture. In fumigated soils, the height of seedlings was generally greater, the greater the soil P content, but in untreated soils it was mostly independent of P (range 1 – 156 mg P litre^-1soil). The differing effects of native P on growth in untreated or fumigated soils were attributed respectively to the presence and absence of vesicular-arbuscular mycorrhizas: their absence in fumigated soils was considered (for apple) to be an artefact in the seedling bioassay. The results for untreated soils indicated that the apple mycorrhizal system was very efficient in retrieving P when there was little available. Growth responses to soil fumigation were usually greater in acidic than in alkaline soils for any given level of P. When soils were P-amended before testing, the effects of native P and pH virtually disappeared and the proportion of orchard soils with economically significant growth responses increased from 39% to 67%.     

江西省茶园土壤肥力特征及其影响因子

为探明江西省典型茶园土壤养分状况和肥力特征,选取江西省21个地区372个典型茶园,分析茶园土壤养分的差异性、空间性、相关性及与地形、土壤类型、海拔和建园时间的关联性。结果表明: 江西省茶园土壤pH、有机质、碱解氮、速效磷、速效钾、全氮、全磷和全钾分别达到优质高效高产茶园土壤营养指标的53.9%、60.1%、56.1%、22.9%、38.5%、43.7%、11.1%和95.5%,其中速效磷为强变异;有效铜、锌、铁、锰和硼达到土壤微量元素含量分级一级标准的占比分别为76.3%、74.2%、96.8%、73.1%和0.0%。江西茶园土壤养分以赣中地区最高,其次是赣东北和赣西北地区,赣南地区最低。除全钾外,土壤pH与有机质、碱解氮、速效磷、速效钾、全氮和全磷均呈显著正相关。不同地形土壤养分以平地最高,高山次之,山地和丘陵最低;不同土壤类型土壤养分以水稻土、砂壤和山地黄棕壤较高,其次是黄壤、红黄壤和紫色土,红壤最低;土壤pH、有机质和全钾随海拔上升而递增,而速效磷随海拔上升而递减;土壤有机质、碱解氮、全氮、速效磷和全磷随建园时间的增加而递增,而土壤pH随建园时间的增加而递减。综上,江西省茶园土壤肥力总体水平良好,有机质、全钾、有效铜、锌、铁和锰均较丰富,但土壤偏酸,速效磷和全磷偏低,有效硼严重缺乏。赣中应提高土壤pH和钾肥,赣东北增加钾和氮肥,赣西北增加有机质和磷肥,赣南应增加氮磷钾肥并配施有机肥;高山茶园补充速效磷和钾肥,山地茶园提高氮和磷肥;红黄壤茶园提高土壤pH和全钾,红壤茶园应提高氮磷钾肥并配施有机肥,黄壤和山地黄棕壤茶园需要增施磷肥,紫色土茶园需提高土壤有机质;茶园需要逐年增加白云石粉、生理碱性肥料和有机肥等,防治茶园土壤酸化。     

福建红壤区不同侵蚀强度马尾松林地土壤营养元素变化特征

采用野外调查和室内分析的方法对福建红壤区不同侵蚀强度马尾松林地土壤营养元素动态进行研究,以揭示红壤侵蚀区不同侵蚀强度对马尾松林地土壤营养元素的影响.结果表明:除速效磷以外,侵蚀强度显著改变了土壤有机质、碱解氮、全钾、速效钾的含量以及土壤pH.土壤有机质和碱解氮在中度侵蚀马尾松林地含量最高,随着侵蚀强度的增加植被覆盖减少,土壤有机质和碱解氮显著降低.土壤全钾和速效钾含量随着侵蚀强度的增加而显著增加,土壤速效磷随着侵蚀强度的增加没有显著的变化.土壤pH值随着土壤侵蚀强度和土壤深度的增加而显著增加.皮尔逊相关关系分析表明:有机质与碱解氮、全钾和pH显著相关.灰色关联度分析表明:除侵蚀强度对营养元素和pH有显著影响外,坡度对土壤营养元素和pH影响较大;覆盖度对有机质、碱解氮和速效磷影响较大.因此,植被恢复和植被生境的综合治理是红壤侵蚀区生态恢复与重建的有效途径.     

