Assessing corn seedbed conditions for emergence

2000 ◽  
Vol 80 (1) ◽  
pp. 53-61 ◽  
Author(s):  
L. M. Dwyer ◽  
B. L. Ma ◽  
R. de Jong ◽  
M. Tollenaar
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Time Domain ◽  
Time Domain Reflectometry ◽  
Planting Date ◽  
Stand Establishment ◽  
Soil Temperatures ◽  
Water Contents ◽  
Soil Water Contents

Seedbed temperature and moisture conditions affect crop emergence rate and stand establishment. A 4 × 4 factorial experiment arranged in a split plot design with four replications was conducted for 3 yr at four sites to measure corn emergence rate and stand establishment while monitoring seedbed temperature and soil water content in situ. Four planting dates, beginning as early as the soil could be worked and every 10 d thereafter, were the main plots and four corn (Zea mays L.) hybrids the subplots. Volumetric soil water content in the top 0.10 m was measured a minimum of two times per week using time domain reflectometry (TDR) and estimated daily using a budget model. Measured and estimated soil water contents were similar (R2 = 0.73) and daily estimated values were used in the analysis. Stand establishment for most planting date-site-years ranged from 80 to 99%. Less than 15% of planting date-site-years had stands below 80%, and they were characterized by soil temperatures at or below 12.5°C combined with high soil water contents (>90% available water). Rate of emergence was not associated with stand establishment (P > 0.10) and could not be predicted from soil temperatures below 12.5°C. Results suggest that reduction in stand establishment under conditions of low (12.5°C) soil temperature and high (>field capacity) soil water content may be a factor in corn yield reductions associated with reduced or no tillage. Key words: Time domain reflectometry, soil water content, soil temperature, maize

The Effects of Temperature and Humidity on a Field Population of Bradysia odoriphaga (Diptera: Sciaridae)

2020 ◽  
Vol 113 (4) ◽  
pp. 1927-1932
Author(s):  
Cai-hua Shi ◽  
Jing-rong Hu ◽  
You-jun Zhang
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Control Strategies ◽  
Beijing City ◽  
Drought Treatment ◽  
High Soil ◽  
Soil Temperatures ◽  
Water Contents ◽  
Soil Water Contents

Abstract The production of Chinese chives is reduced throughout China due to a root-feeding dipteran pest Bradysia odoriphaga Yang et Zhang (Diptera: Sciaridae), therefore deciphering the conditions influencing its growth and development are important in developing ecological control strategies. A study was conducted from 2014 to 2017 to determine the relationship between the abundance of B. odoriphaga and temperature (atmospheric and soil), soil water content, and atmospheric humidity in a Chinese chive field in Beijing City, China. Numbers of adults peaked in March and October to November and were lowest in July to August and December to next February; numbers of larvae were highest in December to next February and lowest in July to August. From 2014 to 2017, the numbers of adults and larvae were significantly correlated with monthly mean atmospheric temperatures and soil temperatures, but were not significantly correlated with monthly mean atmospheric relative humidity and soil water content. However, for both adults and larvae, numbers were significantly greater with high soil water contents compared with drought treatment. The results of this study suggest that the very low soil water contents, high atmospheric temperatures, and high soil temperatures were critical for regulating field populations of B. odoriphaga.

The dielectric behaviour of clay soils and its application to time domain reflectometry

Soil Research ◽  
1996 ◽  
Vol 34 (6) ◽  
pp. 825 ◽  
Author(s):  
BJ Bridge ◽  
J Sabburg ◽  
KO Habash ◽  
JAR Ball ◽  
NH Hancock
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Time Domain ◽  
Time Domain Reflectometry ◽  
Clay Soils ◽  
Dielectric Behaviour ◽  
Swelling Clay ◽  
Network Analyser ◽  
Water Contents

