The effect of liming a neutral soil on the cycle of manganese

Summary A manganese-deficient soil was mixed at pH 7 and pH 8, both moist and dry with (a) -MnO₂ and (b) MnSO₄. The amounts of bivalent manganese were determined after incubating for varying times. With the moist soils more bivalent manganese was released at pH 8 than at pH 7. However, after long air-drying much more bivalent manganese was released than from the moist soils and more was released at pH 7 than at pH 8.     

Interactions Between Nitrogen and Manganese Nutrition of Barley Genotypes Differing in Manganese Efficiency

Ammonium-fed plants may acidify the rhizosphere and thus increaseavailability of Mn in calcareous alkaline soils. The importanceof N nutrition in the differential expression of tolerance toMn deficiency among cereal genotypes is not yet clear. Two factorialexperiments testing effects of the NH₄-N/NO₃-N ratio and Mnfertilization on growth of barley genotypes differing in toleranceto Mn deficiency were conducted in two calcareous alkaline soilsin pots in a controlled environment. In the soil containing80% CaCO₃at pH 8.5, better root and shoot growth and highershoot Mn concentrations were achieved with nitrate supply, especiallyat lower rates of Mn fertilization. The Mn-efficient genotypeWeeah (tolerant of Mn deficiency) achieved better root and shootgrowth than Mn-inefficient Galleon barley (sensitive to Mn deficiency)regardless of experimental treatment. Fertilization with Mndid not influence total N concentration in barley roots andshoots. In the soil containing 5% CaCO₃at pH 7.8, ammonium-fedplants had better root and shoot growth and, at shoot Mn concentrationsabove the critical level, Mn-inefficient Galleon performed betterthan Mn-efficient Weeah barley. It appears that differentialexpression of Mn efficiency among barley genotypes is not associatedwith differences in Mn availability expected to be producedby differential rhizosphere acidification as a response to differentforms of N supply. There is an apparent preference of locallyselected barley genotypes for nitrate nutrition when grown onthe highly calcareous alkaline soils of southern Australia. Ammonium; calcareous soil; Hordeum vulgare ; manganese; nitrate; nitrogen form; nutrient efficiency; rhizosphere     

The effect of liming a neutral soil on the uptake of manganese by plants

Summary The uptake of manganese by oats in a manganese-deficient soil was increased on raising the pH from 7.0 to 8.0 with Ca(OH)₂. This effect occurred in the absence of added manganese as well as when manganese was added to the soil as -MnO₂. When the soil was initially sterilized the uptake of manganese at pH 7.0 was greatly increased at both pH's, but the uptake at pH 8.0 was now a smaller than at pH 7.0.     

Apple replant disease: the influence of soil phosphorus and other factors on the growth responses of apple seedlings to soil fumigation with chloropicrin

The effects of fumigating field soils before replanting apple are frequently predicted from bioassays where apple seedlings are grown in pots, some containing untreated soil and the others containing chloropicrin-fumigated soil. The results from 418 such bioassays made during eight years are discussed with reference to the effects of certain physical and chemical soil features. Soil phosphorus (P) content and pH had large effects on growth in fumigated (but not untreated) soils; they therefore had large effects on the growth response to soil fumigation. There were no indications of important effects due to soil content of potassium or magnesium or to soil texture. In fumigated soils, the height of seedlings was generally greater, the greater the soil P content, but in untreated soils it was mostly independent of P (range 1 – 156 mg P litre^-1soil). The differing effects of native P on growth in untreated or fumigated soils were attributed respectively to the presence and absence of vesicular-arbuscular mycorrhizas: their absence in fumigated soils was considered (for apple) to be an artefact in the seedling bioassay. The results for untreated soils indicated that the apple mycorrhizal system was very efficient in retrieving P when there was little available. Growth responses to soil fumigation were usually greater in acidic than in alkaline soils for any given level of P. When soils were P-amended before testing, the effects of native P and pH virtually disappeared and the proportion of orchard soils with economically significant growth responses increased from 39% to 67%.     

