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1.
The influence of N form on xylem exudate and the guttation fluid concentration in cucumber plants was studied under greenhouse conditions. Plants were hydroponically grown with three NO3:NH4 ratios (100:0, 80:20, and 60:40) at a constant pH of 6.0 in the nutrient solutions. Plants supplied with 60:40 NO3:NH4 ratio displayed a significant decrease of NO3‐N, total‐N, organic‐P, and Mn concentrations in the xylem sap and an increase of H2PO4‐P, SO4‐S, Cl, B, and Zn concentrations. Potassium and Ca uptake in these plants was slightly reduced, indicating that pH control was an important factor for cationic nutrition in cucumber plants fed with NH4. The major ions present in the nutrient solutions are concentrated in the xylem sap, particularly for NO3, K, Ca, and Na. The NO3:NH4 ratio had a small effect on the ionic levels of the guttation fluid. The concentrations of all nutrients in the guttation fluid were substantially reduced, except for Cl, showing that the leaf tissues of cucumber plants remove the excess of Cl ion. Finally, in this study, secondary effects of N source on ion uptake and release were minimized by controlling nutrient solution pH.  相似文献   

2.
Abstract

While it is known that superoptimal concentrations of the nitrate (NO3 ?) ion in solution culture do not increase NO3 ? uptake or dry matter accumulation, the same is not known for the ammonium (NH4 +) ion. An experiment was conducted utilizing flowing solution culture with pH control to investigate the influence of superoptimal NH4 + concentrations on dry matter, nitrogen (N), potassium (K), calcium (Ca), and magnesium (Mg) accumulation by nonnodulated soybean plants. Increasing the NH4 + concentration in solution from 1 to 10 mM did not affect dry matter or N accumulation. Accumulations of K, Ca, and Mg were slightly decreased with the increased NH4 + concentration. The NH4 + uptake system, which is saturated at less than 1 mM NH4 +, is able to regulate uptake of NH4 + at concentrations as high as 10 mM.  相似文献   

3.
Xylem sap plays a major role in long‐distance transport of water, nutrients, and metabolites. However, there is little information on the behavior of metabolites in mineral‐deficient xylem sap. For this reason, the time‐dependent changes in selected metabolites (amino acids, organic acids, and soluble sugars) from tomato xylem sap in response to nitrogen (N), phosphorus (P), or potassium (K)‐deficient condition were investigated. Tomato plants (Solanum lycopersicum L.) were grown hydroponically in liquid culture under three different mineral regimes: N‐deficient [0.5 mM Ca(NO3)2 and 0.5 mM KNO3], P‐deficient (0.05 mM KH2PO4), and K‐deficient (0.5 mM KNO3), respectively. Xylem sap was collected at 10:00 am after 1, 5, 15, and 30 d, and the selected metabolites were analyzed with liquid chromatography. All N, P, or K deficiencies led to a substantial increase in metabolites in the xylem sap. The predominant amino acid in the xylem sap was glutamine and, interestingly, all mineral deficiencies resulted in a substantial amount of γ‐aminobutyric acid (GABA). Additionally, organic acids (citrate and malate) and soluble sugars were strongly increased in all mineral deficiencies, and, in particular, the level of shikimate was greatly affected by N deficiency. Based on these data, it is necessary to clearly elucidate an unknown event taking place in xylem loading in a variety of environmental impacts, and we are now studying to expand our knowledge on metabolic and proteomic responses using GC‐MS and LC‐MS.  相似文献   

4.
Following 13‐year treatments of soil pH and nitrogen (N) source in a peach orchard of North Carolina, the concentration of calcium (Ca), magnesium (Mg), N, phosphorus (P), and potassium (K) in leaves, shoots, trunks and roots, as well as soil pH, soil exchangeable Ca, Mg, and K content, were determined. Through liming, higher soil pH treatment enhanced soil Ca and tissue Ca level. Among six N sources examined, the highest values of soil pH and soil Ca, Mg, and K were detected following poultry manure application. Compared to ammonium sulfate [(NH4)2SO4], calcium nitrate [Ca(NO3)2] increased soil pH and soil Ca and K content, but reduced soil Mg. For most of macronutrients examined in peach tissues, the highest levels were found in manure treatment. Mineral N sources containing Ca(NO3)2 resulted in high tissue Ca and low tissue N. In the above‐ground tissues, Mg concentration was relatively low following application of mineral N materials containing Ca, K, or sodium (Na). Acid‐ forming N, especially (NH4)2SO4, reduced tissue Ca and P. The magnitude of impact of liming and N source on macronutrients was tissue‐type dependent, with leaves and other new growth the most sensitive ones while trunks seldom responded to the treatments.  相似文献   

