Influence of early pasture growth on water movement and leaching of potassium and other cations from sandy soils in a Mediterrranean environment

1970 ◽  
Vol 10 (43) ◽  
pp. 203
Author(s):  
FJ Roberts
Keyword(s):  
Marked Decrease ◽  
Water Movement ◽  
Sandy Soils ◽  
Subterranean Clover ◽  
Growing Season ◽  
Soil Types ◽  
Cation Leaching ◽  
Leaching Loss ◽  
Cation Uptake ◽  
The Mean

Water and cation losses from two soil types were studied in monolith lysimeters fertilized with 375 kg/ha potassium chloride (50 per cent K) and 375 kg/ha superphosphate (22 per cent Ca), in which subterranean clover was grown. An advance of five weeks in time of sowing and germination reduced the mean percolate loss from 26 to 16 cm ; the unsown control lost 31 cm. Potassium leaching decreased from 77 to 37 kg/ha and the unsown treatment lost 87 kg/ha. Magnesium decreased from 26 to 10 kg/ha and the unsown treatment lost 31 kg/ha. With calcium there was a marked decrease from 132 to 51 kg/ha ; the unsown control lost 164 kg/ha. Cation leaching was most severe during the first part of the growing season. Early plant growth reduced cation leaching by increasing the water use and cation uptake. The early sown treatment contained 136 kg/ha K in 9,500 kg/ha DM total tops, whereas the late sown treatment had 94 kg/ha K in 6,300 kg/ha DM total tops. The decreased uptake was similar in magnitude to the increase in leaching loss of potassium.

The effects of grazing on the phosphorus requirement of an annual pasture

1971 ◽  
Vol 22 (1) ◽  
pp. 81 ◽  
Author(s):  
PG Ozanne ◽  
KMW Howes
Keyword(s):  
Subterranean Clover ◽  
Growing Season ◽  
Maximum Growth ◽  
Grazing Pressure ◽  
Light Interception ◽  
Botanical Composition ◽  
Stocking Rate ◽  
Phosphorus Requirement ◽  
Root Size

The applied phosphorus requirement of a pasture sown to subterranean clover was measured with and without grazing. Under moderate grazing pressure, in the year of establishment, the pasture required about 50 % more phosphorus than when ungrazed. In the following season, at a higher stocking rate, the grazed areas needed twice as much phosphorus as the ungrazed to make 90% of their maximum growth. In both years this difference in requirement between stocked and unstocked treatments was present throughout the growing season. Increased phosphorus requirement under grazing is associated with the need for greater uptake of phosphorus under conditions where redistribution of absorbed phosphorus within the plant is prevented by defoliation. It does not appear to be due to effects of defoliation on root size. Nor does it depend on differential light interception or on changes in botanical composition.

Sulfonylurea herbicides applied to acidic sandy soils: movement, persistence and activity within the growing season

1992 ◽  
Vol 43 (5) ◽  
pp. 1157 ◽  
Author(s):  
WM Blacklow ◽  
PC Pheloung
Keyword(s):  
Sandy Loam ◽  
Sandy Soils ◽  
Growing Season ◽  
Shoot Biomass ◽  
Soil Profiles ◽  
Sulfonylurea Herbicides ◽  
Laboratory Bioassay ◽  
Wheat Seedlings ◽  
Late Application ◽  
Lime Addition

Chlorsulfuron and triasulfuron were applied to the surface of acidic, sandy loam at a low rainfall site in 1989 (129 mm June-October) and a high rainfall site in 1990 (217 mm July-August). Four environments were obtained by early and late application times and lime addition in 1989 and by a wetter site in 1990. The pH of the surface 10 cm was 4.9 in 1989, 5.8 in 1990 and 6.5 after the addition of limestone in 1989. The plots were left fallow or sown, prior to herbicide applications, to wheat (cv. Kulin). Hourly averages of rainfall, soil and air temperature were recorded. The temperature range was 2.7�C to 23.2�C. The soil profiles were sampled on 5 to 7 occasions and herbicide residues were determined by a laboratory bioassay (sensitivity >0.4 8g kg-1 soil). Chlorsulfuron and triasulfuron were detected to 300 mm in the wetter environment but neither herbicide was as mobile in the profile as water. More herbicide moved to the lower layers of the profile in the higher pH environment. The half-lives for residues ranged from 12 to 28 days. Shoot biomass of wheat seedlings was suppressed by both herbicides but grain yields were unaffected. The residues failed to prevent reinvasion of the wheat plots by weeds, notably Arctotheca calendula.