The dielectric behaviour of 3 soils, a sandy loam (Red Chromosol), a highly structured non-swelling clay (Red Ferrosol), and a self-mulching swelling clay (Black Vertosol), was investigated using a waveguide and network analyser technique in the frequency range 3.0 GHz to 4.5 GHz. Curves relating the real part of the relative permittivity to water content are presented and compared with the general Topp curve. The Chromosol generally followed the Topp curve, but the Ferrosol and Vertosol both had curves below the Topp curve. The Ferrosol showed a maximum horizontal offset of 0.05 m3/m3 from the Topp curve in the mid soil-water content range of 0.2–0.3 m3/m3 offset from the Topp curve of 0.10 m3/m3, with a maximum of 0.12 m3/m3 occurring at a soil water content of 0.4 m3/m3. Similar dielectric curves were obtained for the Chromosol and Vertosol using time domain reflectometry (TDR). With this method, the Chromosol showed very close agreement with the Topp curve, but the Vertosol again gave a curve below the Topp curve, similar to the one obtained using the waveguide and network analyser, but with a smaller maximum horizontal offset of 0.08 m3/m3. The difference between the waveguide and TDR Vertosol curves was mainly attributed to low bulk densities in the waveguide where packing was difficult. Some was also attributed to the wider spectrum of frequencies used by TDR. Use of the Topp curve for TDR measurements in the Vertosol would underestimate its water content by at least 0.06 m3/m3. These results are in good agreement with others obtained from similar soils. Deviations from the Topp curve are attributed to bound water associated with the clay particles and this depends on clay mineralogy and clay content. The presented calibration curves improve the accuracy of TDR measurements in these types of clay soils. A field comparison between water contents measured by TDR and gravimetric sampling in a similar Black Vertosol is presented. This calibration showed that soil water contents can be severely overestimated by using TDR with long probes and cables. This unexpected and opposite result is discussed in terms of attenuated high frequencies in the 15-m-long connecting cable used, errors in depth of probe placement, and changes in bulk density and DC conductivity.

Studies on the behavior and survival of Phytophthora cactorum in soil

1974 ◽  
Vol 52 (4) ◽  
pp. 795-802 ◽  
Author(s):  
B. Sneh ◽  
D. L. McIntosh
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Germ Tube ◽  
Phytophthora Cactorum ◽  
Moist Soil ◽  
Soil Temperatures ◽  
Water Contents ◽  
Soil Water Contents ◽  
Germ Tube Elongation

Sporangia and oospores of P. cactorum persisted for appreciable periods in soil at temperatures and soil water contents likely to prevail during a growing season.Mycelium lysed more rapidly as soil water content and temperature increased. Hyphae were not viable after 3 days incubation in wet soil at 29 °C but survived for at least 45 days at 4 °C.At soil water contents higher than 3.0 bars suction and at soil temperatures above 10 °C sporangia appeared on mycelium buried in soil. When soil moisture was reduced to 3.0 bars suction and temperature to 10 °C, oogonia were formed.Longevity of sporangia was reduced by increasing soil water content above 0.3 bars suction. Glucose added to soil induced germination of sporangia and germ tube elongation, while asparagine inhibited germination.Sporangia and oospores but not mycelium survived freezing temperatures in moist soil. Sporangia could not be recovered from soil which had been allowed to dry. Some oospores germinated after drying.

scholarly journals Measurement of soil water content using the combined time-domain reflectometry – thermal conductivity probe

1987 ◽  
Vol 24 (1) ◽  
pp. 160-163 ◽  
Author(s):  
T. H. W. Baker ◽  
L. E. Goodrich
Keyword(s):  
Thermal Conductivity ◽  
Dielectric Constant ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Time Domain ◽  
Empirical Relation ◽  
Time Domain Reflectometry ◽  
Apparent Dielectric Constant ◽  
Water Contents

A two-pronged metal probe measures the thermal conductivity and apparent dielectric constant of soils in the laboratory and in the field. One prong acts as a transient line heat source probe in measuring thermal conductivity. The apparent dielectric constant of the soil is determined by the time-domain reflectometry (TDR) technique, using both prongs as a parallel transmission line. Volumetric water content is determined from the apparent dielectric constant, making use of an empirical relation valid for most soils. For volumetric water contents above about 8%, the apparent dielectric constant shows a strong dependence on water content and relatively small changes can be measured; sensitivity increases with water content. For volumetric water contents less than 8%, a soil-dependent empirical relation between water content and thermal conductivity has been developed that is most sensitive at lower water contents. The combined probe provides a means of monitoring the water content of soils over a wide range of values, in the field and in the laboratory. Key words: soil water content, time-domain reflectometry, thermal conductivity.

