Studies of phosphorus and potassium deficiencies in Trifolium subterraneum based on electrical measurements

1982 ◽  
Vol 60 (5) ◽  
pp. 634-644 ◽  
Author(s):  
Charles G. Greenham ◽  
Peter J. Randall ◽  
Warren J. Müller
Keyword(s):  
Low Frequency ◽  
Trifolium Subterraneum ◽  
Nutrient Status ◽  
Maximum Growth ◽  
Nutrient Deficiencies ◽  
Electrical Measurements ◽  
P Deficiency ◽  
Phosphate Treatment ◽  
Phosphorus And Potassium ◽  
Two Parameters

Electrical measurements were used to indicate changes in plant tissue due to alterations in nutrient status. An experiment with Trifolium subterraneum L., grown in soil at five rates of applied P, showed that inadequate P produced high values for (1) resistance to low frequency current (RLM) and (2) radius of the impedance locus (r). With increasing P the values of these two parameters fell, reaching a minimum at the P level giving maximum growth. Increasing the P supply above the optimum had no further effect.A study of K-deficient and of P-deficient plants showed the feasibility of diagnosing either deficiency or of discriminating between the two deficiencies, from changes in certain impedance parameters of the petiole tissue following correction of the deficiencies. Changes in membrane phase angle were consistent with K deficiency delaying and P deficiency hastening aging of the plasma membrane. RLF of both petioles and leaflets was increased by P deficiency, and the value for attached but not detached petioles from P-deficient plants was reduced by treatment with phosphate. RLF values for attached P-deficient leaflets decreased in response to phosphate treatment during leaf development but no longer responded (within 6 days of treatment) after a certain stage of maturity.Changes in RLF and r resulting from the correction of P deficiency show that some factor in addition to increase in tissue K is involved, most likely the plasmodesmata. The differences between RLF changes due to correction of nutrient deficiencies and those due to injury are noted.

Potential production of grass and clover monocultures in a mediterranean-type environment — an experimental approach

1974 ◽  
Vol 25 (6) ◽  
pp. 835 ◽  
Author(s):  
PS Cocks
Keyword(s):  
Dry Matter ◽  
Experimental Approach ◽  
Incident Light ◽  
Trifolium Subterraneum ◽  
Maximum Growth ◽  
Nutrient Deficiencies ◽  
Potential Production ◽  
Area Index ◽  
Before And After ◽  
Differential Ability

Monocultures of Lolium rigidum cv. Wimmera and Trifolium subterraneum cv. Woogenellup were established at four densities and mown at three contrasting heights over a 5 month period. Heavy applications of fertilizer were applied to eliminate nutrient deficiencies. Dry matter yields and leaf areas were measured before and after the 3-weekly defoliations, and shoot numbers before the defoliations. Growth rate was related to leaf area index (LAI) in all but one of the sampling periods. Maximum growth rates were proportional to light energy, and the average efficiency of conversion was 4.5% for the clover and 5.5% for the grass. Total herbage yields as high as 17.3 t ha-1 were obtained from the grass, and up to 16.4 t ha-1 from the clover. The results are discussed in relation to the differential ability of grass and clover to exploit the environment. The grass was leafier and had more shoots, but it is thought that clover intercepted more of the incident light at low LAI. The results indicate that potential yields would be reduced at the low LAI values associated with an efficiently utilized pasture.

Response of Leucaena leucocephala pastures to phosphorus and sulfur application in Queensland

2010 ◽  
Vol 50 (10) ◽  
pp. 961 ◽  
Author(s):  
Alejandro Radrizzani ◽  
H. Max Shelton ◽  
Scott A. Dalzell
Keyword(s):  
Leucaena Leucocephala ◽  
Nutrient Deficiency ◽  
Leaf Tissue ◽  
Nutrient Status ◽  
Primary Objective ◽  
Nutrient Deficiencies ◽  
P Deficiency ◽  
Major Factors ◽  
Shallow Soils ◽  
Grass Growth

