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.     

Manganese-phosphate reactions in aqueous systems and the effects of applications of monocalcium phosphate,on the availability of manganese to oats in an alkaline fen soil

Summary Electrometric titrations and chemical analyses of aqueous systems containing manganese sulphate and phosphoric acid showed that the compositions of manganese phosphates formed at various pH values depended on initial manganese concentrations and Mn : P molar ratios. The results show how phosphate benefits crops on soils containing toxic levesl of manganese.A pot experiment measured the effects of monocalcium phosphate, in the presence or absence of extra manganese, on the availability to oats of manganese in an alkaline manganese-deficient soil. On such a soil, phosphate equivalent to 750 or 1500 pounds of superphosphate per acre is unlikely to enhance manganese availability; such dressings may lessen grain yields considerably.Neutral and alkaline manganese-deficient fen soils were incubated with monocalcium-phosphate with and without added manganese salts. The phosphate dressings had only small effects on soil pH and on exchangeable and readily reducible manganese.     

Experiments on effects of phosphorus on the manganese nutrition of plants

Summary Monocalcium phosphate (MCP), the salt of concentrated superphosphate, applied to a Buganda soil increased the amount of manganese taken up by ryegrass. To investigate the cause of this effect the derivatives of MCP hydrolysis, dicalcium phosphate (DCP) and triple-point solution (TPS) were separated and applied independently. Both derivatives, and a synthetic dicalcium phosphate dihydrate, increased the concentration of manganese in ryegrass showing that dissolution of soil manganese by TPS (pH 1.48) was not a unique cause.DCP derived by hydrolysis of MCP supplied little phosphorus to early crops of ryegrass but a larger proportion of its P was taken up by later crops; TPS supplied more of its P to earlier than to later crops. During 42 weeks the proportions of P taken up from DCP and TPS were similar to the proportions of phosphorus in these forms when MCP hydrolyzes.Phosphorus in DCP derived by hydrolysis of MCP was more available to ryegrass than phosphorus in a synthetic dicalcium phosphate dihydrate, showing that results may be misleading when synthetic materials are used to simulate the compounds that form from fertilizers in soil. re]19760401     

Studies in soil and plant manganese

Summary Results for manganese content of young oat plants and for soil pH from a field experiment involving eight experimental centres receiving applications of lime and phosphate, both at five levels, have been analysed statistically.Manganese content of the oats increased as a result of superphosphate fertilization. This increase was significant at the 0.005 level of probability. Superphosphate treatments have been shown to decrease the soil pH, the effect being significant at the 0.02 level of probability. The roles of phosphate and acidity in increasing the uptake of manganese by the crop have been compared. The possibility of direct and indirect action of these influences has been discussed in the light of other reported investigations.     

Methods for the determination of toxic levels of manganese in glasshouse soils

Summary The manganese status of the soil and the uptake of manganese by lettuce, chrysanthemums and roses were studied in pot and field experiments. The levels of water-soluble and exchangeable manganese in the soil were determined, the former by means of a 1:5 weight extract and a 1:2 volume extract, the latter by means of Morgan's solution, 1:21/2 and 1 N ammonium acetate solution, 1:25. Computation of the correlation coefficients for the relationship between the manganese contents of the soil and the crop showed that a better correlation was obtained with water soluble manganese than with exchangeable manganese. Addition of the pH and an index for the cation exchange capacity of the soil as variables increased the correlation coefficients. This occurred especially in the correlations with exchangeable manganese. The effects of the salt concentration and the salt composition of the soil on the manganese uptake of lettuce and on the manganese status of the soil were also studied in this investigation. Calcium ions proved to have a clear effect, whereas potassium ions did not. re]19760123     

Long-term effect of superphosphate on accumulation of soil phosphorus and exchangeable cations on a grazed,irrigated pasture site

The annual herbage dry matter yield, herbage P concentrations and quantities of P, K, Mg and Ca cycled by grazing sheep were calculated for a 37 year-old grazed pasture supplied with superphosphate at rates of 0, 188 and 376 kg ha^-1 annually. The amount and distribution of inorganic and organic P and exchangeable K, Mg and Ca in the soil below the three grazed treatments was also measured and compared with that below a wilderness area which had not been used for agriculture. Increasing rates of superphosphate increased herbage dry matter yield, herbage P concentrations and thus the amounts of P ingested and, in turn, excreted by the grazing sheep. Annual quantities of K, Mg and Ca cycled back to the pasture in the form of excreta were also increased. The increased cycling of K by animals induced by increasing superphosphate applications resulted in greater losses of K and consequently concentrations of exchangeable and non-exchangeable ‘fixed’ K in soil decreased in the order wilderness > control > 188 > 376. Differences were evident to a depth of 20 cm. Some losses of Mg during cycling also occurred and concentrations of exchangeable Mg followed the order: wilderness > control >188=376. Concentrations of exchangeable Ca increased with pasture development due to additions of Ca in lime and superphosphate. Concentrations of total soil organic P (0–4 cm) increased in the order: wilderness < control <188<376 but for inorganic P and total P the control had a lower content than wilderness indicating losses of P during cycling in the grazed control treatment. Phosphorus fractionation suggested that with increasing superphosphate rates inorganic P primarily accumulated in a form adsorbed to Al hydrous oxides and as calcium phosphate compounds whilst organic P accumulated in both labile forms and forms associated with humic compounds. In the fertilised sites both inorganic and organic P accumulated in the soil profile to a depth of 20 cm.     

