首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 298 毫秒
1.
Abstract

Heavy‐metal inhibition of nitrification in soils treated with reformulated nitrapyrin was investigated. Clarion and Okoboji soils were treated with ammonium sulfate [(NH4)2SO4] and a nitrification inhibitor. Copper(II) (Cu), Zinc(II) (Zn), Cadmium(II) (Cd), or Lead(II) (Pb) were added to each soil. A first‐order equation was used to calculate the maximum nitrification rate (K max), duration of lag period (t′), period of maximum nitrification (Δt), and the termination period of nitrification (t s). In the Clarion soil, the K max decreased from 12 mg kg?1 d?1 without the nitrification inhibitor to 4, 0.25, 0.86, and 0.27 mg kg?1 d?1, respectively, when the inhibitor and Cu, Zn, Pb, or Cd were applied. In the Okoboji soil, K max decreased from 22 mg kg?1 d?1 with no inhibitor to 6, 3, 4, and 2 mg kg?1 d?1, respectively, when an inhibitor and Cu, Zn, Pb, or Cd were added. The t′ varied from 8 to 25 d in the Clarion soil and from 5 to 25 d in the Okoboji soil, due to addition of Cu, Zn, Pb, or Cd and the inhibitor.  相似文献   

2.
Cadmium distribution coefficients, K d were determined at low Cd concentrations (solute: 0.2 to 3.0 μg Cd dm?3, soil: 0.044 to 1.1 mg Cd kg?1) for 63 Danish agricultural soils. The K d values ranged from 15 to 2450 L kg?1. About 40% of the soils had K d values below 200 L kg?1. The observed K d values correlated very well with soil pH (r 2 = 0.72). Introducing soil organic matter content as a second parameter improved the correlation some (r 2 = 0.79). No further improvements were obtained by introducing traditional soil parameters as clay, silt, fine sand, coarse sand and CEC or ‘reactive’ parameters as oxyhydroxides of Mn, Fe and Al. The identified regression equation for predicting K d values indicates that K d approximately doubles for each 0.5 unit increase in pH or 2% increase (weight basis) in organic matter content.  相似文献   

3.
《Journal of plant nutrition》2013,36(10):2315-2331
ABSTRACT

Split root solution culture experiments were conducted to study the effects of the rare earth element lanthanum (La) on rice (Oryza sativa) growth, nutrient uptake and distribution. Results showed that low concentrations of La could promote rice growth including yield (0.05 mg L?1 to 1.5 mg L?1), dry root weight (0.05 mg L?1 to 0.75 mg L?1) and grain numbers (0.05 mg L?1 to 6 mg L?1). High concentrations depressed grain formation (9 mg L?1 to 30 mg L?1) and root elongation (1.5 mg L?1 to 30 mg L?1). No significant influence on straw dry weight was found over the whole concentration range except for the 0.05 mg L?1 treatment. In the pot and field experiments, the addition of La had no significant influence on rice growth.Lanthanum had variable influence on nutrient uptake in different parts of rice. Low concentrations (0.05 mg L?1 to 0.75 mg L?1) increased the root copper (Cu), iron (Fe), and magnesium (Mg), and grain Cu, calcium (Ca), phosphorus (P), manganese (Mn), and Mg uptake. High concentrations (9 to 30 mg L?1) decreased the grain Ca, zinc (Zn), P, Mn, Fe and Mg, and straw Ca, Mn, and Mg uptake. With increasing La concentration, root Zn, P, Mn, Cu, and Ca concentrations increased, and grain Ca and Fe, and straw Mn, Mg, and Ca concentrations decreased. Possible reasons are discussed for the differences between the effects of La in nutrient solutions and in pot and field experiments.  相似文献   

4.
Varying amounts of humic acid (Na-salt; 0 to 10 ppm) were first equilibrated with a dilute suspension of H+ -Kaolin and then with spiked (high activity radioactive 64Cu) water. After filtration, through a 0.45 µm Millipore membrane, the amount of radioactivity on the filter and the filtrate was measured separately using a Gamma ray well counter. Adsorption of Cu (expressed as distribution coefficient — K d ) was plotted against humic acid concentration. K d values decreased sharply upto 1 ppm humic acid concentration and thereafter remained constant up to 10 ppm.  相似文献   