scholarly journals Rapid coral mortality following unusually calm and hot conditions on Iriomote, Japan

F1000Research ◽  
2018 ◽  
Vol 6 ◽  
pp. 1728 ◽  
Author(s):  
Andrew H Baird ◽  
Sally A. Keith ◽  
Erika Woolsey ◽  
Ryuta Yoshida ◽  
Tohru Naruse
Keyword(s):  
Water Movement ◽  
Sea Surface ◽  
Bleaching Event ◽  
Coral Mortality ◽  
Average Wind Speed ◽  
Common Cause ◽  
Wind Speeds ◽  
Average Wind ◽  
The Mean ◽  
Low Wind Speeds

Coral bleaching can be induced by many different stressors, however, the most common cause of mass bleaching in the field is higher than average sea surface temperatures (SST). Here, we describe an unusual bleaching event that followed very calm sea conditions combined with higher than average SST. Patterns of mortality differed from typical bleaching in four ways: 1) mortality was very rapid; 2) a different suite of species were most affected; 3) tissue mortality in Acropora spp. was often restricted to the center of the colony; 4) the event occurred early in summer. The two weeks prior to the event included 8 days where the average wind speed was less than 3 ms-1. In addition, SSTs in the weeks preceding and during the event were 1.0-1.5°C higher than the mean for the last 30 years. We hypothesize that this unusual bleaching event was caused by anoxia resulting from a lack of water movement induced by low wind speeds combined with high SST.

SOIL CONDITIONERS—THEIR EFFECT ON COARSE-TEXTURED SOILS, CROP YIELDS AND COMPOSITION

1957 ◽  
Vol 37 (2) ◽  
pp. 102-112
Author(s):  
R. M. Holmes ◽  
S. J. Toth
Keyword(s):  
Structural Changes ◽  
Crop Yields ◽  
Cultural Practices ◽  
Sandy Soils ◽  
Growing Season ◽  
Soil Aggregate ◽  
Crop Response ◽  
The Third ◽  
Soil Conditioners ◽  
The Stability

Crop response to soil structural changes caused by soil conditioner amendments was studied in several different sandy soils of New Jersey. The response varied with the crop and treatment. Those chemicals that were slightly hydrophobic were most effective and generally crop response was greatest on these treatments. Cations such as Na may be added in large amounts as part of some conditioners, and this may result in reduced uptake of other nutrients such as Mg. and K. Except for this effect, conditioners did not reduce nutrient uptake by plants. When elements such as Na and N are added in large amounts as part of some conditioners, there may be an increased uptake of these nutrients.Catalin and VAMA conditioners produced a dry surface mulch which appeared to reduce evaporation. Moisture reserves were, therefore, preserved through a drought and this resulted in increased growth of crops over those grown on other treatments. Cultural practices destroyed the stability of the conditioned aggregates, since in most cases the effect had largely disappeared by the third growing season. Chemicals which were effective in soil aggregate stabilization were also effective as anti-crustants when crusting was a problem.

Varietal reactions of Trifolium subterraneum L. to Phaseolus virus 2 Pierce.

1954 ◽  
Vol 5 (4) ◽  
pp. 598 ◽  
Author(s):  
EM Hutton ◽  
JW Peak
Keyword(s):  
Trypan Blue ◽  
Continuous Distribution ◽  
Systemic Infection ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Epidermal Cells ◽  
Severe Strain ◽  
Resistant Varieties ◽  
Lethal Reaction ◽  
The Mean

A number of varieties of subterranean clover (Trifolium subterraneum L.) were tested with a severe strain of Phaseolus virus 2 Pierce. Northam First Early, Dwalganup, and Pink Flowered gave lethal necrotic reactions while the rest developed mottles and chlorosis of different degrees of intensity. Reductions in the mean fresh weights of plants of five subterranean clover varieties ranged from 26.1 to 76.7 per cent. Epidermal cells of mottled leaves contained irregular aggregates of viroplasts stained by treatment with phloxine-trypan blue. Viroplasts in young tip leaves did not stain if the plants were held at temperatures below 44.6°F while those in mature basal leaves were not so affected. The lethal-reactors Northam First Early, Dwalganup, and Pink Flowered were resistant in the field to Phaseolus virus 2. With hand inoculation in the glass-house an average of 10 per cent. of plants of these varieties remained free from systemic infection, whereas all the plants of mottle-reacting varieties became systemically infected. The virus had a discontinous distribution in plants of lethal-reactors, compared with a continuous distribution in those of mottle-reactors such as Mount Barker. The lethal reaction is heritable in a dominant fashion in most crosses, so that the development of desirable new virus- resistant varieties is possible.