5.
The influence of three potassium:rubidium (K:Rb) ratios (6:0, 5:1, and 4:2) on the xylematic transport of solutes in cucumber plants cv. Medusa supplied with both nitrate (NO3 ‐) (60%) and ammonium (NH4 +) (40%) was studied in greenhouse conditions. In the xylem sap of plants grown with a K:Rb ratio of 4:2, there was an increase in the transport of NO3 ‐, phosphate (H2PO4 ‐), calcium (Ca2+), magnesium (Mg2+), sodium (Na+), manganese (Mn) and boron (B) while that of organic‐N, organic‐P, K+, zinc (Zn), organic acids, and carbohydrates decreased, if compared with the sap of the plants supplied with K alone. The translocation of NO3 ‐, H2PO4 ‐, Ca2+, Mg2+, and Mn was enhanced and that of K+ and organic acids decreased when the plants were supplied with a K:Rb ratio of 5:1. The K:Rb ratio detected in the xylem sap was the same K:Rb ratio as in the solutions. However, in the cucumber plant substituting 33% of total K by Rb resulted in an alteration in the transport of solutes, probably due to a competition between Rb and K rather than between the latter two and NH4 +.  相似文献   

6.
Nitrogen (N) by form of nutrition, ammonium (NH4+) or nitrate (NO3?), affects metabolic and physiological processes of plants. In general, a high proportion of N in NH4+ form results in poor growth. Nonetheless, a number of species exhibit optimum growth when high levels of NH4+ are provided. In the present study, lisianthus [Eustoma grandiflorum (Raf.) Shinn] was grown in rockwool cultures and irrigated with nutrient solutions containing 15 mM N with varying proportions of NH4+ and NO3?. The results showed that an increase in NH4+-N form increased plant height, number of flowers and leaves, leaf area, and shoot, stem, and leaf dry weight. The proportion of NH4+ also affected leaf concentration of phosphorus, potassium (K), calcium (Ca), and magnesium (Mg), although leaf N concentration was unaffected. Potassium leaf concentration was higher when a low proportion of NH4+ was supplemented in the nutrient solution; however, plants exhibited a decrease in leaf K concentration and a decrease in leaf Ca as the proportion of NH4+-N increased. Shoot dry weight was higher with low leaf K whereas high leaf Ca was associated with high shoot dry weight. Net photosynthesis rate was higher in plants irrigated with solutions containing 75% of total N in NH4+ form than in those irrigated with solutions of 0 or 25%. The results suggest that lisianthus can tolerate high levels of NH4+, probably associated with a higher assimilation of Ca.  相似文献   

7.
用营养液培养方法研究了铁和两种形态氮素(NO3--N和NH4+-N)对玉米植株吸收氮、磷、钾等大量元素和钙、镁等中量元素及其在体内分布的影响。结果表明:与NO3--N相比,供应NH4+-N促进了玉米对氮的吸收,在缺铁条件下,降低了对磷、钾、钙及镁的吸收。铁和NH4+-N都显著提高了玉米植株各器官中氮的含量。与NH4+-N处理相比,NO3--N处理的新叶中磷含量显著增加,但铁的供应对植物体内磷的含量无显著影响。使用NO3--N显著提高了玉米新叶和老叶中钾的含量,根和茎中钾的含量无明显影响。铁的供应降低了新叶和老叶中钾的含量。供铁时,NH4+-N处理的玉米新叶中钙和镁的含量显著低于NO3--N处理,而在缺铁时则无显著差异。  相似文献   

