Adjusting Soil pH Research Articles

红壤砂糖橘果园土壤和叶片养分状况研究

为掌握广东省砂糖橘产区果园的营养状况，实现砂糖橘的优质高产。2015和2016年共采集土壤和叶片样品各130份进行检测并做相关性分析。广东省砂糖橘果园强酸性土壤占比68.46%，pH平均值4.52，土壤整体偏酸；有机质平均含量18.06 g/kg处于适量水平；有效锌和有效硼含量处于适量范围的比例分别为53.85%和42.31%；碱解氮、速效钾低于适量范围的土样分别占比76.16%、56.15%；交换性钙和交换性镁处于极缺范围的土样占比分别为52.31%、93.08%，另有55.38%的土样有效磷处于高量水平；叶片中磷、钾和硼处于适量范围的比例分别为40.77%、79.23%和81.54%；氮元素含量偏低，83.08%的叶样低于适量水平；钙、镁和锌则缺乏严重，处于极缺范围的叶样分别占比48.46%、51.54%和78.46%。相关性分析显示砂糖橘叶片各矿质元素之间以及土壤养分与叶片矿质元素之间存在一定的相关性。广东省砂糖橘果园土壤和叶片钙、镁大量不足，且叶片缺锌最为严重，生产中应注意结合土壤和叶片营养诊断的结果补充土壤钙、镁肥，同时喷施叶面锌肥，调整土壤pH，科学施肥以满足砂糖橘生长的需要。 In order to master the nutritional status of “Shatangju” orchards in Guangdong province, 130 sam-ples of soil and leaves were collected in 2015 and 2016 for test and correlation analysis. The results showed that the overall soil was acid and 68.7% of soil sample was strongly acidic with average pH 4.52. The content of soil organic matter was 18.06 g/kg at suitable level. The content of available Zn and B in the optimum level account for 53.44% and 42.31%, respectively. The available N and K were at lower level and the proportions of soil sample below optimum were 76.16% and 56.15%, respectively. The exchange Ca and Mg were in serious shortage in most soil samples and the proportions in extreme deficiency status were 52.31% and 93.08%, respectively. The available P was at higher level with 55.38% of soil sample. The contents of P, K and B in the leaves were at optimum level with 40.77%, 79.23% and 81.54% leaf sample, respectively. The content of N element was at lower level, accounting for 83.08% of leaf sample. The proportions of leave Ca, Mg and Zn in extreme deficiency status were 48.46%, 51.54% and 78.46%. The correlation analysis showed that there was a certain correlation among the leaf mineral elements or between soil nutrients and the miner-al elements of the leaf. In conclusion, the contents of Ca and Mg in “Shatangju” orchards of Guang-dong province were largely insufficient, and Zn deficiency was the most serious in leaf. In practical production, the supplying of soil Ca and Mg and spraying of Zn foliar fertilizer are applied with paying attention to the results of soil and leaf nutrition diagnosis, together with adjusting soil pH, to meet the need of “Shatangju” growth.

Effects of Different Organic Materials on Bio-availability of Cd, Pb in a Contaminated Greenhouse Soil

