Phosphorus Rates on Growth Parameters of Maize (Zea mays L.) in Reddish Brown Earth under Greenhouse Condition

Phosphorus is an essential element for plants. However, many soils lack sufficient in formthat is readily available to crops to ensure optimum growth especially in dry zone soils in SriLanka. Hence, this study was undertaken with the objective of evaluating the impact ofdifferent rates of Triple Super Phosphate (TSP) as a source of Phosphorus for maize (Var.Sampath) growth under greenhouse condition. Top soils at a depth of 0-25 cm were collectedfrom research farm, Puliyankulama and from a farmland in Kahatagasdigiliya, Anuradhapuradistrict. Greenhouse experiment conducted for both soils. Twenty pots were arranged in acompletely randomized design with four treatments (0, 20, 30 and 40 kg of Phosphorus ha-1)and five replicates for a single experiment. Soil samples were taken at 4, 8, 10, 12 and 16weeks after planting (WAP). The soil samples were analysed for soil pH, electricalconductivity (EC) and available Phosphorus (Olsen’s method). The leaf Phosphorus contentat 50% tasseling stage was measured using dry ash method. The growth parameters wereplant heights at 4, 8, 10 and 12 WAP, number of days to 50% tasseling and number of days to80% silking. Results indicate soil pH, EC, and leaf Phosphorus % are not significantlydifferent (p<0.05) at different levels of Phosphorus in both locations. However, soil availablePhosphorus is significantly different (p<0.05) to the control. Conversely it does not showsignificant different (p<0.05) among fertilized treatments at both sites. Moreover, plant heightat 50% tasseling stage, number of days to 50% tasseling and number of days to 80% silkingare not significantly different (p<0.05) among any treatments at both soil types. Hence, theresults further revealed that the different levels of P treatments have no significant effect onsoil pH, EC, available P, leaf P and growth parameters of maize variety Sampath undergreenhouse conditions.

Phosphorus Release from Unamended and Gypsum- or Biochar-Amended Soils under Simulated Snowmelt and Summer Flooding Conditions

Prolonged flooding changes the oxidation–reduction status of soils, often enhancing P release to overlying floodwater. We studied P release from unamended, gypsum-amended, and biochar-amended soils under simulated snowmelt flooding (previously frozen, cold flooding at +4°C) and summer flooding (unfrozen, warm flooding at +22°C) using two soils, Fyala clay (FYL-Cl) and Neuenberg sandy loam (NBG-SL), from Manitoba, Canada. Amended and unamended soils were packed into vessels and flooded under cold and warm temperatures in the laboratory. Pore water and floodwater samples were taken weekly for 6 wk after flooding (WAF) and thereafter biweekly for 10 WAF and analyzed for dissolved reactive P (DRP), pH, and cation concentrations. The NBG-SL showed a significantly higher DRP concentration in pore water and floodwater despite its low Olsen P content. Redox potential (Eh) decreased slowly under cold versus warm flooding; hence, redox-induced P release was substantially lower under cold flooding. Gypsum amendment significantly decreased the floodwater DRP concentrations in NBG-SL by 38 and 35% under cold and warm flooding, respectively, but had no significant effect in FYL-Cl, which had low DRP concentrations (<1.2 mg L−1) throughout the flooding period. Biochar amendment significantly increased floodwater DRP concentrations by 27 to 68% in FYL-Cl under cold and warm flooding, respectively, but had no significant effect in NBG-SL. The results indicate substantially less P release under cold than under warm flooding. Gypsum was effective in reducing floodwater DRP concentrations only at high DRP concentrations; thus, the effectiveness was greater under warm than under cold flooding conditions."Funding for this research was provided by a National Sciences and Engineering Research Council (NSERC) Discovery Grant and a University of Winnipeg Major Grant to Darshani Kumaragamage, and a fellowship awarded by the University of Winnipeg–Queen Elizabeth Advanced Scholar Program to R.S. Dharmakeerthi."https://acsess.onlinelibrary.wiley.com/doi/10.2134/jeq2019.02.009

Symposium no. 31 Paper no. 974 Presentation: poster 974-1

this paper was to critically examine the past and present land uses in Sri Lanka in a view to propose criteria for land use planning in the futur