A series of fertiliser trials were conducted on leucaena (Leucaena leucocephala subsp. glabrata) pastures growing on a range of soil types in south-east and central Queensland. The primary objective was to determine the extent of phosphorus (P) and sulfur (S) deficiencies in leucaena-grass pastures established on either virgin soils or previously cropped soils. Two experiments were conducted across nine sites and confirmed that, for many soils in Queensland, leucaena growth was restricted by P and S nutrient deficiencies, which limited plant growth directly and suppressed symbiotic N2 fixation. The major factors contributing to the P and S deficiencies and thus affecting leucaena response were: (i) inherent low soil fertility, (ii) nutrient removal by cropping and grazing, (iii) shallow soils, (iv) soil acidity, and (v) grass competition for available water and nutrients. A secondary treatment, inter-row cultivation, had little effect on leucaena growth but significantly increased grass growth in some soils. In all these experiments, leaf S concentrations and N : S ratios in index tissue were inconsistent indicators of adequacy of S. Similarly, leaf P concentrations were not useful indicators of P deficiency due to inappropriate (drought) leaf sampling conditions experienced in these experiments. The experiments demonstrate that the productivity of leucaena-grass pastures, especially in older leucaena plantations, will be limited by nutrient deficiencies on many soils in Queensland. While leucaena yield was suppressed, no foliar symptoms of nutrient deficiency were observed. Growers need to monitor the nutrient status of their leucaena-grass pastures by leaf tissue analysis using a new sampling protocol. Strategic fertiliser application has the potential to increase rainfall use efficiency by 50% with an expected parallel increase in cattle liveweight gain.

Radio and Electrical Measurements on Glacial Streams

1987 ◽  
Vol 33 (114) ◽  
pp. 239-242
Author(s):  
M. E. R. Walford
Keyword(s):  
Electrical Conductivity ◽  
Water Channel ◽  
Water System ◽  
Low Frequency ◽  
Water Channels ◽  
Radiative Loss ◽  
Radio Waves ◽  
Electrical Measurements ◽  
Water Conductivity ◽  
Glacier Surface

AbstractWe discuss the suggestion that small underwater transmitters might be used to illuminate the interior of major englacial water channels with radio waves. Once launched, the radio waves would naturally tend to be guided along the channels until attenuated by absorption and by radiative loss. Receivers placed within the channels or at the glacier surface could be used to detect the signals. They would provide valuable information about the connectivity of the water system. The electrical conductivity of the water is of crucial importance. A surface stream on Storglaciären, in Sweden, was found, using a low-frequency technique, to have a conductivity of approximately 4 × 10−4 S m−1. Although this is several hundred times higher than the conductivity of the surrounding glacier ice, the contrast is not sufficient to permit us simply to use electrical conductivity measurements to establish the connectivity of englacial water channels. However, the water conductivity is sufficiently small that, under favourable circumstances, radio signals should be detectable after travelling as much as a few hundred metres along an englacial water channel. In a preliminary field experiment, we demonstrated semi quantitatively that radio waves do indeed propagate as expected, at least in surface streams. We conclude that under-water radio transmitters could be of real practical value in the study of the englacial water system, provided that sufficiently robust devices can be constructed. In a subglacial channel, however, we expect the radio range would be much smaller, the environment much harsher, and the technique of less practical value.

WORKING DEPTHS FOR LOW FREQUENCY ELECTRICAL PROSPECTING

Geophysics ◽  
1945 ◽  
Vol 10 (1) ◽  
pp. 63-75 ◽  
Author(s):  
William Bradley Lewis
Keyword(s):  
Low Frequency ◽  
Electrical Measurements ◽  
The Earth ◽  
Electrical Prospecting

Electrical measurements were made on the surface of the earth with low frequency commutated current using nineteen separate frequencies and six electrode separations. Analysis of the data indicates that there is an effect of appreciable magnitude attributable to an interface 6000 feet below the surface.

scholarly journals A Site-Specific Fertilizer Recommendation Based on the Phosphorus and Potassium Status in Mempawah District, West Kalimantan