有机酸对土壤无机态磷转化和速效磷的影响

土壤有效磷含量低是影响作物生产的重要限制因素之一.作物根分泌活化难溶性磷的有机酸对改善其磷素营养具有重要意义.采用张守敬和Jackson无机磷分级方法,以湖北省3种pH值土壤为材料,加入不同磷源和有机酸,经过室温培养后,测定速效磷含量和无机磷组分的变化.结果表明:施磷显著提高了土壤中速效磷含量,中性土、酸性土Fe-P和Al-P含量大幅上升, Fe-P占增加量的50%以上,而碱性土Ca-P含量显著增加.加施有机酸使中性土速效磷含量增多,除苹果酸处理的变幅较小外,草酸和柠檬酸的加入速效磷显著增加.由于有机酸的作用,中性土Al-P含量下降,Ca-P含量上升,变幅大小依次为草酸＞柠檬酸＞苹果酸;酸性土中Al-P含量呈下降趋势,碱性土中Ca-P含量有不同程度的减少,3种土壤中O-P含量均有所增加.说明有机酸活化的磷主要来源于中性土和酸性土Al-P、Fe-P及碱性土Ca-P中的磷,同时有机酸能够促进土壤中闭蓄态磷(O-P)的形成与积累.     

菜地和一般农田土壤主要养分累积的差异

选取不同类型菜地和一般农田 ,测定了 0～ 2 0 0cm土壤剖面的有机质、全氮、硝态氮、铵态氮、速效磷、速效钾等主要养分含量及其分布 .结果表明 ,菜地土壤中养分大量累积 ,其中硝态氮和速效磷累积程度较高 .大棚和露天菜地 0～ 2 0 0cm土层的硝态氮累积总量分别为 15 2 0 .9kg·hm-2 和 135 8.8kg·hm-2 ,比农田高出 5 .2和 4.5倍 ;速效磷分别为 978.1kg·hm-2 和 5 0 3.3kg·hm-2 ,比农田高出 6 .2和 2 .7倍 .而其它养分增加相对较少 .有机质累积总量分别为 2 80 .5Mg·hm-2 和 2 6 9.3Mg·hm-2 ,比一般农田高出 12 .5 %和 8.0 % ;全氮分别为 37.5Mg·hm-2 和 32 .7Mg·hm-2 ,比农田高出 36 .2 %和 18.6 % ;铵态氮分别为 2 11.5kg·hm-2 和 197.8kg·hm-2 ,比农田高出 2 9.6 %和 2 1.2 % ;速效钾分别为 6 5 6 7.8kg·hm-2 和 5 5 2 3 .6kg·hm-2 ,比农田高出 30 .6 %和 9.8% .此外 ,菜地土壤中累积的养分不仅分布在表层 ,在深层土壤也大量存在 ,说明菜地存在严重的养分淋溶现象 .     

北京地区耕地碳酸盐褐土不同农作物氮及灰分元素生物循环的比较研究

京郊耕地碳酸盐褐土小麦、大麦、玉米、高梁、花生五种农作物氮及灰分元素生物循环的研究结果表明：1．不同作物存留、归还、吸收不同元素数量的差别很大。豆科作物花生以对钙、镁吸收量大为其显著特征;禾本科作物吸收较高数量硅、铁、铝、锰、钠。在四种禾本科作物中,高梁吸收较高数量氮、磷,钾、钙、镁、硅,大麦吸收较高数量钠、硫和锰。2．不同作物以根、茬形式对11种元素和灰分向土壤中的归还有三种情况：1)低度归还类型：氮磷钾,归还比例一般低于10%;2)中度归还类型：镁钙硫硅钠和灰分,归还比例介于10—30%;3)高度归还类型：铁铝和锰,归还比例一般为30%。 3．不同农作物生物循环特点对研究农田生态系统元素平衡、耕地土壤肥力变化和形成过程以及施肥、耕作制度改革,都有重要意义。     

