VA菌根真菌对石灰性土壤不同形态磷酸盐有效性的影响

用32P示踪法研究了VA菌根真菌对石灰性土壤不同形态磷酸盐有效性的影响。结果表明，VA菌很真菌显著增加了玉米吸收肥料和土壤的磷量。菌根植物和非菌根植物都可不同程度地吸收利用土壤中的Ca2-P、Ca8-P、Fe-P和Al-P，VA菌根真菌增加了玉米对它们的吸收。试验结果还表明，施Ca10-P时接种VA菌很真菌对玉米生长的促进作用比施用其它磷酸盐明显，但Ca10-P不能直接被玉米植株所利用。说明VA菌根真菌能提高土壤中的有效性磷（Ca2-P和Al-P）和缓效性磷（Ca8-P和Fe-P）的有效性。     

Enhanced plant growth by uniform placement of superphosphate with rock phosphate in acidic soils

Abstract

Partially acidulated rock phosphate or compacted soluble phosphate‐rock phosphate mixture has been suggested as an alternative phosphorus (P) source for plants in acidic soils. Interaction between the soluble and the insoluble fractions would be conducive to plant utilization of both P sources in the fertilizer material. Direct evidence supports the beneficial reactions between the two P sources, however, was still insufficient. A pot experiment was hence conducted to evaluate the possible interaction of ³²P‐labeled single superphosphate (SSP) and a less reactive rock phosphate (RP) from Jinxiang mine, China. In the experiment, SSP and RP were applied to two acidic red soils (typic Hapludults) in a manner that would favor or diminish their interaction either by distributing both P sources homogeneously within the whole volume of the pot soil (uniform placement) or by separating them vertically with each being applied to half of the soil volume (fraction placement). The reference treatments of SSP and RP were arranged in similar manners. Two successive harvests of ryegrass were made during a 2‐month period. Results indicated that uniform placement of SSP and RP significantly enhanced plant growth and P uptake, and that P recovery of SSP‐P in the higher P‐fixing soil was almost twice that of the fraction placement. The data of plant PdfL% (percentage of P derived from labeled‐P), which indicated that >80% of plant P was derived from SSP, however, failed to support the idea that soluble P had increased plant utilization of RP. Alternatively, it is considered that the low grade RP had increased plant utilization of both SSP‐P and soil‐P. Uniform placement of RP and SSP also strikingly improved plant calcium (Ca) and magnesium (Mg) nutrition. The phenomenon suggested that SSP‐RP mixture might be a good P source on similar acidic soils in subtropical China.     

Effect of High Humic Substance Levels on Growth and Nutrient Concentration of Corn under Calcareous Conditions

This study investigated the effect of high humic substance (HS) levels (0, 500, 1000, and 2000 mg HS kg^?1) on growth and nutrient concentrations of corn grown on calcareous soils. For these, soil samples were collected from the six different provinces of Turkey. According to the average values, HS levels had no significant effect alone on dry weight, nitrogen (N), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), zinc (Zn), copper (Cu), and manganese (Mn) concentrations. Soil differences significantly affected dry weight, N, Mg, and Cu concentrations (p ≤ 0.05). Looking at HSxsoil interactions on K, Ca, Fe, and Mn concentrations, it could be seen that there was no effect or that the effect was negative. Only plant Fe concentrations obtained from Konya and Urfa provinces were positively affected from HSxsoil interaction. It was concluded that high level of HS had no or negative effect on corn growth and some nutrient concentration under calcareous conditions.     

Suppression of superphosphate-phosphorus fixation by farmyard manure I. High phosphorus uptake from superphosphate

Pot and field experiments were conducted on alkaline calcareous soils of Pakistan to determine the effect of premixing superphosphate (SUP) with farmyard manure (FYM) on the fraction of plant phosphorus derived from the ³⁰P labelled SUP (y value). Premixing (SUP with FYM) before their addition to soil, markedly increased the uptake of SUP-P by plants. The premixed treatment also increased crop yield on phosphorus deficient soli. Optimum quantity of FYM required was twice that of SUP. Higher quantities of FYM had no additional effect on phosphorus availability from SUP.