On the magnetic field dependence of deuterium metabolic imaging

Deuterium metabolic imaging (DMI) is a novel MR-based method to spatially map metabolism of deuterated substrates such as [6,6'-2H2]-glucose in vivo. Compared with traditional 13C-MR-based metabolic studies, the MR sensitivity of DMI is high due to the larger 2H magnetic moment and favorable T1 and T2 relaxation times. Here, the magnetic field dependence of DMI sensitivity and transmit efficiency is studied on phantoms and rat brain postmortem at 4, 9.4 and 11.7 T. The sensitivity and spectral resolution on human brain in vivo are investigated at 4 and 7 T before and after an oral dose of [6,6'-2H2]-glucose. For small animal surface coils (Ø 30 mm), the experimentally measured sensitivity and transmit efficiency scale with the magnetic field to a power of +1.75 and −0.30, respectively. These are in excellent agreement with theoretical predictions made from the principle of reciprocity for a coil noise-dominant regime. For larger human surface coils (Ø 80 mm), the sensitivity scales as a +1.65 power. The spectral resolution increases linearly due to near-constant linewidths. With optimal multireceiver arrays the acquisition of DMI at a nominal 1 mL spatial resolution is feasible at 7 T

Impact of stacked conservation practices on phosphorus and sediment export at the catchment scale

Best management practices (BMPs) are effective in reducing nutrient and sediment export, but further understanding of the benefits of the stacked BMPs is needed. This catchment‐scale study was established to evaluate the impact of hydrology and BMPs on phosphorus and sediment losses. Two adjacent catchments, one with a lower (Low‐BMP #11) and one with a higher level of BMP adoption (High‐BMP #12), were compared for total phosphorus (TP) and total suspended solids (TSS) export. The BMPs include nutrient management plans, reduced tillage, grassed waterways, terraces, and perennial vegetation. The TP‐event‐flow‐weighted (EFW) concentration was significantly higher at Low‐BMP #11 (0.293 mg L−1) than at High‐BMP #12 (0.069 mg L−1). There was no significant difference in TP‐base‐flow‐weighted (BFW) concentrations between Low‐BMP #11 (0.035 mg L−1) and High‐BMP #12 (0.037 mg L−1). The TSS‐EFW (148.0 vs. 18.6 mg L−1) and TSS‐BFW (13.3 vs. 6.9 mg L−1) concentrations were also higher at Low‐BMP #11 than at High‐BMP #12. High‐BMP #12 had lower TP (0.36 vs. 0.59 kg ha−1 yr−1) and TSS (253 vs. 1961 kg ha−1 yr−1) loading than Low‐BMP #11. The lower TP export at High‐BMP #12 was likely attributed to the effectiveness of stacked erosion control BMPs and nutrient management plans. Overall, lower phosphorus and sediment loading was observed when a greater areal extent of stacked practices were implemented at the catchment level. This finding provides vital information to encourage wider BMPs adoption at the watershed scale

On the magnetic field dependence of deuterium metabolic imaging

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On the magnetic field dependence of deuterium metabolic imaging

Deuterium metabolic imaging (DMI) is a novel MR-based method to spatially map metabolism of deuterated substrates such as [6,6’-2H2]-glucose in vivo. Compared with traditional 13C-MR-based metabolic studies, the MR sensitivity of DMI is high due to the larger 2H magnetic moment and favorable T1 and T2 relaxation times. Here, the magnetic field dependence of DMI sensitivity and transmit efficiency is studied on phantoms and rat brain postmortem at 4, 9.4 and 11.7 T. The sensitivity and spectral resolution on human brain in vivo are investigated at 4 and 7 T before and after an oral dose of [6,6’-2H2]-glucose. For small animal surface coils (Ø 30 mm), the experimentally measured sensitivity and transmit efficiency scale with the magnetic field to a power of +1.75 and −0.30, respectively. These are in excellent agreement with theoretical predictions made from the principle of reciprocity for a coil noise-dominant regime. For larger human surface coils (Ø 80 mm), the sensitivity scales as a +1.65 power. The spectral resolution increases linearly due to near-constant linewidths. With optimal multireceiver arrays the acquisition of DMI at a nominal 1 mL spatial resolution is feasible at 7 T