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1.
灌溉施用氮肥后氮素在土壤中的转化及淋失状况: 土柱模拟研究 总被引：4，自引：0，他引：4
A soil column method was used to compare the effect of drip fertigation (the application of fertilizer through drip irrigation systems, DFI) on the leaching loss and transformation of urea-N in soil with that of surface fertilization combined with flood irrigation (SFI), and to study the leaching loss and transformation of three kinds of nitrogen fertilizers (nitrate fertilizer, ammonium fertilizer, and urea fertilizer) in two contrasting soils after the fertigation. In comparison to SFI, DFI decreased leaching loss of urea-N from the soil and increased the mineral N (NH4+-N + NO3--N) in the soil. The N leached from a clay loam soil ranged from 5.7% to 9.6% of the total N added as fertilizer, whereas for a sandy loam soil they ranged between 16.2% and 30.4%. Leaching losses of mineral N were higher when nitrate fertilizer was used compared to urea or ammonium fertilizer. Compared to the control (without urea addition), on the first day when soils were fertigated with urea, there were increases in NH4+-N in the soils. This confirmed the rapid hydrolysis of urea in soil during fertigation. NH4+-N in soils reached a peak about 5 days after fertigation, and due to nitrification it began to decrease at day 10. After applying NH4+-N fertilizer and urea and during the incubation period, the mineral nitrogen in the soil decreased. This may be related to the occurrence of NH4+-N fixation or volatilization in the soil during the fertigation process. 相似文献
2.
第四纪红色粘土发育的红壤中营养元素的淋失 总被引：13，自引：2，他引：11
A red soil derived from Quaternary red clay was employed to study nutrient leaching with soil columns repacked in laboratory. The objective was to identify the effects of fertilization practices on leaching patterns and magnitudes of Ca2+, Mg2+, K+, NH4+, and NO3-. The treatments were CK (as a control), CaCO3, CaSO4, MgCO3, Ca(H2PO4)2, urea, KCl, and multiple (a mixture of the above-mentioned fertilizers). The fertilizers were added to the bare surface of the soil columns, and then the columns were leached with 120 mL deionized water daily through peristaltic pumps over a period of 92 days. Leaching processes of NH4+, and NO3- were only measured in CK, urea, and multiple treatments which were directly related to N leaching. Results showed that sole application of CaSO4, and Ca(H2PO4)2 scarcely had any effect on the leaching losses of Ca2+, Mg2+, and K+; the application of MgCO3 stimulated the leaching of Mg2+; the application of CaCO3 promoted the leaching of Ca2+, Mg2+ and K+; urea treatment also promoted the leaching of K+ and NH4+, and NO3- leaching mainly occurred at late stage of leaching process in particular; under KCl treatment, leaching of Ca2+, Mg2+, and K+ was promoted to a large extent; under multiple treatment, leaching of Ca2+, Mg2+, K+, NH4+, and NO3- was all increased and NO3- was mainly leached at the end of leaching process and still had a trend of increase. 相似文献
3.
KCl, CaCl2, NH4Cl, NaCl, K2SO4 and KF solutions were used for studying the effects of cations and anions on the dissolution of aluminum and the distribution of aluminum forms respectively. Power of exchanging and releasing aluminum of four kinds of cations was in the decreasing order Ca2+ >K+ >NH4+ >Na+. The dissolution of aluminum increased with the cation concentration. The adsorption affinity of various soils for aluminum was different. The aluminum in the soil with a stronger adsorption affinity was difficult to be exchanged and released by cations. The Al-F complexes were main species of inorganic aluminum at a low concentration of cations, while Al3+ became major species of inorganic aluminum at a high concentration of cations. The results on the effect of anions indicated that the concentrations of total aluminum, three kinds of inorganic aluminum (Al3+, Al-F and Al-OH complexes) and organic aluminum complexes (Al-OM) when SO42- was added into soil suspension were lower than those when Cl- was added. The dissolution of aluminum from soils and the distribution of aluminum forms in solution were affected by the adsorption of F- on the soil. For soils with strong affinity for F-, the concentrations of the three inorganic aluminum species in soil solution after addition of F- were lower than those after addition of Cl-; but for soils with weak affinity for F-, the concentrations of Al3+ and Al-OM were lower and the concentrations of Al-F complexes and total inorganic aluminum after addition of F- were higher than those after addition of Cl-. The increase of F- concentration in soil solution accelerated the dissolution of aluminum from soils. 相似文献
4.