青海三江源地区风沙土养分及微生物区系

采用常规方法研究了青海三江源地区风沙土的养分状况及微生物区系.结果表明,从流动、半固定风沙土到固定风沙土的演化过程中,土壤有机质含量明显增加,固定风沙土的有机质含量分别为流动和半固定风沙土的5.9和3.8倍;土壤氮素和磷素含量的变化趋势与有机质基本一致,均呈递增趋势;土壤钾素含量和土壤pH无明显变化规律.随着植被发育、流沙固定及土壤养分状况改善,风沙土中的微生物数量和区系组成也发生了显著变化.固定和半固定风沙土中的细菌、真菌及放线菌数量均明显高于流动风沙土,其细菌数量分别约为流动风沙土的4.0和2.8倍,真菌数量分别约为19.6和6.3倍,放线菌数量分别约为12.4和2.6倍;真菌种类数明显增加,放线菌区系组成也变得复杂.即随着风沙土由流动变为固定,土壤微生物生态系统中微生物的生物多样性增强,微生物组成趋于多样化.风沙土中的微生物数量与土壤有机质、全氮、速效氮及速效磷含量显著或极显著相关,与土壤全磷、全钾、速效钾含量及土壤pH之间相关性未达显著水平.     

拉杰沙希大学校园药用植物菌根研究

Forty different medicinal plants were investigated for arbuscular mycorrhizal association in the Rajshahi University Campus in Bangladesh. The results indicated that 35 different plants were infected by AM (arbuscular mycorrhizal) fungi as found by trypan blue staining procedure. The percentage of root colonization by AM fungi varied from 13.3% to 100%. Mangifera indica and Morus indica have maximum percentage of colonization (100%). The intensity of root colonization were abundant in the plants belonging to the families Anacardiaceae, Asclepiadaceae, Moraceae, Leguminosae and Apocynaceae whereas the intensity of colonization of crop roots were moderate and poor belonging to Gramineae and Leguminosae. The presence of greater number of spore in soil was always associated with the incidence of abundant mycelia. In plant roots the formation of spore and mycelia was restricted by low pH. Number of mycorrhizal fungus spores ranged between 35 to100 per 100g air dried soil in different family respective soils. The frequency of mycorrhizal fungus infection showed positive correlation with soil pH, moisture, water holding capacity, texture, total nitrogen, organic carbon, phosphorus, calcium, potassium, and magnesium. Especially phosphorus and nitrogen in the soil greatly influenced the plant root infection by AM fungi.     

Multivariate Interpretation of the Distribution of Nitrogen-fixing Blue--green Algae in Rice Soils in Central Sri Lanka

The ecology of nitrogen fixing blue-green algae in rice fieldsof Central Sri Lanka was studied using multi-variate techniquesof analyses. In this study 73 strains of heterocystous blue—greenalgae, belonging to 21 genera were isolated and the distributionof the 46 most abundant strains was examined in relation toecological parameters. Besides pedological factors such as pH, water holding capacityand available phosphorus; environmental factors including rainfalland altitude have shown up as parameters influencing the distributionof the algal species. On the other hand, soil organic carbon,total nitrogen, potassium and calcium, do not appear to playan important role in determining the composition of the algalflora. While certain algal species were ubiquitous in their distributionsome were restricted, and a few even showed a tolerance to standswith low soil pH and low levels of phosphorus. The agronomicpotential of such species is of value especially in relationto rice-growing soils of this District, where low pH and lowlevels of phosphorus are major limiting factors for the profusegrowth of blue—green algae. Blue-green algae, nitrogen fixation, Sri Lanka, rice-growing soils, multivariate analysis     

江门市新会区耕地土壤养分空间变异特征

运用地统计学方法,结合GIS技术研究了江门市新会区土壤pH值、有机质、阳离子交换量、全氮、有效磷和缓效钾种养分要素的空间分布特征.结果表明,各变量符合正态分布或经对数转换后符合正态分布.半方差函数分析结果显示,除全氮具有强空间相关外,其余均具有中等空间相关性.Kriging插值结果表明,研究区域耕地土壤pH值和阳离子交换量在东北部最高,有机质含量在中部和东北部较高;全氮含量在1.5～2.0g·kg^-1的面积占研究区域耕地面积的74.7%,主要分布于研究区域西部和东部地区;有效磷含量＞40mg·kg^-1的面积占研究区域耕地面积的48.7%,主要分布于研究区域东北部和西部;缓效钾含量在10～350mg·kg^-1的面积占研究区域耕地面积的48.1%,主要分布于研究区域东部、东北部和中部.     