8.
陈沂岭  赵学强  张玲玉  沈仁芳 《土壤》2019,51(2):243-250
NH_4~+和NO_3~–是对植物有效的两种主要无机氮源。水稻一般被认为是偏好NH_4~+的植物,但是在NO_3~–条件下,水稻也能良好地生长。大多数关于水稻铵硝营养的报道是在pH 6.0左右的水培条件下开展的,但是对于酸性条件下水稻铵硝营养研究很少。随着土壤酸化的加重及一些边际酸性土壤被用作水稻种植,研究酸性条件下水稻的铵硝营养具有重要意义。本文采用水培试验,在pH 5.0的条件下,通过添加和不添加pH缓冲剂MES(2-(N-吗啡啉)乙磺酸),研究了NH_4~+和NO_3~–对水稻生长、氮效率和矿质养分(N、P、K、Ca、Mg、Fe、Zn、Cu、Mn)吸收的影响。结果表明,在不添加MES的条件下,水稻地上部生长(株高、叶绿素含量、干重)在NH_4~+和NO_3~–之间没有显著差异,而添加MES后,NH_4~+处理的水稻地上部生长优于NO_3~–。不管是否添加MES,NO_3~–处理的水稻地下部生长(根长、根表面积和根物质量)优于NH_4~+。水稻含氮量和氮利用效率在不同NH_4~+和NO_3~–处理之间没有显著差异,但是NH_4~+处理的水稻氮吸收效率高于NO_3~–。与NO_3~–相比,NH_4~+增加了水稻地上部P和Fe含量,而降低了水稻地上部Ca、Mg、Zn、Cu和Mn含量,对K含量影响较小。上述结果表明,NH_4~+有利于改善水稻地上部生长,提高氮吸收效率、地上部P和Fe含量,而NO_3~–则有利于水稻发根,提高地上部Ca、Mg、Zn、Cu和Mn含量。  相似文献   

9.
Leaf concentrations of nitrogen (N), phosphorus (P), potassium (K), iron (Fe), and manganese (Mn) in ‘Sterling’ muscadine grapes (Vitis rotundifolia Michaux) grown for two years in sand culture were not influenced by different N‐fertilizer sources. Leaf zinc (Zn) and copper (Cu) were higher with ammonium nitrate (NH4NO3)than ammonium sulfate [(NH4)2SO4]. Shoot growth was greatest with NH4NO3. Leaf Ca, Mg, Mn, and Cu content decreased and leaf N increased as N‐fertilizer rates were raised. Plant growth was positively correlated with leaf N, but was negatively correlated with leaf Ca, Mg, Fe, Cu, and Mn content. Percent Mg in the leaves was reduced when N levels, regardless of N source, were raised from the low (1.8 mM) to the middle (5.4 mM) rate. High leaf‐N levels were correlated with lower Ca and Mg in the leaves, indicating a relationship between N fertilization and the late‐season Mg deficiency often observed in muscadine grapes.  相似文献   

10.
Green bean Helda in autumn cycle (118 days) was grown under greenhouse conditions in sand-mulched sandy loam soil. The crop was irrigated with disinfected urban wastewater (DUW) obtained from ozone from the Almería Purifying Plant. The average nutrient parameters of DUW were 0.4 mM of nitrate (NO3 ?), 2.1 mM of ammonium (NH4 +), 0.8 mM of potassium (K+), and electrical conductivity (EC) 1.6 dS m?1. Three different treatments were established: DUW without additional fertilization (FDUW), DUW with fertilization until the recommended rate was obtained (10.0 mM of N and 3.4 mM of K) (FNK), and DUW with fertilization until 1.5 FNK rate (15.0 mM of N and 5.1 mM of K) (F1.5NK) was obtained. The dry-matter production was not conditioned by the fertilizer level. Treatments FNK and F1.5NK showed the greatest yield and uptake of N and K independent of the fertilizer level. The most nitrogen (N), calcium (Ca), and magnesium (Mg) were in the leaf, phosphorus (P) was high in fruit, and K was similar in leaf and fruit. With regard to the macronutrient absorption efficiency, the F1.5NK treatment showed the least N and K efficiency and the greatest soil salinity.  相似文献   

11.
Abstract

Broccoli (Brassica oleracea var. italica) plants were grown in the greenhouse and supplied continuously with 18 mM N in the following NH+ 4:NO? 3 ratios: 100:0, 75:25, 50:50, 25:75, 0:100. At commercial maturity, the plant characteristics and partitioning of nitrogen in xylem and phloem saps and in plant tissue were determined. Plants fed solely with NH+ 4 were stunted, exhibited signs of marginal necrosis on the lower leaves, and accumulated NH+ 4 in the foliage. The maximum yield and shortest harvest time, together with minimal NO? 3 and NH+ 4 accumulation were found at a ratio of 75:25. Ammonium concentrations in xylem sap decreased linearly with decreasing NH+ 4 portion in the nutrient solution, whereas the NO? 3 concentrations reached a maximum when NO? 3 constituted 50% of the N supply. The glutamate family dominated the amino acid composition of both xylem and phloem saps, but did not vary much with NH+ 4:NO? 3 ratio. It is suggested that the NH+ 4 concentration in xylem sap may be used to assess NH+ 4 vs NO? 3 utilization by broccoli grown under field conditions.  相似文献   