5.
The effects of aluminium on plant nutrition in small birch plants (Betula pendula Roth) were investigated. By using relative addition rate (r A, g g?1 d?1) of nutrients as the growth-controlling variable, it was possible to grow the plants at very low external nutrient concentrations and to simulate plant requirements at two different fertility levels. Before aluminium addition the plants were at steady-state relative growth rate, (R G, g g?1 d?1). The two addition rates were free access of nutrients with R G ≈ 0.215 d?1, or nutrient-limited, R Aand R G=0.10 d?1. Internal concentrations of calcium and magnesium decreased with increasing Al3+ conncentration in the nutrient solution while nitrogen concentrations in the plants remained unchanged or increased. It was demonstrated in both nutrition treatments that calcium and magnesium decrease per se does not reduce plant growth and that uptake has to be considered in relation to plant requirement at different growth rates. The interpretation of the effects of aluminium on Ca and Mg uptake and plant biomass development suggested that processes other than disturbances in Ca and Mg uptake are the cause of the decrease in growth.  相似文献   

6.
The effects of four rates of phosphorus (P) fertilization (0, 0.56, 5.6 and 56.0 mg l?1) in soilless medium on the growth and physiology of mahogany seedlings were examined. The greatest response occurred at the 56 mg l?1 rate, with relatively small differences between other treatments. Biometric parameters increased at the 56 mg l?1 compared to 0 mg l?1 rate except root dry mass. Both the concentration and the total content of P and Kjeldahl nitrogen (N) increased in leaves, stems and roots with P application rate. Foliar concentrations of potassium (K), calcium (Ca), magnesium (Mg), manganese (Mn) and sulfur (S) declined, and boron (B) and copper (Cu) increased with P limitations; zinc (Zn) and iron (Fe) were unaffected. Physiological adaptations of mahogany to P limitations include the preferential allocation of carbon (C) to plant roots, and increases in P utilization efficiency, P acquisition efficiency and the concentration of organic acids in xylem fluid. Root phosphatase activity was not influenced by P fertilization.  相似文献   

7.
The aim of the experiment was to evaluate the effect of organic fertilization on nutrient uptake and partitioning in potted peach trees. The study was carried out on 72 peach (Prunus persica L.) plants. The following treatments were compared: 1) unfertilized control, 2) mineral fertilization [713 mg nitrogen (N), 119 mg phosphorus pentoxide (P2O5), 476 mg potassium oxide (K2O) pot?1], 3) cow manure (119 g dw pot?1) and 4) compost (119 g dw pot?1). Compared to the untreated control, plant biomass was improved by supplying cow manure and compost. Potassium concentration in fine roots and leaves was higher in compost treated trees. Leaf concentrations of calcium (Ca) and magnesium (Mg) were decreased by applications of compost and cow manure. Nutrient concentrations in fine roots were always positively correlated with nutrients in coarse roots, only N showed a negative correlation. With the exception of Ca and Mg, macronutrients removed by trees were higher after compost fertilization than in unfertilized controls.  相似文献   

8.
Determining potassium (K) fertilizer requirement using sorption isotherms is considered more accurate than conventional soil K tests. A total of 59 surface soil samples were used to establish K exchange isotherm. To evaluate K requirement sorption test, a glasshouse experiment using perennial ryegrass (Lolium perenne, cv. Roper) was carried out on 10 soil samples. The experiment was laid out as a completely randomized design with four replications and four K levels (K0, K20, K40, K80). Concentrations of K in solution established by adding K in the pots estimated from the sorption curve ranged from 20 to 80 mg K l?1 including check treatment (no K). Dry matter yield of ryegrass in most soils approached maximum as adjusted K levels were increased to 20 mg K l?1. The amounts of K required to bring the soils to 20 mg l?1 in soil solution varied among soils and ranged from 99 to 399 mg kg?1, on average 205 mg kg?1 soil. It was found that a useful regression model for the prediction of standard K requirement (K20) included the combination of plant available K extracted by NH4OAc (Av-K) and clay content: K20 = ?41 ? 0.63 Av-K + 9.0 Clay (R2 = 0.61, p < 0.001, n = 59).  相似文献   

