Effects Of Soil Phosphorus Research Articles

Aplikasi Pemberian Pupuk NPK dan Pengaturan Air terhadap P-Tersedia, Serapan P dan Hasil Padi Sawah (Oryza Sativa L.) pada Inceptisols Asal Jatinangor

This research was conducted to find out the effect of application NPK compound and water regulation on soil phosphorus, P uptake and yield of rice (Oryza sativa L.) on Inceptisols. The study was conducted from in late May to October 2015. at the field station of soil and water management, Soil Science and Land Resources Department, Faculty of Agriculture, Padjadjaran University, Jatinangor, Sumedang. The experimental design used was Randomized Block Design (RBD) with ten treatments and three replications, consisted of : without treatment (control), waterlogged 5 cm; 150 kg Ha-1, waterlogged 5 cm; 300 kg Ha-1, waterlogged 5 cm; 450 kg Ha-1, waterlogged 5 cm; 600 kg Ha-1, waterlogged 5 cm; 750 kg Ha-1, waterlogged 5 cm; local recommended dosage, waterlogged 5 cm; 450 kg Ha-1, macak-macak; 450 kg Ha-1, intermittent 1 day, macak-macak; 450 kg Ha-1, intermittent 3 days, macak-macak. The results showed that there were effect of soil phosphorus, P uptake and yield of Rice on Inceptisol. Suppy NPK dose of 750 kg ha-1 were waterlogged 5 cm provides the highest content of available P amounted to 51.88 ppm P, P uptake of 0.93% and the highest yield of 9.24 kg.ha-1.

The effects of soil phosphorus on aboveground biomass are mediated by functional diversity in a tropical cloud forest

Soil phosphorus is a key driver of plant biodiversity and aboveground biomass (AGB) in tropical forests. A plant community’s ability to exploit such limiting resources may be better represented by functional diversity than species or phylogenetic diversity, and may therefore have the higher predictive power regarding how soil phosphorus influences AGB in tropical forests. However, nearly no studies have tested this in tropical high-altitude forest ecosystems. Here we aim to test: 1) the relative influence of three biodiversity metrics (functional diversity, species diversity, and phylogenetic diversity) on aboveground biomass in a tropical cloud forest and 2) the interrelationships among soil phosphorus, biodiversity, and AGB in this ecosystem. In a tropical cloud forest in Hainan Island, China, we measured 13 key functional traits for 195 species in 48 plots of size 20 × 20 m2 each. We also measured soil phosphorus in all plots and computed the community phylogeny. Using this dataset, we tested the interrelationships among soil phosphorus, species diversity, functional diversity, phylogenetic diversity, and AGB using Generalized Additive Modeling and Redundancy Analysis. Functional diversity was significantly positively related to AGB, whereas species diversity and phylogenetic diversity were not significantly related to AGB. Functional diversity explained 53% of AGB, while species diversity and phylogenetic diversity only explained 17% and 6%, respectively. Soil phosphorus explained 56% of the variation in functional diversity, but only explained 22%, 13% and 21% of the variation in species diversity, phylogenetic diversity and AGB, respectively. Functional diversity, rather than species and phylogenetic diversity, are the better predictors of AGB. The influence of functional diversity on AGB appears to be linked to how variation in soil phosphorus affects functional diversity. We suggest that functional diversity should be incorporated into models that are designed to test how soil resources influence ecosystem function in tropical forest ecosystems.

The effects of soil phosphorus and zinc availability on plant responses to mycorrhizal fungi: a physiological and molecular assessment