The possible mechanism of this effect and the implications of these observations in phosphorus nutrition of plants have been discussed.     

Waste water renovation through soil percolation

A laboratory experiment simulating high-rate effluent renovation by soil percolation involved leaching secondary sewage effluent through columns of three differing soils. Analyses of P in 22 leachate collections and distribution of both organic and inorganic P in column sections revealed the mechanisms of P removal, the influence of differing soil properties, and the effect of continuous utilization. Renovation of effluent P was greatest with percolation through columns of acid Milner soil which contains abundant Al and Fe, and, although Squilax soil removed more P from initial leachings due to its higher exchangeable Ca content, Glenmore soil was the more suitable of these two alkaline soils over the long term. The leachate N0₀3-N levels were lower than the original N0₃-N content of effluent for the first ten leachings but N0₃-N enrichment occurred for the last effluent percolations through all three soils. Analyses of Ca, Mg, K, and Na in leachates and soil columns indicated losses of exchangeable cations from the calcareous Squilax and Glenmore soils enriched effluent content and the accumulation of the cations in the acid soil reduced concentrations in effluent that passed through Milner soil.     

The effect of vesicular-arbuscular mycorrhizae in decreasing Ca acquisition by alfalfa plants in calcareous soils

Summary The legume Medicago sativa L. was grown in three calcareous soils supplied with increasing amounts of soluble phosphate, or a vesicular-arbuscular mycorrhizal (VAM) inoculum. The three test soils had high concentrations of extractable Ca. Analyses of dry-matter production and of the concentrations and content of the nutrients N, P, K, Ca, and Mg in plant tissues showed that, for each soil, a particular level of P application was able to match the VAM effects on N, P, and K levels. The Ca concentration and content in the VAM inoculated plants were, however, significantly lower than those in the P-supplied non-mycorrhizal treatments that matched the VAM effects. The N:P and the K:P ratios were about the same for mycorrhizal and non-mycorrhizal P-supplied control plants in all the three soils, but VAM inoculation lowered the Ca:P ratio in all soils. The mycorrhizae decreased Mg uptake in one of the soils, where non-mycorrhizal plants had high Mg concentrations in tissues. It is concluded that VAM depress the excessive acquisition of Ca by plants in calcareous soils.     

Alfalfa cultivar response to phosphorus and potassium deficiency: Elemental composition of the herbage

While phosphorus (P) and potassium (K) use efficiencies in alfalfa (Medicago sativa L.) are subject to genetic control, selection for these traits also affects the utilization of other nutrients. It is not clear whether other nutrients are as susceptible to genetic alterations directly or whether alteration of P and K uptake may simply alter the general synergisms and antagonisms among the elements in plants.

Our objectives were to compare the P‐ and K‐use efficiencies of five commercial alfalfa cultivars (CVs) growing on a low‐P, low‐K calcareous soil, and to evaluate the impact of P and K fertilization on the herbage concentrations of these and other elements. The CVs were selected for uniformity of disease resistance and other agronomic traits. Three levels each of P and K fertilizer were applied in factorial combination, with CV as the whole plot and fertilizer treatment as the split plot. Herbage samples, consisting of the top half of the shoot, were collected at the first cut in 1992 and 1993 and were analyzed by wet digestion and inductively coupled plasma emission spectrometry (ICP).

There were appreciable amounts of aluminium (Al), iron (Fe), sulfur (S), and silicon (Si) in the alfalfa herbage but CV and soil treatment did not affect the concentrations of these elements. Plant breeding and selection for P‐use efficiency seems to be feasible. There was a positive soil P influence on herbage concentrations of sodium (Na), calcium (Ca), magnesium (Mg), and strontium (Sr) which was attributed to increased plant ATP. There was a negative effect of soil P on herbage K apparently due to the mutual antagonisms among K, Na, Ca, and Mg. There was significant variance among CVs for manganese (Mn) and zinc (Zn) but not for boron (B) and copper (Cu). Soil P had a negative effect on concentrations of B, Cu, Mn, and Zn in the herbage. Soil K had a negative effect on herbage B, Cu, and Mn. Only Cu approached deficiency levels, which needs further evaluation for this calcareous soil.     