Soil Erosion as A ffected by Polyacrylamide Application Under Simulated Furrow Irrigation with Saline Water 总被引：1，自引：0，他引：1
The reduction of soil and water losses under furrow irrigation with saline water is important to environmental protection and agricultural production.The objective of this study was to determine the effect of polyacrylamide(PAM)application on soil infiltration and erosion under simulated furrow irrigation with saline water.Polyacrylamide was applied by dissolving it in irrigation water at the rates of 1.5,7.5,and 15.0 mg L-1 or spreading it as a powder on soil surface at the rates of 0.3,1.5,3.0,and 6.0 g m-2,respectively.The effectrolyte concentration of tested irrigation water was 10 and 30 mmolc L-1 and its sodium adsorption ratio(SAR)was 0.5,10.0,and 20.0(mmolc L-1)0.5.Distilled water was used as a control for irrigation water quality.Results indicated that the effectrolyte concentration and SAR generally did not significantly affect soil and water losses after PAM application.Infiltration rate and total infiltration volume decreased with the increase of PAM application rate.Polyacrylamide application in both methods significantly reduced soil erosion,but PAM application rate did not significantly affect it.The solution PAM application was more effective in controlling soil erosion than the powdered PAM application,but the former exerted a greater adverse influence on soil infiltration than the latter.Under the same total amounts,the powdered PAM application resulted in a 38.2%-139.6% greater infiltration volume but a soil mass loss of 1.3-3.4 times greater than the solution PAM application. 相似文献
5.
A pot experiment was catried out to study alleviation of soil acidity and Al toxicity by applying analkaline-stabilised sewage sludge product (biosolids) to an acid clay sandy loam (pH 5.7) and a strongly acidsandy loam (pH 4.5). Barley (Hondeum vulgare L. cv. Forrester) was used as a test crop and was grownin the sewage sludge-amended (33.5 t sludge DM ha-1) and unamended soils. The results showed that thealka1ine biosloids increased soil pH from 5.7 to 6.9 for the clay sandy loam and from 4.5 to 6.0 for the sandyloam. The sludge product decreased KCl-extractable Al from 0.1 to 0.0 cmol kg-1 for the former soil and from 4.0 to 0.1 cmol kg-1 for the latter soil. As a result, barley plants grew much better and grain yield increased greatly in the amended treatments compared with the unamended controls. These observations indicate that alkaline-stabilised biosolids can be used as a liming material for remedying Al phytotoxicity instrongly acid soils by increasing soil pH and lowering Al bioavailability. 相似文献
6.
The effect of background anion on cation exchange reactions, such as Na-Ca and Na-Cu exchange reactions, on montmorillonites has been studied, but the results are not always clear and discrepancies exist in the literature. In this study, the exchange of zinc (Zn2+) for sodium (Na+) on Wyoming montmorillonite was investigated at 298°K using Cl-, ClO4-, NO3-, OAc-, and SO42- solution media at a constant total metal charge concentration of 0.0200 molc L-1. Results indicated that the clay CEC values were essential similar for Cl-, ClO4-, NO3- and SO42- solution media with an average CEC of 0.856 ± 0.008 molc kg-1; in an OAc+ solution the clay CEC was much higher than that in other anion media. The specific adsorption of Zn (SAZn), as defined by the extraction of Zn using 0.05mol L-1 Na2-EDTA, was different in the various background solutions. The highest value for SAZn was 0.359 ± 0.0350molc kg-1, which occurred in OAc-solution. There was essentially no difference in the total apparent adsorbed metals (the sum of adsorbed equivalents of Na and Zn per kilogram of clay, Q) among the various background solutions. The average Q for all anion media was 0.807 ± 0.011 molc kg-1 and was independent of exchanger composition. Experimental results indicated that there were no significant monovalent cation complexes such as ZnCl+ or ZnNO3+ that were adsorbed by montmorillonite. The Na-Zn exchange isotherms indicated that there was an adsorption preference for Zn over Na on Wyoming montmorillonite. 相似文献
7.
