Increase of Available Phosphorus by Fly‐Ash Application in Paddy Soils

Abstract

Fly ash from the coal‐burning industry may be a potential inorganic soil amendment to increase rice productivity and to restore the soil nutrient balance in paddy soil. In this study, fly ash was applied at rates of 0, 40, 80, and 120 Mg ha^?1 in two paddy soils (silt loam in Yehari and loamy sand in Daegok). During rice cultivation, available phosphorus (P) increased significantly with fly ash application, as there was high content of P (786 mg kg^?1) in the applied fly ash. In addition, high content of silicon (Si) and high pH of fly ash contributed to increased available‐P content by ion competition between phosphate and silicate and by neutralization of soil acidity, respectively. With fly‐ash application, water‐soluble P (W‐P) content increased significantly together with increasing aluminum‐bound P (Al‐P) and calcium‐bound P (Ca‐P) fractions. By contrast, iron‐bound P (Fe‐P) decreased significantly because of reduction of iron under the flooded paddy soil during rice cultivation. The present experiment indicated that addition of fly ash had a positive benefit on increasing the P availability.     

Estimation of Plant‐Available Nitrogen in Soils using Rapid Chemical and Biological Methods

The relationships between potential laboratory indices for plant‐available nitrogen (N) and the plant N uptake in a pot experiment with ryegrass were assessed for 13 mineral soils and 2 peat soils. The methods included aerobic soil incubation, soil incubation in a bioreactor, hot potassium chloride (KCl)–extractable mineral N, 0.01 M calcium chloride (CaCl₂)–extractable N, and N loss at heating. The indices for total plant‐available N accounted for 63–93% of the variance in N uptake in a statistical analysis with all soils (n = 15) and 27–89% for the mineral soils (n = 13). Most indices were not a direct quantitative measure of the plant N uptake. The N mineralization indices accounted for 57–86% of the variance in N mineralization for all soils and 5–50% for the mineral soils. Hot KCl‐extractable mineral N and 0.01 M CaCl₂–extractable N were the most promising rapid indices for plant‐available N.     

Interrelation of Inorganic Phosphorus Fractions and Sorghum‐Available Phosphorus in Calcareous Soils of Southern Khorasan

The objectives of this research were to determine inorganic phosphorus (P) fractions in calcareous soils of southern Khorasan and find their relationship with sorghum‐available P. Eighty soil samples were obtained and analyzed for some physical and chemical characteristics, among them 24 samples that varied in plant‐available P and soil properties were used for soil testing. From 24, 8 samples were selected for P fractionation as well. Five extraction procedures were used for soil testing. Results indicate that the extracted plant‐available P by the Olsen et al. (1954 Olsen, S. R., Cole, C. V., Watanabe, F. S. and Dean, L. A. 1954. Estimation of available phosphorus in soils by extraction with sodium bicarbonate (USDA Circ. 939), Washington, D.C.: U.S. Government Printing Office.  [Google Scholar]) and Paauw (1971 Paauw, F. V. 1971. An effective water extraction method for the determination of plant available phosphorus.. Plant and Soil, 34: 497–481.  [Google Scholar]) methods show the greatest correlation coefficients with plant P uptake and sorghum dry matter. The sequential inorganic P extraction analyzing indicated that the abundance of various inorganic fractions was in the order Ca₁₀‐P > Al‐P > Ca₈‐P > Ca₂‐P > Oc‐P > Fe‐P. The results also indicate Olsen P correlates positively and significantly with Ca₂‐P and Fe‐P fractions and positively but not significantly with the Al‐P fraction.     

Early Supplies of Available Nitrogen to Seed‐Row of a Canola Crop as Affected by Fertilizer Placement