Copper induced iron deficiency in wheat (Triticum aestivum L)

Abstract

A pot experiment was conducted to study the interaction effects of phosphorus and copper on wheat. The soils used were calcareous loamy sand (ls) and non calcareous sandy loam (sl). Four levels of Cu (0, 5, 10 and 20?mg Cu kg^?1 soil) and six levels of P (0, 25, 50, 100, 200 and 400?mg P kg^?1 soil) were applied in all possible combinations with three replications. Soil pH decreased with Cu application while Olsen P increased with P application in both soils. Growth and yield of wheat improved significantly with graded levels of applied P. However, when any level of P was combined with 20?mg Cu kg^?1 soil, severe iron chlorosis of leaves, a drastic reduction in growth and chlorophyll content was observed in calcareous ls only. The results indicated that it was Cu and not P that induced Fe deficiency in wheat grown in alkaline calcareous soil and the Cu requirement of the crop seemed to be much lower in the calcareous ls. Root dry matter, grain and straw yield decreased with increasing levels of applied Cu in ls but in sl maximum increase of 62.5, 74.3 and 63.7 per cent in root, grain and straw yield was observed with a combined application of 400?mg P and 5?mg Cu kg^?1 soil over control. Accumulation of Cu in roots decreased the Fe absorption by roots which indicated that Fe chlorosis of wheat leaves is expected when Cu: Fe concentration ratio in root is > 0.30.     

Effect of Phosphorus in Alleviation of Adverse Impacts of Salinity on Wheat Grown on Different Soils

Fertilization management is an important technique to alleviate the adverse effects of salinity stress on plants. A pot experiment was conducted to evaluate the ameliorative role of inorganic phosphorus (P) and organic P sources on wheat grown under salt stress in three soil types deficient in available P. Wheat (Triticum asetivum L. cv. Shakha 93) was grown on alluvial, sandy, and calcareous soils under salinity levels of 4, 8, and 12 dS m^?1 of saturated paste extract (EC_e) and supplied with constant rate of 30 mg P₂O₅ kg soil^?1 as superphosphate (SP), cattle manure (CM), and 1:1 mixture of SP and CM. The results revealed that plants grown on the sandy soil were more susceptible to the adverse effects of salinity compared with those planted on the alluvial one, especially at zero P. Plants grown on the calcareous soil were moderately affected. Varying soil type caused significant differences in the aboveground biomass and uptake of nitrogen (N), potassium (K), P, and zinc (Zn). It was obvious that P ameliorated wheat growth under salt stress, and this role was greater under moderate and high salinity. The increases in N, P, K, and Zn uptake appeared driven by P application were more conspicuous in the sandy and calcareous soils. Results also indicated that combined application of inorganic and organic P sources surpassed both when applied solely under all soil types and salinity levels.     

Effect of pH on soil magnesium and its absorption by corn

Abstract

Lime induced depression of exchangeable Mg had been observed previously and it was postulated that yield decreases, which frequently occur at high pH levels may in some instances be due to Mg deficiency. This study was conducted to evaluate the influence of pH on exchangeable Mg in a wide range of acid soils and to determine the effects on recovery of Mg by corn (Zea mays L.) in the greenhouse. Treatments consisted of five pH levels, three P levels, and three Mg levels. Soil Mg was extracted with two neutral salt solutions and double acid. Salt extractable Mg decreased markedly at near neutral pH values, but double acid extractable Mg remained essentially unchanged. In several of the soils where yields were depressed at the highest pH levels, plant Mg content was also significantly lower. However, yield depressions were not ameliorated by Mg applications and could not be ascribed to induced Mg deficiency. Decreased plant uptake of Mg at both low and high pH levels was considered to have resulted from competitive effects between Mg and Al. The evidence suggested that salt extractable Mg did not accurately reflect plant availability.