9.
The increasing use of land application of organic wastes presents a potential pathway for metals to enter the environment and cause phytotoxicity. Studies to evaluate the response of corn (Zea mays L.) to annual applications of Cu-enriched pig manure or CUSO4 were established as ongoing field experiments in 1978 on three soils. The soils varied in texture from fine sandy loam to clay loam and ranged in CEC from 5.0 to 12.3 cmol(+) kg?1. Five treatments in each field experiment consisted of a control, low and high Cu-enriched pig manure levels, and low and high CuSO4 levels. After 6 yr 638 Mg ha?1 of wet Cu-enriched pig manure containing from 185 to 198 mg Cu kg?1 had been applied for the high treatments on the three soils. The Cu-enriched pig manure, which contained 1290 mg Cu dry kg?1, was produced by pigs fed diets with 242 mg Cu kg?1. In the sixth year, leaf blade Cu concentrations were increased by ≤ 3.3 mg kg?1 due to the high Cu treatments but remained in the middle of the Cu sufficiency range. Grain Cu was 73 to 84% lower than blade Cu and was unaffected by the treatments. The DTPA (diethylenetriaminepentaacetic acid) extractable Cu was not related to either leaf or grain Cu levels. However, the DTPA extractable Cu was linearly related, r = 0.92, to applied amounts of Cu in the three soils. Overall, this research indicated that application of up to 638 Mg kg?1 of wet Cu-enriched pig manure did not cause an environmental hazard.  相似文献   

10.
ABSTRACT

A field study was conducted with the objective of determining response of dry bean (Phaseolus vulgaris L.) to liming and copper (Cu) fertilization applied to an Oxisol. The lime rates used were 0, 12, and 24 Mg ha?1 and Cu rates were 0, 2.5, 5, 10, 20, and 40 kg Cu ha?1. Liming significantly increased common bean grain yield. Liming also significantly influenced soil chemical properties in the top (0–10 cm) as well as in the sub (10–20 cm) soil layer in favor of higher bean yield. Application of Cu did not influence yield of bean significantly. Average soil chemical properties across two soil layers (0–10 and 10–20 cm) for maximum bean yield were pH 6.4, calcium (Ca), 4.2 cmolc kg?1, magnesium (Mg) 1.0 cmolc kg?1, H+Al 3.2 cmolc kg?1, acidity saturation 40.4%, cation exchange capacity (CEC) 8.9 cmolc kg?1, base saturation 63.1%, Ca saturation 45.7%, Mg saturation 18.0%, and Potassium (K) saturation 2.9.  相似文献   

11.
ABSTRACT

The effectiveness of nitrogen (N)+ zinc (Zn) soil and foliar fertilizer applications on growth, yield, and quality of apple (Malus domestic Borkh ‘Golden Delicious’) fruit was studied in the Zanjan province, Iran. There were eight treatments 1) control (no fertilizer), 2) soil applied N, 3) soil applied Zn, 4) soil applied N+Zn, 5) foliar applied N, 6) foliar applied Zn, 7) foliar applied N+Zn and 8) combined soil and foliar applied N+Zn. The N source was urea [CO(NH2)2, 46% N] applied at 276 N tree? 1 yr?1 and the Zn source was zinc sulfate (ZnSO4,7H20, 23% Zn) applied at 110 g Zn tree? 1 yr? 1. The soil treatments of N and Zn, were applied every two weeks during June through August (total of 6 times/year) in a 1 m radius around the tree trunk (drip line of trees). The foliar solutions of N (10 g l? 1 urea) and Zn [8 g l? 1 zinc sulfate (ZnSO4)] were sprayed at the rate of 10 L tree? 1 every two weeks at the same times as described for soil applications. The highest yield (49 kg tree? 1), and the heaviest fruits (202 g) were obtained in the soil and foliar combination of N+Zn treatment. The lowest yield (35 kg tree? 1), and the smallest fruits (175 g) were recorded in the control. Nitrogen, and to a lesser extent Zn, foliar application resulted in decreasing fruit quality (caused russeting, and lower soluble solid), but increasing N leaf and fruit concentrations (2.4% DW and 563 mg kg? 1, respectively). There were significant differences among yield and leaf mineral nutrient concentration in different treatments. But there was no significant difference between fruit mineral nutrient concentration (except N). Ratio of N/calcium (Ca), potassium (K)/Ca, and [magnesium (Mg)+K]/Ca in fruits were found suitable for fruit quality prediction. Combining the zinc sulfate with urea in the foliar applications increased the concentration of Zn from 0.7 to 1.5 mg per kg of apple tissue. Leaf N concentration varied during growth season. Foliar applied nutrient can be more efficient than soil applied, but a combination of soil and foliar applications is recommended for apple tree nutrient management.  相似文献   