Abstract

A field experiment was conducted at Star City (legal location SW6‐45‐16‐W2); Saskatchewan, Canada from May 2000 to June 2000, to measure nitrogen (N) and phosphorus (P) supply rates from fertilizer bands to the seed‐row of canola crop. Ion exchange resin membrane probes (PRS^TM) were used to measure N and P supply rates in four treatments [80 kg N ha^?1 of urea as side‐row band, 80 kg N ha^?1 of urea as mid‐row band, check/no N (side‐row)/P side‐row, check/no N (mid‐row)/seed placed P]. The treatments were arranged in a randomized complete block design with four replications. Two anion and cation exchange resin probes (PRS^TM) were placed in each plot in the seed‐row immediately after seeding and fertilizing. The probes were allowed to remain in the field for 2 days and replaced with another set of probes every 4 days for a total of 14 days until canola emerged. Ammonium‐N, nitrate‐N and P supply rates were calculated based on the ion accumulated on the probes. Urea side‐row band treatments (fertilizer N 2.5 cm to side of every seed‐row) had significantly higher cumulative available N supply rates than mid‐row band placement in which fertilizer N was placed 10 cm from the seed‐row in between every second seed‐row. No significant differences were observed in P supply rates. The higher N rates (120 kg N ha^?1) resulted in lower grain yield in side‐row banding than mid‐row banding possibly due to seedling damage. However, the earlier fluxes of N into the seed‐row observed with side‐row banding may be an advantage at lower N rates in N deficient soils.     

Boiling Potassium Chloride–Extractable Nitrogen as an Index of Potentially Mineralizable and Plant‐Available Nitrogen in Soil

Abstract

Mineralization of soil organic nitrogen (N) and its contribution toward crop N uptake is central to developing efficient N‐management practices. Because biological incubation methods are time consuming and do not fit into the batch‐analysis techniques of soil‐testing laboratories, an analytical procedure that can provide an estimate of the mineralizable N would be useful as a soil‐test method for predicting plant‐available N in soil. In the present studies, the ability of boiling potassium chloride (KCl) to extract potentially mineralizable and plant‐available N in arable soils of semi‐arid India was tested against results from biological incubations and uptake of N by wheat in a pot experiment. Mineralization of organic N in soils was studied in the laboratory by conducting aerobic incubations for 112 days at 32°C and 33 KPa of moisture. Cumulative N mineralization in different soils ranged from 8.2 to 75.6 mg N kg^?1 soil that constituted 2.7 to 8.8% of organic N. The amount of mineral N extracted by KCl increased with increase in length of boiling from 0.5 to 2 h. Boiling for 0.5, 1, 1.5, and 2 h resulted in an increase in mineral‐N extraction by 9.3, 12.7, 19.6, and 26.1%, respectively, as compared to mineral N extracted at room temperature. The boiling‐KCl‐hydrolyzable N (ΔN_i) was directly dependent upon soil organic N content, but the presence of clay retarded hydrolysis for boiling lengths of 0.5 and 1 h. However, for boiling lengths of 1.5, and 2 h, the negative effect of clay was not apparent. The ΔN _i was significantly (P=0.05) correlated to cumulative N mineralized and N‐mineralization potential (N₀). The relationship between N₀ and ΔN _i was curvilinear and was best described by a power function. Boiling length of 2 h accounted for 78% of the variability in N₀. Results of the pot experiment showed that at 21‐ and 63‐day growth stages, dry‐matter yield and N uptake by wheat were significantly correlated to boiling‐KCl‐extractable mineral N. Thus, boiling KCl could be used to predict potentially mineralizable and plant‐available N in these soils, and a boiling time of 2 h was most suitable to avoid the negatively affected estimates of boiling‐KCl‐hydrolyzable N in the presence of clay. The results have implications for selecting length of boiling in soils varying widely in clay content, and this may explain why, in earlier studies, longer boiling times (viz. 2 or 4 h) were better predictors of N availability as compared to 0.5 and 1 h.     

Available Nitrogen for Corn and Winter Cereal in Spanish Soils Measured by Electro‐ultrafiltration,Calcium Chloride,and Incubation Methods

Abstract

Comparison of methods is necessary to develop a quick and reliable test that can be used to determine soil‐available nitrogen (N) in an attempt to increase the efficiency of N fertilizers and reduce losses. The objectives of this research were to compare the fractions extracted by the calcium chloride (CaCl₂) and the electro‐ultrafiltration (EUF) methods and to correlate them to the mineralization rate (k) obtained from a 112‐d incubation of 61 soil samples. Thirty‐five soil samples were collected from cornfields and 26 from winter cereal fields. Subsamples were either aerobically incubated to calculate k or extracted by the EUF and CaCl₂ methods to identify three fractions: nitrate (NO₃ ^?)‐N, ammonium (NH₄ ⁺)‐N, and Norg‐N. The Norg‐N extracted by both methods was larger in soils from cornfields than in soils from winter cereal fields. In samples from cornfields, the Norg‐N fraction obtained by the EUF method was correlated to the Norg‐N measured by the CaCl₂ method (r=0.46). Soil N content was related to k in samples from cornfields (r=0.40) but not in samples from winter cereal fields. Also, k was correlated to inorganic N content extracted by both chemical methods. The CaCl₂ method was a reliable alternative for laboratories to determine soil‐available N for corn but not for winter cereal.     

