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1.
土壤扩散磷的分布及动态 总被引：3，自引：0，他引：3
用＾３２Ｐ标记扩散池法结合冷冻切片法测定了四种质地土壤中扩散磷的分布动态。结果表明，扩散磷（Ｊｉ）在土壤中的分布随距界面距离（ｘ）的增加急骤下降，其关系符合幂函数Ｊｉ＝ａｘ＾－ｂ。磷扩散数量随时间而增加，扩散物范围随之扩大，扩散磷分布的时（ｔ）空（ｘ）关系可用ｊｉ与ｘ，ｔ的三次非线性方程模拟。同一水肥条件下，磷扩散率轻质土大于粘质土。 相似文献
2.
不同冬小麦基因型磷有效性的特性 总被引：3，自引：0，他引：3
采用水培试验对两个冬小麦品种（丰抗８号，７９０８９）进行比较研究。结果表明，两品种的干物质累积最大值时的介质浓度不同，“丰抗８号”的介质浓度高于“７８０８９”，两者间的生长速率、磷吸收效率、植株体内磷浓度和根／冠比值间都有显著差异（Ｐ＝０．０５）。磷在植株体内的分布趋势相同，在磷胁迫条件下，两个品种都是靠增加根系的生长量来吸收介质中的磷素，以满足生长发育的需要。 相似文献
3.
石灰性潮土长期定位施肥对小麦根际无机磷组分及其有效性的影响 总被引：4，自引：0，他引：4
在长期定位施肥的基础上，采用网室盆栽试验，研究了石灰性潮土中不同施肥处理对冬小麦根际土壤与非根际土壤中无机磷组分及其有效性的影响。结果表明，不同施肥处理的供试土壤无机磷组分均以磷酸钙盐为主，平均占无机磷总量的73．9％，其它组分占26．1％。不施磷肥的各处理（CK、N、NK）中，小麦生物量和吸磷量均较低，小麦根际土壤与非根际土壤中无机磷总量变化不大，Ca2-P和Ca8—P在各处理的根际土壤中含量均很低。在施用磷肥的各处理（NP、PK、NPK）中，NP和NPK处理小麦的生物量和吸磷量均显著高于PK处理，而PK处理根际与非根际土壤中无机磷各组分的增幅明显高于NP和NPK处理。磷肥和有机肥处理，均显著提高小麦的吸磷量和生物学产量，各处理根际与非根际土壤中无机磷组分含量和总量增加的幅度以1．5（M＋NPK）处理最高。对不同施肥处理的小麦根际各无机磷形态及其与土壤速效磷间的相关分析表明，Ca2-P与土壤速效磷间的相关性达极显著水平，Ca8-P、Al-P、Fe—P达显著水平，O-P、Ca10—P不显著。 相似文献
4.
砂土供磷能力及磷肥用量模式研究 总被引：3，自引：1，他引：2
在河南省黄泛平原沙土区进行多年多点田间试验．结果表明,砂土小麦磷肥的肥效与土壤Olsen－P含量呈y＝16．8432－10．881ogx（n＝33,r＝－0．9700**）极显著曲线负相关小麦相对产量和吸磷量与Olsen－P含量呈显著正相关．据此可以判断土壤供磷的丰缺程度．Olsen－P含量与小麦磷肥用量呈显著负相关,为生产实践中测土施磷提供了指标． 相似文献
5.
采用剥落分离法对三倍体毛白杨＋黑麦草与三倍体毛白杨＋自然草2种模式的根际与非根际土化学特性进行研究表明：两模式林地非根际土C／N值和pH值均大于其对应的根际土。自然草模式根际与非根际土C／N值大于黑麦草模式根际与非根际土,而pH值却相反,黑麦草模式根际（或非根际）土pH值大于的自然草模式根际（或非根际）;两模式根际与非根际土N／P值（有效N与有效P的比值）接近14：1;两模式根际与非根际土速效K在4—5月均处于低谷,10-11月处于高峰;黑麦草模式根际土C／N值与速效K呈现较显著正相关,自然草模式根际土C／N值与N／P值呈现较显著正相关。 相似文献
6.