The positive effects of arbuscular mycorrhizal fungi (AMF) have been demonstrated for plant biomass, and zinc (Zn) and phosphorus (P) uptake, under soil nutrient deficiency. Additionally, a number of Zn and P transporter genes are affected by mycorrhizal colonisation or implicated in the mycorrhizal pathway of uptake. However, a comprehensive study of plant physiology and gene expression simultaneously, remains to be undertaken. Medicago truncatula was grown at different soil P and Zn availabilities, with or without inoculation of Rhizophagus irregularis. Measures of biomass, shoot elemental concentrations, mycorrhizal colonisation, and expression of Zn transporter (ZIP) and phosphate transporter (PT) genes in the roots, were taken. Mycorrhizal plants had a greater tolerance of both P and Zn soil deficiency; there was also evidence of AMF protecting plants against excessive Zn accumulation at high soil Zn. The expression of all PT genes was interactive with both P availability and mycorrhizal colonisation. MtZIP5 expression was induced both by AMF and soil Zn deficiency, while MtZIP2 was down-regulated in mycorrhizal plants, and up-regulated with increasing soil Zn concentration. These findings provide the first comprehensive physiological and molecular picture of plant-mycorrhizal fungal symbiosis with regard to soil P and Zn availability. Mycorrhizal fungi conferred tolerance to soil Zn and P deficiency and this could be linked to the induction of the ZIP transporter gene MtZIP5, and the PT gene MtPT4.

Variable soil phosphorus effects on nitrogen nutrition, abundance and associated carbon costs of a savanna legume, Vachellia sieberiana grown in soils from varying altitudes

Vachellia sieberiana (DC.) Kyal. is a leguminous indigenous tree that occurs in savannas of southern and tropical Africa. The tree is known to tolerate frost, which possibly accounts for its presence in in high-altitude areas. However, there is less abundance of this tree in high-altitude areas of KwaZulu-Natal Province, South Africa. The aim of this study was to investigate if variation in soil phosphorus affected the tree growth and nitrogen nutrition, consequently reducing its abundance in high-altitude areas. Seeds of V. sieberiana were germinated and grown in the greenhouse in soils collected from three sites in the Van Reenen Pass area of KwaZulu-Natal Province (i.e. Zandspruit, altitude 1165 m; Wyford, altitude 1326 m; and Waterfall, altitude 1697 m). These sites had different V. sieberiana tree abundance, soil phosphorus (P) and nitrogen (N) nutrient concentrations. Although the nodulating rhizobia (Mesorhizobium sp.) in V. sieberiana root nodules were similar regardless of the differences in altitude as well as P and N concentrations, the total plant biomass and N source nutrition was altered. In this regard, V. sieberiana saplings grown in glasshouse conditions and in soils collected from Zandspruit accumulated more biomass, and relied on both atmospheric derived N and soil derived N. In addition, these V. sieberiana saplings had a higher total P and N concentration. The saplings grown in the Waterfall soil which had the lowest P and N concentration, relied equally on both atmospheric- and soil- derived N, and had an increased specific N utilisation rates and carbon construction costs compared with saplings grown in soils from the other two sites. The variation in soil P and N nutrient with increasing altitude affected growth and N source preference.

Effects of Phosphorus Supplies on the Nutritional Status of Maize (Zea mays L.)

The effects of soil phosphorus (P) supplies on the yield and nutritional status of maize and on interactions between individual nutrients was studied in a long-term maize fertilization experiment set up in 1989 on a chernozem meadow soil calcareous in the deeper layers, with four levels each of nitrogen (N), P, and potassium (K) supplies. The present article discusses the P fertilization results obtained in years 12–19 of the experiment, between 2001 and 2008. Depending on the P fertilizer level, the ammonium (NH4)–lactate (AL)–phosphorus pentoxide (P2O5) content of the ploughed layer ranged from 120 to 360 mg kg−1. Maximum grain yields were recorded at AL–phosphorus pentoxide (P2O5) levels of 160–220 mg. Leaf analysis at the beginning of tasselling indicated that, on the basis of correlation analysis on the maize leaf P concentration and the yield, the limit values for satisfactory P supplies were 0.20–0.37 P% for a yield level of 10–14 t ha−1. In most years the P supply level had an influence on the zinc (Zn) and copper (Cu) nutritional status of maize. The P-Zn antagonism that accompanies increasing P supplies was increasingly experienced from a soil AL-P2O5 level of 160 mg kg−1, and P-Cu antagonism from a level of 190 mg kg−1. The leaf Zn concentration required for a yield of 10–14 t ha−1 was 10–32 mg kg−1, with a P/Zn ratio of 80–330, whereas the satisfactory Cu concentration in the present experiments was 2–11 mg kg−1. In most years the satisfactory P/Cu ratio was 250–550, but high yields can still be achieved at a P/Cu ratio of 900–1100. The N, K, calcium (Ca), magnesium (Mg), iron (Fe), and manganese (Mn) concentrations of the maize leaf at tasselling were not influenced by the P supplies in the majority of years.

