Growth Behavior,Nitrogen-Form Effects on Phosphorus Acquisition,and Phosphorus–Zinc Interactions in Brassica Cultivars under Phosphorus-Stress Environment

Phosphorus (P) and zinc (Zn) interact both in plants and soils and hence may affect the availability and utilization of each other. To investigate P and Zn nutritional status and P–Zn interactions, two genetically diverse Brassica cultivars classified as P tolerant (Brown Raya) and P sensitive (Sultan Raya) were grown in a sand-based pot culture. Jordan rock phosphate (RP) and monocalcium phosphate [Ca(H₂PO₄)₂] were used as P sources, and ammonium nitrate (NH₄NO₃) or nitrate (NO₃ ^--) only were used as nitrogen (N) sources. Two Zn levels [0.25 (low Zn) and 2.5 (high Zn) mg zinc sulfate (ZnSO₄·5H₂O) kg^?1 sand, respectively] were applied along with recommended doses of other essential nutrients in the culture media. Cultivars differed significantly for their response to added P for biomass accumulation, but Zn supply had little effect. Cultivar Brown Raya had greater P uptake and P-utilization efficiency (PUE) than Sultan Raya under a P-stress environment, irrespective of Zn and N supply. Zinc supply had little effect on tissue P concentration and P uptake per unit of root dry matter (RDM) in either cultivar, irrespective of N supply. An increase in P supply caused a significant reduction in specific Zn uptake (Zn uptake per unit of RDM; SZnU) and tissue Zn concentration of both cultivars. The reduction in tissue Zn concentration cannot be ascribed entirely to a dilution effect. Zinc concentrations and uptake by P-efficient cultivar Brown Raya were significantly lower and more sensitive to P uptake than those of P-sensitive Sultan Raya cultivar. It is suggested that high PUE may depress plant Zn uptake and therefore cause a reduction in Zn concentration of Brassica grown in low-P and possibly low-Zn soils. In NH₄NO₃ nutrition, plants had significantly lower cation concentrations compared to NO₃ ^-- nutrition only. Brown Raya consistently had lower cation concentrations than Sultan Raya under P stress. The differences in cation concentrations decreased with increased P availability, but Zn supply had no significant effect. In Brown Raya, the ratio of potassium in roots to shoots was always greater than in Sultan Raya. This suggested that lower cation concentrations in Brown Raya were due to root carboxylate exudations, which in turn were related to better P acquisition and PUE under insufficiently buffered P-stress environment.     

Transformation of Applied Phosphorus in a Calcareous Fluvisol

A new inorganic phosphorus (IP) fractionation scheme developed by Jiang and Gu was used in an incubation experiment to investigate the transformation of applied P in a calcareous fluvisol. The results show that after addition of common superphosphate (CSP), the Ca2-P in the soil decreased gradually and transformed largely to the less available Fe-P, Al-P and Ca8-P, rather than to the unavailable forms of Ca10-P and O-P. The different IP fractions ranked in the following order with respect to the increment by addition of CSP after 120 days of incubation: Fe-P> Al-P>Ca8-P>Ca2-P. After addition of pig manure, the content of Ca2-P in the soil increased rapidly at first and then decreased slowly, and the amount of different IP fractions accumulated after 120 days of incubation ranked in the following order: Ca2-P > Fe-P > Ca8-P > Al-P.     

Residual Effect of Phosphorus Fertilizer in a Low‐Humic Andosol with Low Extractable Phosphorus

Abstract

Phosphorus (P) fertilization is quite important for crop production grown on Andosols. Fertilizer P‐use efficiency was 17% in a long‐term wheat experiment on a low‐humic Andosol. Residual effects of P fertilization were investigated using field soils in pot experiments. Topsoil was collected from the plots with or without annual P fertilizer at the rate of 65 kg‐P ha^?1 for 23 years (nitrogen phosphorous potassium (NPK) soil and nitrogen potassium (NK) soil, respectively). There was no significant difference in dry matter of wheat and P uptake between NPK and NK soils. However, dry matter of rice and P uptake were higher in NPK soil than in NK soil. Inorganic aluminum P (Al‐P_i) and iron P (Fe‐P_i) increased in NPK soil. Increase in Al‐P_i and Fe‐P_i during 23 years contributed little to P uptake by wheat, and repeated P fertilization is indispensable to obtain acceptable grain yield.     