12.
The effect of ascorbic acid and pesticides (thiotox and malathion) on certain haematological parameters of a fishSaccobranchus fossilis was studied. The sublethal concentrations of thiotox (0.002 mg l?1) and of malathion (5.2 mg l?1) were tested. Ascorbic acid (2mg 100 g?1 body weight) was given with food. The alterations in haematological parameters (CT, PT, Hb, RBC, WBC, ESR, PCV, MCH, MCHC, MCV, glucose, protein, total P, Na, K, Mg, Ca, and Cl) were measured after 15 and 30 days exposure. Thiotox and malathion induced significant alteration in blood parameters while ascorbic acid played a protective role.  相似文献   

13.
The effect of increasing manganese (Mn) concentrations on calcium (Ca), potassium (K), magnesium (Mg), sodium (Na), and phosphorus (P) absorption and translocation was studied in rice (Oryza sativa L. cv. Safari), before and after the end of mobilization of seed reserves. Rice plants were grown over a 15-, 21-, and 28-day period in nutrient solutions containing Mn concentrations varying between 0.125 and 32 mg L?1. It was found that increasing Mn concentrations in the nutrient solution was coupled to an increasing net uptake, total shoot accumulation, and root and shoot contents of this metal during all the experimental periods. Concerning the translocation rates, in 15-day-old plants a decrease was found after the 2 mg L?1 Mn treatment, but from the 21st day onward an increase was found until the highest treatment. The modulating action of Mn in macronutrient accumulation displayed different patterns among the experimental periods. In the root tissues of 15-day-old plants, Ca decreased significantly until the 2 mg L?1 treatment and Na increased. In the shoots, the contents of P and Na decreased, but K and Mg showed significant increases. Until the 32 mg L?1 Mn treatment, the ratio between root and shoot concentrations of K and Mg decreased in these plants. A similar pattern was also found for Ca until the 2 mg L?1 Mn treatment. That ratio increased for Na. Plant total amount of Ca sharply decreased. Shoot total amount of Na and P also decreased, but the pattern of Ca increased until the 2 mg L?1 Mn treatment. The concentrations of K increased in the root tissues 21 days after germination, but the levels of Ca, Mg, Na, and P decreased. In the shoots, the concentrations of Ca and Mg decreased significantly. Until the 32 mg L?1 Mn treatment, the ratio between root and shoot concentration of Na and P increased, whereas those of Ca and Mg decreased. An increase was found for the plant and shoot total amount of Ca, K, and Mg until the last Mn treatment, but an opposite trend was found for Na and P. Additionally, until the 32 mg L?1 Mn treatment, an increase was found for the proportions of Ca and Mg translocated to the shoot, but an opposite trend was detected for P. It was concluded that before and after the end of the mobilization of seed reserves, the net uptake rate of Ca is reversed, and, moreover, a similar trend is shown for the net translocation of Mg. A major implication of this process is the alteration of the related pattern for shoot accumulation. Eventually a different selectivity of the K+:Na+ ratio is also developed in the roots.  相似文献   

14.
Risk assessment of cadmium (Cd) contamination in soils requires identifying the bioavailable portion of the total Cd, a portion that is determined by environmental conditions such as pH and calcium (Ca) level in soils and by the physiological processes going on in the plant roots. Growth tests in solutions were conducted to develop a terrestrial biotic ligand model to describe uptake and rhizotoxicity of Cd to pea (Pisum sativum L. cv. Lincoln). Inhibition concentration associated with a 50% reduction in root elongation (IC50) values were found to vary with external Ca2+ and H+ activities. Root-bound Ca was found to reach a plateau of about 63 µmol g?1 (dry weight) although Ca treatment increased from 0.04 to 2 mmol L?1. When experimental treatments (e.g., pH 6, Ca 0.2 to 2 mM) resulted in sufficient Ca supply, dose–response curves relating root elongation to root-bound Cd could be modeled with Weibull equations; IC50 values were expressed in terms of root-bound Cd concentration. When the treatments (e.g., pH 4 or 5, Ca 0.04 mM) suggested a low Ca supply, root elongation was more sensitive to Ca content and root-bound Ca concentration became the dominant predictor variable. Cd accumulation was modeled by treating the pea roots as an assemblage of biotic ligands with known site densities (Q Lj ) and proton binding constants (K HLj ). The logK Ca and logK Cd values were established using measured root-bound ion concentrations and solution chemistry. The logK Ca values were negatively correlated to root Ca contents. The logK Cd values were positively correlated to logK Ca values. Explanations for the changing of constants are discussed.  相似文献   