A two-season soil culture experiment was continually conducted to study the effects of three organic materials,namely Danty, Peat and Biochar,respectively,on combined forms and bio-availability of cadmium (Cd) and lead (Pb) under Cd and Pb in single and combined pollution during 2014-2015. This study aimed to provide a theoretical basis for remediating greenhouse soil contaminated with heavy metals Cd and Pb using organic materials. The main results were as follows: the content of DTPA-Cd decreased significantly by 11.9%(P<0.05) in the soil of Cd and Pb combined pollution with the application of danty, the total of exchangeable Cd, carbonate-bound Cd and iron-manganese oxide bound Cd was reduced by 26.4% and 34.4% in the soil, and the accumulation of Cd in shoots was significantly cut down by 32.0% and 28.0% (P<0.05) respectively in Cd single and Cd and Pb combined pollution after applying danty; the content of DTPA-Pb was significantly depleted by 83.5% and 83.8%(P<0.05), the total of exchangeable Pb, carbonate-bound Pb and iron-manganese oxide bound Pb was decreased by 34.5% and 13.9% in the soil and the accumulation of Pb in shoots was significantly reduced by 32.0% and 30.0% (P<0.05) in Pb single and Cd and Pb combined pollution respectively as the use of danty. The content of DTPA-Cd was significantly decreased by 18.9% (P<0.05) in the soil of Cd and Pb combined pollution with the use of peat, the accumulation of Cd in shoots was reduced by 38.0% and 23.4%(P<0.05) in Cd single and Cd-Pb combined pollution respectively after the application of peat; The content of DTPA-Pb was significantly decreased by 2.7% and 7.2%(P<0.05), the total of exchangeable Pb, carbonate-bound Pb and iron-manganese oxide bound Pb was decreased by 15.8% and 14.6% in the soil and the accumulation of Pb in shoots was significantly reduced by 12.7% and 23.4% (P<0.05) respectively in Pb single and Cd and Pb combined pollution due to the application of peat. The pH value of the soil was increased by the use of biochar, the content of DTPA-Cd was reduced by 4.7% and 15.0% respectively in the soil of Cd single and Cd and Pb combined pollution, and the accumulation of Cd in shoots was significantly minified by 38.0% and 23.4% respectively in Cd single and Cd and Pb combined pollution as the application of biochar. The content of DTPA-Pb was decreased by 6.8% and 1.0% and the total of exchangeable Pb, carbonate-bound Pb and iron-manganese oxide bound Pb was cut down by 11.9% and 30.0% in the soil of Pb single and Cd and Pb combined pollution respectively by the application of biochar. The content of Cd in plant was most significantly positively correlated with the content of exchangeable Cd in soil (P<0.01). The content of Pb in plant was most significantly positively correlated with the total of exchangeable Pb, carbonate-bound Pb and iron-manganese oxide bound Pb (P<0.01). In summary, after the application of danty, peat and biochar, the proportion of highly active content of Cd and Pb was minified through adjusting soil pH and immobilizing Cd and Pb by means of adsorption and complexation in greenhouse soil. With the analysis of input-output, the application of danty, peat and biochar costs 4050 yuan·hm-2, 11250 yuan·hm-2 and 22500 yuan·hm-2, respectively. Thus danty, peat and biochar could be used as effective organic agents in the remediation of Cd and Pb contaminated greenhouse soil.

Use of Amendments to Restore Ecosystem Function to Metal Mining-Impacted Sites: Tools to Evaluate Efficacy

As in situ use of amendments for restoration of metal-contaminated mining sites becomes increasingly accepted, the expected level of ecosystem function at these sites will increase. Use of appropriate tools to measure both the level and value of that function is critical to expand use of this approach. For these sites, amendment mixtures must reduce metal availability in situ and restore ecosystem function. Combinations of mixtures, typically consisting of a material with high metal binding capacity (cyclonic ashes, municipal biosolids, or other materials rich in Fe, Al, or Mn oxides), material to adjust soil pH (sugar beet lime, cement kiln dust, dolomitic limestone), and an organic residual to provide soil structure and nutrients (composts, animal manures, municipal biosolids) have been tested in multiple lab and field trials on metal-contaminated sites. This review focuses on field tests of this approach with the goal of providing methods to quantify reduction of hazard and restoration of functional systems. Methods to evaluate success of amendments including extractions to measure changes in metal availability, microbial function and diversity, phytoavailability of metals, and earthworm and small mammal assays are discussed. In most cases, measures of metal availability and ecosystem function are related. For example, surveys of small mammals on restored sites provide information on metal availability as well as suitability of restored habitat. Additional measures of ecosystem function including soil fertility, physical properties, and diversity of habitat are described. Finally, measures of the value of this approach for restoring ecosystems are detailed.