Nutrient changes in surface soils after an intense fire in jarrah (Eucalyptus marginata Donn ex Sm.) forest

The effects of an intense fire on the nutrient status of jarrah(Eucalyptus marginata Donn ex Sm.) forest soils were investigated. At seven experimental sites, representing a range of soil and vegetation types, surface soils were sampled to a maximum depth of 20 cm before, immediately after, and 1 year after the fire. Immediately after the fire, concentrations of total and extracted nutrients in surface (0–3 cm) soils increased markedly. One year later, concentrations of extracted nutrients in surface soils had returned to levels close to pre-burn concentrations. During this period, some properties of sub-surface (3–20 cm) soils also changed: Bray-extractable phosphorus and electrolytic conductivity decreased, whereas ex-tractable potassium and pH increased relative to pre-burn concentrations. Initial increases in concentrations of extractable forms of nutrients were determined largely by the amounts of nutrients deposited in fine ash, whereas the changes after 1 year depended more on the leaching of ions and their reactions with the mineral soil. Increases in total amounts of major nutrients in surface soils arising from additions of fine ash were generally well correlated with amounts in pre-burn litter and with amounts in the components of organic matter likely to be consumed in the fire. Significant quantities of all nutrients are redistributed from aboveground sources to the soil surface during intense fires, including nutrients which are most susceptible to losses through volatilization. This redistribution of nutrients is discussed in relation to short-term and long-term effects on plant growth and functioning of the jarrah ecosystem.     

江苏省不同农业区土壤线虫群落分布特征

调查了江苏省不同农业区农田土壤线虫群落多样性,分析了土壤线虫数量和群落结构与土壤环境因子的关系,并探讨了土壤线虫对土壤健康的生物指示作用.结果表明： 农田土壤线虫共鉴定出2纲7目19科41属.6个农业区的土壤线虫的密度、群落组成均具有一定的差异性.沿海农业区的线虫数量最多(每100 g干土400条),显著高于徐淮、宁镇扬和沿江农业区(P＜0.05),而沿江农业区的土壤线虫数量最少(每100 g干土232条),这可能是由于土壤质地、年均降雨量和年均气温等因素的差异造成的.地理位置相近的农业区线虫优势属相似.相关性分析结果显示,土壤线虫数量与土壤有机质、全氮、速效氮、速效钾和速效磷均呈显著正相关关系;RDA分析表明,土壤全氮含量、速效磷及pH对线虫群落种属组成影响较大.分析江苏省农田土壤线虫群落空间分布特征,可为农田土壤生态系统健康状况评价提供数据支撑.     

Build up and depletion of soil phosphorus and potassium and their uptake by rice and wheat in a long-term field experiment

Summary In a field experiment initiated at the Central Soil Salinity Research Institute, Karnal in 1974 involving rice wheat cropping sequence and NPK fertilizer use on sodic soil (pH 9.2, ESP 32.0), an attempt was made to evaluate the available P and K status of the soil and their uptake by the crops during 1982–83 and 83–84.Application of P to either or both the crops significantly enhanced the yields of rice and improved available P status of the soil. Wheat yields remained unaffected. Fertilizer N reduced P content in rice but increased P uptake in crops and considerably brought down available P to a level (4.5 ppm) where rice plants showed reduced tillering and phosphorus deficiency. Application of K did not affect the yield of either crop but enhanced its available status in soil and uptake by the crops. Contribution of the non-exchangeable K towards total potassium removal was about 93% in the absence of applied K which decreased to 87% with the use of K. Application of K to both crops resulted in lesser uptake from non-exchangeable form as compared to its application to either crop. Laboratory studies carried out on soils of the experimental plots showed that cumulative K release measured after five successive extractions was higher in K-treated soils as compared to untreated ones. The major difference was only in the first extraction representing the exchangeable K after which release became independent of the available K of the soil.     