Soil Phosphorus Effects on Forage Harvested and Nitrogen Fixation on Canadian Organic Dairy Farms

Declining soil‐test phosphorus (STP) levels on eastern Canadian organic dairy farms is a concern because of potential negative impacts on forage growth and biological nitrogen fixation (BNF). This study examined the relationship between STP, forage productivity, and BNF on organic or transitional‐organic dairy farms in Ontario (ON) and Nova Scotia (NS). More than two‐thirds of 28 legume–grass mixed forage fields in the study were low in available P by provincial soil‐test guidelines. Averaged across all fields over 2 yr, forage legume proportion was 46%, forage harvested 5.9 Mg ha–1, BNF 64 kg ha–1, and N harvested 153 kg N ha–1. Forage tissue P concentrations were clearly correlated with STP in the low soil‐test categories (<10 mg Olsen P kg–1 of soil in ON; <30 mg Mehlich‐3 P kg–1 of soil in NS), above which there was little response. Inclusion of soil total P or organic P did not improve the fit of regressions. However, STP explained a very small fraction of variation in forage harvested and BNF. Ninety percent of tissue P concentrations were above 2 g P kg–1 of tissue, a frequently cited critical minimum, and the only apparently P deficient forage crops were on fields that received no manures or fertilizers for more than 5 yr. In the term of this study, low STP was apparently not having a significant impact on forage harvested or BNF on the majority of eastern Canadian organic dairy farms. This result may not apply to seedling‐year forages or other crops.

The effect of soil phosphorus on particulate phosphorus in land runoff

SummaryAccumulation of surplus phosphorus (P) in the soil and the resulting increased transport of P in land runoff contribute to freshwater eutrophication. The effects of increasing soil P (19–194 mg Olsen‐P (OP) kg−1) on the concentrations of particulate P (PP), and sorption properties (Qmax, k and EPCo) of suspended solids (SS) in overland flow from 15 unreplicated field plots established on a dispersive arable soil were measured over three monitoring periods under natural rainfall. Concentrations of PP in plot runoff increased linearly at a rate of 2.6 μg litre−1 per mg OP kg−1 of soil, but this rate was approximately 50% of the rate of increase in dissolved P (< 0.45 μm). Concentrations of SS in runoff were similar across all plots and contained a greater P sorption capacity (mean + 57%) than the soil because of enrichment with fine silt and clay (0.45–20 μm). As soil P increased, the P enrichment ratio of the SS declined exponentially, and the values of P saturation (Psat; 15–42%) and equilibrium P concentration (EPCo; 0.7–5.5 mg litre−1) in the SS fell within narrower ranges compared with the soils (6–74% and 0.1–10 mg litre−1, respectively). When OP was < 100 mg kg−1, Psat and EPCo values in the SS were smaller than those in the soil and vice‐versa, suggesting that eroding particles from soils with both average and high P fertility would release P on entering the local (Rosemaund) stream. Increasing soil OP from average to high P fertility increased the P content of the SS by approximately 10%, but had no significant (P > 0.05) effect on the Psat, or EPCo, of the SS. Management options to reduce soil P status as a means of reducing P losses in land runoff and minimizing eutrophication risk may therefore have more limited effect than is currently assumed in catchment management.

SHORT COMMUNICATION: On Scientific Publications

The effect of soil phosphorus (P) administered to the host plant on the growth of external hyphae of Gigaspora margarita was investigated in a glasshouse experiment using pots divided into three compartments i.e. one for donor plants (DPC), one for external fungal hyphae (EHC) and one for receiver plants (RPC) respectively. The DPC was filled with a sterilized soil/sand mix previously set up to have 5, 16 or 26 mg Bray-1 P kg-1 soil (P1, P2,or P3; categorized as low, intermediate or high level of P-availability) at pH 5.3 and inoculated with and without the fungal inoculums, while the RPC was filled with P3 without inoculation. Two pre-germinated seeds of cowpea were then grown there for 2 weeks before filling the EHC with the original sterilized soil/sand mix having pH 4.6 and 12 mg Al3+ kg-1 soil. These plants were harvested after further grown for 4-8 weeks. P fertilizer induced different growth conditions of host plants, which could control the production of external hyphae by the fungal partner. In supporting G. margarita to develop an optimum extent of external hyphae in acidic soils with a toxic level of Al3+, cowpea plants required soil P availabilities at about the intermediate level.