Because soil reaction has profound effects on the availability of aluminum and many elements essential to plants, liming should be practiced primarily to optimize the utilization of the nutrient resources of soil. While pH values near neutrality are regarded as optimal in many areas of the world, particularly where legumes have traditionally been part of the rotational system, yield depressions have sometimes been reported at such pH levels on highly weathered acid soils of tropical and subtropical origin.     

Determining the optimum range of soil Olsen P for high P use efficiency, crop yield, and soil fertility in three typical cropland soils

Soil Olsen P level has a major influence on crop yield, efficient P utilization, and soil fertility. In this study, the optimum Olsen P range was determined from long-term (1990-2012) field experiments in three typical soil types of China under single cropping of maize or double cropping of maize and wheat. The critical soil Olsen P value for crop yield was evaluated using three different models, and the relationships among P use efficiency (PUE), Olsen P, and total P were analyzed. The agronomic critical soil Olsen P values obtained from the three models for the neutral soil of Gongzhuling and the calcareous soil of Zhengzhou were similar; however, the values from the linear-linear and linear-plateau models for both maize and wheat were substantially lower than those from the Mitscherlich model for the acidic soil of Qiyang. The PUE response change rates (linear equation slopes) under different soil Olsen P levels were small, indicating slight or no changes in the PUE as the soil Olsen P increased in all three soils. A comparison of the Olsen P levels that achieved the maximal PUE with the agronomic critical values derived from the three models indicated that the linear-plateau model exhibited the best performance. The regression equation coefficients of Olsen P response to total P decreased as follows:Zhengzhou (73 mg g^-1) > Qiyang (65 mg g^-1) > Gongzhuling (55 mg g^-1). The Olsen P level increased as the total P increased, which may result in a decrease in PUE. To achieve a relatively high crop yield, PUE, and soil fertility, the optimum Olsen P range should be 13-40, 10-40, and 29-40 mg kg^-1 at Gongzhuling, Zhengzhou, and Qiyang, respectively.     

Calcium,magnesium, and potassium uptake by crested wheatgrass grown on calcareous soils

Abstract

Forage intake with potassium/(calcium + magnesium) [K/(Mg + Ca)] values in excess of 2.2 are associated with grass tetany and Mg deficiencies in ruminants. This study was conducted to determine the degree to which forage K and Mg concentrations and K/(Ca + Mg) ratios could be predicted from soil bicarbonate (HCO₃) extractable phosphate‐phosphorus (PO₄‐P), and saturation extract Ca, Mg, K, sodium (Na), and nitrate‐nitrogen (NO₃‐N) concentrations. Crested wheatgrass (Agropyron spp) strains and cultivars representing four ploidy levels were grown in the greenhouse on eight calcareous soils with different saturation extract Ca, Mg, K and K/Mg ratios. The plants were harvested three times. Soil solution K/(Ca + Mg) and K/Mg ratios were the only measured soil parameters that showed a consistent correlation with plant K/(Ca + Mg) ratios. Bicarbonate extractable soil P was positively related to plant P and K uptake in the first harvest, but was not related in the second and third harvests nor was soil P related to plant Ca or Mg content. There was a tendency for the higher ploidy level entries to have higher plant K/(Ca + Mg) ratios. It was concluded that soil K/(Ca + Mg) ratios can be used to predict relative forage K/(Ca + Mg) ratios for grasses grown under similar conditions.     

Plant availability of phosphorus in dead herbage ingested by surface-casting earthworms

A combined field and glasshouse technique was developed to evaluate the plant-availability of phosphorus from two sources. The first source was ryegrass which had been ingested by earthworms and excreted in surface casts, and the second was untreated ryegrass. Surface casts labelled with ³²P were obtained in the field from earthworms fed with ³²P-labelled ryegrass. In a glasshouse study, labelled casts or labelled herbage were placed on the surface of soil in which ryegrass was growing. Ryegrass recovered proportionately more ³²P from cast material than from dead herbage. The results suggest that earthworms increase the short-term plant availability of P derived from plant litter by two to three fold. The effect of surface-casting earthworms on the rate of cycling of P in soils of different P status is discussed.     