12.
Forty-two-day-old wheat (Triticum aestivum L. var. Asakazekomugi) plants were treated with complete, K-free (—K), Ca-limited (—Ca), and Mg-free (—Mg) nutrient solutions for 10 days using 2 mM NH4NO3 as the nitrogen source, which was replaced with 4 mM 15 NH4C1 or Na15NO3 for the subsequent 2 days to investigate the absorption, translocation, and assimilation of inorganic nitrogen in relation to the mineral supply. In another experiment plants were grown on NO3 ?, NH4 +, NH4N03, and K-free and Ca-limited NH4N03 nutrient solutions for 10 days, and then in the latter three treatments the nitrogen source was replaced with NO3 ? and half of the —K plants received K for 6 days to examine the changes in the nitrate reductase activity (NRA).

Wheat plants absorbed NH4 ?N and NO3-N at a similar rate. Influence of K on the absorption of N03-N was stronger than that on the absorption of NH4-N in wheat plants. The supply of K to the —K plants increased the absorption of NO3-N, while the absorption of NH4-N still remained at a lower rate in spite of the addition of K. A limited supply of Ca and lack of Mg in nutrient media slightly affected the absorption of NH4-N. The influence of K was stronger on the translocation of nitrogen from roots to shoots, while Ca and Mg had little effect. When K was supplied again to the —K plants the translocation of NO3,-N was more accelerated than that of NH4-N. Incorporation of NH4-N into protein was higher than that of NO3-N in all the tissues; root, stem, and leaf. Assimilation of NH4-N and NO3-N decreased by the —K and —Mg treatments.

Leaf NRA of wheat plants decreased in the —K and —Ca plants. Higher leaf NRA was found when K was given again to the —K plants than when the plants were continuously grown in K-free media. Replacement of NO3 ? with NH4 + as the nitrogen source caused a decline of leaf NRA, while the supply of both NH4 ?N and NO3-N slightly affected the leaf NRA.  相似文献   

13.
ABSTRACT

This study was conducted to evaluate the effect of nitrogen (N) and potassium (K) stress on nitrate (NO3 ?) and potassium ion (K+) uptake of two sugarcane (Saccharum officinarum L.) cultivars known to differ with regard to their resistance to drought and salinity stress. The plants were hydroponically grown in a greenhouse and subjected to varying levels of N and K. Nitrogen and K stress increased root affinity for NO3 ? and K+ absorption by increasing apparent maximum uptake rate (Vmax) and decreasing apparent affinity (Km) for NO3 ? and K+ uptake in both cultivars. In addition, dry-matter allocation to roots increased with decreasing N and K supply. The results suggest that the acclimation to long-term N starvation in sugarcane involves regulation of both nitrate-specific assimilatory steps and growth responses. The cultivar ‘H69-8235,’ which was drought and salinity resistant, showed greater adaptability to a low- nutrient environment due to its higher root allocation and affinity for NO3 ? and K+ under N and K stress, suggesting that the resistance of sugarcane to multiple stresses may involve a general stress-response system.  相似文献   

14.
Co-composting of chicken slurry and rice straw with clinoptilolite zeolite and urea as additives was conducted to determine the characteristics of a compost and their effects on controlling ammonium (NH4+) and nitrate (NO3?) losses from urea. Quality of the compost was assessed based on temperature, moisture content, ash, pH, electrical conductivity, carbon/nitrogen (C/N) ratio, NH4+, NO3?, macronutrients, heavy metals, humic acid, microbial population, germination index, and phytotoxicity test. Moisture content and C/N ratio of the compost were 43.83% and 15, respectively. Total N, humic acid, ash, NH4+, NO3?, phosphorus (P), calcium (Ca), magnesium (Mg), potassium (K), and sodium (Na) increased after co-composting rice straw and chicken slurry. Copper, iron (Fe), manganese (Mn), zinc (Zn), and microbial biomass of the compost were low. The germination rate of Zea mays on distilled water and Spinacia oleracea growth on peat-based growing medium (PBGM) and compost were not significantly different. Urea amended with compost reduced N loss by retaining NH4+ and NO3? in the soil.  相似文献   