Effects of liming on Cr(VI) reduction and Cr phytotoxicity in Cr(VI)-contaminated soils

Liming is the most common approach for the amelioration of soil acidity in agriculture, and is widely used to reduce the mobility and bioavailability of heavy metals in soil. The purpose of this study was to investigate the hexavalent chromium [Cr(VI)] reduction and chromium (Cr) phytotoxicity in Cr(VI)-contaminated soils at different pH levels as a result of liming. Calcium carbonate (CaCO3) was added to two acid agricultural soils of Taiwan (Neipu and Pinchen) at their natural pH of about 4, to adjust soil pH to approximately 5 and 6, respectively. The soils were then spiked with six levels of Cr(VI) (0, 150, 300, 500, 1000 and 1500 mg kg−1). X-ray absorption near edge structure spectroscopy (XANES) of Cr was used to determine the extent of the reduction of Cr(VI) at different pH levels. At the same time, extractions of Cr by Dowex M4195 and Chelex 100 resins were carried out to determine the availability of Cr(VI) and trivalent chromium [Cr(III)] in the Cr(VI)-spiked soils, respectively. Also, a pot experiment with wheat (Triticum vulgare) seedlings was carried out to test the phytotoxicity of the Cr(VI)-spiked soils. The results showed that for Cr(VI)-contaminated soils which contain a high amount of organic matter, such as the Neipu soil, the effect of liming on Cr(VI) reduction and Cr phytotoxicity is insignificant. However, for Cr(VI)-contaminated soils which have a low amount of organic matter, such as the Pinchen soils, liming could decrease the extent of Cr(VI) reduction and increase the availability of Cr(VI), thereby enhancing the phytotoxicity of Cr.

The remediation of the lead-polluted garden soil by natural zeolite

The current study investigated the remediation effect of lead-polluted garden soil by natural zeolite in terms of soil properties, Pb fraction of sequential extraction in soil and distribution of Pb in different parts of rape. Natural zeolite was added to artificially polluted garden soil to immobilize and limit the uptake of lead by rape through changing soil physical and chemical properties in the pot experiment under greenhouse conditions. Results indicated that the addition of natural zeolite could increase soil pH, CEC, content of soil organic matter and promote formation of soil aggregate. The application of zeolite decreased the available fraction of Pb in the garden soil by adjusting soil pH rather than CEC, and restrained the Pb uptake by rape. Data obtained suggested that the application of a dose of zeolite was adequate (≥10 g kg −1) to reduce soluble lead significantly, even if lead pollution is severe in garden soil (≥1000 mg kg −1). An appropriate dose of zeolite (20 g kg −1) could reduce the Pb concentration in the edible part (shoots) of rape up to 30% of Pb in the seriously polluted soil (2000 mg kg −1).

A conceptual framework for improving the P efficiency of organic farming without inputs of soluble P fertiliser

The issues for P availability to agricultural plants are 3-fold: the solution concentration of P during early growth (intensity factor); the quantity of P in the soil ‘bank’ to meet plant and animal needs (capacity or quantity factor); and the rate at which P becomes available from mineral and organic sources (kinetic factor). These three needs can be met by: (1) applying traditional (manure, compost) and novel (biosuper) sources; (2) modifying or selecting plants for their root architecture, phytase activity, carboxylate excretion, and P translocation inefficiency; (3) encouraging rhizosphere conditions which favour phytase and carboxylase activity; (4) developing symbioses with mycorrhiza and Penicillium species; (5) developing exoenzyme products which release inositol P; (6) adjusting soil pH to 6–7 for maximum availability of native mineral P sources or lowering pH for maximum availability of reactive rock P; (7) developing rotations which maximise organic P cycling. These 7 broad groupings of strategies to improve P nutrition each operate by 1 or more of the 3 mechanisms of quantity, intensity, and kinetic factors. The possible application of these strategies to ‘organic’ farming is outlined in this review. However, a successful application of these strategies might also improve the P efficiency of conventional agriculture.

EFFECTS OF SOIL ACIDITY AND CROPPING ON SOLUBILITY OF BY-PRODUCT-IMMOBILIZED PHOSPHORUS AND EXTRACTABLE ALUMINUM, CALCIUM, AND IRON FROM TWO HIGH-PHOSPHORUS SOILS

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Soil pH Effects on Uptake of Cd and Zn by Thlaspi caerulescens