scholarly journals Main features of Poaceae pollen season in Madeira region (Portugal)

2015 ◽  
Vol 68 (4) ◽  
pp. 367-372
Author(s):  
Irene Câmara Camacho ◽  
Rita Câmara ◽  
Roberto Camacho
Keyword(s):  
Pollen Season ◽  
Airborne Pollen ◽  
Growing Season ◽  
Onset Date ◽  
Critical Levels ◽  
Pollen Monitoring ◽  
Madeira Island ◽  
Poaceae Pollen ◽  
The Mean ◽  
Low Levels

<p>The pollinic spectrum of the Madeira region is dominated by grass pollen, which also represents an important aeroallergen in Europe. The present work aims to analyze the main features of the Poaceae pollen season in the Madeira region to determine the allergic risk. The study took place in Funchal city, the capital of Madeira Island, over a period of 10 years (2003–2012). The airborne pollen monitoring was carried out with a Hirst type volumetric trap, following well-established guidelines.</p><p>In the atmosphere of Funchal, the mean annual Poaceae pollen index was 229. The mean Poaceae pollen season lasts 275 days, with an onset date in January/March and an end date in November/December. Poaceae counts showed a seasonal variation with 2 distinct peaks: a higher peak between March and June, and the second one in autumn. The peak values occurred mainly between April and June, and the highest peak was 93 grains/m<sup>3</sup>, detected on the 27th May of 2010. The Poaceae pollen remaining at low levels during the whole growing season, presenting a nil to low allergenic risk during most of the study period. Higher critical levels of allergens have been revealed after 2006. In general, the pollen risk from Poaceae lasted only a few days per year, despite the very long pollen season and the abundance of grasses in the landscape of Madeira Island.</p>

scholarly journals Effects of repeated phosphorus fertilisation on field crops in Finland 2.Sufficient phosphorus application rates on silty and sandy soils

2008 ◽  
Vol 15 (4) ◽  
pp. 423 ◽  
Author(s):  
I. SAARELA ◽  
H. HUHTA ◽  
P. VIRKAJÄRVI
Keyword(s):  
Relative Yield ◽  
Sandy Soils ◽  
Application Rate ◽  
Application Rates ◽  
P Application ◽  
The Mean ◽  
Yield Responses ◽  
Phosphorus Application ◽  
Phosphorus Fertilisation ◽  
Annual Application

In order to update fertilisation recommendations for Finnish silty and sandy soils, the effects of repeated phosphorus (P) fertilisation on the yields of cereals, grasses and other crops were measured at ten sites for 9 to 18 years. Results of some earlier studies were also used in examining the relationships of the yield responses to applied P and to the soil test values measured by the Finnish ammonium acetate method (PAc). Significant effects of P fertilisation were observed at all sites that had low or medium PAc values; in the case of potatoes, even at sites with fairly high values. The mean relative yield without applied P divided by yield with 60 or 45 kg P ha-1 of the ten sites was 81% (mean PAc 11.6 mg dm-3) varying from 55% at the PAc value of 4.7 mg dm-3 to 100% at the highest PAc values. In order to achieve a relative yield of 97%, which is considered the optimum for cereals and leys, the required mean annual application of P in the later parts of the experiments was 25 kg ha-1 (variation 0-42 kg ha-1). On the six soils that had low or medium PAc values (4.5-9.1 mg dm-3, mean 8.0 mg dm-3), relative yield was 97% at the P application rate of 35 kg ha-1 (variation 22-42 kg ha-1), while 11 kg P ha-1 (variation 0-25 kg ha-1) sufficed on the four soils that had higher PAc values (mean 20.8 mg dm-3, variation 11.7-35.2 mg dm-3). Reasons for the poor availability of P in silty and sandy soils were discussed.;

scholarly journals The accuracy of simple soil water models in climate forecasting

1997 ◽  
Vol 1 (2) ◽  
pp. 241-248 ◽  
Author(s):  
E. M. Blyth ◽  
C. C. Daamen
Keyword(s):  
Soil Water ◽  
Sandy Soils ◽  
Clay Soils ◽  
Soil Types ◽  
Layer Model ◽  
Climate Forecasting ◽  
Number Of Layers ◽  
Overall Performance ◽  
Two Layer Model ◽  
Water Models