The effects of lime and superphosphate on manganese toxicity in steam-sterilized soil

Summary The effects of liming and superphosphate application on the manganese nutrition of lettuce were studied in factorial experiments. A fairly acid silt loam of the Hamble series, which on steam-sterilization released considerable amounts of manganese in readily available forms, was used in the investigation.Manganese toxicity in lettuce was prevented by liming to increase the pH of the soil. The amounts of water-soluble, exchangeable and total active manganese present in the soil, and the manganese content of lettuce plants, decreased with increasing soil pH; easily reducible soil manganese increased with increasing soil pH.The effect of added superphosphate depended on the pH of the untreated soil. When the soil had a high pH, application of phosphate invariably decreased the pH and increased the manganese uptake. In acid soil supplying excessive amounts of manganese, application of phosphate reduced the manganese content of the plants; the pH of the soil was either unchanged or slightly increased by the treatment.Correlations were calculated between soil pH, various fractions of soil manganese, and the manganese content and yield of lettuce.From a comparison of plants grown in soil and sand culture it was concluded that the presence of a further toxic factor in the soil was probable.The results are discussed in relation to those obtained by other investigators.     

水稻苗床土壤调酸后对土壤酶活性及一些营养元素的影响

水稻苗床土壤调酸后对土壤酶活性及一些营养元素的影响唐咏,梁成华,张中原,李焕珍（沈阳农业大学,１１０１６１）（沈阳市土肥工作站,１１００３４）ＥｆｆｅｃｔｓｏｆＳｏｉｌＡｃｉｄｉｆｉｃａｔｉｏｎｏｎＥｎｚｙｍｅＡｃｔｉｖｉｔｉｅｓａｎｄＮｕｔｒｉｅｎ...     

CONTROL OF SEED-BED LOSSES OF GROUNDNUTS BY SEED TREATMENT

Fungicide treatment of groundnut ( Arachis hypogaea L.) seed usually reduced seed-bed losses and improved emergence, plant populations and yields of this crop when cultivated under rain in the sandy soils of Kordofan (west-central Sudan) or under irrigation in the alkaline clay soils of the Gezira. These beneficial effects were greatest with slightly damaged seeds, such as would occur with machine sowing, but were present even when selected undamaged seed was sown by hand; they were attributed to protection against a number of soil micro-organisms, including Aspergillus niger van Tieghem, A.flavus Link and Rhizopus spp. Agrosan GN (organo-mercurial, 1% mercury equivalent) or 50% thiram powder, both applied at the rate of 1 g./lb. of seed, are suggested as suitable dressings for groundnut sowing seed in the two areas studied. Combined fungicide-insecticide dressings containing up to 40% by weight of γ-BHC did not control a late attack of wilt, due to root attack by cockchafer grubs ( Schizonycha sp.), which developed some 8 weeks after sowing in the Gezira.     

Effects of Manganese Deficiency and Added Cerium on Nitrogen Metabolism of Maize

Manganese is one of the essential microelements for plant growth, and cerium is a beneficial element for plant growth. However, whether manganese deficiency affects nitrogen metabolism of plants and cerium improves the nitrogen metabolism of plants by exposure to manganese-deficient media are still unclear. The main aim of the study was to determine the effects of manganese deficiency in nitrogen metabolism and the roles of cerium in the improvement of manganese-deficient effects in maize seedlings. Maize seedlings were cultivated in manganese present Meider's nutrient solution. They were subjected to manganese deficiency and to cerium chloride administered in the manganese-present and manganese-deficient media. Maize seedlings grown in the various media were measured for key enzyme activities involved in nitrogen metabolism, such as nitrate reductase, glutamate dehydrogenase, glutamine synthetase, and glutamic-oxaloace transaminase. We found that manganese deficiency restricted uptake and transport of NO(3)(-), inhibited activities of nitrogen-metabolism-related enzymes, such as nitrate reductase, glutamine synthetase, and glutamic-oxaloace transaminase, thus decreasing the synthesis of chlorophyll and soluble protein, and inhibited the growth of maize seedlings. Manganese deficiency promoted the activity of glutamate dehydrogenase and reduced the toxicity of excess ammonia to the plant, while added cerium relieved the damage to nitrogen metabolism caused by manganese deficiency in maize seedlings. However, cerium addition exerted positively to relieve the damage of nitrogen metabolism process in maize seedlings caused by exposure to manganese-deficient media.     