Leaching of boron （B） and zinc （Zn） can be significant in some pedomorphic conditions, which can cause contamination of shallow groundwater and economic losses. Boron and Zn adsorption and transport was studied using 8.4 cm diameter × 28 cm long intact columns from two calcareous soil series with differing clay contents and vadose zone structures： Lyallpur soil series, clay loam （fine-silty, mixed, hyperthermic Ustalfic Haplargid）, and Sultanpur soil series, sandy loam （coarse-silty, mixed, hyperthermic Ustollic Camborthid）. The adsorption isotherms were developed by equilibrating soil with 0.01 tool L^-1 CaCl2 aqueous solution containing varying amounts of B and Zn and were fitted to the Langmuir equation. The B and Zn breakthrough curves were fitted to the two-domain convective-dispersive equation. At the end of the leaching experiment, 0.11 L 10 g L^-1 blue dye solution was also applied to each column to mark the flow paths. The Lyallpur soil columns had a slightly greater adsorption partition coefficient both for B and Zn than the Sultanpur soil columns. In the Lyallpur soil columns, B arrival was immediate but the peak concentration ratio （the concentration in solution at equilibrium/concentration applied） was lower than that in the Sultanpur soil columns. The breakthrough of B in the Sultanpur soil columns occurred after about 10 cm of cumulative drainage in both the columns; the rise in effluent concentration was fast and the peak concentration ratio was almost 1. Zinc leaching through the soil columns was very limited as only one column from the Lyallpur soil series showed Zn breakthrough in the effluent where the peak concentration ratio was only 0.05. This study demonstrates the effect of soil structure on B transport and has implications for the nutrient management in field soils. 相似文献
8.
Estimation of the plant-available water capacity (PAWC) of soils at a regional scale helps in adopting better land use planning, developing suitable irrigation schedules for crops, and optimizing the use of scarce water resources. In the current study, 72 soil profiles were sampled from the Barossa region of South Australia to estimate pedo-transfer functions deduced from easily estimated soil properties. These functions were then used to estimate the fixed (10 and 33 kPa) and dynamic pressure head (hfc) water contents at field capacity (FC) for minimum drainage flux (0.01 and 0.001 cm d-1), which serves as the upper boundary for plant-available water in soils. The estimated residual water content was corrected for subsoil constraints, especially the exchangeable sodium percentage (ESP). The results showed that the mean values of hfc in sand-dominated light and medium textured soils (i.e., sand, loamy sand, sandy loam, and loam) varied in a narrow range (15.8–18.2 kPa), whereas those in the clay-dominated heavy textured soils (i.e., clay loam) showed a wide range (11.3–49.3 kPa). There were large differences in PAWC for dynamic FC (PAWCfc) and fixed FC at 10 kPa (PAWC10), 33 kPa (PAWC33), and a mix of 10 and 33 kPa (PAWC10,33) pressure heads depending on soil texture. Normally, the difference between PAWC at 10 kPa and hfc (∆PAWC10) was positive, whereas that between 33 kPa and hfc (∆PAWC33) was negative across all sites. Nevertheless, the estimation of PAWC assuming a fixed FC at 10 and 33 kPa pressures (i.e., PAWC10,33) for sandy, clay, and silty soils reduced the difference between fixed and dynamic pressure PAWCs to < 10% across the region. The estimation of PAWC was improved by incorporating the impact of subsoil constraints, such as high ESP, which was more pronounced for clay and silty soils. These findings demonstrate the inherent inconsistencies between static pressure and flux-based dynamic FC estimations in soils. Soil heterogeneity, intra-texture variability, subsoil constraints, and swell-shrink clays can have great impacts on the water retention capacity in response to dynamic and fixed pressure FC values. 相似文献
9.