Re‐analysis of the Relationship between Organic Carbon and Loss‐on‐Ignition in Soil

The suitability of loss‐on‐ignition (LOI) as an alternative to direct measurement of organic carbon (OC) has been debated for decades without resolution. The literature contains an abundance of different linear regression models to describe the LOI–OC relationship, most based on untransformed values of LOI and OC. Such regression is suspect because the variables are unable to occupy Euclidean space. Logratio transformation—based on relative rather than absolute differences—eliminates this constraint. Re‐analysis of the relationship on new and 10 previously published datasets using logratio techniques reveals that the relationship is nonlinear and that the profusion of regression models is in part a function of the range of LOI. Although LOI may offer a crude estimate of OC at high LOI levels, OC/LOI ratios when LOI is less than about 25% are too variable for reliable OC estimation, and interstudy comparisons remain dubious. Direct measurement of OC is recommended.     

Acid‐soil‐stress influence on mineral‐ion contents of sorghum leaves and juvenile panicles

Sorghum [Sorghum bicolor (L.) Moench cv RTX430, SC214, SC574, SC599, TAM428, and SC326xSC103] were grown on soils of pH 4.2 or 6.2–6.5. Leaf and nonexserted juvenile panicle tissues were collected at 75 days after planting. Fresh and dry weights were measured and element contents [sulfur (S), phosphorus (P), magnesium (Mg), calcium (Ca), potassium (K), zinc (Zn), iron (Fe), and copper (Cu)] were measured by atomic absorption. Significant cultivar differences in ion concentration (μmol/g dry weight) were found. Juvenile panicles had higher ion concentration (μmol/g dry weight) [S, P, Mg, Ca, K, Zn, and Cu) than leaves. Within leaf tissue, ion concentration (μmol/g dry weight) was correlated with tissue water content (g water/g dry weight).     

The evolution of glucose‐6P‐dehydrogenase and 6P‐gluconate‐dehydrogenase activities and the ortho‐diphenolic content of sunflower leaves cultivated under different boron treatments.

Both enzymatic activities increased under B‐deficient and B‐toxic treatments. The ortho‐diphenolic content did not change with B levels.

Our results suggest that the primary B action on the OPP pathway is at the first enzyme (glucose‐6P‐dehydrogenase) level and that the B effect on 6P‐gluconate‐dehydrogenase is secondary to this. The B action on the enzymatic activities seems not to be caused by any direct interaction with substrates, as B infiltration of B‐deficient culture “in vivo”; seems to result in long term effects on cell structures and/or processes not easily r

In this paper the glucose‐6P‐dehydrogenase and 6P‐gluconate ‐ dehydrogenase activities and ortho‐diphenolic content of hydroponically‐cultivated sunflower‐leaves with moderately deficient, normal and toxic B levels were measured. The change in these parameters during time was considered, together with the restoration of enzymatic activities by means of borate infiltration of deficient and normal leaves. The micronutrient content of the leaves was alsversible by B infiltration of leaves. The positive correlation found between the 6P‐gluconate‐dehydrogenase activity and the Zn content in leaves might be interpretable as and indirect B effect on that activity through modification of Zn content.     