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.     

THE BACTERIOLOGY OF THE ROOT REGION OF THE OAT PLANT GROWN UNDER CONTROLLED POT CULTURE CONDITIONS

SUMMARY: The bacteriology of the root region of oat plants grown under controlled conditions has been studied by means of improved techniques for separate estimation of the microfloras of the rhizosphere soil and of the root surface. The plate count of bacteria in the root region increased during the growing period of the plants; superphosphate produced a greater increase, which was probably due to increased plant growth, as no such effect was observed in uncropped soil.
The numbers of acid producing and dicalcium phosphate dissolving bacteria were increased in the root region, but the latter were not preferentially stimulated. Dressings of superphosphate and dicalcium phosphate also did not preferentially stimulate either group. No evidence was obtained, by the plate method used, of the presence of organisms capable of dissolving variscite, strengite, or gafsa rock phosphate, although the plants showed appreciable response to gafsa rock phosphate.     

Soil Manganese Enrichment from Industrial Inputs: A Gastropod Perspective

Manganese is one of the most abundant metal in natural environments and serves as an essential microelement for all living systems. However, the enrichment of soil with manganese resulting from industrial inputs may threaten terrestrial ecosystems. Several studies have demonstrated harmful effects of manganese exposure by cutaneous contact and/or by soil ingestion to a wide range of soil invertebrates. The link between soil manganese and land snails has never been made although these invertebrates routinely come in contact with the upper soil horizons through cutaneous contact, egg-laying, and feeding activities in soil. Therefore, we have investigated the direct transfer of manganese from soils to snails and assessed its toxicity at background concentrations in the soil. Juvenile Cantareus aspersus snails were caged under semi-field conditions and exposed first, for a period of 30 days, to a series of soil manganese concentrations, and then, for a second period of 30 days, to soils with higher manganese concentrations. Manganese levels were measured in the snail hepatopancreas, foot, and shell. The snail survival and shell growth were used to assess the lethal and sublethal effects of manganese exposure. The transfer of manganese from soil to snails occurred independently of food ingestion, but had no consistent effect on either the snail survival or shell growth. The hepatopancreas was the best biomarker of manganese exposure, whereas the shell did not serve as a long-term sink for this metal. The kinetics of manganese retention in the hepatopancreas of snails previously exposed to manganese-spiked soils was significantly influenced by a new exposure event. The results of this study reveal the importance of land snails for manganese cycling in terrestrial biotopes and suggest that the direct transfer from soils to snails should be considered when precisely assessing the impact of anthropogenic Mn releases on soil ecosystems.     

Impact of phosphate-solubilizing fungi on the yield and phosphorus-uptake by wheat and faba bean plants

Three fungal isolates (phosphate-dissolvers), Aspergillus niger, A. fumigatus and Penicillium pinophilum were isolated from the rhizosphere of different plants grown in Ismailia and South Sinai Governorates. They effectively solubilized rock phosphate or tricalcium phosphate in Pikovskaya's liquid medium. In pot and column experiments, they significantly reduced pH and increased available phosphorus in the soil treated with either rock phosphate or superphosphate. The yield components of wheat and faba bean plants increased as a result of soil inoculation with the isolated fungi. Penicillium pinophilum was the most efficient isolate. It increased the yield of wheat grains by 28.9 and 32.8% in the soil treated with rock phosphate and superphosphate, respectively. Similarly, it increased the production of faba bean seeds by 14.7 and 29.4% with the same treatments. The uptake of phosphorus by both crops significantly increased due to inoculation of the soil with the tested fungi.     

The effects of water content of the topsoil on micronutrient availability and uptake in a siliceous sandy soil

Summary Effects of water content of the topsoil on the supply of manganese, zinc and copper to plants from an acid, siliceous sandy soil were investigated. The experiment was designed to provide a good supply of water and of nutrients other than those mentioned above at all times.Water content of the topsoil affected the root growth in that layer significantly. However, drying of the topsoil for as long as 42 days did not significantly affect the concentration of micronutrients in the shoots of oats, provided the plants did not experience water stress.Despite the acidic, siliceous sandy nature of the topsoil it showed a surprisingly high ability to render added manganese, zinc and copper unavailable. This phenomenon, probably mediated by organic matter, had a dominant effect on the exchangeable micronutrients in comparison to the effects due to fluctuations in soil water content.     