2020 ◽  
Vol 25 (2) ◽  
pp. 93
Author(s):  
Muhammad Hatta
Keyword(s):  
Soil Analysis ◽  
Nutrient Status ◽  
Soil Samples ◽  
Paddy Fields ◽  
Site Specific ◽  
West Kalimantan ◽  
Fertilizer Recommendation ◽  
Fertilizer Recommendations ◽  
Phosphorus And Potassium ◽  
A Site

The recommendations of Phosphorus (P) and Potassium (K) fertilization for rice are still not site-specific yet due to a lack of required soil data information.  The P and K status of the paddy fields that provide information on the low, medium, and high P and K nutrient status are very useful for determining recommended the site-specific fertilizer in the the district area. The purpose of the research was to determine the site-specific fertilizer recommendation for paddy field based on their P and K status. This research was based on the field survey and the soil analysis in the laboratory. The soil samples were taken using a grid system, and the P and K levels were assessed by using a 25% HCl extraction. Soil samples were taken in a composite manner on all paddy fields in which their status have been identified. The composite soil samples were determined from 10 - 15 individual samples (sub-samples) with a sampling distance of each sub-sample of 25-50 m in the field.  The soil samples were taken in the overlay with a depth of 0-20 cm. Taking sub-samples were done by a diagonal or a zigzag method according to the conditions of paddy fields. The results of the study presented that the nutrient status of P and K and the fertilizer recommendations in paddy fields for rice plants located in 9 sub-districts in Mempawah Dsitrict had shown that nutrient status of P, on average, were from moderate to high levels, meanwhile, the nutrient status of K was from low to high levels. Recommendations for fertilizing rice fields in several sub-districts in Mempawah Regency are mostly 150 kg NPK (15:15:15) ha-1, 200 kg Urea ha-1 and 25 kg KCl ha-1.

The origin of the observed low-frequency electrical polarization in sandstones

Geophysics ◽  
2006 ◽  
Vol 71 (5) ◽  
pp. G235-G238 ◽  
Author(s):  
Julian B. Scott
Keyword(s):  
Double Layer ◽  
Electrical Double Layer ◽  
Ionic Composition ◽  
Low Frequency ◽  
Ionic Mobility ◽  
Electrical Measurements ◽  
Pore Throat ◽  
Polarization Model ◽  
Electrical Relaxation ◽  
Water Saturated

There has been an increasing debate regarding the mechanism controlling the low-frequency polarization (megahertz to kilohertz) in sandstones. The polarization and related electrical relaxation are extremely important because they can be used to provide a significant amount of information on length scales within the sandstone. Complex electrical measurements, in the mHz to kHz range, were made on gel-filled samples. This gel decreases the ionic mobility in the bulk pore fluid while keeping the ionic composition similar to that in a water-saturated sample. The presence of the gel was shown to have little effect on the electrical relaxation. This adds to the argument that the electrical double layer close to the grain surface is where the polarization originates. The correlation between pore-throat size and the relaxation time is consistent with the polarization mechanism of ion diffusion within the electrical double layer. The membrane-type polarization model, used previously to explain the polarization in pore-throat regions, is likely to be incorrect because of the relative thinness of the electrical double layer.

scholarly journals Organic wastes from bioenergy and ecological sanitation as a soil fertility improver: a field experiment in a tropical Andosol

SOIL ◽  
2016 ◽  
Vol 2 (2) ◽  
pp. 147-162 ◽  
Author(s):  
Ariane Krause ◽  
Thomas Nehls ◽  
Eckhard George ◽  
Martin Kaupenjohann
Keyword(s):  
Zea Mays ◽  
Crop Yield ◽  
Nutrient Management ◽  
Chemical Properties ◽  
Nutrient Status ◽  
Crop Productivity ◽  
Exchange Capacity ◽  
Biogas Slurry ◽  
Crop Species ◽  
P Deficiency