Distribution of sludge‐borne manganese in field‐grown maize

Abstract

The uptake and distribution of manganese (Mn) in field‐grown maize (Zea mays L.) was studied in a long‐term sewage sludge field trial on an acid sandy soil at Bordeaux. Since 1974, sewage sludge had been applied at levels of 101 dry matter (DM) ha^‐1 year^‐1 (SS 10) and 1001 DM ha^‐1 per 2 years (SS 100) on annually cropped maize plots. Treatment with farmyard manure (FYM) at a rate of 10 t DM ha^‐1 year^‐1 served as unpolluted control. Five replicate plants per treatment were examined at six different growth stages. At each stage, the whole plant was separated into its different organs and the Mn distribution was determined in at least 12 different plant parts. Manganese concentrations were always higher in SS 100 plants compared to FYM and SS 10 treated plants. Significant treatment‐dependent differences occurred almost all in the roots and in the different leaf levels while we found similar Mn concentrations in the stalk and in the reproductive organs. In the different stalk levels and in the ear composites we determined low Mn concentrations with critical deficiency values in FYM and SS 10 plants while Mn concentrations in SS 100 plants were in the normal range. Soil treatment also significantly influenced the initial absorption by the roots. Despite low absolute Mn concentrations in the roots of FYM plants, the Mn transfer coefficient (plant Mn concentration/soil Mn concentration) was highest in FYM plants and lowest in SS 100 plants indicating a relatively low Mn plant availability in the sludge‐treated plots.     

Loss‐on‐ignition as an estimator of soil organic carbon in a‐horizon forestry soils

Abstract

The determination of soil organic matter by wet digestion techniques is a slow and laborious analysis. Loss‐on‐ignition (LOI) provides a simple alternative technique for the estimation of soil organic carbon in non‐calcareous A horizon soils of the Natal midlands and Zululand forestry regions. Using multiple regressional techniques, the relationships between loss‐on‐ignition, Walkley organic carbon and soil texture for 55 soils were determined over a range of ignition temperatures. The relationships hold best for soil samples with relatively low organic carbon contents (< 5%). The optimum temperature for ignition was found to occur at 450°C and resulted in the relationship: Soil organic carbon = 0.284*LOI percent. No advantage is gained through ignition at higher temperatures due to the loss of clay mineral structural water, even if the soil texture is accurately known.     

Metal‐Associated Forms and Speciation in Biosolid‐Amended Oxisols

Abstract

The objective of this study was to determine the effects of pH and ionic strength on the distribution and speciation of zinc (Zn), copper (Cu), and cadmium (Cd) in surface soil samples from two Brazilian Oxisols amended with biosolids. Soils and biosolids were equilibrated in an experimental dual‐chamber diffusion apparatus that permits the soils and biosolids to react through a solution phase via diffusion across a membrane. After equilibrium was reached, soil and biosolids samples were sequentially fractionated to identify various solid forms of Zn, Cu, and Cd. Metal concentrations in the solution phase were determined and mass balance calculated. Equilibrating pH had no major effect on Cu solubility from biosolids and, at pH range from 4 to 7, most Cu remained in the biosolids. Soluble Zn and Cd concentration increased with decreasing pH because of the increased solubility of the biosolids. Copper and Zn were primarily associated with the residual fraction and Fe oxides in one soil, but were primarily associated with chemically unstable fractions, or adsorbed to the surface of oxides, in the other soil. In both soils, Cd was primarily associated with readily bioavailable fractions. The effect of pH on the metal distribution was more evident than the ionic strength effect. Free ions were the predominant metal species in solution, especially at lower pH values.     

Response of alfalfa to a phillipsite‐based slow‐release fertilizer

Abstract

A greenhouse experiment was conducted with alfalfa (Medicago sativa L. cv. Aragon wide leaf) to test the performance of a zeolite (phillipsite) phosphorus‐potassium (P‐K) fertilizer versus soluble potassium dihydrogen phosphate (KH₂PO₄) applied to a coarse‐textured substratum consisting of a mixture 1: 4 (in volume) soihbasaltic ash. Plants were sown at four fertilization rates and five harvests were collected after nine months. The nutrient content in plant tissue was higher in the plants treated with zeolitic fertilizer, although the response was primarily due to P. No differences due to the fertilizer source were observed for dry matter yield. When considering nutrient uptake, differences between the two fertilizers were enhanced, although the results for P are more pronounced. The soil nutrient content found after the experiment shows that available P was significantly higher in those pots that received the zeolite fertilizer, but no differences were found for K.     