Effect of the diverse combinations of useful microbes and chemical fertilizers on important traits of potato

The belowground soil environment is an active space for microbes, particularly Arbuscular Mycorrhizal Fungi (AMF) and P hosphate Solubilizing Bacteria (PSB) that can colonize with roots of higher plants. In the present experiment, we evaluated the combination of microbial inoculants with the different doses of urea and superphosphate in a complete randomized block design (CRBD). Three different doses of urea and superphosphate were tested, i.e., recommended dose, 75% of the recommended dose and 125% of the recommended dose, independently and in combination with three microbial groups viz. Glomus mosseae (AMF), Bacillus subtilis (PSB) and Nitrifying microorganisms (Nitrosomonas + Nitrobacter, NN). Overall, there were 16 treatment combinations used, and studied the number of tubers per plant, the weight of tubers, moisture content, and the number of nodes per tubers which were best in treatment comprising of AMF + PSB + NN + 75% of urea + superphosphate. From our results, it is suggested for the growers to use a lesser quantity of fertilizers from the recommended dose along with some bioinoculants to maintain the soil fertility and also to achieve the yield targets by decreasing the cost of chemical fertilizers.     

Effects of cultivation and long-term superphosphate applications on pasture soil sulphur mineralisation and availability in the field

The mineralisation of soil organic sulphur (S) by soil micro-organisms constitutes a significant source of S for pasture plant growth. Cultivation and fertiliser applications affect microbial activity which in turn affects soil S mineralisation and the release of plant-available S. A field trial was conducted with cultivated and uncultivated subplots superimposed on the main plots of a long-term pasture trial in New Zealand receiving annual applications of superphosphate (0, 188, 376 kg ha^?1) since 1952. The aim was to provide information on soil S mineralisation and availability as affected by cultivation and superphosphate applications under field conditions. Carrier-free ³⁵SO₄-S was applied to all plots in the field, allowed to pre-condition for two weeks before perennial ryegrass (Lolium perenne L.) seeds were sown to cultivated sub-plots, while in uncultivated subplots existing pasture was cut and removed and then allowed to re-grow. Five plant harvests followed by soil sampling each time were conducted over a period of one year. Herbage and soil samples were analysed for total S and ³⁵S and different extractable soil S and ³⁵S fractions (HI-reducible S, C-bonded S). Results obtained showed that cultivation and fertilisation significantly affected plant dry matter yield, soil S mineralisation and plant S uptake. These effects were affected by seasons. Plant S uptake was strongly related to soil S supply to plants and the plant S uptake provided a better measure of soil S availability to plants than changes in the extractable soil S fractions examined in the current study.     

The effect of ferrous sulphate on the yield and manganese uptake of oats on sandy soil fertilized with natural pyrolusite

Summary The effects of soil treatments with ferrous sulphate and an equivalent amount of hydroquinone on the yield of dry matter and the manganese uptake of oats were investigated in pot experiments using a sandy soil deficient in manganese, with and without additions of finely ground, natural pyrolusite containing some manganite.In soil not fertilized with pyrolusite an application of hydroquinone gave a higher yield of dry matter and a considerably higher manganese uptake than an application of the equivalent quantity of ferrous sulphate.In soil fertilized with hydroquinone an increase of 23 per cent in the yield of dry matter and an increase of 50 per cent in the manganese uptake per pot were found when the soil was fertilized with 100 g of natural pyrolusite <50µ per pot. In soil fertilized with a quantity of ferrous sulphate equivalent to hydroquinone, an increase of 21 percent in the yield of dry matter and an increase of about 200 per cent in the manganese uptake per pot were found when the 100 g of pyrolusite was applied.     

Soluble and slow-release PK-fertilizers for seedlings and transplants ofPicea sitchensis andPicea abies in two English nurseries

Summary In a heathland nursery on an acid sandy podsol and in a nursery on moderately acid agricultural land, four PK fertilizers were compared with superphosphate alone, using seedlings and transplants of Sitka sprucePicea sitchensis and Norway sprucePicea abies as test crops. The four fertilizers were: 1) a compound prepared from KCl and superphosphate (KCl/superphosphate), 2) the same compound supplemented by three summer topdressings of potassium nitrate, 3) potassium dihydrogen phosphate, 4) potassium metaphosphate. Except for potassium nitrate all fertilizers were applied in the spring before sowing or transplanting.Mid-season analyses (confined to Sitka spruce seedlings) showed that the effectiveness of different fertilizers depended on the rainfall pattern during growth. Phosphorus and potassium were leached less and nutrients used more efficiently with potassium metaphosphate than with KCl/superphosphate. Potassium nitrate applied on three occasions during the summer to plots with KCl/superphosphate maintained the best growth and largest K-concentrations in the seedlings. Differences between fertilizers were small for transplants at the heathland nursery and for all crops at the nursery on an agricultural-type soil. Losses of P and K by leaching on the sandy podsol both decreased in the order KCl/superphosphate > or=potassium dihydrogen phosphate > potassium metaphosphate.     

