Soil solarisation combined with low rates of soil fumigants controls clubroot of cauliflowers, caused by Plasmodiophora brassicae Woron

1991 ◽  
Vol 31 (6) ◽  
pp. 843 ◽  
Author(s):  
IJ Porter ◽  
PR Merriman ◽  
PJ Keane
Keyword(s):  
Population Density ◽  
Water Content ◽  
Methyl Bromide ◽  
Plasmodiophora Brassicae ◽  
Moist Soil ◽  
Combined Treatments ◽  
Disease Rating ◽  
Dry Soil ◽  
Type Water ◽  
Soil Fumigants

The effect of solarisation combined with low rates of soil fumigants on the severity of clubroot and yield of cauliflowers was determined at 2 locations in southern Victoria. The effectiveness of treatments was shown to be dependent on location; on the type, water content and temperature of soil; and on the population density of Plasmodiophora brassicae. Yields were reduced depending upon the disease severity, usually within 60 days after transplanting. Propagules of P. brassicae could survive for more than 28 days in ovens at 45�C when in dry soil but died within 14 days at 40�C in moist soil. At Werribee in 1985 on a red brown earth, solarisation combined with dazomet (100 kg dazomet/ha) gave significantly better control than either treatment alone. This treatment reduced P. brassicae in the 0-10 cm layer, reduced the disease rating from 2.7 to 0.9 (0-3), and increased yield from 2.4 to 47 t/ha compared with controls. In 1986, solarisation combined with 98% methyl bromide-2% chloropicrin (100 and 250 kg/ha) reduced the population density of P. brassicae in the 0-10 and 10-20 cm layers of soil, reduced the disease rating from 3 to 1.8, and increased yield from 0 to 22 t/ha. These treatments were more effective than solarisation and dazomet used alone or in combination. At Keysborough in 1985 on a grey sand, separate treatments of solarisation or dazomet (100 and 250 kg dazometha) were as effective as combined treatments and significantly reduced disease and increased yields compared to controls. Solarisation combined with either fumigant significantly reduced the distribution and total number of weeds at all sites and was generally more effective than separate treatments.

Survival of methanogens in air-dried paddy field soil and their heat tolerance

1997 ◽  
Vol 36 (6-7) ◽  
pp. 517-522 ◽  
Author(s):  
Atsuko Ueki ◽  
Kazuhiro Ono ◽  
Aya Tsuchiya ◽  
Katsuji Ueki
Keyword(s):  
Population Density ◽  
Paddy Field ◽  
Anaerobic Bacteria ◽  
Field Soil ◽  
Moist Soil ◽  
Oxic Condition ◽  
Cultivation Period ◽  
Field Soils ◽  
Paddy Field Soil ◽  
Dry Soil

Population density of methanogens in moist paddy field soil during the cultivation period of rice was usually at the order of 105 MPN g−1 (dry soil). When the soil was air-dried and preserved under oxic condition, the population of methanogens decreased to about one fourth of that in the original moist soil after four months of storage. The population density of methanogens in the air-dried soil, however, did not decrease significantly during the following storage and the population in the soil after two years was almost identical to that in the soil preserved for four months. The population of anaerobic bacteria in the air-dried soil was 34% of that in the original moist soil after two years and that of aerobic bactertia was about 1 to 3%. When slurries of various air-dried paddy field soils which were preserved for different times were incubated anaerobically in the presence of added methanogenic substrates, production of methane usually proceeded actively. When these air-dried paddy field soils were heated at various temperatures for different times and the slurries of the soils were incubated anaerobically in the same way, it was shown that methanogens surviving in the air-dried paddy field soils could withstand temperatures up to 105°c for 10hrs or 140°c for 30 min. H2-producing bacteria in the air-dried soils also endured almost the same level of heat treatment.

Effect of initial soil water content and application of water on urea applied to pasture

1995 ◽  
Vol 46 (4) ◽  
pp. 821 ◽  
Author(s):  
GN Mundy
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Ph ◽  
Simulated Rainfall ◽  
Moist Soil ◽  
Mineral N ◽  
Initial Soil ◽  
Dry Soil