15.
Due to the high levels of crude protein in the achene, sunflower (Helianthus annuus L.) is one of the main oilseeds grown worldwide, particularly for the oil and meal production for animal feed. Despite these advantages, there are few studies on nutrient use efficiency under tropical conditions, especially nitrogen (N). The experiment was conducted in greenhouse conditions to evaluate the effects of N sources and rates on sunflower achene yield (AY), yield and physiological components, and nutritional status of sunflower. The five N sources (calcium nitrate (Ca(NO3)2), potassium nitrate (KNO3), ammonium nitrate (NO3NH4), ammonium sulfate ((NH4)2SO4), and urea (CO(NH2)2)), and four N rates (0, 50, 100, and 200 mg kg?1) were studied. AY was reduced with the ammonia sources application from the 100 mg N kg?1. Plant height and capitulum dry weight (CDW), capitulum diameter, shoot dry weight (SDW), and chlorophyll content were significantly related with N sources and rates. Except for potassium (K), the N rates changed the N, P, Ca, Mg, and S concentration in the leaves and N concentration in achene. In the comparison of sources, on the average of N rates, urea application was more effective than the other N fertilizers in the AY.  相似文献   

16.
Loading of chemical elements in precipitation at the Solling For the period 1969–1976 (NH4, NO3: 1971–1976) monthly values of concentrations and flows of the ions NH4, H, Na, K, Ca, Mg, Fe, Mn, Al, Cl, NO3, SO4, P and organic bound N in precipitation are passed on. From the correlations between elements the following main ion sources are concluded: sea water (Na, Cl), combustion processes (SO4, NO3, NH4), lime dust after dissolution by H2SO4 and HNO3 (Ca, Mg), soil dust after dissolution by H2SO4 and HNO3 (Al, Fe), leaching from plants (K, NO3, SO4, Mg, Ca), biogenic contaminations (P, organic N, K, NH4, NO3). Seasonal variations in the concentrations are most evident for Na and Cl, less for NH4, SO4 and NO3. During the measuring period the flux of NH4 is significantly increased; for H and SO4, less for NH4, Mg, Ca and Fe, the increasing trend was interrupted in winter 1973/74 (oil crisis). Consequences for sampling are discussed.  相似文献   

17.
Domesticated and wild-type tepary beans (Phaseolus acutifolius A. Gray) were grown with or without inoculation with rhizobia in pots under bacteriologically controlled conditions in a temperature-controlled glasshouse. Seeds were inoculated with a mixture of seven strains isolated from nodules collected from domesticated field-grown tepary bean in Arizona, USA, or with a commercial inoculant strain for Phaseolus vulgaris (CC511). Different degrees of plant reliance upon N2 fixation for growth were generated by supplying the inoculated plants throughout growth with nutrients containing a range of concentrations of 15N-labeled NO3 (0, 1, 2, 5 or 10 mM). An uninoculated treatment that received 10 mM 15N-labeled NO3 was included to provide data for plants solely dependent upon NO3 for growth. Six weeks after sowing, shoots were harvested for dry matter determination and subsequent 15N analysis, root-bleeding xylem sap was collected, and nodulation assessed. With regard to shoot biomass production, domesticated lines were more responsive to inoculation, but less responsive to applied N than wild types. All inoculated plants were nodulated, but the field isolates from tepary bean were more effective in N2 fixation than strain CC511. It was concluded that tepary bean requires a specific inoculant to benefit from fixation of atmospheric N2. Xylem sap samples were analysed for ureides (allantoin and allantoic acid), amino acid content (α-amino-N), and NO3 concentration. The amount of ureide-N present in xylem sap was expressed as a percentage of total solute N, described as the relative abundance of ureide-N (RUN), for each N treatment and was compared to the proportion of plant N derived from N2 fixation (%Ndfa) calculated using a 15N dilution technique. The RUN values ranged from 8% for saps collected from uninoculated plants provided with 10 mM NO3 in the nutrient solution (%Ndfa=0) to 86-91% for nodulated plants grown in the absence of externally supplied NO3 (%Ndfa=100). These data indicated that ureides were the principal product of N2 fixation exported from the nodules to the shoot in xylem sap. Since RUN values were closely related to %Ndfa, it was proposed that N-solute analysis of xylem sap could provide a valuable analytical tool to monitor the symbiotic performance of tepary bean.  相似文献   