不同类型氮肥与施氮量下夏玉米水、氮利用及土壤氮素表观盈亏 总被引：18，自引：5，他引：18
以两个夏播玉米品种为材料，研究了不同类型氮肥与不同施氮量下华北平原夏玉米的水分与氮素利用及土壤氮素表观盈亏．结果表明：（1）随施氮量增大．产量、耗水量及水分生产效率（WPE）增大，氮肥利用率（NUE）降低；（2）夏玉米WPE与NUE具有较明显的基因型差异。WPE郑单958较大。NUE农大108较大；（3）wPE与NUE均受到氮肥类型的影响．WPE郑单958复合肥〉普通尿素〉包膜尿素．农大108处理间差异较小，以复合肥略大，普通尿素和包膜尿素相当。与普通尿素相比，包膜尿素与复合肥利用率较高，郑单958施N90kg／hm^2与农大108施N180kg／hm^2时，两者对NUE的提高尤为明显；（4）本试验条件下，经过夏玉米生长季，两品种各处理均出现土壤氮素表观亏缺，亏缺量随施氮量增大而降低，各条件下郑单958亏缺量较农大108大；氮肥类型间土壤氮素表观亏缺量表现为复合肥〉包膜尿素〉普通尿素。 相似文献
7.
不同磷效率油菜根际土壤磷活化机理研究 总被引：6，自引：2，他引：6
筛选和培育耐低磷植物是缓解磷矿资源缺乏和提高磷肥利用效率的有效途径之一。本研究在前期材料筛选的基础上,通过根箱试验研究不同磷效率油菜根际土壤磷活化机理,其结果如下:在施磷和不施磷处理条件下,磷高效油菜品种B56（HG）的吸磷量和生物量均高于磷低效品种B10（LG）;两油菜品种根际土壤中的NaHCO3-Pi, NaHCO3-Po和 NaOH-Pi,NaOH-Po四种磷素形态均有显著的亏缺现象;磷高效品种（HG）根际土壤上述四种磷素形态亏缺程度大于磷低效品种（LG）,但Resin-P则出现富集,并且HG的富集程度大于LG,这可能与HG具有较高吸磷能力有关。两油菜品种根际土壤HCl-Pi 和 残渣态磷（Residual-P）没有发生明显的亏缺现象。相比较而言,HG能分泌更多的酸性磷酸酶,该酶活性与NaHCO3-Po含量呈显著的负相关,说明酸性磷酸酶对有机磷矿化起着非常重要的作用。 相似文献
8.
为揭示根-土界面微域养分的吸收、累积与亏缺状况,运用X-射线电子探针研究盐胁迫对白蜡根际和根内营养元素相对含量及其分布的影响。结果表明,与对照（0 g/L）相比,低浓度（3 g/L）盐分处理使白蜡根系吸收较多的Ca、Mg、Cl等元素; 而高浓度（9 g/L）处理则使根系吸收Ca、Mg、Cl的能力下降。白蜡根内Na、K、Fe的累积量和根际Na的含量随盐浓度增加均有升高; 其中,过量的Na会破坏白蜡根细胞原生质膜的结构,引起胞内营养大量外泌,造成植物营养缺乏,从而诱发盐害。因此,Na在根际微域的累积是引起白蜡盐害的主要原因。 相似文献
9.
土区长期施肥对小麦-玉米轮作体系钾素平衡与钾库容量的影响 总被引：4，自引：2，他引：4
本文研究了土区小麦-玉米轮作体系长期氮磷钾化肥不同配合施用方式及氮磷钾化肥与秸秆或有机肥配合施用对钾素平衡以及土壤钾库的影响。试验包括9个处理,分别为不施肥（CK）、单施氮（N）、氮钾（NK）、磷钾（PK）、氮磷（NP）、氮磷钾（NPK）、氮磷钾配合一季秸秆还田（SNPK）、氮磷钾配合低量有机肥（M1NPK）和高量有机肥（M2NPK）。结果表明,除NK、PK和M2NPK处理外,其它处理小麦和玉米钾的携出量均大于钾的投入量,导致土壤钾素处于亏缺状态,20年累计亏缺量为6174333 kg/hm2。与试验前相比,长期施肥种植没有显著影响土壤全钾含量; 长期施用钾肥显著提高土壤速效钾含量,但长期不施钾肥处理的土壤速效钾含量也未显著降低; 无论施钾与否土壤非交换性钾（Mactotal K）以及非交换性钾中更容易被HNO3溶解提取的钾（Step K）均明显低于试验前水平。表明土壤非交换性钾可以作为该土壤钾素消耗的指标。考虑到施钾肥的经济投入和现有资源高效利用（如秸秆、有机肥）,从长远的角度出发,维持土壤钾素肥力以及土地可持续生产力,土区小麦-玉米轮作体系采用秸秆全部还田或施有机肥是必要的。 相似文献
10.