A 15N study with microplots was conducted to determine the effect of initial soil water content and of water application on the recovery of 15N-labelled urea applied at 60 kg N/ha to a paspalum-dominant pasture. A second experiment with the same pasture type investigated the effects of individual urea granules on soil pH and mineral nitrogen (N) after application to a moist soil with and without follow up rain and to wet soil without follow up rain. The 15N balance showed that initial soil water content and 10 mm of simulated rainfall affected the recovery of 15N in the soil/pasture. Fertilizer recovery was lowest (79%) from dry soil (evaporation minus rainfall (ER) 50 mm) without rainfall, but when the initial soil water (ER 25 mm) was higher, the recovery of fertilizer was greater. Simulated rainfall (10 mm) after urea application to the dry soil increased urea recovery to 90%. The recovery of applied 15 N was greater than 90% following the application of the urea to saturated soil (E-R 0 mm) and was comparable to the recommended procedure of irrigation after application. In experiment 2, the initial soil water content and follow up rain (10 mm) were important factors affecting soil pH and mineral N concentrations at urea granule sites after urea was applied to soil. Urea increased soil pH of granule sites to more than 8.5 in moist soil, but with 10 mm of rain or with wet soil, pH only reached 7.6. Similar effects with soil mineral N were also measured. The effects of these changes in pH and mineral N are discussed in relation to recovery of urea applied to pasture soil.

The Influence of Soil Moisture and Soil Type on the Oviposition Behaviour of the Migratory Grasshopper, Melanoplus sanguinipes (Fabricius)

1965 ◽  
Vol 97 (4) ◽  
pp. 401-409 ◽  
Author(s):  
Roy L. Edwards ◽  
Henry T. Epp
Keyword(s):  
Soil Moisture ◽  
Free Choice ◽  
Melanoplus Sanguinipes ◽  
Moist Soil ◽  
Moist Sand ◽  
Subsurface Soil ◽  
Water Ph ◽  
Dry Soil ◽  
Oviposition Sites ◽  
Different Soils

Abstract Three different soils – sand, loam and clay – at each of three moisture levels – saturated, intermediate, and dry – were offered to female Melanoplus sanguinipes as oviposition sites. When given a free choice the females preferred moist sand to all other oviposition sites and avoided soil that was completely dry. When no moist soil was available, coarse dry soil was preferred to fine dry soil, but the oviposition rate was reduced. The females would probe and dig at random into any of the soil offered but would withhold their eggs temporarily if the subsurface soil was not moist. Soil water pH appeared to have very little influence on the females' acceptance of an oviposition site as egg pods were deposited in soils with a range of pH from 3.0 to 11.6. It is suggested that although the absence of moisture in the soil may affect the distribution of egg-pods in the microhabitat and may reduce the rate of egg-pod production slightly, the temperature prevailing during the oviposition period is perhaps a more important factor in determining the number of egg-pods deposited.

scholarly journals Effects of soil water depletion on the water relations in tropical kudzu

1999 ◽  
Vol 34 (7) ◽  
pp. 1151-1157
Author(s):  
Adaucto Bellarmino de Pereira-Netto ◽  
Antonio Celso Novaes de Magalhães ◽  
Hilton Silveira Pinto
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Water Content ◽  
Soil Water ◽  
Cover Crop ◽  
Soil Water Depletion ◽  
Pueraria Phaseoloides ◽  
Water Depletion ◽  
Relative Water ◽  
Dry Soil

Tropical kudzu (Pueraria phaseoloides (Roxb.) Benth., Leguminosae: Faboideae) is native to the humid Southeastern Asia. Tropical kudzu has potential as a cover crop in regions subjected to dryness. The objective of this paper was to evaluate the effect of soil water depletion on leaflet relative water content (RWC), stomatal conductance (g) and temperature (T L) in tropical kudzu. RWC of waterstressed plants dropped from 96 to 78%, following a reduction in SWC from 0.25 to 0.17 g (H2O).g (dry soil)-1.Stomatal conductance of stressed plants decreased from 221 to 98 mmol.m-2.s-1, following the reduction in soil water content (SWC). The day after re-irrigation, g of water stressed plants was 15% lower than g of unstressed plants. Differences in T L between waterstressed and unstressed plants (deltaT L) rose linearly from 0.1 to 2.2ºC following progressive water deficit. RWC and T L of waterstressed plants paralled RWC and T L of unstressed plants the day after reirrigation. The strong decrease in SWC found in this study only induced moderate water stress in tropical kudzu. In addition, tropical kudzu recover rapidly from the induced water stress after the re-irrigation.

scholarly journals Effect of soil drought on evapotranspiration of a  young spruce forest