Phosphorus relationships in no‐till small grains

Abstract

Phosphorus (P) fertilizer recommendations for no‐till small grain production are poorly defined. These studies were conducted to determine small grain‐P response relative to the Olsen‐P soil test and compare P‐fertilizer placements with the seed and banded below and to the side of the seed under no‐till field conditions. Phosphorus rates of 0 to 26 kg P/ha were evaluated on seven spring barley (Hordeum vulgare L.), 11 spring wheat, and six winter wheat (Triticum aestivum L.) locations in central and northcentral Montana between 1986 and 1990. Grain yield, grain protein, test weight, above‐ground crop yield, plant P concentration at maturity, and P uptake were measured. One winter wheat location had a significant yield response to P; all other locations had non‐significant yield responses. Grain protein, test weight, P concentration, and P uptake were all unaffected by P rate or P placement. Both the ANOVA and paired t‐test were used to analyze the P‐placement data and were all nonsignificant. Slopes of grain yield response (grain yield for each P rate minus the grain yield without P), P concentration, and P uptake versus P rate were analyzed with the t‐test; none of the P‐response slopes were greater than zero. The P responses by individual crop were regressed against P rate, Olsen‐P soil test, available soil water at planting, and pH. Phosphorus rate was not a significant factor in any of the equations. Significant and useful predictive equations for grain yield response could not be generated; however, equations predicting P concentration and P uptake were developed. The Cate‐Nelson graphical analysis was unsuccessful in estimating an Olsen‐P soil test critical level. All attempts failed to relate grain yield or grain yield response to the Olsen‐P soil test and/or P rate. When P soil tests are higher than 12 mg/kg, no‐till grain growers should consider applying a maintenance level of P fertilizer, about 5 to 10 kg P/ha either banded below or with the seed, to maintain soil P levels.     

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.     

Fractionation of Zinc in Paddy Soils of China

The rice fields in China amount to 25.4 million hectares of which low yield paddy soils areabout 26％(Xu,1981;Xiao,1981).One of the most important causes of low yield is the defi-ciency in nutrients including zinc.Zinc deficiency usually occurs in calcareous paddy soils withpH>6.5(Zhu and Liu,1981).And the availability of zinc in calcareous paddy soils is lowerthan that in neutral and acid paddy soils.     

Microspectroscopy – Promising Techniques to Characterize Phosphorus in Soil

Phosphorus (P) is an essential element for all forms of life and is applied as fertilizer in agriculture. The P availability for plants may be highly dependent on the chemical state of P in fertilizers and soils; however, the nature of this dependence remains obscure due to the limitations of generally applied wet chemical and instrumental analytical approaches. This paper focuses on recently developed infrared, Raman, ultraviolet and X-ray microspectroscopic techniques for the characterization of P in soil. Microspectroscopic techniques have the advantage that discrete P phases can be distinguished and characterized even if their mass fractions are very low. However, only small volumes of soil can be analyzed by microspectroscopic methods hence a combination of macro- and microspectroscopic techniques is a promising concept.     

Zinc‐boron interaction effects in oilseed rape

The interaction effect of applied zinc (Zn) and boron (B) on early vegetative growth and uptake of Zn and B by two oilseed rape (canola) (Brassica napus L.) genotypes was investigated in a sand culture experiment under controlled environmental conditions. Two genotypes (Yickadee and Dunkeld) were grown at three Zn levels (0.05, 0.25, and 2.0 mg kg^‐1 soil) and two B levels (0.05 mg kg^‐1 soil and 0.5 mg kg^‐1 soil). Dunkeld produced significantly higher shoot and root dry matter than Yickadee at low Zn and low B supply indicating the superiority of Dunkeld over Yickadee for tolerance to both low Zn and low B supply. Chlorophyll content of fresh leaf tissue was increased significantly by an increase in Zn and B supply. Zinc deficiency enhanced B concentration in younger and older leaves. Boron concentration was higher in older leaves than in the younger leaves irrespective of B deficiency and sufficiency indicating immobility of B in two oilseed rape genotypes tested. Zinc concentration was higher in younger leaves than in the older leaves indicating mobility of Zn. An increased supply of Zn enhanced B uptake under high boron supply only. Zinc uptake in Dunkeld was enhanced significantly with an increased rate of B supply under high Zn supply, while the effect was not significant in Yickadee. Dunkeld proved to be more efficient in Zn and B uptake than Yickadee.     