Field studies were conducted to determine the dissipation and movement of metribuzin and metolachlor applied at conventional rates to a Verndale sandy loam (Udic Argiboroll) in north-central Minnesota under irrigated potato production in two years. The rapid dissipation of both metribuzin and metolachlor was found during the initial 10 to 15 days in both years, and more than 70% of the applied herbicide dissipated during this period. From 10 to 15 days after application up to the end of growing season in both years, the levels of both herbicides decreased slowly with time. Metolachlor dissipated at a slower rate than metribuzin in surface soil and could carry over to the next cropping season. Metribuzin and metolachlor were detected in only 6 and 1 of 154 soil samples in the first year and in 3 and 4 of 225 soil samples in the second year, taken from 15 to 75 cm, respectively. Fifty to 67% of water samples from suction samplers at 135-cm depth contained detectable levels (>0.4 μg L-1) of herbicides in both years. Under laboratory conditions degradation of both herbicides was much slower than their dissipation in field. Therefore, it appeared that leaching might be an important dissipation pathway for metribuzin and metolachlor under irrigated potato production. 相似文献
10.
Global climate changes can lead to the destruction of the permafrost zone and contribute to the active transfer of pollutants to natural waters. This can be especially pronounced in the areas of oil and gas production in the Arctic. This study aimed to define the landscape components (i.e., groundwater, soil water, soil, and indicator plant species) of chemical pollution with metals, oil hydrocarbons, and polycyclic aromatic hydrocarbons, from the discharge of drill cuttings. Studies at two sites in the forest-tundra zone of Western Siberia (Russia) were carried out within two years of pollution. Pollutant migration was found in peaty-gley heavy loamy soils and iron-illuvial clayey podburs, but lateral migration of different pollutants did not exceed 200 m. Additionally, radial migration was practically absent owing to the high buffering capacity of the soil organic horizon and the upward flow of matter in the seasonal melt layer. The main indicators of drilling waste pollution were high concentrations of Sr, Ba, petroleum hydrocarbons, and Cl- ions. At the waste disposal sites, the concentration of Ba and Sr in the soil water were 1 150 and 1 410 μg L-1, respectively; in groundwater, they reached 721 and 2 360 μg L-1, respectively. In the soil, Ba and Sr accumulated in the peaty horizon (798 and 706 mg kg-1, respectively). The concentration of Cl- ions in the soil water at the site of waste discharge was 1 912 mg L-1, and at a distance of 200 m, it decreased to 77.4 mg L-1. The Cl- concentration in the groundwater was lower, and at a distance of 200 m, it was 38.9 mg L-1. The highest concentration of petroleum hydrocarbons in the surface layer was found in the peaty-gley soils (up to 2 400 mg kg-1). In glandular-illuvial podburs, it was 420 mg kg-1. In horizons BH and BC, it was close to the background values (27 and 33 mg kg-1, respectively). Alkalinization of soils and water under the influence of drill cuttings led to the death of oligotrophic and acidophilic vegetation at a distance of up to 50 m, and to the restructuring of the species and spatial structure of plant communities up to 100 m. 相似文献
11.