For phytoextraction to be successful and viable in environmental remediation, strategies that can optimize plant uptake must be identified. Thlaspi caerulescens is an important hyperaccumulator of Cd and Zn, whether adjusting soil pH is an efficient way to enhance metal uptake by T. caerulescens must by clarified. This study used two soils differing in levels of Cd and Zn, which were adjusted to six different pH levels. Thlaspi caerulescens tissue metal concentrations and 0.1 M Sr(NO3)2 extractable soil metal concentrations were measured. The soluble metal form of both Cd and Zn was greatly increased with decreasing pH. Lowering pH significantly influenced plant metal uptake. For the high metal soil, highest plant biomass was at the lowest soil pH (4.74). The highest shoot metal concentration was at the second lowest pH (5.27). For low metal soil, due to low pH induced Al and Mn toxicity, both plant growth and metal uptake was greatest at intermediate pH levels. The extraordinary Cd phytoextraction ability of T. caerulescens was further demonstrated in this experiment. In the optimum pH treatments, Thlaspi caerulescens extracted 40% and 36% of total Cd in the low and high metal soils, respectively, with just one planting. Overall, decreasing pH is an effective strategy to enhance phytoextraction. But different soils had various responses to acidification treatment and a different optimum pH may exist. This pH should be identified to avoid unnecessarily extreme acidification of soils.

Improved Procedures for Adjusting Soil pH for Pot Experiments

Liming is an effective method of correcting soil acidity, but the cost and other factors, such as sub-soil acidity, topography, and nutrient availability may limit its benefits. An alternative option is to grow acid tolerant plants. Pot experiments are an effective way of identifying plants with the genetic potential to grow in acidic soils. These experiments require a range of acidity levels. The soil used in this study was a sandy loam. Increments of aluminum sulfate [Al2(SO4)3.18H2O] and calcium carbonate (CaCO3) were added to derive dose-pH response relationships. The derived relationships were used to estimate the quantity of aluminum sulfate and lime required to change the pHCa (1:5, w:v, soil:10 mM CaCl2) of the soil from 4.4 to 3.89 and 4.4 to 5.2, respectively. The estimated quantities of aluminum sulfate (380 g) and calcium carbonate (48 g) were thoroughly mixed through 100 kg batches of the soil, which was potted (2 kg/pot). Then the acidified soils were leached to remove excess salts. The initial pHCa achieved was 3.86 and rose to 3.94 after leaching. A wide range of soluble aluminum (Al) concentrations (1:5, w:v, soil:10 mM CaCl2) was obtained from this study, e.g., 52 mg Al/kg soil in acidified soil and 1.8 mg Al/kg soil in limed soil. The variation in pH and EC between replicate pots was negligible (range 0.05 pH and 0.02 dS/m) and these remained relatively unchanged after six months. During the next six months some pots were held in the laboratory with 3 wetting/drying cycles; however, most were placed outdoors where they were sown with seed of Austrodanthonia spp. During this time, the pHCa of the acidified soils increased slightly to: 4.10 (laboratory), 4.18 (outdoors without plants), and 4.20 (outdoors with plants). A similar increasing trend was also observed in limed soils. It was concluded that adding aluminum sulfate and calcium carbonate followed by washing with water are quick and convenient methods for adjusting soil pH for pot experiments.

Kura clover and birdsfoot trefoil response to soil pH1

Use of the rhizomatous perennial forage legume kura clover (Trifolium ambiguum M. Bieb.) has been limited by slow establishment. Mature kura clover responds to liming on some acid soils, but the soil pH required for vigorous growth of young plants is unknown. A factorial greenhouse experiment was conducted with two kura clover cultivars (Rhizo and Endura) and one cultivar of birdsfoot trefoil (Lotus corniculatus L., Norcen) planted in three soil types (Sartell loamy fine sand, Hubbard loamy sand, and Sanborg clay loam) amended with Ca(OH)2 to obtain six soil pH levels. The experiment was performed twice, once using soil taken directly from the field and once using steamed soil. Response of kura clover and birdsfoot trefoil to soil pH differed. Maximum yield increases in kura clover obtained by adjusting soil pH from 4.9 to 6.5 were about 50% on nonsteamed soil and more than 150% on steamed soil. Birdsfoot trefoil did not respond to liming on nonsteamed soil. On steamed soil birdsfoot trefoil response to liming was inconsistent. Optimal soil pH for growth of kura clover and birdsfoot trefoil was generally between pH 6 and 7. Biomass yield was correlated with nodulation in both kura clover and birdsfoot trefoil, but nodulation was correlated with nitrogen uptake only in kura clover. Increased biomass yield of young kura clover plants in response to liming was best explained by alleviation of aluminum (Al), zinc (Zn), and manganese (Mn) toxicities and increased availability of phosphorus (P) and molybdenum (Mo) at higher soil pH levels. Joint contribution of the Minnesota Agricultural Experiment Station and USDA-ARS.