15.
Release rates of nonexchangeable K from Ap material of a Luvisol (‘Eckerde’ loess, 15% clay) are determined using a percolation procedure which avoids the common artifacts due to shaking or stirring soil suspensions and thus provides less biased kinetic data. CaCl2 solution (10 mMc. 20 °C. pH 5.8) is percolated through packages of soil aggregates (0.5–1 mm grain size, 0.5 g samples) with 0.02 to 25 ml h?1. Solute K (CK) was varied between < 1 and > 10 μM and is shown to have a dominant influence on the rates of interlayer K release. These increase exponentially below 3.5 μM (no steady state but steady decrease of release rates in each sample). The difference between the related CK between moderate and high release rates is as small as 1 μM K. The average rates, of a 10-day-interval, starting after 1.3 times the exchangeable K had been removed, are 40 μmol K kg?1 soil d?1 at 4 μM CK and 240 μmol kg?1 d?1 at 3 μM CK, respectively. It is concluded that larger quantities of interlayer K become plant available in the studied soil if the of soil solutions gets below 3.5 μM (for 10 mMc Ca, 20 °C, pH 5.8), probably because the dominant dioctahedral illites start to join the release process below this critical limit. The higher K concentration range was accounted for by K-Ca exchange isotherms which, by alteration of shape, indicate that Knex release becomes measurable below 10 to 20 μM K. It is further argued that existing diffusion or reaction kinetics approaches towards K release are incomplete because the influence of solute K is not considered.  相似文献   

16.
ABSTRACT

Glauconite is a potassium (K) bearing mineral, which generally contains 6–10% K2O and mostly available in various natural deposits in India. Glauconite mineral was converted to nano-particle form by grinding in a high-energy ball mill. The release of K from glauconite nano-particle in soil was studied in a pot culture experiment. Five different treatments viz., 0 mg K2O kg?1, 100 mg K2O kg?1, 150 mg K2O kg?1, 200 mg K2O kg?1 used glauconite nano-particle (GNP) as a K source and 100 mg K2O kg?1 from muriate of potash (MOP), were applied in soil to grow maize (Zea mays L.) plant. The highest K+ concentration was observed in shoot at the application of 200 mg K2O kg?1 through GNP and recorded 2 times more K+ concentration in shoots as compared to 0 mg K2O kg?1 treatment whereas 1.1 times more than the MOP treated soil at 5th harvesting stage. Selected plant physiological parameters namely electrical conductivity of plant cell, height, leaf area and nitrate reductase activity were also recorded maximum at 200 mg K2O kg?1 GNP treated soil. Overall, glauconite nano-particle could supply K throughout the growth period and enhanced biomass yield of maize plant without showing any K deficiency symptom.  相似文献   

17.
Dry matter production, net photosynthetic rate, leaf nutrient status and trunk anatomical characteristics of Fagus crenata seedlings grown in brown forest soil acidified by adding H2SO4 solution were investigated. The soil acidification leaded to decreased (Ca+Mg+K)/Al molar ratio in the soil solution. Dry mass per plant of the seedlings grown in the soil treated with H+ at 120 mg·L?1 was significantly reduced compared with the control value at 0 mg·L?1. When net photosynthetic rate was reduced in the seedlings grown in the soil treated with H+ at 120 mg·L?1, the carboxylation efficiency and maximum net photosynthetic rate at saturated CO2-concentration were lower than the control values. The addition of H+ to the soil at 120 mg·L?1iinduced a reduction in the concentration of Ca in the leaf. By contrast, the concentration of Al in the leaf was increased with increasing the amount of H+ added to the soil. The annual ring formed in the seedlings grown in the soil treated with H+ at 120 mg·L?1 was significantly narrower than that at 0 (control), 10, 30, 60 or 90 mg·L?1. Based on the results obtained in the present study, we conclude that Fagus crenata is relatively sensitive to a reduction in the (Ca+Mg+K)/Al molar ratio of soil solution compared with Picea abies.  相似文献   