18.
Evaluations of vegetative growth and leaf concentrations of nitrogen (N), potassium (K), calcium (Ca), magnesium (Mg), and iron (Fe) were made of apple (Malus domestica Borkh. cvs. Granny Smith, Gala, and Golab) grown with five treatments of NO3?:NH4+ ratios in pot culture. The concentrations of NO3?:NH4+ ratios were 2.5:0.1, 6:0.3, 6:0.5, 6:0.7, and 6: 1 meq L?1. Regression analysis showed that growth parameters of main stems and branches were not affected by increases of NH4+ in the ratios. Granny Smith, Gala, and Golab differed in some of these parameters. Concentrations of N and Fe increased as NH4+ increased, whereas K and Ca decreased and Mg was not affected significantly. Generally, the treatment of 2.5:0.1 produced leaves with lower N but higher K, Ca, and Mg concentrations than the other treatments. This research showed that vegetative growth was not affected by NH4+ concentration whereas elemental composition was affected.  相似文献   

19.
Abstract

Nitrogen‐form effect on nutrient uptake and the subsequent concentration of nutrients in turfgrass plant tissue has not been thoroughly investigated. This study evaluated the effects of clipping regime and N‐form on the tissue concentration of macronutrients and micronutrients and macronutrient uptake in ‘Penncross’ creeping bentgrass (Agrostis palustris Huds.). Turfgrass plugs were grown under greenhouse conditions in a modified Hoagland's solution with a combination of three nutrient solutions (100% NO3 ?, 100% NH4 +, and 50:50 ratio of NH4 +:NO3 ?) and two cutting regimes (cut and uncut). Concentrations of macronutrients and micronutrients were determined for shoot, root and verdure. Nutrient uptake was determined weekly. Uncut NO3 ?‐treated plants accumulated higher concentrations of K, Ca, Mg, B and Cu in the shoot tissue; P, K, Ca, Mg, B, Cu, Mn and Zn in the root tissue; and P, Ca, Mg, B, Fe and Mn in the verdure compared to uncut NN4 +‐treated plants. Nitrate uptake was greater with uncut NO3 ?‐treated plants than was NH4 + absorption with uncut NH4 +‐treated plants. Plants grown with the uncut 50:50 treatment adsorbed more NH4 + than NO3 ?. Plants grown with the uncut NO3 ? and 50:50 treatments adsorbed higher amounts of P, K, and Ca compared to the NH4 + treatment. The cut NO3 ?‐treated plants accumulated higher concentrations of K in the shoot tissue; P, Ca, Mg, B, Cu, Fe and Mn in the root tissue; and B in the verdure than did the cut NH4 +‐treated plants. Cut NO3 ?‐treated plants adsorbed less NO3 ? than did cut NH4 +‐treated plants adsorbed NH4 +. The cut 50:50 treatment adsorbed more NH4 + than NO3 ?. Plants grown with NO3 ? and 50:50 treatments, under both cutting regimes, resulted in higher concentrations of most macro‐ and micronutrients and greater nutrient uptake compared to the NH4 +‐treated plants.  相似文献   

20.
Abstract

The effect of soil pH on the exchangeability and solubility of soil cations (Ca, Mg, Na, K, and NH4‐N) and anions (NO3‐N, Cl, and P) was investigated for 80 soils, spanning a wide range in physical and chemical properties and taxonomic groups. This information is needed from environmental and agronomic standpoints to estimate the effect of changes in soil pH on leachability and plant availability of soil nutrients. Soils were incubated with varying amounts of acid (H2SO4) and base (CaCO3) for up to 30 days. Although acid and base amendments had no consistent effect on cation exchangeability (as determined by neutral NH4OAc), amounts of water‐soluble Ca, Mg, Na, K, NH4‐N, and P decreased, while NO3‐N and Cl increased with an increase in soil pH. The increase in cation solubility was attributed to an increase in the negative charge of the soil surface associated with the base addition. The change in surface electrostatic potential had the opposite effect on amounts of NO3‐N and Cl in solution, with increases in N mineralization with increasing soil pH also contributing to the greater amount of NO3‐N in solution. The decrease in P solubility was attributed to changes in the solubility of Fe‐, A1‐, and Ca‐P complexes. The logarithm of the amount of water‐soluble cation or anion was a linear function of soil pH. The slope of this relationship was closely related (R2 = = 0.90 ‐ 0.96) to clay content, initial soil pH, and size of the cation or anion pool maintaining solution concentration. Although the degree in soil pH buffering increased with length of incubation, no effect of time on the relationship between cation or anion solubility and pH was observed except for NO3‐N, due to N mineralization. A change in soil pH brought about by acid rain, fertilizer, and lime inputs, thus, affects cation and anion solubility. The impact of these changes on cation and anion leachability and plant availability may be assessed using the regression equations developed.  相似文献   

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