《Communications in Soil Science and Plant Analysis》2012,43(22):2935-2946
The concern for groundwater pollution by agrichemicals through solute movement within the soil is widespread. Zeolite is a type of soil amendment that is utilized to improve physical properties of soil and ameliorate polluted soil. The high negative charge of the zeolite and its open space structure allows adsorption and access of heavy metals and other cations and anions. The objectives of this research were (i) to determine the effects of different application rates of zeolite (0, 2, 4, and 8 g kg?1) on the immobile water content and mass exchange coefficient in a loam soil and then (ii) to determine the effects of optimum application rate of zeolite on the immobile water content and mass exchange coefficient of sandy loam and clay loam soils in saturated conditions by a mobile and immobile (MIM) model. In a disturbed soil column, a method was proposed for determination of MIM model parameters, that is, immobile water content (θim), mass exchange coefficient (α), and hydrodynamic dispersion coefficient (Dh). Breakthrough curves were obtained for different soil textures with different zeolite applications in three replicates, by miscible displacement of chloride (Cl?1) in disturbed soil column. Cl?1 breakthrough curves were evaluated in terms of the MIM model. The results showed that the pore water velocity calculated based on the total soil volumetric water content (θim+ θm) and real pore water velocity calculated based on the mobile water content (θm) increased in the loam soil with an increase in zeolite application rate, so that, between these different rates of zeolite application, the maximum value of pore water velocity and real pore water velocity occurred at zeolite application rates of 8.6 and 11.5 g kg?1, which are indicated as the optimum application rates. However, the comparison between different soils showed that the zeolite application rate of 8 g kg?1 could increase pore water velocity of sandy loam and loam soils by 31% more than that of clay loam soil. The immobile water content and mass exchange coefficient of loam soil were correlated with the zeolite application rate and reduced with an increase in the rate of applied zeolite. In a comparison between different soils at zeolite application rate of 8 g kg?1, the immobile water contents of the zeolite-treated soil decreased by 57%, 60%, and 39% on sandy loam, loam, and clay loam soils, respectively, compared with the untreated soil. Furthermore, zeolite application could reduce mass exchange coefficient by 9%, 43%, and 21% on sandy loam, loam, and clay loam soils, respectively. A positive linear relationship was found between θim and α. Zeolite application increased real pore water velocity of sandy loam soil by 39% and 46% compared with loam and clay loam soils, respectively. In other studies there was a decrease in ammonium and nitrate leaching due to the zeolite application, and therefore, an increase in real pore water velocity due to zeolite application in sandy loam soil, as compared with the loam and clay loam soils, may not show more rapid movement of solute and agrichemicals to the groundwater. 相似文献
12.
S. Andersson M. Simonsson L. Mattsson A. C. Edwards & I. Öborn 《Soil Use and Management》2007,23(1):10-19
Annual potassium (K) balances have been calculated over a 40‐year period for five field experiments located on varying parent materials (from loamy sand to clay) in south and central Sweden. Each experiment consisted of a number of K fertilizer regimes and was divided into two crop rotations, mixed arable/livestock (I) and arable only (II). Annual calculations were based on data for K inputs through manure and fertilizer, and outputs in crop removal. Plots receiving no K fertilizer showed negative K balances which ranged from 30 to 65 kg ha?1 year?1 in rotation I, compared with 10–26 kg ha?1 year?1 for rotation II. On sandy loam and clay soils, the K yield of nil K plots (rotation I) increased significantly with time during the experimental period indicating increasing release of K from soil minerals, uptake from deeper soil horizons and/or depletion of exchangeable soil K (Kex). Significant depletion of Kex in the topsoil was only found in the loamy sand indicating a K supply from internal sources in the sandy loam and clay soils. On silty clay and clay soils, a grass/clover ley K concentration of ～2% (dry weight) was maintained during the 40‐year study period on the nil K plots, but on the sandy loam, loam and loamy sand, herbage concentrations were generally less than 2% K. 相似文献
13.
《Communications in Soil Science and Plant Analysis》2012,43(16):1934-1943
Potassium (K) leaching is affected by soil texture and available K, among other factors. In this experiment, effects of soil texture and K availability on K distribution were studied in the presence of roots, with no excess water. Soils from two 6-year field experiments on a sandy clay loam and a clay soil fertilized yearly with 0, 60, 120, and 180 kg ha?1 of K2O were accommodated in pots that received 90 kg ha?1 of K2O. Soybean was grown up to its full bloom (R2). Under field conditions, K leaching below the arable layer increased with K rates, but the effect was less noticeable in the clay soil. Potassium leaching in a sandy clay loam soil was related to soil K contents from prior fertilizations. With no excess water, in the presence of soybean roots, K distribution in the profile was significant in the lighter textured soil but was not apparent on the heavier textured soil. 相似文献
14.