不同农业施肥制度对红壤稻田土壤磷肥力的影响 总被引：9，自引：0，他引：9
采用田间定位试验研究了几种不同农业施肥制度对红壤稻田土壤肥力的影响。结果表明：（１）在移耕农业，施化学Ｎ肥和ＮＫ施肥制下，农田系统磷素亏缺量大，７年间达１４０ｍｇ／ｈｍ＾２以上，土壤有效磷降低；（２）有机农业和施化学Ｐ肥施肥制可促进农田系统磷素平衡，改善土壤供磷状况，提高稻株含磷量和磷累积量； 相似文献
11.
The experiments were conducted in the artificial climate laboratory using 32P labelled soil and soil-root plane system to investigate phosphate distribution and its movement in the soil-root interface zone and their relations with phosphate uptake by plant as well as transpiration rate (atmosphere humidity).It was found that although the phosphate in the soil-root interface zone was of depletive distribution as a function C/Co=ax^b(C/Co is the relative content of fertilizer phosphate in a distance from the root surface x,a and b are the regression constants),and a relative accumulation zone of phosphate within 0.5 mm near the root surface was often boserved especially in the heavier texture soils because of root phosphate secretion.The depletion intensity of phosphate in the soil-root interface zone was in agreement with the phophate uptake by plants under two humidities very well.However,the effects of air humidity on characteristics of the phosphate distribution near wheat or maize root surface were different.Wheat grew better under lower atmosphere humidity while maize,under higher humidity,which caused a more intensive uptake and thus a stronger depletion of phosphate in the rhizosphere,Moreover,the depletion intensity was greater by the bottom or the middle part of wheat roots and by the top or the middle part of maize roots.The depletive distribution of phosphate in the rhizosphere soil and the relative contribution of phosphate diffusion to plant,which was more than 98% in the cultural experiments,indicated that diffusion was a major process for phosphorus supply to plants. 相似文献
12.
The phosphate in the soil-root interface zone under various soil water contents and application rates of phosphate was still of depletion distribution which could be described by a power function in the form of C/Co= axb(C/Co is the relative content of fertilized phosphate in a distance from the root surface x, a and b are the regression constants). The depletion rate of phosphate in soil near the root surface was higher and the depletion range was narrower under lower soil moisture. On the contrary, at higher soil water content the depletion range was wider, generally. The application rate of phosphate led to the greater depletion intensity of phosphorus was higher in the heavier texture soils. In general, the depletion intensity in the soils, which decreased with increasing clay content or increasing buffering power of soil, decreased in the order as loessal soil and black lou soil > lou soil > yellow cinnamon soil when 50 or 100 mg of phosphorus were applied in the form of KH2PO4. This result indicated that the phosphate distribution and its movement in the soil-root interface zone closely related with the buffering capacity of soil. 相似文献
13.
根-土界面区域磷酸盐的分布和移动: Ⅲ. 动力学 总被引：1，自引：0，他引：1
The depletion rate of phosphate in the soil-root interface zone increased along with growth and phosphate uptske of wheat or maize,which indicated that the phosphate distribution in soil near the root surface agreed well with the phosphate movement in rhizosphere and phosphate uptake by plant,The relative accumulation zone of phosphate within 0.5mm apart from the root surface developed at the 15th day or so after cultivating wheat or maize since the root phosphate secretion increased gradually in this stage.The phosphate distribution in the soil-root interface zone against the growing time(t)and the distance from the root plane(x) could be described by the non-linear regression equation with the third powers of x and t. 相似文献
14.