Abstract. Several simple soil water models with four layers or less, typical of those used in GCMS, are compared to a complex multilayered model. They are tested by applying a repeating wetting/drying cycle at different frequencies, and run to equilibrium. The ability of the simple soil models to reproduce the results of the multilayer model vary according to the frequency of the forcing cycle, the soil type, the number of layers and the depth of the top layer of the model. The best overall performance was from the four layer model. The two layer model with a thin top layer (0.1 m) modelled sandy soils well while the two layer model with a thick top layer (0.5 m) modelled clay soils well. The model with just one layer overestimated evaporation during long drying periods for all soil types.

Site Index Curves for Norway Spruce in Southern Ontario1

1989 ◽  
Vol 6 (1) ◽  
pp. 23-26 ◽  
Author(s):  
Andrew M. Gordon ◽  
Peter A. Williams ◽  
Edward P. Taylor
Keyword(s):  
Norway Spruce ◽  
Soil Texture ◽  
Sandy Soils ◽  
Site Index ◽  
Height Growth ◽  
Stem Analysis ◽  
Mean Values ◽  
Breast Height ◽  
Drainage Class ◽  
The Mean

Abstract Four dominant or codominant Norway spruce trees from each of 55 sites were destructively sampled and the annual height growth determined by stem analysis. The sampled sites were stratified by soil textural class (coarse, medium, and fine) and depth to distinct mottling (0-16, 16-40, and 40 in.). Two sets of an-amorphic site index curves were constructed using a total age of 30 years (SI30), and breast height age of 25 years (SIBH25) as base ages. The mean SI30 from Ontario (53 ft) was found to be 17.8% higher than the mean values published from Vermont (45 ft) and currently used in Ontario. SIBH25 values had a range of 34.6 to 74.8 ft with a mean of 55.3 ft. Analysis of variance showed significant differences in SIBH25 due to soil texture and drainage class, and in years to breast height (BH) due to drainage class. SIBH25 was highest on sites with loamy soils and distinct mottling at 16-40 in. It took an average of 6.5 years for seedlings to reach BH with a range of 3 to 12 years. Years to BH was lowest on sites with sandy soils and those with distinct mottling below 40 in. North. J. Appl. For. 6(1):23-26, March 1989.

THE ROLE OF MELATONIN IN THE REGULATION OF THYROTROPHIN SECRETION

1968 ◽  
Vol 57 (3) ◽  
pp. 363-373 ◽  
Author(s):  
J. N. Panda ◽  
C. W. Turner ◽  
Mary Powell
Keyword(s):  
Thyroid Gland ◽  
Marked Decrease ◽  
Haemagglutination Inhibition ◽  
Regulatory Effect ◽  
Hormone Synthesis ◽  
Thyroid Glands ◽  
Tsh Secretion ◽  
The Mean ◽  
Inhibition Technique

ABSTRACT The fact that melatonin, a pineal substance, causes a depression in thyroid function of prepuberal rats has been reported. A possible site of this action on the thyroid gland has been studied by estimating the TSH content of blood and hypophysis in rats from 35 days to 65 days of age. Haemagglutination-inhibition technique has been used to assay very small amounts of TSH in plasma. Rats receiving 100 μg of melatonin daily for 10 days were sacrificed at 35, 45, 55 and 65 days of age. The mean thyroid weight of each group was markedly higher than that of the corresponding controls. The plasma TSH/ml level was higher in experimental groups, with a marked decrease (0.10 > P > 0.05) in TSH/mg of hypophysis (wet), especially at 45 and 55 days of age. Rats similarly treated with 400 μg/100 g body weight of tapazole daily for 10 days and sacrificed at 45 and 55 days of age showed higher plasma and lower hypophyseal TSH levels than the controls and the results were comparable to those of the melatonin treated groups. The dry-fat-free tissue of the thyroid glands of the melatonin treated groups were higher than the corresponding controls and their DNA content was significantly higher (0.050 > P > 0.025) also, indicating hyperplasia and hypertrophy of the thyroid glands resulting from the action of melatonin. The histological picture of the melatonin treated animals showed goitrogenic effect. It may be concluded from these data that melatonin exerts its regulatory effect on TSH secretion directly acting on the thyroid gland and in some way inhibiting thyroid hormone synthesis or release.

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