Rainfall leaching soil column trials wereused to characterize the downward movement ofpotential contaminants through a sandy loam and sandysoil following the application of an anaerobicallydigested sewage sludge at the rates of 10 and 25%(v/v). Leachate pH did not vary significantly withsludge application except for sandy loam with 25%sludge, while initial electrical conductivity (EC) anddissolved organic carbon (DOC) increased linearly withsludge application and declined shortly to levelsfound in soils without sludge. A higher initialleaching loss of ammonium (NH4 +) was found in sandy soilthan loamy sand due to its lower cation exchangecapacity. Nitrate (NO3 -) was the dominant anion inleachates with an average in excess of 10 mg L-1 NO3 - at all loading rates after 12 weeks. The highestconcentration of NO3 - occurred with the highest sludgeapplication rate. Leachate zinc (Zn) content increasedin loamy sand columns at the high sludge loading rateat the end of the experiment owing to the reduced pHfollowing nitrification. No significant difference inleachate copper (Cu) and phosphate (PO4 3-) contents werenoted for both soils receiving various sludgeapplication rates. Evaluation of the soluble nutrientspresent in the soil profiles at the end of theleaching experiment showed that EC, NH4 + and PO4 3- increased according to sludge application rate up toa depth of 20 cm. Significant accumulation of NO3 - wasfound in sandy loam with sludge application to thedepth of 50 cm. Analyses of leachates and soils forthe selected contaminants revealed that NO3 - leaching islikely to occur without plant growth at the currentapplication rate. Therefore, the application rate forsludge should not exceed 10% (v/v), and the provisionof vegetation on the amended soil would reduce theleaching loss of NO3 -. 相似文献
15.
Behzad Murtaza Gohar Zaman Muhammad Imran Ghulam Mustafa Shah Muhammad Amjad Naveed Ahmad 《Communications in Soil Science and Plant Analysis》2019,50(8):1013-1029
A pot experiment was conducted in sandy clay loam saline-sodic soil to assess the effects of farm yard manure (FYM), municipal solid waste (MSW) composts and gypsum application on nitrate leaching, soil chemical properties and crop productivity under rice-wheat cropping system. It also aims at establishing the correlation between soil phsico-chemical properties and yield response using principle component analysis and Pearson correlation analysis. The MSW was decomposed aerobically, an-aerobically and co-composted. Maximum nitrate leaching was observed during rice (75.9 mg L?1) and wheat (37.2 mg L?1) with an-aerobically decomposed MSW as compared with control treatment. Results revealed a decrease in soil pH (?6.95% and ?8.77%), electrical conductivity (EC) (?48.13% and ?51.04%), calcium carbonate (CaCO3) (?40.30% and ?48.96%), and sodium adsorption ratio (SAR) (?40.27% and ?45.98%) with an-aerobically decomposed MSW compost during rice and wheat, respectively. In this treatment, organic matter (OM) (93.55% and 121.51%) and cation exchange capacity (CEC) (19.31% and 31.79%) were the highest as compared with control treatment during rice and wheat, respectively. Rice and wheat growth were significantly (p≤ 0.05) increased by an-aerobically decomposed MSW followed by co-compost, aerobically decomposed MSW, FYM, gypsum and control. Furthermore, Pearson correlation coefficients predicted significant positive correlation of yield with soil OM, and CEC while inverse relationship was observed with EC, pH, CaCO3, and nitrogen use efficiency. Soil amelioration with organic and gypsum amendments was further confirmed with principal component analysis. This study has proved an-aerobically decomposed MSW as an effective solution for MSW disposal, thereby improving soil chemical properties and crop productivity from sandy clay loam saline-sodic soil. 相似文献
16.