Bulk soil pH and rhizosphere pH of peach trees in calcareous and alkaline soils as affected by the form of nitrogen fertilizers

One-year old nectarine trees [Prunus persica, Batsch var. nectarina (Ait.) Maxim.], cv Nectaross grafted on P.S.B2 peach seedlings [Prunus persica (L.) Batsch] were grown for five months in 4-litre pots filled with two alkaline soils, one of which was also calcareous. Soils were regularly subjected to fertigation with either ammonium sulphate or calcium nitrate providing a total of 550 mg N/tree. Trees were also grown in such soils receiving only deionized water, as controls. Rhizosphere pH, measured by the use of a microelectrode inserted in agar sheet containing a bromocresol purple as pH indicator and placed on selected roots, was decreased by about 2–3 units compared to the bulk soil pH in all treatments. This decrease was slightly less marked when plants were supplied with calcium nitrate rather than ammonium sulphate or control. Measurements conducted during the course of the experiment indicated that ammonium concentration was similar in the solution of soils receiving the two N fertilizers. During the experiment, soil solution nitrate-N averaged 115 mg L^–1 in soil fertilized with calcium nitrate, 68 mg L^–1 in those receiving ammonium sulphate and 1 mg L^–1 in control soils. At the end of the experiment nitrate concentrations were similar in soils receiving the two N sources and bulk soil pH was decreased by about 0.4 units by ammonium sulphate fertigation: these evidences suggest a rapid soil nitriflcation activity of added ammonium. Symptoms of interveinal chlorosis in apical leaves appeared during the course of the experiment in trees planted in the alkaline-calcareous soil when calcium nitrate was added. The slightly higher rhizosphere pH for calcium nitrate-fed plants may have contributed to this. The findings suggest that using ammonium sulphate in a liquid form (e.g. by fertigation) in high-pH soils leads to their acidification and the micronutrient availability may be improved.     

Phosphorus nutrition of rice in relation to flooding and temporary loss of soil-water saturation in two lowland soils of Cambodia

In the rainfed lowlands, temporary loss of soil-water saturation during crop growth is a common factor limiting rice (Oryza sativa L.) yield but its effects on phosphorus (P) availability are poorly understood. Rice plants were transplanted into pots containing soils that were either continuously flooded, maintained at field capacity or flooded and then dried to field capacity for 3 weeks during the vegetative stage. A black clay soil (Kandic Plinthaquult) and a sandy soil (Plinthustalf) from south-east Cambodia were compared with or without amendments by rice straw and P fertilizer. Under continuously flooded conditions, the growth of rice was vigorous without straw addition and there was a strong response of rice growth to the addition of P fertilizer. The soil underwent reduction, which increased pH from 4.2 to 5.5 or 6.0, in the black clay or sandy soil, respectively. By contrast, a loss of soil-water saturation 3 weeks before panicle initiation (PI) markedly impaired the growth of rice. This was not through any effect of water stress, and the growth reductions were not as strong as with continued loss of soil-water saturation from transplanting to PI. Fluctuations in soil pH and Eh corresponded closely to changes in soil-water regimes. Growth reductions were attributed to reduced shoot P levels resulting from the decline in P availability during the loss of soil-water saturation. The addition of rice straw stimulated soil reduction and lessened changes in soil pH and Eh during the loss of soil-water saturation in both soils. Straw addition enhanced P uptake by the rice plants during loss of soil-water saturation, but its beneficial effects could not be attributed to the direct addition of P, N or K to the soils. Thus the application of rice straw may be effective in lessening the effects of temporary loss of soil-water saturation on rice growth in lowland rice soils by minimising the decline in P availability. This revised version was published online in August 2006 with corrections to the Cover Date.     