EFFECT OF CURRENT FERTILIZATION PRACTICES ON NUTRITIONAL STATUS OF DOUBLE-CROPPED TOMATO AND CUCUMBER PRODUCED WITH PLASTICULTURE

When vegetables are double-cropped on polyethylene mulch, fertilizer recommendations for each crop may need to be adjusted because liming and preplant applications are done prior to laying plastic. When current fertilizer recommendations for single crops were used for cucumber following tomato, the cucumber plants looked like green, indicating a nitrogen (N) and/or potassium (K) deficiency was developing, suggesting that nutrient availability for the second crop was not adequate for producing the highest yields. Therefore, the nutritional status of both crops was diagnosed using sufficiency range data and DRIS norms to determine which nutrient(s) was limiting crop nutrition. Regardless of N source used as a sidedress injection material (at a rate of 7 kg N ha−1wk−1 as ammonium nitrate or calcium nitrate) or liming material used to adjust soil pH to 6.5 (carbonate- or oxide-based calcitic or dolomitic lime), foliar levels of N and K, and possibly phosphorus (P) were found to be limiting factors according to sufficiency range data and DRIS norms. This study suggests that current fertility recommendations for tomato and cucumber grown as single crops in Alabama need to be reevaluated for double crops.

Comparison of Chemical Properties and Application as Acid Soil Amendment of Pretreatment Center Slag and Other Slags

Chemical properties of Pretreatment center slag (PTC-slag) were analyzed and compared to those of converter slag (C slag) and blast furnace slag (BF slag). PTC slag had a high EC value as well as citric acid soluble P and contained more Ca, Si, P, K, and Na but less Mg and Fe than C slag. Compared to BF slag, PTC slag contained more Fe, Ca, Mg, P, Mn, and Na but less Si, Al, and K. Although neutralizing value of PTC slag was lower than that of C slag, its ability to neutralize soilacidity was markedly higher. A pot experiment using Andisol from Tochigi Prefecture and komatsuna plant was carried outto evaluate PTC slag as liming material as well as P fertilizer. PTC slag, C slag, and dolomite were applied as liming materials and combined with super phosphate (SP). Addition of SP of 2.5 and 5.0% phosphate absorption coefficient (PAC) to PTC slag significantly improved the yield of komatsuna.This result, however, only apply for PTC slag adjusting soil pH to 6.5. Addit~ono f the same dosage of SP to PTC slag adjusting soil pH to 7.5 did not give significant effect. On the other hand, addition of SP of 2.5 and 5.0% PAC to C slag or dolomite significantly improved the yield for both C slag ordolomite adjusting. the soil pH to 6.5 and 7.5. Results of the experiment also indicated that P'TC slag and C slag significantly increased soil pH; exchangeable Ca, and Mg and improved available P, B, and Mn in Andisol. The magnitudes ofthese effects of the two slags, however, were difference. As compared to C slag and dolomite, PTC slag increased lower exchangeable Mg but higher available P. These results suggest that for acid soil amendment, PTC slag was better than dolomite and C slag due to the fact that this material supplymore P and B. Application of PTC slag as acid soil amendment will reduce the demand of P fertilizer, and even in high dosage can meet the P demand of komatsuna plant.