《Communications in Soil Science and Plant Analysis》2012,43(19):2550-2563
The continuous use of heavy machinery and vehicular traffic on agricultural land led to an increase in soil compaction, which reduces crop yield and deteriorates the physical conditions of the soil. A pot experiment was conducted under greenhouse conditions to study the effects of induced soil compaction on growth and yield of two wheat (Triticum aestivum) varieties grown under two different soil textures, sandy loam and sandy clay loam. Three compaction levels [C0, C1, and C2 (0, 10 and 20 beatings)], two textural classes (sandy loam and sandy clay loam), and two genotypes of wheat were selected for the experiment. Results indicated that induced soil compaction adversely affected the bulk density (BD) and total porosity of soil in both sandy loam and sandy clay loam soils. Compaction progressively increased soil BD from 1.19 Mg m?3 in the control to 1.27 Mg m?3 in C1 and 1.40 Mg m?3 in C2 in sandy loam soil while the corresponding increase in BD in sandy clay loam was 1.56 Mg m?3 in C1 and 1.73 Mg m?3 in C2 compared to 1.24 Mg m?3 in the control. On the other hand, compaction tended to decrease total porosity of soil. In case of sandy loam, porosity declined by 5% and 17% in C1 and C2, respectively, and declined in sandy clay loam by 29% and 54%, respectively. Averaged over genotypes and textures, shoot length decreased by 15% and 26% at C1 and C2, respectively, and straw yield decreased by 21% and 61%, respectively. The compaction levels C1 and C2 significantly decreased grain yield by 12% and 41%, respectively, over the control. The deleterious effect of compaction was more pronounced on root elongation and root mass, and compaction levels C1 and C2 decreased root length by 47% and 95% and root mass by 41% and 114%, respectively, over the control. Response of soil texture to compaction was significant for almost all the parameters, and the detrimental effects of soil compaction were greater in sandy clay loam compared to sandy loam soil. The results from the experiment revealed that soil compaction adversely affected soil physical conditions, thereby restricting the root growth, which in turn may affect the whole plant growth and grain yield. Therefore, appropriate measures to avoid damaging effects of compaction on soil physical conditions should be practiced. These measures may include soil management by periodic chiseling, controlled traffic, conservation tillage, addition of organic manures, and incorporating crops with deep tap root systems in a rotation cycle. 相似文献
17.
Narges Mehrab Mostafa Chorom Saeid Hojati 《Communications in Soil Science and Plant Analysis》2016,47(10):1306-1316
Leaching of nutrients in soil can change the surface and groundwater quality. The present study aimed at investigating the effects of raw and ammonium (NH4+)-enriched zeolite on nitrogen leaching and wheat yields in sandy loam and clay loam soils. The treatments were one level of nitrogen; Z0: (100 kg (N) ha?1) as urea, two levels of raw zeolite; Z1:(0.5 g kg?1 + 100 kg ha?1) and Z2: (1 g kg?1 + 100 kg ha?1), and two levels of NH4+-enriched zeolite; Z3: (0.5 g kg?1 + 80 kg ha?1) and Z4: (1 g kg?1 + 60 kg ha?1). Wheat grains were sown in pots and, after each irrigation event, the leachates were collected and their nitrate (NO3?) and NH4+ contents were determined. The grain yield and the total N in plants were measured after four months of wheat growth. The results indicated that the amounts of NH4+ and NO3? leached from the sandy loam soil were more than those from the clay loam soil in all irrigation events. The maximum and minimum concentrations of nitrogen in the drainage water for both soils were observed at control and NH4+-zeolite treatments, respectively. Total N in the plants grown in the sandy loam was higher compared to plants grown in clay loam soil. Also, nitrogen uptake by plants in control and NH4+-zeolite was higher than that of raw-zeolite treatments. The decrease in the amount of N leaching in the presence of NH4+-zeolite caused more N availability for plants and increased the efficiency of nitrogen fertilizers and the plants yield. 相似文献
18.
Ahmed Elgharably 《Soil Science and Plant Nutrition》2013,59(3):396-402
Fertilization with nitrogen (N) or phosphorus (P) can improve plant growth in saline soils. This study was undertaken to determine wheat (Triticum aestivum L; cv Krichauff) response to the combined application of N and P fertilizers in the sandy loam under saline conditions. Salinity was induced using sodium (Na+) and calcium (Ca2+) salts to achieve four levels of electrical conductivity in the extract of the saturated soil paste (ECe), 2.2, 6.7, 9.2 and 11.8?dS?m?1, while maintaining a low sodium adsorption ratio (SAR; ≤1). Nitrogen was applied as Ca(NO3)2?·?4H2O at 50 (N50), 100 (N100) and 200 (N200)?mg?N?kg?1 soil. Phosphorus was applied at 0 (P0), 30 (P30) and 60 (P60)?mg?kg?1?soil in the form of KH2PO4. Results showed that increasing soil salinity had no effect on shoot N or P concentrations, but increased shoot Na+ and chlorine ion (Cl?) concentrations and reduced dry weights of shoot and root in all treatments of N and P. At each salinity and P level, increasing application of N reduced dry weight of shoot. At each salinity and N level P fertilization increased dry weights of shoot and root and shoot P concentration. Addition of greater than N50 contributed to the soil salinity limiting plant growth, but increasing P addition up to 60?mg?P?kg?1 soil reduced Cl? absorption and enhanced the plant salt tolerance and thus plant growth. The positive effect of the combined addition of N and P on wheat growth in the saline sandy loam is noticeable, but only to a certain level of soil salinity beyond which salinity effect is dominant. 相似文献
19.