2019 ◽  
Vol 48 (No. 4) ◽  
pp. 166-172 ◽  
Author(s):  
F. Matejka ◽  
J. Rožnovský ◽  
T. Hurtalová ◽  
D. Janouš
Keyword(s):  
Water Regime ◽  
Model Simulation ◽  
Global Radiation ◽  
Forest Stand ◽  
Soil Drought ◽  
Transfer Model ◽  
Moist Soil ◽  
Dry Period ◽  
Soil Desiccation ◽  
Dry Soil

Daily courses of the actual transpiration of a forest stand were determined by an experimentally verified mathematical Soil – Vegetation – Atmosphere Transfer model. The results refer to the Norway spruce (Picea abies [L.] Karst.) monoculture situated in the highest locations of the Beskids Mts. Drought-free transpiration was estimated as a model simulation run for nonlimiting soil moisture exceeding the level of decreased availability of water. Drought-induced reduction in transpiration was quantified as a difference between actual transpiration and simulated transpiration for moist soil. The results led to conclusions that dry soil causes a significant reduction in actual evapotranspiration and its components in comparison with moist soil. Simultaneously, the effect of soil desiccation was compensated by extremely high evaporative demands of the atmosphere, so that the daily totals of evapotranspiration and its components remained sufficiently high. The high values of global radiation and saturation deficit in the air favourably influenced the water regime of the analysed forest stand in the dry period.

scholarly journals CONTROL OF CUTWORMS IN ASPARAGUS FIELDS IN THE INTERIOR OF BRITISH COLUMBIA

1957 ◽  
Vol 37 (2) ◽  
pp. 108-112
Author(s):  
F. L. Banham ◽  
R. H. Handford
Keyword(s):  
British Columbia ◽  
Soil Surface ◽  
Moist Soil ◽  
Highly Effective ◽  
Euxoa Ochrogaster ◽  
Dry Soil

Emulsions of dieldrin, aldrin, isodrin, toxaphene and chlordane applied to the soil surface and incorporated to a depth of about 4 inches proved highly effective in controlling the red-back cutworm, Euxoa ochrogaster (Guen.) when tested in asparagus fields in the interior of British Columbia in the summer of 1953 and 1954. In 1953 aldrin emulsion mixed with the soil was much more effective than when it was left on the soil surface, Bran bait containing paris green, although giving fairly satisfactory control, was less effective and slower in action than the emulsions. In 1952, dieldrin, aldrin, and isodrin dusts, applied to the soil surface, were superior to and faster in action than bran baits containing aldrin or endrin; all of the 1952 treatments were apparently slower in action in dry soil than in relatively moist soil. A survey of asparagus fields treated by growers in 1953 but not in 1954 indicated that aldrin emulsion, mixed with the soil at about 4 lb. of toxicant per acre, protects asparagus for at least two years.

The determination of the size distribution of soil clods and crumbs

1940 ◽  
Vol 30 (2) ◽  
pp. 210-234 ◽  
Author(s):  
E. W. Russell ◽  
R. V. Tamhane
Keyword(s):  
Size Distribution ◽  
Maximum Amount ◽  
Moist Soil ◽  
Personal Factor ◽  
Water Stable Aggregates ◽  
Dry Soil ◽  
Pre Treatment ◽  
The Individual ◽  
And Training

1. It is possible to determine the size distribution of clods in the field by simple sieving of the soil without any pre-treatment provided the soil is not too wet. There is a personal factor involved in the sieving, but with care and training this will not affect comparisons of results obtained by that person. If the soil is too wet the individual clods smaller than 3 mm. stick together on the 3 mm. sieve. This sticking together is first apparent on the 3 mm. sieve but may become appreciable on the ¼ in. (6 mm.) sieve. No certain way was found for overcoming this difficulty.2. There appears to be no best method for determining the size distribution of the soil crumbs, i.e. of the water-stable aggregates in the soil. The method and the technique must be chosen so as to give the maximum amount of useful information. If an appreciable proportion of the crumbs are larger than ½ mm., a water-sieving method is practically essential.3. The method of wetting to be used can only be chosen from a consideration of what information is wanted. If possible it would be desirable for general purposes to use a very slow or a vacuum wetting technique and a very rapid wetting technique such as wetting the soil by immersion in water.4. The decision whether air-dry or field-moist soil should be used depends entirely on the information needed. For general purposes the use of air-dry soil is recommended.