Phosphate potential and phosphate capacity of soils

Summary The relationship between the phosphate potential (I) and the amount of phosphate (Q), added to the soil has been examined by equilibrating soil samples with 0.001M or 0.01M CaCl₂ solutions containing various amounts of phosphate. For one neutral and two alkaline soils the Q/I relationship depends on the CaCl₂ concentration and the pH in such a way that the apparent values of I decrease when the CaCl₂ concentration increases from 0.001 M to 0.01M. The difference between the two values increases when the pH increases. When correction is made for the formation of the soluble calcium phosphate complex, CaHPO₄, the Q/I relationship becomes independent of the CaCl₂ concentration. The initial phosphate potential (I₀) determined by interpolation, is also found to be independent of the CaCl₂ concentration. The necessary amount of phosphate to be added or removed per gram of soil in order to obtain a certain alteration of the phosphate potential is designated the differential phosphate potential buffering capacity, DPBC. For ten soils DPBC-values are determined on the basis of the Q/I relationships, (ΔQ/ΔI)_Io, and found to be independent of the CaCl₂ concentration. The content of colloids and of inorganic phosphate accounts for a significant part of the variation in the DPBC for different soils. The importance of the DPBC for characterization of the phosphate status of soils in respect to phosphate supply to plants is briefly discussed. The author is indebted to professor, Dr. H. C. Aslyng, head of the department for his suggestions and helpful criticism during the progress of this work.     

Effects of liming on phosphate availability in acid soils

Summary The critical factors involved in the plant-soil-phosphorus-lime interaction are outlined and discussed. Conflicting reports suggest that the prior liming of highly weathered acid soils can result in an increase, a decrease, or no change in the availability of applied phosphate. Adsorption of phosphate by amphoteric soil surfaces generally decreases slowly as the pH is raised from 4.0 to 7.0. However, in soils initially high in exchangeable Al³⁺, liming results in the formation of new, highly active, phosphate adsorbing surfaces as the Al³⁺ ions precipitate as insoluble polymeric hydroxy-Al cation species. Thus, if an acid soil is reacted with lime and then phosphate, without intervening air drying, liming can increase phosphate adsorption. If the same limed soil is air dried before reaction with phosphate (e.g. adsorption isotherm studies), liming decreases phosphate adsorption. Apparently, air drying alters the surface characteristics of recently limed soils, probably by promoting the crystallization of the hydroxy-Al cation polymers as gibbsite.An important phenomenon, which is often overlooked, is that liming can increase phosphate availability by stimulating mineralization of soil organic phosphorus. However, at high soil pH values, the precipitation of insoluble calcium phosphates can decrease phosphate availability. Since Al toxicity is characterised by the inhibition of the uptake, translocation and utilization of phosphate by plants, liming often increases the utilization of soil phosphate by plants through amelioration of Al toxicity.When making lime recommendations or interpreting the data collected from lime-phosphate experiments, it is important to consider all the complex interacting soil and plant factors involved.     

Soil chemistry and plant distributions in rock habitats of southern Sweden

The vascular plant flora of open land on superficial bedrock in southem Sweden (northwards to 59°N) is described and related to soil chemical properties. including soil acidity (pH), exchangeable Al, Ca, Fe, Mn, Mg, and phosphate, as well as to soil solution pH and concentrations of Al, Ca and Mg, and to the contents of soil organic matter, soil depth and bedrock types (sandstone, gneiss, granites, various dark igneous rocks and limestones). About 120 localities with totally 652 sites (4 m²) have been examined. Experimental evidence for the toxicity of acid soils and mineral nutrient deficiency of neutral and alkaline soils is related to field data. Hydrogen and Al ion toxicity in acid soils and low phosphate solubility in neutral - alkaline soils are identified as major factors limiting the field distributions of rock habitat plants. Some species (e.g., Rumex acetosella and Sedum telephium ) were limited by phosphate also in acid soils. The relative importance of H and Al ion concentrations to plant performance under variously acid soil conditions is discussed, and strong evidence is given for a decisive influence of Al ion toxicity on species diversity at pH-KCI > 4.5. The importance of grazing and former land use is considered briefly and the floristic differences between the western and the eastern half of the study area are discussed originating from differences in general distribution patterns of species and soil chemical properties.     