Effect of Zinc Humate on Growth of Soybean and Wheat in Zinc‐Deficient Calcareous Soil

Abstract

Humic acids have many benefits for plant growth and development, and these effects may be maximized if these materials are combined with micronutrient applications. In the present study, pot experiments were conducted to evaluate the effects of zinc (Zn) humate and ZnSO₄ on growth of wheat and soybean in a severely Zn‐deficient calcareous soil (DTPA‐Zn: 0.10 mg kg^?1 soil). Plants were grown for 24 (wheat) and 28 days (soybean) with 0 or 5 mg kg^?1 of Zn as either ZnSO₄ or Zn humate. Zinc humate used in the experiments was obtained from Humintech GmbH, Germany, and contained 5% of Zn. When Zn was not supplied, plants rapidly developed visible symptoms of Zn deficiency (e.g., chlorosis and brown patches on young leaves in soybean and necrotic patches on middle‐aged leaves in wheat). Adding Zn humate eliminated Zn‐deficiency symptoms and enhanced dry matter production by 50% in soybean and 120% in wheat. Zinc‐humate and ZnSO₄ were similarly effective in increasing dry matter production in wheat; but Zn humate increased soybean dry matter more than ZnSO₄. When Zn was not supplied, Zn concentrations were 6 mg kg^?1 for wheat and 8 mg kg^?1 for soybean. Application of Zn humate and ZnSO₄ increased shoot Zn concentration of plants to 36 and 34 mg kg^?1 in wheat and to 13 and 18 mg kg^?1 in soybean, respectively. The results indicate that soybean and wheat plants can efficiently utilize Zn chelated to humic acid in calcareous soils, and this utilization is comparable to the utilization of Zn from ZnSO₄. Under Zn‐deficient soil conditions, plant growth and yield can be maximized by the combined positive effects of Zn and humic acids.     

Influence of Organic Manure on Organic Phosphorus Fraction in Soils

The transformation of organic P(Po) from organic manures in two types of soils (ultisol and entisol) and the influences of external addition of organic substance or inorganic P(Pi) on Po under the condition of the 60% maximum water capacity were investigated.The results obtained from Po fractionation experiments indicated that all the Po fractions except for the highly resistant Po fraction decreased during incubation.Application of pig feces and cow feces could largely increase each fraction of Po in the soils.Immediately after application of organic manure into the soils a large part of labile and moderately labile Po from organic manure was transferred into moderately resistant Po,which might be due to the fact that Ca-or Mg-inositol P was precipitated into Fe-inositol P.However,the availability of Po from organic manure in the soils would increase again after incubation because of the transformation of moderately labile and resistant Po fractions into labile Po fractions.Addition of cellulose or Pi into the soils showed a good effect on increasing all the Po fractions except for the highly resistant Po,and this effect was much more pronounced when cellulose was applied in combination with Pi.Therefore,in view of the effect of organic manure on improving P nutrition to plant,attention should be paid to both the Po and the organic substances from organic manure,It is suggested that application of Pi fertilizer combined with organic manure may be referred to as an effective means of protecting Pi from chemical fixation in soil.     

Relative Efficiency of Zinc Sulfate and Zinc Oxide–Coated Urea in Rice–Wheat Cropping System

Abstract

Rice–wheat cropping system covers about 24 million hectares in China, India, Pakistan, Nepal, and Bangladesh, and zinc deficiency is widespread in rice–wheat belts of all these five countries. The current practice of applying zinc sulfate heptahydrate (ZnSO₄ · 7H₂O) to soil is problematic because of the poor quality of the nutrients available in the market to the farmers. Zinc (Zn)–coated urea is therefore being manufactured to guarantee a good‐quality Zn source. This article reports the results from a field study conducted to study the relative efficiency of zinc sulfate and zinc oxide (ZnO)–coated ureas in rice–wheat cropping system. The highest grain yield of rice–wheat cropping system was obtained with 2.0% coating of urea. Zinc sulfate was also a better coating material than ZnO. Partial factor productivity, agronomic efficiency, apparent recovery, and physiological efficiency of applied Zn decreased as the level of Zn coating was increased.     