The cytogeography of Aster lanceolatus. III. Cytoecology in southern Ontario

1983 ◽  
Vol 61 (7) ◽  
pp. 1879-1886 ◽  
Author(s):  
J. G. Chmielewski ◽  
J. C. Semple
Keyword(s):  
Chromosome Number ◽  
Water Content ◽  
Community Type ◽  
Essex County ◽  
Southern Ontario ◽  
Historical Factors ◽  
Kent County ◽  
Type Water

Aster lanceolatus Willd. is represented by five polyploid levels in southern Ontario: tetraploid (2n = 32), pentaploid (2n = 40), hexaploid(2n = 48), heptaploid (2n = 56), andoctoploid(2n = 64). Tetraploids were absent from the Niagara Peninsula in the southeast and Essex County, Kent County, Lambton County, and Elgin County in the southwest, whereas the hexaploids were ubiquitous. Correlations were found between chromosome number and habitat (community type), water content of the soil, physiographic region, and grouped physiographic region. These correlations notwithstanding, the distribution of the two predominant cytotypes in southern Ontario may also be related to historical factors.

Death of Pseudomonas aeruginosa in soil

1982 ◽  
Vol 28 (7) ◽  
pp. 788-794 ◽  
Author(s):  
James M. Zechman ◽  
L. E. Casida Jr.
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Water Content ◽  
Pure Culture ◽  
Death Rate ◽  
Soil Microbes ◽  
Initial Rate ◽  
Resistant Form ◽  
Dry Soil ◽  
Short Time

When incubated in natural (nonsterilized) soil, Pseudomonas aeruginosa died initially at a rate which approximated the rate for starvation of a pure culture in buffer. Predation by other soil microbes or phage did not appear to be involved, and pycocyanin either was not produced or was ineffective. The initial rate of death was followed by a second, considerably slower rate. Cells initially added in low numbers to soil also underwent biphasic death as above. Slow drying of the soil caused a period of rapid death of P. aeruginosa, but this then slowed to give residual numbers and a death rate similar to the second death rate noted for soil not allowed to dry. The cells in the dry soil had not changed genetically to a desiccation-resistant form. Pseudomonas aeruginosa died out completely in a relatively short time when the soil was first quickly dried to a water content similar to that obtained initially through slow drying and then further allowed to dry slowly. These observations appear to point to a dormant form, in some ways resembling a cyst, for P. aeruginosa in soil.

Influence of moist - dry cycles on pH changes in surface soils

Soil Research ◽  
1999 ◽  
Vol 37 (6) ◽  
pp. 1057 ◽  
Author(s):  
K. I. Paul ◽  
M. K. Conyers ◽  
A. S. Black
Keyword(s):  
Soil Moisture ◽  
New South ◽  
N Mineralisation ◽  
Moist Soil ◽  
Water Acidification ◽  
Acidic Soils ◽  
Surface Soils ◽  
Soil Layers ◽  
South Wales ◽  
Dry Soil

It is well established that in the moderately acidic soils of southern Australia, the 0–2 cm layer commonly has a higher pH than soil layers between 2 and 10 cm depth. The surface 2 cm of soil is also exposed to much greater fluctuations of moisture content than deeper soil layers. There are contradictory or speculative reports in the literature on how soil moisture fluctuation affects pH and processes which influence pH. Therefore, the aim of this study was to determine the effect of moist–dry cycles on pH, and on processes involving H+ transformations, in 3 surface soils (0–2 cm) sampled from southern New South Wales. Following a pre-incubation, the 3 surface soils were incubated for 28 days at 30°C and were: (i) maintained continuously dry, (ii) subjected to short (2 days dry, 5 days moist) or long (7 days dry, 7 days moist) moist–dry cycles, or (iii) maintained continuously moist. During the incubation, the pH of continuously dry soil slightly increased by 0.03–0.10 units, while the pH of continuously moist soil decreased by 0.16–0.39 units. In soils subject to both short and long moist–dry cycles, the pH decreased by 0.06–0.34 units. However, relative to soils maintained moist, exposure to moist–dry cycles suppressed acidification by 0.05–0.26 pH units. In dry soils the pH increased, since some of the NH4+-N produced by net N mineralisation was not subsequently nitrified, and there was a net reduction of Mn. In soils which received water, acidification was predominately attributed to nitrification. Relative to soils maintained moist, acidification was suppressed by 1.6–6.5 mmol H+/kg due to the 11–35% decrease of nitrification on exposure to moist–dry cycles. In acidic surface soils (pH <5.5), acidification rates were further suppressed by 0.1–1.0 mmol H+/kg due to the 1.06–2.06 times greater net Mn reduction in moist–dry soils than in continuously moist soils.

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