Manganese deficiency of sugar beet in organic soils

Summary The manganese content of sugar beet grown in pots of organic soils taken from fields where crops regularly show symptoms of manganese deficiency, and the effects on it of foliar sprays of manganous sulphate and of manganous oxide or manganese silicate frit applied to the soil, of changing the soil pH, air-drying the soil, and growing the plants either in the glasshouse or outside were determined. All the manganese treatments increased the concentration of manganese in the plants and decreased deficiency symptoms, but increased the dry matter yield only slightly. Increasing the pH by liming greatly increased symptoms and decreased the manganese concentration in the dry matter; air-drying the soil before cropping had the opposite effect. Plants grown in pots of the same soil in the glasshouse or outdoors showed similar symptoms and had similar manganese content.The concentration of manganese in the leaves was related to the percentage of plants with deficiency symptoms and to the concentration of active soil manganese. Leaves usually had symptoms when the concentration of manganese in the dried leaves was less than 30 ppm, and always had severe symptoms when they contained less than 15 ppm Mn. The soil analyses suggest that sugar beet grown in organic soil with pH greater than 7.0 and containing less than 40 ppm active soil manganese is likely to show deficiency symptoms.     

Studies on the manganese uptake of lettuce on steam-sterilised glasshouse soils

Summary During steam sterilisation of glasshouse soils appreciable amounts of easily reducible manganese are converted into exchangeable manganese. The reverse process takes place much more gradually. As a result, manganese toxicity occurs in several crops on newly steamed soils. In the Netherlands, lettuce has been found to be particularly prone to manganese toxicity. An investigation was carried out to obtain more information about the manganese status of steamed glasshouse soils in which lettuce was used as the test crop. The following results were noted.The uptake of exchangeable manganese is easier in the lighter soils than in heavy soils. Application of iron to the soil inhibits manganese uptake by the plant, but the iron must be applied in the form of chelate. The pH has a profound effect on manganese uptake on steamed as well as on unsteamed soils. However, the relationship between the pH and the manganese content of the crop on steamed soils is different from that found on unsteamed soils.The slow rate of oxidation of manganese in steamed glasshouse soil may be explained by the fact that the oxidising bacteria are killed during the steam sterilisation process. The fixation of manganese can be accelerated appreciably by inoculating the steamed soil with manganese-oxidising bacteria.The effect on manganese uptake of five soil desinfection chemicals used in the investigation proved to be very small.The lettuce varieties used in the Netherlands show a wide variation in susceptibility to manganese toxicity. This cannot be explained by different rates of manganese uptake. It is more likely that the varietal differences are based on different levels of resistance to manganese present in the plants.     

Évaluation par des extractions sélectives de l'immobilisation du Cd après l'apport de matériaux inorganiques dans deux terres polluées

Two soils, contaminated by sludge application or by smelter activities, have been amended with : lime (CaO), lime + Al-pillared smectites (CaO + Sm), phosphate basic slags (SCO), manganese oxide (HMO), iron oxide (HFO) and steel shot (GA). Four single soil extractions (water, 0.1 M Ca(NO₃)₂ 0.05 M ED TA-NH₄ and acetic acid (0.43 M HAc)) and the two plant cultures (tobacco and ryegrass) were used to evaluate the effect of these inorganic additives on the mobility and plant-availability of cadmium in the soils. The Cd extracted by the different solutions was compared to the concentration of Cd in the shoots of ryegrass and tobacco. The effect of treatments on Cd mobility in soil was easily discriminated by the use of either water or Ca(NO₃)₂. The addition of HMO and GA reduced both the mobility and the phyto-availability of Cd in the two soils. Conversely, the alkaline additives and HFO decreased the Cd mobility, but not the Cd plant availability. Single soil extractions using either water or Ca(NO₃)₂ are a useful tool for estimating Cd immobilization, but not sufficient for assessing Cd plant availability ; a validation by plant tests must be conducted.     