Zinc Nutrition in ‘Nagpur’ Mandarin on Haplustert

ABSTRACT

Zinc (Zn) deficiency is the most prevalent nutritional disorder in citrus orchards world over. The management strategy of Zn deficiency today is still governed by the efficacy of two conventionally used methods of Zn supply to plants via soil or foliar fertilization. A field experiment with 12-yr-old ‘Nagpur’ mandarin (Citrus reticulata Blanco) orchard was, therefore, carried out during 2004–07 comparing soil application versus foliar application of Zn, each at three levels viz., 100, 200, and 300 g tree^?1 with constant doses of N (600 g tree^?1), P (200 g tree^?1), K (300 g tree^?1), and Fe(60 g tree^?1) on Haplustert soil type with reference to response on flowering intensity, fruit set, tree volume, fruit yield, changes in soil fertility/leaf nutrient status, fruit quality, and transformation of native soil Zn fractions. Soil application of Zn at all the three levels, produced significantly higher increase in tree volume over foliar application on equivalent rates viz., T₁ (2.53 m³) vs. T₄ (2.06 m³) and T₂(4.30 m³) vs. T₅ (2.23 m³). The yield-determining parameters like flowering and fruit set intensity (no. m^?1 shoot length) were, respectively, much higher with soil applied (135.74 and 21.90) than foliar applied Zn (31.20 and 11.6). These observations set the favorable conditions required for yield response, e.g., all the three treatments involving soil application of Zn, T₁ (32.1 kg tree^?1), T₂ (52.6 kg tree^?1), and T₃ (51.8 kg tree^?1) were correspondingly superior over T₄ (22.5 kg tree^?1), T₅ (34.3 kg tree^?1), and T₆ (42.1 kg tree^?1) as foliar application treatments. All the three major fruit quality parameters (juice, acidity, and TSS) were likewise more influenced by soil application than foliar application of Zn. Improvements in soil Zn fractions (mg kg^?1) viz., exchangeable Zn (0.25–0.60), complex-Zn (2.71 to 4.86), organically bound Zn (0.86 to 2.0), and Zn-bound to carbonates and acid soluble minerals (2.56–4.96) were observed in response to Zn fertilization with treatments T₁–T_3. On the other hand, foliar applied Zn treatments (T₄–T₆) produced no such changes in any of the soil Zn fractions.     

Differences in Root Exudation Among Phosphorus‐Starved Genotypes of Maize and Green Gram and Its Relationship with Phosphorus Uptake

Abstract

Availability of phosphorus (P) in soil and its acquisition by plants is affected by the release of high and low molecular weight root exudates. A study was carried out to ascertain the qualitative and quantitative differences in root exudation among the genotypes of maize (Zea mays L.) and green gram (Vigna radiata L.) under P‐stress. Results showed that both inter‐ and intra‐species differences do exist among maize and green gram in terms of root exudation, P uptake, and shoot and root P content. In general, green gram, a legume crop, had greater root exudation compared to maize. However, the amino acid content of the total root exudates in maize was two‐fold as compared to green gram. The maize and green gram genotypes possessed genetic variability in root exudation. Irrespective of the species or genotypes, a positive relationship was found among P uptake rates, total root exudation, and shoot and root ³²P content. The amount of sugars and amino acid present in the root exudates of P‐starved seedlings also add to the variation in P uptake efficiency of genotypes.     

Transformation and Availability of Various Forms of Zinc in Soils

The transformation and availability of various forms of Zn applied into a cinnamon soil and a carbonate meadow soil as well as the effects of fertillizer-P on them were studied by using the field experiment method and chemically sequential extraction procedure.Zn added into the soils was found to be rapidly transformed into the various forms. In the cinnamon soil,the amount of Zn transformed into the carbonate bound form was the highest,and the carbonate bound form was proven by the analyses of intensity factor and capacity factor to be the primary available Zn pool.But in the carbonate meadow soil,the Zn transformed was relatively homogeneously distributed in the various forms though the amount of Zn transformed into the Mn-oxide bound form was relatively high,and the organically bound,Mn-oxide bound and amorphous Fe-oxide,bound forms were found to be the main available Zn pool.Fertilizer-P took part in the regulation and control of available Zn in the soils to a certain degree.In the carbonate meadow soil,application of P fertilizer probably aggravated Zn deficiency at low Zn rate,while it was favorable to the storage of available Zn in the case of high Zn rate.     

Effect of Submergence on Iron Transformation and Phosphorus Availability in Calcareous Soils

A thermostatic incubation experiment was carried out to estimate the effects of flooding periods,stalk application and P addition of Fe transformation and P availability in calcareous soils.Submergence increased amorphous Fe,especially in the case of stalk application.The newly formed amorphous Fe with a great surface area played an important role in Psorption;and submergence also stimulated the dissolution of inorganic P,thus increasing the availability of soil P in calcareous soils.Meanwhile,a part of soluble P was absorbed and fixed again on the surface of newly formed amorphous Fe,thus resulting in a decrease of P availability.Soil rapidly available P increased after 150-day incubation.There existed significantly negative correlations between soil amorphous Fe content and soil Fe-P and rapidly available P contents.Submerged conditions promoted the transformation of inorganic P added toward Fe-P in calcareous soils,especially in the case of stalk application.     