Soil N and P affected reflectance signatures of individual Colophospermum mopane leaves

Reflectance and derivative spectra of greenhouse‐grown mopane (Colophospermum mopane) were analyzed to investigate whether the interactive effect of soil phosphorus and nitrogen treatments on plant‐chemical composition can be detected using non‐destructive techniques. Reflectance spectra were affected by changes in soil nitrogen. Derivative spectra showed significant differences as a result of nitrogen and phosphorus treatment. Several spectral bands that showed different spectral signatures between soil treatments also showed significant correlation to condensed tannin, phosphorus and nitrogen concentration in mopane leaves. This shows the potential to detect the effect of soil properties on the plant's physiology with hyperspectral remote sensing.

Effect of Soil Phosphorus on Leaf Development and Senescence Dynamics of Field‐Grown Maize

Phosphorus deficiency generally decreases plant biomass accumulation by limiting interception of photosynthetically active radiation (PAR) rather than reducing efficiency of conversion of PAR into dry matter. To document the role of P availability in leaf growth and senescence dynamics in maize (Zea mays L.), a 3‐yr field experiment was conducted in southern France with very low, moderate, high, or very high soil test P levels. Leaf appearance rate, individual leaf area, and green fraction changes were recorded at weekly intervals. Rates and duration of expansion and senescence processes were derived independently from fitted logistic functions. Phosphorus deficiency slowed the rate of leaf appearance and reduced the final area of leaves located below the main ear by 18 to 27%, depending on year. The reduction in leaf expansion rates accounted for most of the area reduction over leaf position and years. Senescence rates of the lower leaves were reduced by 29%. The expansion and senescence dynamics of upper leaves were little affected by soil P level. The whole plant peak green leaf area was lower under P‐stressed conditions (16%), and its date of occurrence was significantly delayed (6%). Plant senescence rate was reduced by 15 to 33% during most of the grain filling period. Leaf area duration from emergence to complete senescence was reduced by 13.5%. The early effects of P deficiency on leaf dynamics accounted for most of the 7 to 10% reduction in the amount of absorbed PAR, observed as soon as canopy development allowed maximum light interception.

The effect of soil phosphorus on the external mycelium growth of arbuscular mycorrhizal fungi during the early stages of mycorrhiza formation

The effects of soil P amendments and time of application on the formation of external mycelium by different arbuscular mycorrhizal (AM) fungi were studied. In the first experiment the external mycelium produced in the soil by the AM fungus Glomus etunicatum Beck. and Gerd., during the early stages of root colonization (7 and 14 days after inoculation), was quantified by the soil-agar film technique. A Brazilian Oxisol was used with three different phosphate levels, varying from deficient to supra-optimal for the plant. Significant differences were observed in the phosphate and inoculation treatments for plant dry weight, P content in the tissue, root length and root colonization, at fourteen days after planting. At 7 days, mycelium growth, root colonization and their relationship were reduced at supra-optimal P concentrations. Applications of P one week after planting reduced mycelium growth and root colonization more than when applied to the soil before planting. In a second experiment the arbuscular mycorrhizal (AM) fungi, Scutellospora heterogama (Nicol. and Gerd.) Walker and Sanders and E3 were tested and compared with Glomus etunicatum. For the species studied, the length of external hyphae per unit of colonized root length was affected by small P additions but no further significant differences were observed at high P levels. The three AM endophytes showed marked differences in their response to P in the soil: Scutellospora heterogama, although producing external mycelium more profusely than the Glomus spp., showed a higher sensitivity to soil P supply.