Phosphate depletion at the soil — root interface and the phosphate uptake of maize and rape Maize and rape plants were grown in flat containers in a 33P-labelled sandy soil and the distribution of soil phosphate near roots was determined by using densitometric scans of autoradiographs. The concentration of isotopically exchangeable phosphate at the root surface decreased within a few days by 42 per cent with rape and by 50–65 per cent with maize. Initially the width of the depletion zone is very small. Within six days the depletion zone extended to the final distance from the surface of the root cylinders of about 2 mm for maize and 2.6 mm for rape. The soil within the range of the mean length of root hairs (0.7 mm for maize and 1.3 mm for rape) is almost equally depleted. This indicates that root hairs are very important for P-uptake from soil. This is further supported by higher P-uptake rates per cm root length of rape than of maize. The P-concentration of the soil solution was estimated by means of the phosphate desorption curve. Within the root hair cylinder the P-concentration of the soil solution decreased from 0.8 to 0.03 mg P/l. Changes of the P-depletion profile with time were used to calculate P-uptake rates for roots of different age. The results indicate that for the first 3–5 days P-uptake rates remained near maximum, even though the P-concentration of the soil solution at the root surface had strongly decreased within two days. Phosphate uptake rates per cm root length did not decrease unless the whole root hair cylinder had been depleted. 相似文献
15.
Rubidium depletion of the soil-root interface by maize plants Maize plants were grown in flat containers with radioactive labelled rubidium. Changes of the Rb concentration in soil in the vicinity of the roots were determined by means of the film density of autoradiographs. Results were as follows: The Rb concentration of the soil at the root surface decreased markedly within one day; only small changes occured after this period. Initially, the width of the depletion zone was very small. It extended in the following days in a radial direction. Therefore, after the initial phase the Rb supply of the plants depended on transport from more remote parts of the soil. Soil texture and Rb level strongly influenced both degree and distance of Rb depletion. Thus, the Rb concentration at the root surface decreased by 80% of the initial value in a sandy soil (4% clay) and by only 30% in a silt loam soil (loess, 21% clay). The depletion zone extended to a distance of 2 mm in the silt loam soil from the surface of the root cylinder and to 5 mm in the sandy soil. Hence, in the silt loam about 20% and in the sandy soil almost 100% of the total soil volume contributed Rb to the plant, assuming a root density of 1 cm per cm3 of soil. Increased levels of Rb enhanced Rb availability by increasing both the degree of soil depletion near the root surface and the size of the depletion zone. The quantity of Rb available per cm of root varied between 0.05 μmol in the silt loam with low Rb application and 2.7 μmol in the sandy soil with high Rb application. The amount of Rb depleted from the soil, expressed as per cent of the Rb exchangeable by ammoniumacetate ranged from 3 to 7% in the silt loam and from 20 to 30% in the sandy soil, calculated on the basis of 1 cm root per cm3 of soil. The Rb concentration of the soil solution near the root surface was reduced to 2 μmolar. 相似文献
16.
土壤-根系微区养分状况的研究 Ⅵ.不同形态肥料氮素在根际的迁移规律 总被引：13，自引：0，他引：13
本文研究了不同形态氮肥施用后,氮素在作物根际的分布规律,及其与作物种类、土壤水分条件的关系.在淹水条件下的水稻根际土壤中,(NH4)2SO4和(NH2)2CO荨NH4+-N肥,其亏缺率随离根面距离增加呈指数相关的减小.而旱作条件下的玉米、大麦、黑麦草等作物根际NH4+-N肥料在离根面1-3毫米内存在相对累积,然后再出现亏缺梯度.试验证明,NH4+-N在旱作根际的相对累积,部分来源于根系分泌物.然而,NO3--N肥即使在淋失量较大的情况下,无论在淹水水稻还是旱作根际土壤中均未测出亏缺,仅存在累积. 相似文献
17.