To study the influence of potassium (K) fertilizer rate on soil test K values, crop yield, and K-leaching in sandy soils, four long-term fertilizer experiments (0–60–120–180 kg K ha?1 a?1) were initiated in 1988 in northern Germany on farmers fields. Clay content of the plow layer was about 4%, and organic matter between 2% and 5%. Plant available soil K was estimated with the double lactate (DL) method. Small grain cereals (rye and barley) did not respond to K fertilization in the 7-year period even though the soil test value of the K-0 plots decreased from ca. 90 to ca. 30 mg KDL kg?1 within 3 years. This value remained almost constant thereafter. Crop removal (including straw) of 75 kg K ha?1 a?1 was therefore apparently supplied from nonexchangeable K fractions. Compared to the optimum, no K application reduced the yield of potato by up to 21%, and that of white sugar yield up to 10%. Maximum potato yield was obtained by annually applying 60 kg K ha?1 which resulted in a test value of 60 mg KDL kg?1 soil. Maximum potato yield was also obtained at 40 mg KDL kg?1 soil, however, with a single application of 200 kg K ha?1. Similar results were obtained with sugar beet. This indicates that for maximum yield, even for K demanding crops, it is not necessary to maintain KDL values above 40 mg K kg?1 soil throughout the entire crop rotation. Soil test values increased roughly proportional to the K fertilizer level. About 120 kg fertilizer K ha?1 a?1, markedly more than crop K removal, was required to maintain the initial KDL of 90 mg kg?1. The K concentration of the soil solution in the top soil measured after harvest was increased exponentially by K fertilizer level and so was K leaching from the plow layer into the rooted subsoil. The leached quantity increased from 22 kg K ha?1 a?1 in the plot without K application to 42.79 and 133 kg Kha?1 a?1 in plots supplied with 60, 120 and 180 kg K ha?1 a?1 respectively. Soil test values around 100 mg KDL kg?1 on sandy soils, as often found in the plow layer of farmers fields, lead to K leaching below the root zone that may exceed the critical K concentration of 12 mg K T?1 for drinking water. 相似文献
20.
Several studies have focused on the formation and losses of dissolved organic matter in forest systems, whereas a limited number have dealt with this aspect in agricultural soils. The purpose of this study was to estimate the leaching of dissolved organic carbon (DOC) and nitrogen (DON), with focus on the period after cultivating grass-clover swards. Grass-clovers were ploughed in the spring prior to sowing cereals followed by either catch crops or bare soil. The concentrations of DOC and DON decreased with soil depth and ranged at 90-cm soil depth between 7 and 21 mg C L−1 and between 1 and 3 mg N L−1, respectively, in a sandy loam soil, and between 16 and 63 mg C L−1 and between 1 and 10 mg N L−1, respectively, in a coarse sandy soil. The resulting DOC/DON ratios were in the range between 2 and 42, with higher values in the coarse sandy soil than in the sandy loam soil. The total percolation was 218 mm in the sandy loam soil and 596–645 mm in the coarse sandy soil, which resulted in an annual leaching of 22–40 kg DOC ha−1 year−1 and 3–4 kg DON ha−1 year−1 in the sandy loam soil, and 174–310 kg DOC ha−1 year−1 and 10–31 kg DON ha−1 year−1 in the coarse sandy soil. It was shown that higher amounts of DOC were lost by leaching under the catch crops than from bare soil, that losses of DON were higher from bare soil than from soils with catch crops and that DON contributed significantly to the total N loss. Thus, DON needs to be taken into account in N-balance calculations. 相似文献