18.
Oil palm (Elaeis guineensis Jacq.) is a heavy feeder of nutrients and requires balanced and adequate supply of nutrients for optimum growth and yield. Information regarding soil nutrient status and leaf nutrient concentration is very much required for proper fertilizer application. Therefore, a survey was conducted for assessment of soil nutrient status and leaf nutrient concentration in 64 oil palm plantations in the state of Goa lying in the west coastal region of India. Soil pH, electrical conductivity (EC), organic carbon (OC), available potassium (K) (ammonium acetate-extractable K) (NH4OAc-K), available phosphorus (P) (Bray’s-P), exchangeable calcium (Ca) (Exch. Ca) and magnesium (Mg) (Exch. Mg), available sulphur (S) (calcium chloride-extractable S) (CaCl2-S), and hot water soluble boron (B) (HWB) in surface (0–20 cm depth) soil layers ranged from 4.25 to 6.77, 0.05 to 1.06 dS m–1, 5.07 to 48.4 g kg–1, 58.1 to 1167 mg kg–1, 1.80 to 415 mg kg–1, 200 to 2997 mg kg–1, 36.0 to 744 mg kg–1, 3.00 to 87.7 mg kg–1 and 0.09 to 2.10 mg kg–1, respectively. Diagnosis and Recommendation Integrated System (DRIS) norms were established for different nutrient expressions and were used to compute DRIS indices. As per DRIS indices, the order of requirement of nutrients in the region was found to be P > Mg > K > nitrogen (N) > B. Optimum leaf nutrient ranges as per DRIS norms varied from 1.64 to 2.79%, 0.36 to 0.52%, 0.37 to 0.75%, 0.89 to 1.97%, 0.35 to 0.63%, 0.89 to 1.50%, 3.10 to 13.9 mg kg?1, 7.50 to 32.2 mg kg?1, 35.0 to 91.1 mg kg?1, 206 to 948 mg kg?1, and 895 to 2075 mg kg?1 for N, P, K, Ca, Mg, S, B, copper (Cu), zinc (Zn), manganese (Mn), and iron (Fe) respectively. On the basis of DRIS-derived sufficiency ranges, 14, 5, 11, 6, 6, 6, 8, 2, 3, 6, and 16% of leaf samples had less than optimum concentrations of N, P, K, Ca, Mg, S, B, Cu, Zn, Mn, and Fe respectively. The optimum ranges developed can be used as a guide for routine diagnostic and advisory purpose for balanced utilization of fertilizers.  相似文献   

19.
We studied the dynamics of Cd uptake and depuration in epilithic periphyton and in the grazing amphipod Hyalella azteca. Both stable Cd, sufficient to achieve an aqueous concentration of 90 ng L?1, and its radiotracer 109Cd, were added during 1987 to the epilimnion of oligotrophic Lake 382 of the Experimental Lakes Area in northwestern Ontario. Cadmium dynamics within both periphyton and Hyalella were rapid, with equilibrium being approached within two weeks. For periphyton, the Cd uptake rate constant (K uw ) was 3.8×104 d?1 with a depuration rate of 0.29 d?1. For Hyalella the depuration rate was 0.36 d?1, 10% due to growth dilution and 90% to excretion or desorption. The total Cd uptake rate (k ut ) by Hyalella was 6.1×104 d?1, with more of the uptake (58%) derived from food (periphyton) than from water. Hyalella assimilated 80% of ingested Cd. Steady-state bioconcentration factors (BCF) were at least 10-fold higher than previously published values for Amphipoda. In periphyton and Hyalella the BCF were 1.2×105 and 3.2×105, respectively.  相似文献   

20.
Composition and properties of leachates from farmyard manure heaps Besides some rheological characteristics, the Ntotal, NH4+-N, NO3? -N, P, K+, dry matter and ash content, as well as chemical oxygen demand and conductivity of farmyard manure leachates were examined. The K+ concentration was highest with an average of 5921 mg l?1, followed by Ntotal (1139 mg l?1, 66% of it as NH4+-N and 4% NO3?-N) and P (334 mg l?1). All parameters were highest in leachates of fresh manure and lowest at the end of a 6 months storage period. During the storage, the P concentration in leachates showed a decrease of 67.7%, followed by a decrease in Nt (-57.3%) and K+ (-24.0%). In leachates from a manure with an relatively high initial Nt content of 0.51% and a low C:N ratio of 16.8 the Nt concentration was 0.5–1 times higher than that of a manure with 0.44% Nt and a C:N ratio of 19.9. The viscosity and the thixotropy of leachates were both relatively high at the beginning of the manure's storage period, which led to a strongly developed blocking of porous systems. These properties that contribute to explain the high retention rate of nutrients in the top soil layer at manure storage sites, decreased with an increase in storage time.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号