The development of mycorrhizal infection in cucumber: effects of P supply on root growth, formation of entry points and growth of infection units

summaryThis paper describes an experiment in which the effects of soil phosphorus (P) on root growth and mycorrhizal colonization of Cucumis salivus L. were studied. The aim was to determine the relative contributions of root growth, formation of new infections and growth of infections within the root to the % colonization. Plants were harvested daily between 7 and 24 d. Added P had no effect on root or shoot f. wt or on root length up to 14 d. After that time plants given additional P grew well, but those with no added P grew poorly and showed signs of P deficiency. Increase in root length with added P was due both to an increase in the number of root apices produced per unit length of root per unit time and to an increase in the mean rate of extension of those apices. Effects of P on the % colonization of the roots by the mycorrhizal fungus Glomus intraradices Schenk and Smith were apparent before any effects on root length were observed. The length of the lag phase was not affected by addition of P. The rate of formation of new entry points was similar with and without added P up to 15 d, and reduction in % colonization up to this time could be attributed entirely to reduction in the rate of growth of infection units within the roots. Later, there was a marked increase in the rate of formation of (secondary) entry points in the absence of added P, which was not observed when P was added. At 15, 20 and 25 d, additional plants were harvested to quantify the development of arbuscules and vesicles in colonized regions of the roots. At all three times, numbers of arbuscules and vesicles were lower with added P. We conclude that at very early stages of colonization P exerts its effect via reduced growth of infection units. After approx. 2 wk, an increase in the rate of growth in length of roots and low rates of formation of secondary infections also contribute to the low values of % colonization.

Effects of soil phosphorus and Glomus intraradices on growth, nonstructural carbohydrates, and photosynthetic activity of Citrus aurantium

Sour orange (Citrus aurantium L.) grown in low-P (9–12 ppm) and high-P (420 ppm) soil inoculated with or without Glomus intraradices (G.i.), were evaluated for biomass, carbohydrates, ribulose bisphosphate carboxylase (RuBPCase), phosphoenolpyruvate carboxylase (PEPCase) activity, leaf 14CO2 incorporation, and other physiological parameters. Growth of plants in the low-P, noninoculated soil was lowest, with total dry biomass reduced up to half of the low-P, inoculum treatment. Total nonstructural carbohydrates were 40% lower in leaves of plants in the low-P, noninoculated soil, compared with the other treatments. Inoculation of the low-P soil enhanced leaf 14CO2 incorporation by 67%, total chlorophyll content by 28%, and RuBPCase activity by 42%, compared with low-P, noninoculated treatment. Improved P-use efficiency by G.i. in low-P soil was comparable to high-P nutrition in improving leaf 14CO2 incorporation and concentration of major leaf photosynthetic products that include starch and sucrose. Leaf PEPCase activity in the low-P, noninoculated treatment, however, was at least threefold higher than the other treatments, suggesting a possible alteration in organic acid metabolism in sour orange leaves as a result of P deficiency.

Effects of Soil Phosphorus on Growth and Minor Element Nutrition of Citrus

The effect of phosphorus fertilization of three different soils on the growth and minor element nutrition of citrus was evaluated in greenhouse studies. These soils were collected from uncultivated areas in San Diego County, Calif., where citrus had benefited from P fertilization. The soils were placed in 3-gallon crocks and treated with monocalcium phosphate in amounts equivalent to 0, 76, 360, and 900 lbs. P per acre. Budded lemons and/or sour orange seedlings were subsequently planted in these soils. After 6 months of growth the plant tops were harvested, weighed, and analyzed. In later experiments the soils were pretreated with Cu at the rate of 20 ppm. Cu, and tested for P interrelations using only sour orange seedlings as indicator plants. Severe Cu deficiencies were induced in the citrus plants by as little as 360 lbs. P per acre. Plant growth in the soils treated with high concentrations of P was greatly reduced when compared to that of the controls. Typical symptoms of Cu deficiency as well as markedly reduced leaf Cu values were associated with the heavy P treatments. Pretreating the soil with Cu at the rate of 20 ppm. Cu only partially modified the P-Cu effect. Zinc absorption also was reduced by excessive P fertilization. Iron and Mn appeared to be unaffected.