Potassium dynamics at the soil-root interface in relation to the uptake of potassium by maize plants Young maize plants were grown in flat containers on a sandy and a silt loam soil after addition of 43K as tracer. Changes of the K concentration in soil in the vicinity of the roots were determined by scanning the film density of autoradiographs. A distinct zone of K depletion in the soil adjacent to the root surface was observed, similar to those found earlier with phosphate and rubidium. The highest degree of depletion occured within a distance of 0.7 mm from the surface of the root cylinder which corresponds to the average length of root hairs of the cultivar used. The quantity of K released within 2.5 days per unit of this part of the soil exceeded the exchangeable K by a factor of two. In a radial direction the zone of maximum depletion was followed by a depletion profile which extended over 5 mm in the sandy and over 3 mm in the silt loam soil. The K concentration of the soil solution decreased to 2–3 μmoles K/l at the root surface. In order to determine the effect of depleting the K concentration by plant roots on the release of soil K, desorption studies were carried out in parallel. For this purpose the soil was successively extracted by solutions with cation concentrations corresponding to the soil solution, except for K. With this procedure a massive release of K from the soil was observed after the equilibrium concentration decreased to 2–3 μmoles K/l. It is concluded that
- – in one growing season only part of the soil volume of the rooted layer contributes potassium to the plant and, on the other hand
- – substantial part of the potassium absorbed by plants is derived from nonexchangeable soil K, even in short periods of time.
18.
Influence of potassium supply on the availability of potassium in the rhizosphere of rape (Brassica napus) Potassium depletion of the soil in the proximity of roots was studied in order to obtain quantitative information on the availability of potassium. For this purpose rape seedlings were grown in pots which separate roots from soil by a fine meshed screen; root hairs penetrated the screen. The soil adjacent to the screen was sliced by microtome into layers about 0.1 mm thick which were separately analysed for k. Plant roots strongly depleted the soil in their proximity; further distant ranges remained unchanged. A loess derived loam, brought to different levels of exchangeable K by precropping or K application, was equally depleted to 150 μmoles/100g soil at the root surface. Therefore, the quantity of K released from this source increased with initial K level. In addition, the distance of the depletion zone extended with K level from 4,6 to 6.3 mm from the surface of the root cylinder. Hence, the volume of soil contributing K to the root increased from 0.7 to 1.2 cm3 per cm root length. The combination of these two parameters, i.e. the quantity of exchangeable soil K released per unit of root length increased by a factor of 20 whereas exchangeable soil K was raised by a factor of 4.5 only. K uptake of the plants after 4 days was in agreement with the depletion of exchangeable soil K in the high K treatment only. The other treatments had obviously taken up considerable percentages of nonexchangeable K. This fraction was released from the soil ranging less than 1.5 mm from the root. The distance of the K depletion zone was also extended by application of NaCl and MgCl2. Because of cation exchange, K concentration of the soil solution was increased, K buffer power decreased and, therefore, K diffusion was enhanced. It is concluded that plants in the field do not uniformly deplete the total rooted soil volume. Whereas roots in their proximity strongly deplete the soil including parts of nonexchangeable K they do not even use exchangeable K in a slightly greater distance. The quantity of K available per unit of root length is, therefore, determined by both - the degree of soil K depletion at the root surface and -the distance of the depletion zone, i.e. the volume of soil that contributes K to the root. Either factor was markedly affected by the level of soil K and thus by K application. 相似文献
19.
根土界面的研究 Ⅰ.钾离子向稻根迁移的数学模型 总被引：1，自引：0，他引：1
用数学模型分析土壤中的养分离子向植物根系的移动,最早由Bouldin[1],Olsen[9]和Passioura[10]在六十年代初所提出,近年又陆续发展出若干数学模型来处理土壤一植物系统中的离子迁移过程。如Nye[7,8]的瞬时态模型,Baldwin[2]的稳态模型以及Claassen等[3,4]的模拟模型等。这些模型都是根据连续性方程式的某一形式,并按照实际问题采用直角坐标、柱坐标或球坐标来列出偏微分方程,然后求得满足初始条件与各种边界条件下的解析解或数值解。各种模型的主要区别在于假定体系是有限的还是无限的以及根表面的边界条件的不同。存在于植物根表面的状况是不知道的,所以必须采用简化的估计。 相似文献
20.
To simulate processes tending to raise the pH of soil near a plant root, a stack of moist HCO-3saturated ion exchange resin papers was placed in contact with non-calcareous soil of varying pH, containing HC1 + CaCl2 in the soil solution. Changes in the concentration profiles of Ca2+, Cl- and H+ in the soil were followed. HCO-3 released from the resin in exchange for soil Cl- reacted with the soil and raised its pH. Increases of up to 1 unit were measured near the interface. The zone of pH increase extended into the soil much less than the zone of chloride depletion. It was shown that Ca2+ could accumulate near the interface in the absence of mass flow in this experimental system. 相似文献