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.     

Cadmium Uptake by Lettuce in Fields Treated with Cadmium‐Spiked Phosphorus Fertilizers

The rate of cadmium (Cd) uptake by lettuce (Lactuca savita var. longifolia) over an entire growing season was investigated in a field treated with phosphorus (P) fertilizers spiked to different Cd levels. Romaine lettuce was planted following the standard cultivation practices. Over the growing period, soil and plant samples were taken to determine the total soil Cd content, Cd concentration of 1:0.5 (soil‐to‐water) extracts, and Cd content of plant tissue. Results indicated that lettuce can accumulate as much as 20 mg Cd per kilogram dry biomass without adverse effects on growth. The Cd content in the plant tissues decreased exponentially with time, indicating a dilution factor existing along with the plant growth. The plant uptake rate on a per‐unit‐area basis increased over time and can be simulated by a sigmoid pattern model. The plant uptake coefficient (α, L solution kg biomass^?1 day^?1) decreased as the Cd treatment level increased.     

Phosphorus‐sorption characteristics of intensely weathered soils in south‐central kentucky

Abstract

Studies were conducted to investigate phosphorus (P)‐sorption characteristics of some intensely weathered soils in south‐central Kentucky. Phosphorus adsorption characteristics reflected the chemical and mineralogical properties of the soils studied. All adsorption data were adequately described by first order kinetic reactions which implied that the soils have uniform surfaces for P sorption. In spite of the limitations of the Langmuir equation, its usefulness in summarizing data into one adsorption maximum value was demonstrated by nearly identical adsorption maxima estimated by three linear transformations of the equation and small deviations from the observed maxima. Variations in adsorption maxima between surface and subsoils and among soils were best correlated with extractable aluminum (Al) (r = 0.93, p<0.01) and crystalline iron (Fe) oxy‐hydroxides (r = 0.97, p<0.01). Clay content was also highly correlated with P sorption (r = 0.97, p <0.01) as well as with extractable Al (r = 0.83, p<0.05) and crystalline Fe oxides (r = 0.92, p<0.01) suggesting that its contribution may have been through its association with these soil components. In contrast, organic matter had a negative association with P sorption (r = ‐0.83, p<0.05). The results indicate higher P sorption in subsoil than in surface horizons, controlled mainly by extractable Al and crystalline Fe oxyhydroxides.     

Magnesium,Potassium and Phosphorus in Available Forms in Luvisols in the Vicinity of Głogów Copper Smelter

Region near G?ogów is characterized as industrial—agricultural area, intensively used. Presented study was undertaken to estimate the impact of agricultural land use and the vicinity of G?ogów copper smelter on the contents of available forms of magnesium, phosphorus and potassium in selected profiles of Luvisols. The following analysis were performed: soil particle-size distribution, pH, organic carbon contents, CaCO₃ contents. The contents of available forms of phosphorus and potassium were determined by Egner- Riehm method and that of magnesium using Schachtschabel’s method. The results of the study showed that the contents of available P is medium (III class of abundance), very low in K (V class) and for available Mg very low (V class) to medium for surface horizons and very high (I class of abundance) in other soil horizons. The soils, in spite of the elevated copper content in humus horizons, according to IUNG, were classified as uncontaminated soils, therefore, can be used in plant production for all types of crops.     

Phosphorus Mobility Through Soil Increased with Organic Acid-Bonded Phosphorus Fertilizer (Carbond® P)

Phosphorus fertilizer is critical to crop production but inefficiently absorbed and consequently linked to surface water pollution. Phosphorus mobility was measured on three soils using 0.18 m soil columns treated with Carbond® P (CBP, 7-24-0), ammonium polyphosphate (APP, 10-34-0) and monoammonium phosphate (MAP, 11-52-0) applied either by mixing thoroughly or in concentrated bands at rates of 20 and 30 kg P ha^?1. Mobility of P was measured in leachate collected 24, 48, 110 and 365 d after fertilization (daf). Carbond® P produced the highest total P leachate values over 365 d study period compared to MAP or APP for both mixed and band applications. On individual days, CBP generally allowed more soluble P leachate than MAP or APP up until 110 daf (one exception) but not at 365 daf. Higher solubility of P with CBP explains higher P uptake by plants from soils and could reduce total P applications to crops.