Potassium fixation of some calcareous soils after short term extraction with different solutions

This investigation was done to determine the release of potassium (K) from five calcareous soils of southern Iran using 0.025 M CaCl₂, HCl and citric acid during six successive extractions and to study the K fixation capacity of the soils after K release experiment. Mineralogical study indicated that Vertisols and Mollisols were dominated with smectites; while other soils had illite, chlorite, palygorskite and smectite. Results indicated that citric acid extracted more K than CaCl₂ and HCl (137 vs. 111 and 113 mg kg^?1, respectively). The analysis of calcium (Ca), magnesium (Mg) and K concentrations in the solutions suggests that the exchange of K with soluble Ca and Mg (originated from dissolution of carbonates by acidic solutions) is the main mechanism of K release, but citrate is able to dissolve K-bearing minerals and release K in slightly calcareous soils. Soils with more illite released more K. Potassium fixation capacity of soils increased after extractions of soils with different extractants from 324 to 471 mg kg^?1, with no significant difference. It is suggested to apply more K fertilizers in K-depleted calcareous soils and use of different solutions for extracting K from soil minerals may be a temporary and short term solution.     

Maize grain production,plant nutrient concentration and soil chemical properties in response to different residue levels from two previous crops

ABSTRACT

The incorporation of previous crop residues in agricultural management benefits soil fertility, crop production, and environment. However, there is no enough information about maximum residue application level without negative effect over next crop yield. To evaluate maize (Zea mays L.) yield under short-time conservation management with incorporation and/or importation of different residue levels, a biannual rotation experiment was conducted in ash volcanic soil in south-central Chile. The experiment consisted of two previous crops, canola (Brassica napus L.) and bean (Phaseolus vulgaris L.), and four levels of residue incorporation (0%, 50%, 100%, and 200% of generated residue; from 0 to 21.4?Mg?ha^?1 for canola and from 0 to 19.0?Mg?ha^?1 for bean). Previous crop species and residue level affected some nutrients concentrations in grain and plant and some soil chemical properties, without effect in maize yield, which averaged 16.6?Mg?ha^?1. Bean residue increased Ca and reduced S in maize plant, increasing soil P, Ca, Mg and K (P?<?0.05). Maize grain Ca content was positively and proportionally affected by canola residue level and negatively and proportionally affected by bean residue level. All canola residue levels increased soil pH and Mg, but the highest level reduced soil S; soil P concentration increased proportionally with bean residue level. The highest bean residue level increased soil S. Different crop and levels of residue did not affect maize yield but did some plant nutrient concentration, and also affected some soil chemical properties.     

Annual ryegrass response to limestone and phosphorus on an ultisol 1

Decreasing winter pasture productivity in unlimed Ultisols has been associated with increased soil acidity due to fertilizer N application. The susceptibility of cool season grasses to soil acidity and associated infertility factors that result in reduced forage yield are not well understood. This field study was undertaken to evaluate the effects of factorial combinations of limestone and P applications on annual ryegrass (Lolium multiflorum Lam. ‘Marshall') dry matter production and tissue mineral concentrations on a strongly acid (pH 4.7), sandy soil. Limestone was applied to a Lilbert loamy fine sand (loamy, siliceous, thermic, arenic Plinthic Paleudult) at rates of 0, 672, or 3808 kg ha^‐1. Phosphorus was applied to split plots at rates of 0, 30, 60, 90, 120, 240, or 480 kg P ha^‐1. Over three harvest years, ryegrass yields increased 90 to 750% and 25 to 80% at the highest lime and P rates, respectively. In the second year, yield response to applied P was significantly less at the high lime rate which indicated that liming made soil P more plant available. Lime and applied P increased plant tissue P, Ca, and Mg concentrations. Yield was positively correlated with soil pH, P, Ca, and Mg and negatively related to soil K and Al. Clear relationships between individual soil test levels and leaf mineral concentrations with yield fluctuations could not be established because these variables were inextricably related to the lime and P rates. Nevertheless, excessive soil Al, coupled with inadequate P, Ca, and Mg availability, were indicated as important nutritional factors limiting annual ryegrass growth in unlimed soil.     