Zinc uptake by plants on amended polluted soils

This study evaluated the efficacy of various soil amendments in reducing Zn availability in an ultisol Appling silt loam. Zinc was added to the soil at two rates (1000 and 2000 mg kg−1) as a defined mixture of various Zn sources (40% of ZnSO4, 25% of ZnCO3, 20% of ZnO, and 15% of ZnCl2). After soil equilibration, one of five amendments was added: lime, apatite, natural zeolite (phillipsite), Fe-richTM, and N-viro (an alkaline stabilized sewage sludge). Lime was added to adjust soil pH to a value of 6.5 and the zeolite, apatite, Fe-richTM, and N-viro were added at a rate of 25 g kg−1. Early plant mortality resulted from Zn-treated soils receiving no amendment. In contrast, each of the soil amendments reduced Zn uptake by plants. Based on plant yield, Zn tissue concentrations, and extractability of Zn in treated soils, Fe-richTM, apatite, and N-viro appear to be more effective in reducing Zn availability than either lime or zeolite.

Control of Sweet Potato Soil Rot Disease by Application of Microbial Materials for Soil Amendment, Adjusting Soil pH and Crop Rotation of Peppermint in the Field

Control of Sweet Potato Soil Rot Disease by Application of Microbial Materials for Soil Amendment, Adjusting Soil pH and Crop Rotation of Peppermint in the Field

Induced phosphorus fixation and the effectiveness of phosphate fertilizers derived from Sukulu Hills phosphate rock

A greenhouse study was conducted with two surface, acidic soils (a Hiwassee loam and a Marvyn loamy sand) to measure the effect of increasing P-fixation capacity, on the relative agronomic effectiveness (RAE) of phosphate fertilizers derived from Sukulu Hills phosphate rock (PR) from Uganda. Prior to fertilizer application, Fe-gel was added to increase P-fixation capacity from 4.4 to 14.3% for the Marvyn soil and from 37.0 to 61.5% for the Hiwassee soil. Phosphate materials included compacted Sukulu Hills concentrate PR + Triple superphosphate (CTSP) at a total P ratio of PR:TSP = 50:50; 50% partially acidulated PR (CPAPR) from Sukulu Hills concentrate PR made with H2SO4; and Sukulu Hills concentrate PR (PRC) made by magnetically removing iron oxide from raw PR ore. Triple superphosphate (TSP) was used as a reference fertilizer. After adjusting soil pH to approximately 6, P sources were applied at rates of 0, 50, 150, and 300 mg total P kg−1 soil. Two successive crops of 5 week old corn seedlings (Zea mays L.) were grown. The results show that the RAE of the phosphate materials measured using dry-matter yield or P uptake generally decreased as P-fixation capacity was increased for both soils. CTSP was more effective in increasing dry-matter yield and P uptake than CPAPR. PRC alone was an ineffective P source. Soil chemical analysis showed that Bray 1 and Mehlich 1 extractants were ineffective on the high P-fixation capacity Fe-gel amended Hiwassee soil. Mehlich 1 was unsuitable for soils treated with PRC since it apparently solubilizes unreactive PR. When all of the soils and P sources were considered together, Pi paper was the most reliable test for estimating plant available P.

Germination and growth effects of hexavalent chromium in Orocol TL (a corrosion inhibitor) on Phaseolus vulgaris

This research was designed to address the potential for germination and growth effects in bush beans ( Phaseolus vulgaris L. var. Bush Blue Lake) from hexavalent chromium in Orocol TL, a proprietary chromated, zinc-phosphate compound added to DOE cooling water systems for corrosion inhibition. Studies were conducted at low and high Orocol TL concentrations in the soil by adjusting soil pH and the percent of organic matter. Germination effects were determined for seeds germinated in soils adjusted to differing pH ranges (4–4.5, 5–5.5, and 6.5–7), levels of organic matter (1.8%, 3%, and 5%), and Orocol TL amendments (control of 0, 10, and 500 μg/g chromium). Growth responses (effects) were determined from plants cultured in the same soil treatment combinations as described for the germination study. High levels (500 μg/g) of hexavalent chromium in soil (as Orocol TL) affected germination and growth, while a high level of organic matter significantly reduced chromium toxicity on germination. At lower chromium concentrations there was significant uptake by all plant parts, with a corresponding reduction in biomass of leaves. Consequently, adjustments of soil pH from 4.0 to 7.0 appear to have no significant effect on chromium uptake in plants. Increasing the organic matter level to 5%, while decreasing the toxicity of high chromium levels to germinating seed, did not affect chromium uptake.