Response of Corn Growth in Salt‐Affected Soils of Northeast China to Flue‐Gas Desulfurization By‐product

Abstract

In semiarid and arid regions, plant growth is limited by high pH, salinity, and poor physical properties of salt‐affected soils. A field experiment was conducted in the semiarid region of Kangping in northeast China (42°70′ N, 123°50′ E) to evaluate a soil‐management system that utilized a by‐product of flue‐gas desulfurization (FGD). Soil was treated with 23,100 kg ha^?1 of the by‐product. Results of corn growth were grouped into three grades (GD) according to stages of corn growth: GD1, seeds did not germinate; GD2, seeds germinated but corn was not harvested; and GD3, plants grew well and corn was harvested. The pH, electrical conductivity (EC), bicarbonate (HCO₃ ^?), carbonate (CO₃ ^2?), exchangeable and soluble calcium (Ca²⁺), chloride (Cl), and sulfate (SO₄ ^2?) in surface soils of the three grades (>20 cm) was measured to assess the correlation between corn growth and soil properties. Vertical differences in subsoil properties (0‐100 cm) between GD1 and GD3 were compared to known benchmark soil profiles. The FGD by‐product significantly increased EC, exchangeable and soluble Ca²⁺, and SO₄ ^2? and decreased CO₃ ^2?, exchangeable sodium (Na⁺), and soluble Na⁺. pH, EC, HCO₃ ^?, CO₃ ^2?, and Cl^? were higher in surface soils of GD1 than GD3. Soil hardness, soil moisture content, Cl^?, and calcium carbonate (CaCO₃) were higher in GD1 than in GD3, whereas the amount of available P was lower in GD1. Interestingly, the concentration of Cl^?, a toxic element for plant growth, was 2.5 and 1.5 times higher in GD1 than in GD3 and control soil, respectively. In the comparison study of subsoils, GD1 and GD3 were classified as having typical characteristics of saline‐alkali soil (pH>8.5; exchangeable‐sodium‐percentage [ESP]>15; EC>4.0) and alkali soil (pH>8.5; ESP>15; EC<4.0), respectively.     

Wirkung der bodenversauerung auf den N‐, P‐, K‐ und Mg‐gehalt junger Sommergerstepflanzen*

Auf 31 Ackerstandorten (Sand bis stark lehmiger Sand) mit sichtbarer Wachstumsminderung von Sommergerste infolge Bodenversauening wurden von geschädigter und gesunder Teilfläche Boden‐ und Pflanzenproben entnommen. Die Böden wurden auf den pH‐Wert (0,1 N KCl), den DL‐löslichen P‐ und K‐Gehalt sowie den Mg‐Gehalt nach Schachtschabel, die Pflanzenproben auf den N‐, P‐, K‐ und Mg‐Gehalt untersucht. Die Sommergerste war sichtbar geschädigt und im Wachstum gemindert, wenn der pH‐Wert des Bodens unter 4,6 lag. Unter den Bedingungen einer starken Bodenversauerung war der N‐, P‐, K‐ und Mg‐Gehalt der geschädigten Pflanzen im Vergleich zu den Vergleichspflanzen bis um 80% reduziert. Der pH‐Wert des Bodens korreliert mit den N‐, P‐ und K‐Gehalten der Pflanzen, jedoch nicht mit dem Mg‐Gehalt. Signifikante Beziehungen zwischen Gehalt im Boden und in der Pflanze liegen bei P, K und Mg vor. Induzierter Mangel, insbesondere an P und K, trägt nach diesen Ergebnissen zur Wachstumsminderung von Sommergerste auf stark versauerten Böden bei.     

Measurement of nitrous oxide emissions from grassland soil using photo‐acoustic infra‐red spectroscopy,long‐path infra‐red spectroscopy,gas chromatography,and continuous flow isotope‐ratio mass spectrometry