Stimulative effects of elemental sulfur in the presence of ammonium on chile and broccoli growth in calcareous soils

The chile pepper plant seldom responds to N and P fertilizers on fertile soils. Surplus industrial H₂SO₄ and elemental S have created interest in “mining”; calcareous soils for additional supplies of P, Ca, Mg and micronutrients. The effect of variable S, on the growth of chile and broccoli was evaluated holding other nutrients constant. Growth of chile and broccoli plants was significantly increased in the greenhouse and chile yield increased in the field. Incremental S additions increased the water extractable and desorbable Ca + Mg and P contents of soil. The total N and K content of chile plant grown in the greenhouse increased, and then decreased, P decreased, as S rates increased. Yield of dry red chile with constant N peaked at 16.5 g S m^‐2 and then decreased with increasing S in the field. Rroccoli responded more to S application than to directly applied foliar micronutrient solutions (Fe and 7n), and responded much better to (NH₄)₂SO₄ + S than to Ca(NO₃)₂ at equivalent N rates. Increased soluble Ca + Mg content of the soil in the presence of S was thought to influence plant absorption of NH₄ and/or K.     

Utilization of Compost Increases Organic Carbon And Its Humin,Humic and Fulvic Acid Fractions In Calcareous Soil

Organic carbon sustainability in a gravelly calcareous soil is a great challenge under the humid conditions of south Florida. The beneficial effects of compost utilization on soil fertility prompted an investigation on (i) accumulation of total organic carbon and (ii) the soil organic carbon (SOC) in humin, humic acid (HA) and fulvic acid (FA) fractions in a gravelly calcareous soil amended with composts or inorganic fertilizer. In 1996 and 1998, compost from municipal solid waste (MSW) (100% MSW), Bedminster cocompost (75% MSW and 25% biosolids) and biosolids compost (100% biosolids) at 72, 82.7 and 15.5 Mg ha^?1, respectively, were each incorporated in soil beds and inorganic fertilizer (6-2.6-10) NPK at 2.8 Mg ha^?1. A control (no amendment) treatment was also included. Total organic carbon and various fractions of soil organic carbon were determined in two depths (0-10 and 10-22 cm) for both soil particles (< 2mm) and pebbles (> 2mm). Inorganic and organic soil amendments had decreased soil pH and increased soil electrical conductivity (EC) 19 months from initial application. Total organic carbon contents in soil particle were 4-, 3-, and 2-fold higher in MSW compost, Bedminster cocompost and biosolids compost treatments, respectively, than those in fertilizer treated or non-treated soils. MSW compost increased total organic carbon in pebbles by 4- and 3-fold in the 0-10 and 10-22 cm deep layers, respectively, more than other treatments. The soil organic carbon accumulation decreased with depth in all treatments in soil particles, but did not in pebbles. Amending soils with MSW compost significantly increased the organic carbon in humin, HA and FA fractions more than those treated with inorganic fertilizer or non-amended. MSW compost has a potential to be used as a soil amendment to increase and sustain the organic carbon in calcareous soils of south Florida.     

长期试验地红壤与潮土的矿化和硝化作用特征比较

采用培育试验研究了红壤与潮土两个长期定位试验中不同处理小区表层土壤的矿化和硝化作用特征。结果表明:红壤的矿化作用和硝化作用都很弱,而潮土硝化作用非常强烈。采用适宜的施肥措施培肥后氮素的矿化和硝化速率都有很大的提高;pH是影响硝化作用的重要因素之一,硝化速率与土壤pH呈显著正相关。合理施用肥料调控土壤肥力是提高红壤和潮土肥力的重要措施。