Abstract. Andosols require the regular application of phosphorus (P) to sustain crop productivity. On an Andosol in NW Tanzania, we studied the short-term effects of amending standard compost, biogas slurry and CaSa compost (containing biochar and sanitized human excreta) on (i) the soil's physico-chemical properties, on (ii) biomass growth and crop productivity, and on (iii) the plants' nutrient status. The practice-oriented experiment design included the intercropping of seven locally grown crop species planted on 9 m2 plots with five repetitions arranged as a Latin rectangle. Differences in plant growth (biomass production and crop yield, e.g., of Zea mays) and crop nutrition (total C, N, P, K, Ca, Mg, Zn, etc.) were related to pH, CEC (cation exchange capacity), total C and the availability of nutrients (N, P, K, etc.) and water (water retention characteristics, bulk density, etc.) in the soil. None of the amendments had any significant effect on soil water availability, so the observed variations in crop yield and plant nutrition are attributed to nutrient availability. Applying CaSa compost increased the soil pH from 5.3 to 5.9 and the level of available P from 0.5 to 4.4 mg per kg. Compared to the control, adding biogas slurry, standard compost and CaSa compost increased the aboveground biomass of Zea mays by, respectively, 140, 154 and 211 %. The grain yields of maize on soil treated with biogas slurry, standard compost and CaSa compost were, respectively, 2.63, 3.18 and 4.40 t ha−1, compared to only 1.10 t ha−1 on unamended plots. All treatments enhanced crop productivity and increased the uptake of nutrients into the maize grains. The CaSa compost was most effective in mitigating P deficiency and soil acidification. We conclude that all treatments are viable as a substitute for synthetic fertilizers. Nevertheless, further steps are required to integrate the tested soil amendments into farm-scale nutrient management and to balance the additions and removals of nutrients, so that the cycle can be closed.

scholarly journals The multi-thermal chromosphere

2020 ◽  
Vol 634 ◽  
pp. A56 ◽  
Author(s):  
J. M. da Silva Santos ◽  
J. de la Cruz Rodríguez ◽  
J. Leenaarts ◽  
G. Chintzoglou ◽  
B. De Pontieu ◽  
...  
Keyword(s):  
Thermal Structure ◽  
Low Frequency ◽  
Solar Chromosphere ◽  
Quiet Sun ◽  
Average Brightness ◽  
Near Ultraviolet ◽  
Plage Region ◽  
Hydrogen Ionization ◽  
Two Parameters ◽  
Average Brightness Temperature

Context. Numerical simulations of the solar chromosphere predict a diverse thermal structure with both hot and cool regions. Observations of plage regions in particular typically feature broader and brighter chromospheric lines, which suggests that they are formed in hotter and denser conditions than in the quiet Sun, but also implies a nonthermal component whose source is unclear. Aims. We revisit the problem of the stratification of temperature and microturbulence in plage and the quiet Sun, now adding millimeter (mm) continuum observations provided by the Atacama Large Millimiter Array (ALMA) to inversions of near-ultraviolet Interface Region Imaging Spectrograph (IRIS) spectra as a powerful new diagnostic to disentangle the two parameters. We fit cool chromospheric holes and track the fast evolution of compact mm brightenings in the plage region. Methods. We use the STiC nonlocal thermodynamic equilibrium (NLTE) inversion code to simultaneously fit real ultraviolet and mm spectra in order to infer the thermodynamic parameters of the plasma. Results. We confirm the anticipated constraining potential of ALMA in NLTE inversions of the solar chromosphere. We find significant differences between the inversion results of IRIS data alone compared to the results of a combination with the mm data: the IRIS+ALMA inversions have increased contrast and temperature range, and tend to favor lower values of microturbulence (∼3−6 km s−1 in plage compared to ∼4−7 km s−1 from IRIS alone) in the chromosphere. The average brightness temperature of the plage region at 1.25 mm is 8500 K, but the ALMA maps also show much cooler (∼3000 K) and hotter (∼11 000 K) evolving features partially seen in other diagnostics. To explain the former, the inversions require the existence of localized low-temperature regions in the chromosphere where molecules such as CO could form. The hot features could sustain such high temperatures due to non-equilibrium hydrogen ionization effects in a shocked chromosphere – a scenario that is supported by low-frequency shock wave patterns found in the Mg II lines probed by IRIS.