Distribution of burrows of the African giant rat (Cricetomys gambianus Waterhouse) in relation to soil characteristics

A study was made of soil characteristics in giant rat habitat in order to examine the possibility that the location of their burrows is related to soil texture and minerals. Physical and mineral analysis of soils from giant rat burrows have been carried out. Significant chemical differences were observed between soils from occupied or vacated burrows and from locations without burrows. Striking differences in correlation coefficients of different minerals (calcium, phosphorus, sodium, potassium and manganese) were observed in vacated and occupied burrows. The implication of these findings are discussed in relation to present knowledge of the animal's nutritional requirements.     

Determination of Spatial Distribution Patterns of Clay and Plant Available Potassium Contents in Surface Soils at the Farm Scale using High Resolution Gamma Ray Spectrometry

Variation in dryland crop yield is often related to underlying soil properties such as water availability and soil fertility. There are often significant difficulties in adequately defining the spatial distribution of such properties at the farm scale. Gamma ray spectrometry (radiometrics) is a relatively new soil sensing technique that can potentially address this by improving the mapping of soil texture and plant available potassium (bic-K). Three sites North Nolba, South Nolba and Summerset were investigated using exploratory linear correlation analysis. Mapping analysis was focused on the Summerset site. In contrast to the two Nolba sites, the soils from Summerset had sufficient soil texture range and parent material conditions that allowed for calibrations to be developed. Soil properties were mapped at Summerset using multivariate linear regression and tree-based models with radiometric, topographic and location data as the inputs. A multivariate linear regression analysis using radiometric data was associated with greater than 70% of the variance in bic-K and soil texture at Summerset. Field checked maps indicated that up to 66% and 60% of the variation in clay and bic-K contents respectively, could be predicted. The overall lowest map errors in root mean square error (RMSE) were 2.4 dag/kg clay and 103 mg/kg bic-K contents. This study concludes that for a site with weathered soils of sufficient soil texture range, radiometrics can reliably predict clay and plant available potassium contents. Radiometrics has practical farm scale applications at a precision that is useful for understanding potential yield variation across a farm.     

生物炭提高土壤磷素有效性的整合分析

生物炭改善土壤肥力和提高作物产量的作用与土壤磷素有效性的提高密切相关,但是关于生物炭添加对土壤磷素有效性影响的定量效应尚不明确。本研究对95篇符合条件的文献中的507组数据进行整合分析,以评估生物炭添加对土壤磷素有效性的定量影响。结果表明: 不论生物炭原料、制备温度、C/N、施用量、配施化肥与否,以及土壤质地、pH、有机碳含量如何变化,生物炭添加均使土壤有效磷含量显著提高,平均较不添加对照提高57.6%。同时,生物炭添加促进了作物对磷的利用,但植株含磷量对不同添加条件下生物炭的响应程度基本上均低于土壤有效磷,部分条件下未达到显著水平,平均响应比为30.6%。在砂质和壤质土壤中,添加拥有较多灰分的畜禽粪便生物炭,以及较低C/N、低温裂解的碱性生物炭、较大施用量对增加土壤有效磷和植株磷含量更有效。作为土壤磷素循环的主要酶,生物炭添加使碱性磷酸酶活性平均增加2.8%,而酸性磷酸酶活性则平均降低17.8%。总体上,生物炭对土壤有效磷和植株磷含量有显著的正向效应,但对土壤磷酸酶活性的影响较小,磷素有效性的提高可能主要源于生物炭自身携带较高含量的有效磷组分。     