Abstract

This study evaluated the performance of photo‐acoustic infra‐red spectroscopy (PAIRS) for measuring nitrous oxide (N₂O) fluxes in the field, in comparison with long‐path infra‐red spectroscopy ('Hawk'), gas chromatography (GC), and continuous flow isotope‐ratio mass spectrometry (CF‐IRMS). The N₂O flux measurements from fertilized and grazed grassland were made simultaneously by the different methods, before and after water application. Before irrigation, mean N₂O fluxes ranged from 3 to 20 g N ha¹ day¹ for the PAIRS and GC measurements, but were undetectable with the Hawk. Within 2 hours of irrigation, mean fluxes increased to 740, 640, and 270 g N ha‘¹day¹, based on GC, PAIRS, and Hawk measurements, respectively. After about 24 hours, irrigation had reached its full effect and N₂O fluxes had increased to 1,050,710, and 410 g N ha¹ day¹. The GC measurements were consistently higher than the PAIRS measurements. However, a second experiment, comparing the PAIRS analyzer with continuous flow isotope‐ratio mass spectrometry (CF‐IRMS), suggested that the former was negatively biased; the PAIRS response was about 33% lower than CF‐IRMS. When the resulting correction factor was applied to the results of the first experiment, there was very good agreement between the PAIRS and GC measurements. The Hawk measurements were lower than PAIRS and GC, but a statistical comparison was not possible, due to the limited number of Hawk measurements that could be made in the windy weather conditions. Windy conditions also resulted in an underestimation of the N₂O flux by PAIRS compared to GC and CF‐IRMS analysis, which could not solely be attributed to a change in the analyzer sensitivity. There was no obvious explanation for this discrepancy and further investigations are needed to resolve this issue.     

Ion interactions in calcium‐efficient and calcium‐inefficient tomato lines 1

Two Ca‐efficient and 3 Ca‐inefficient tomato lines selected on the basis of dry matter production, Ca concentrations in tissues, and severity of Ca deficiency symptoms were grown in nutrient solutions containing 6 levels of total Ca ranging from 15 to 365 mg in 70 mg increments. All lines responded to increased Ca supply by increasing in dry weight and by accumulating Ca. The critical Ca concentrations in the shoots were 0.25% and 0.40% on a dry weight basis for the efficient and inefficient lines, respectively. Concentrations of Ca, K, Mg, P, and NO₃ ^‐ were lower in shoots and except for Mg were lower in roots of efficient plants than in the inefficient plants. For all lines as more Ca was available in the media and as Ca increased in the shoots and roots, the concentrations of the nutrients other than Ca declined. The declines in concentrations of K and Mg were not due to dilution by higher dry matter production in the efficient lines relative to the inefficient ones, although the total accumulation of Ca, P, and NO₃ ^‐ did not vary with Ca supplied. Antagonism among cations may account for differences in efficiency among lines of tomato.     

Orthophosphate and organic phosphate in the soil solution of four sandy soils in relation to pH‐evidence for humic‐FE‐(AL‐) phosphate complexes

Abstract

Soil from the Ap‐horizon of four acid sandy soils differing mainly in Corg content was adjusted to pH values between 3 and 7.5 with NaOH and HCl respectively and incubated for two weeks. Afterwards, displaced soil solution was obtained and analyzed.

The concentrations of Fe, Al, and P showed a broad minimum in the pH range from 4 to 6. The concentration of these elements strongly increased with the increase of pH to 7.5. Acidification below pH values of 4 led to a slight increase.

Separation of dissolved organic carbon by ultrafiltration before the photometric orthophosphate determination decreased measured concentrations in comparison to direct determination in two of the four soils. This decrease was more pronounced for soil solutions with higher concentrations of organic carbon. The effect of acid hydrolysis of organic phosphorus during orthophosphate determination can be explained by existence of humic‐Fe‐(Al phosphate complexes in the soil solution. These complexes can account for more than 50% of the total organic P in solution.     

Determination of organic matter content in arid‐zone soils using a simple “loss‐on‐ignition” method

Abstract

A simple and rapid procedure for the determination of organic matter content in mineral soils by loss‐on‐ignition without pretreatment was studied. Attention was given to the possible effect of inorganic compounds abundant in mineral soils on the estimation of organic matter content by this method. Both fast heating (DTA‐TGA type) studies and prolonged heating procedures were employed on natural and “synthetic”; soils. The results were compared to those obtained by the dichromate wet‐oxidation method widely used in soil laboratories for organic matter determination. In a group of 91 soils collected from various mineral soils in Israel, and having OM contents between 0.09 and 13.23%, a correlation coefficient of 0.972 was obtained for the linear regression between organic matter content measured by the proposed method and organic carbon measured by the dichromate wet‐oxidation method.