Microbial resource allocation for phosphatase synthesis reflects the availability of inorganic phosphorus across various soils

According to the resource allocation model for extracellular enzyme synthesis, microorganisms should preferentially allocate their resources to phosphorus (P)-acquiring enzyme synthesis when P availability is low in soils. However, the validity of this model across different soil types and soils differing in their microbial community composition has not been well demonstrated. Here we investigated whether the resource allocation model for phosphatase synthesis is applicable across different soil types (Andosols, Acrisols, Cambisols, and Fluvisols) and land uses (arable and forest), and we examined which soil test P and/or P fraction microorganisms responded to when investing their resources in phosphatase synthesis in the soils. The ratio of alkaline phosphatase (ALP) to β-d-glucosidase (BG) activities in the arable soils and the ratio of acid phosphatase (ACP) to BG activities in the forest soils were significantly negatively related with the available inorganic P concentration. We also observed significant effects of available inorganic P, pH, soil types, and land uses on the (ACP + ALP)/BG ratio when the data for the arable and forest soils were combined and used in a stepwise multiple regression analysis. These results suggest that microbial resource allocation for phosphatase synthesis is primarily controlled by available inorganic P concentration and soil pH, but the effects of soil types and land uses are also significant.     

On the effect of ferrous sulphate on the available manganese in the soil and the uptake of manganese by the plant

Summary Application of iron as ferrous sulphate or chloride to a loam not deficient in manganese had no effect on the yield but increased the uptake of manganese even in barley which grew vigorously.In an experiment with sugar beet on two soils contrasted with regard to their available manganese supply, applications of manganese, iron and nitrogen were tested in all combinations. On the Købelev soil, not deficient in manganese, no increases in yields were obtained on addition of ferrous sulphate while increases in manganese uptake were found for all combinations of treatments except where iron was added in the presence of manganese.On the manganese deficient Faarevejle soil, significantly higher increases in yields of roots were obtained from ferrous sulphate in the presence of nitrogen than in the presence of manganese. The effect of iron in the presence of nitrogen on the yield of tops was also significant. These treatments also gave the highest increases in manganese uptake.The amounts of manganese extractable from the soils by magnesium nitrate over a range of pH 2–8 could be increased considerably by addition of ferrous sulphate.The results support the suggestion that application of ferrous sulphate to some soils has the same effect as an addition of manganese.     

Studies in manurial values of seaweeds

Summary The effect of applying dry meal of the seaweedPachymenia himantophora to soil has been investigated. The seaweed was found to greatly increase the availability of manganese which became toxic to plant growth on acid soils. The release of manganese appears to be due to altered soil physical conditions causing waterlogging of soils low in calcium.     

模拟酸雨对不同土壤有机碳和作物秸秆分解的影响

为研究酸雨对不同pH值水稻土中有机碳分解的影响,选择酸性（pH 5.48）、碱性（pH 8.18）和中性（pH 6.70）水稻土（分别设置施用秸秆0、15 g·kg^-1土处理）在20 ℃条件下进行40 d的培养试验,各土壤组分别用pH值为6.0、4.5、3.0的模拟雨水将土壤含水量调为400 g·kg^-1(以风干土计).结果表明：秸秆、酸雨和土壤共同对土壤系统CO₂释放产生影响,秸秆的添加可显著提高土壤CO₂释放速率.培养期间,酸雨未显著影响土壤有机碳分解,但对土壤中作物秸秆的分解影响显著. pH 3.0酸雨处理下酸性和碱性土壤中秸秆40 d总分解量比pH 6.0处理高8%;酸雨抑制了中性水稻土中秸秆的分解,pH 3.0酸雨处理下秸秆40 d总分解量比pH 6.0处理低15%.pH 3.0酸雨处理下,酸性水稻土有机碳分解速率分别比中性和碱性水稻土高43%和50%（P<0.05）,秸秆在中性水稻土中分解量分别比其在酸性和碱性水稻土中低17%和16%（P<0.05）.