土壤纤毛虫群落对退牧还草生态恢复的响应——以玛曲县为例

为研究退牧还草对土壤纤毛虫群落特征的影响、退牧还草后土壤环境变化以及如何利用原生动物纤毛虫群落特征来评价退还效果的可行性,于2015年5月至2016年3月在甘肃省甘南藏族自治州玛曲县选取3个不同恢复年限的草地样点和1个未经过退牧还草对照样点,采用"非淹没培养皿法"、活体观察法和培养直接计数法对土壤纤毛虫的物种数和密度进行测定,同时测定了土壤温度、pH值、含水量、土壤孔隙度、速效钾、速效氮、速效磷、全氮、全钾、全磷和有机质含量,并分析了在生态逐渐恢复条件下,土壤纤毛虫群落特征与土壤环境因子间的相关性。研究共鉴定到纤毛虫95种,隶属9纲15目21科28属。研究发现,退牧还草样地与未退牧还草样地的土壤纤毛虫的物种分布存在明显差异:退牧还草后的3个样点间的物种相似性减小,群落组成复杂化,纤毛虫丰度、丰富度指数、均匀度指数和物种多样性指数增高。相关性分析结果表明,退牧还草后,对纤毛虫群落结构稳定性影响最主要的是土壤有机质、含水量和土壤全氮、全磷和全钾的含量,不同恢复年限样点的土壤纤毛虫群落组成差异较大。土壤纤毛虫群落对退牧还草生态恢复过程中土壤环境条件的变化有较好的响应。     

坡向对毛竹林土壤养分及其生态化学计量特征的影响

采集浙江省龙游县境内毛竹林地不同坡向(阴坡和阳坡)的土壤样品进行对比分析,研究坡向对毛竹林地土壤养分及其生态化学计量特征的影响.结果表明: 土壤养分受坡向和土层深度的影响,采样区内土壤的养分水平呈阴坡＞阳坡、表层土壤＞底层土壤的变化趋势.阴坡土壤的阳离子交换量、总有机碳、全氮、碱解氮、速效磷、全钾和速效钾含量显著高于阳坡,分别高43.7%、103.8%、92.0%、75.5%、22.4%、89.4%和240.7%,而阴坡和阳坡土壤的全磷含量并无显著性差异.0～20 cm、20～40 cm和40～60 cm 3个土层中,无论是阴坡还是阳坡,其土壤C/N差异均不显著,而阴坡土壤C/P显著高于阳坡,分别高180.8%、42.0%和54.3%;各土层中,阴坡和阳坡土壤的C/K和N/K之间的差异不显著,而阴坡和阳坡土壤的C/K和N/K在3个土层间存在极显著性差异.采样区域内阴坡土壤有机碳与全氮、全磷和全钾之间呈极显著的正相关关系,并且与各速效养分间也均呈极显著的正相关关系.总体而言,毛竹林阴坡的土壤养分及其生态化学计量特征优于阳坡.     

Studies on the nutrition of forage legumes

Summary Surface samples of six Ontario soils were selected to provide a range in pH, texture and carbonate content. Phosphorus was added to the soil samples at the rate of 200, and 2000 pounds. P₂O₅ per acre and the inorganic phosphates associated with aluminum (Al-P), iron (Fe-P) and calcium (Ca-P) were analysed 15, 30, and 335 days after treatment. Samples of the check soils were leached with the equivalent of 7 litres of soil-percolated water and then analysed for phosphate fractions. In 5 soils with added phosphorus the Al-P fraction increased at both rates of added phosphorus, Fe-P increased only at the higher rate of added phosphorus and Ca-P did not increase at either rate. In the sixth soil (69.9% CaCO₃ equivalent) Ca-P increased at both rates of added phosphorus, but proportionately less than the water-soluble phosphorus. These changes in phosphorus values existed relatively unchanged for 335 days after the addition of phosphorus. Leaching generally removed phosphorus from all phosphorus fraction. At or below pH 7.1 (soil paste) the Al-P decreased proportionately more than the Fe-P and Ca-P. Above pH 7.1 the Ca-P decreased proportionately more than the other two fractions upon leaching.Contribution from Dept. of Soil Science, O.A.C., Guelph, Canada. Part of thesis submitted by junior author to the Graduate School, University of Toronto, in partial fulfilment of the requirements for the M.S.A. degree.     

云南保山西庄山地流域土地利用方式与土壤肥力关系研究

以云南省保山地区西庄流域为例,研究了自然因素及人为活动对土壤性质的影响。该流域的土壤通常pH较低,缺乏有效磷和交换性阳离子。仅发育于石灰岩的土壤具适宜的pH和交换性阳离子量。海拔对土壤有机碳含量具显著影响。文中详细讨论了海拔、母质和土地利用方式等对土壤肥力及土壤侵蚀的影响。