Review Lecture - Picoplankton

1986 ◽  
Vol 228 (1250) ◽  
pp. 1-30 ◽  
Keyword(s):  
Natural Waters ◽  
Heterotrophic Bacteria ◽  
Marine Ecosystem ◽  
Radiant Energy ◽  
Euphotic Zone ◽  
Nutrient Status ◽  
Maximum Growth ◽  
Accessory Pigment ◽  
High Concentrations ◽  
Dynamic Population

Picoplankton consists of those organisms found in the open waters of seas and lakes which are capable of passing through a filter with 2 μm pores but not through one with 0.2 μm pores. Cells in this size range are well adapted to planktonic life in that they sink extremely slowly and are more efficient than larger forms in taking up nutrients and absorbing radiant energy. Picophytoplankton includes coccoid cyanobacteria and a variety of eukaryotic algal forms. Strains studied in the laboratory have all been found to show maximum growth at relatively low irradiances, the eukaryotic forms being more efficient than the cyanobacteria in utilizing the blue light which predominates at the bottom of the photic zone in clear oceanic waters. Oceanic strains of coccoid cyanobacteria, however, are characterized by high concentrations of phycoerythrin, which appears to function as a nitrogenous reserve as well as an accessory pigment in photosynthesis. The seasonal and spatial distribution of picophytoplankton seems explicable in terms of these physiological characteristics. Numbers of coccoid cyanobacteria have shown a striking correlation with temperature in a number of different situations. Heterotrophic bacteria are also included in the picoplankton, and a review of the information concerning them suggests that they form a highly dynamic population subsisting on dissolved organic matter liberated by living phytoplankton and zooplankton and by decomposition of dead matter. The productivity of this population in the euphotic zone approaches that of the phytoplankton. Both the picophytoplankton and the bacterioplankton are preyed on by phagotrophic flagellates. Both bacteria and flagellates are active in regeneration of mineral nutrients. Regardless of the salinity, temperature or nutrient status of the water, the numbers of heterotrophic bacteria, picophytoplankton and flagellates tend to be around 10 6 , 10 4 and 10 3 organisms per millilitre respectively. It is suggested that these populations form a basic, self-sustaining and self-regulating community in all natural waters. From present information, it seems that little of the energy which passes through this community finds its way into the larger planktonic organisms, but the role of picoplankton in recycling nutrient elements is of great importance in the marine ecosystem.

Effects of Lake Size on Phytoplankton Nutrient Status

1994 ◽  
Vol 51 (12) ◽  
pp. 2769-2783 ◽  
Author(s):  
S. J. Guildford ◽  
L. L. Hendzel ◽  
H. J. Kling ◽  
E. J. Fee ◽  
G. G. C. Robinson ◽  
...  
Keyword(s):  
Nutrient Status ◽  
Canadian Shield ◽  
Small Lakes ◽  
Large Lakes ◽  
P Deficiency ◽  
Water Renewal ◽  
Mixed Layers ◽  
Shield Lakes ◽  
Lake Size ◽  
Total P

Phytoplankton nutrient status measurements (C/P, C/N, C/chlorophyll, N/P, alkaline phosphatase activity, and N debt) were measured for 6 yr in seven remote Canadian Shield lakes. Lakes Nipigon and Superior were also studied for 2 yr. These lakes varied in surface area from 29 to 8.223 × 10 ha, they all stratified fully during the summer and had water renewal times > 5 yr. All lakes were severely P deficient; however, the large lakes (> 2000 ha) were consistently less P deficient than small lakes. A growth-rate indicator (photosynthesis normalized to particulate C) agreed with nutrient status indicators, in that small lakes had lower rates than large lakes. Total P was a good predictor of chlorophyll, but factors related to lake size (temperature and mixed depth) were equally good or better predictors of nutrient status. Decreasing mean water column light intensity could not explain the lower P deficiency of large lakes. The deeper, more energetic mixed layers in large lakes apparently cause P to be recycled more efficiently. Extrapolation of observations or experimental results from small to large lakes requires recognition that phytoplankton in large lakes are less nutrient deficient and may have higher growth rates.

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