The effect of soil desiccation on the nutrient status of Eucalyptus regnans F. Muell seedlings

The poor growth of young Eucalyptus regnans seedlings in undried soil from the mature forest of E. regnans can be overcome by previously air-drying the soil or by adding sufficient amounts of complete soluble fertilizer or equivalent concentrations of P (as NaH₂PO₄) and N (as NaNO₃). A factorial pot experiment in which phosphate and nitrate were added to undried soil indicated that P was the primary deficiency for young seedlings and that response to N did not occur until this lack was satisfied. In dried soil, seedlings also responded to additions of complete fertilizer but most of this effect was due to N rather than P. Field trials in the mature forest also indicated greater growth in dried soil than undried soil and confirmed a response of young seedlings to superphosphate. In pot experiments, the concentration of P and N per g plant dry weight after four months was relatively constant irrespective of the final size of the plant. Seedlings in dried soil extracted up to 15 times more P than did those grown in undried soil. In general, chemical analysis of soil indicated more extractable P and N from dried soil although this was not always consistently so. Soil desiccation resulted in an increase in soil surface area due to the fragmentation of larger peds and to an increase in the number of microfractures which remained in the soil crumbs after rewetting. Mycorrhiza are likely to be important since the differentiation of the growth response of seedlings in dried and undried soil, which occurred at 5–6 weeks, corresponded with the establishment of full ectomycorrhizal development (80% root tips). The factors concerned with the increase in fertility after air-drying are discussed.Abbreviations GR Growth Ratio     

Monthly variations of soluble P in a volcanic ash derived soil as affected by organic and mineral fertilizers

Summary The effect of organic amendments (cow manure and green manure) on monthly variations of soluble P in a volcanic-ash-derived soil was studied. Soluble P (Truog's method) showed minimums at the beginning of August and at the beginning of January. Cow manure produced a remarkable increase of soluble P and removed the January minimum. In soils treated with legume green manure, soluble SP markedly decreased during the first and second month. Data for organic P suggested that the summer decreases of soluble P were partly due to microbial immobilization. In soil treated with mineral fertilizers only, more than half of the P added as superphosphate was found as Al and Fe phosphate after one month. Organic amendments, especially cow manure, decreased the immobilization of superphosphate P.     

The influence of manganese on the development of potato scab

Summary The development of common scab on potato crops growing in slightly acid to neutral soils has been shown to be greatly reduced by application of manganese sulphate to the soil at planting time. A general improvement in health and appearance of tubers was noted and increased yields of marketable tubers were obtained. The possibility that environmental factors known to influence the development of scab are only important in so far as they affect the solubility of soil manganese is discussed.     

Cumulative dressings of potassium metaphosphate and soluble PK-fertilizers for seedlings and transplants ofPicea sitchensis in two English nurseries

Summary Cumulative dressings of potassium metaphosphate tested on seedlings and transplants ofPicea sitchensis gave promising results from 1964 to 1966¹ at two nurseries — a sandy podsol and a sandy loam with better nutrient retention. The four experiments, which also included superphosphate alone, KC1/superphosphate, with and without topdressings of KNO₃, and potassium dihydrogen phosphate, were continued until 1969. On the podsol, potassium metaphosphate maintained its superiority for seedlings and also left larger residues in the surface soil. It had no special merit on the sandy loam or for transplants on either soil.     

Effect of rock phosphate on soil properties and apparent phosphorus recovery in acid soil of Sumatra

The effects of rock phosphate (RP) on soil properties and apparent P recovery of corn in acid soil of Sumatra were investigated. The soil was dominated by kaolinitic minerals, very acid and low in extractable phosphorus. The experiment was conducted in two steps: incubation and greenhouse. The treatments were rock phosphate and triple superphosphate (TSP) at 0, 200, 400 and 600 µg P g^-1 for the incubation experiment, and at 0, 50, 100, 150 and 200 µg P g^-1 for greenhouse experiment In the incubation experiment, rock phosphate reduced exchangeable Al and increased pH_H2O better than TSP, and supplied Bray-1 extractable P as much as did TSP. In the greenhouse experiment, apparent P recovery values of rock phosphate were very close to those of TSP and the values tended to decrease at higher rates of P. Although corn yields of the rock phosphate treatment were lower than TSP, its relative agronomic effectiveness was quite high.