Measuring Soil Water Content With Time Domain Reflectometry

Soil Science ◽  
2010 ◽  
Vol 175 (10) ◽  
pp. 469-473 ◽  
Author(s):  
Zhaoqiang Ju ◽  
Xiaona Liu ◽  
Tusheng Ren ◽  
Chunsheng Hu
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Time Domain ◽  
Time Domain Reflectometry

MITIGATION YIELD SCALED METHANE EMISSION FROM RICE GROWN IN WATER STRESS CONDITIONS WITH BIOCHAR AND SILICATE AMENDMENTS

2021 ◽  
Author(s):  
MUHAMMAD ASLAM ALI ◽  
SANJIT CHANDRA BARMAN ◽  
MD. ASHRAFUL ISLAM KHAN ◽  
MD. BADIUZZAMAN KHAN ◽  
HAFSA JAHAN HIYA
Keyword(s):  
Water Stress ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Field Capacity ◽  
Saturated Soil ◽  
Rice Grain ◽  
Standing Water ◽  
Water Contents ◽  
Soil Water Contents

Climate change and water scarcity may badly affect existing rice production system in Bangladesh. With a view to sustain rice productivity and mitigate yield scaled CH4 emission in the changing climatic conditions, a pot experiment was conducted under different soil water contents, biochar and silicate amendments with inorganic fertilization (NPKS). In this regard, 12 treatments combinations of biochar, silicate and NPKS fertilizer along with continuous standing water (CSW), soil saturation water content and field capacity (100% and 50%) moisture levels were arranged into rice planted potted soils. Gas samples were collected from rice planted pots through Closed Chamber technique and analyzed by Gas Chromatograph. This study revealed that seasonal CH4 emissions were suppressed through integrated biochar and silicate amendments with NPKS fertilizer (50–75% of the recommended doze), while increased rice yield significantly at different soil water contents. Biochar and silicate amendments with NPKS fertilizer (50% of the recommended doze) increased rice grain yield by 10.9%, 18.1%, 13.0% and 14.2%, while decreased seasonal CH4 emissions by 22.8%, 20.9%, 23.3% and 24.3% at continuous standing water level (CSW) (T9), at saturated soil water content (T10), at 100% field capacity soil water content (T11) and at 50% field capacity soil water content (T12), respectively. Soil porosity, soil redox status, SOC and free iron oxide contents were improved with biochar and silicate amendments. Furthermore, rice root oxidation activity (ROA) was found more dominant in water stress condition compared to flooded and saturated soil water contents, which ultimately reduced seasonal CH4 emissions as well as yield scaled CH4 emission. Conclusively, soil amendments with biochar and silicate fertilizer may be a rational practice to reduce the demand for inorganic fertilization and mitigate CH4 emissions during rice cultivation under water stress drought conditions.

scholarly journals An empirical model for describing the influence of water content and concentration of sulfamethoxazole (antibiotic) in soil on the total net CO2 efflux

2020 ◽  
Vol 68 (4) ◽  
pp. 351-358
Author(s):  
Miroslav Fér ◽  
Radka Kodešová ◽  
Barbora Kalkušová ◽  
Aleš Klement ◽  
Antonín Nikodem
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Solution Treatment ◽  
Soil Microbial Activity ◽  
Soil Samples ◽  
Co2 Efflux ◽  
The Impact ◽  
Water Contents ◽  
Soil Water Contents

AbstractThe aim of the study was to describe the impact of the soil water content and sulfamethoxazole, SUL, (antibiotic) concentration in soil on the net CO2 efflux. Soil samples were taken from topsoils of a Haplic Fluvisol and Haplic Chernozem. Soil samples were packed into the steel cylinders. The net CO2 efflux was measured from these soil columns after application of fresh water or SUL solution at different soil water contents. The experiments were carried out in dark at 20°C. The trends in the net CO2 efflux varied for different treatments. While initially high values for water treatment exponentially decreased in time, values for solution treatment increased during the first 250–650 minutes and then decreased. The total net CO2 effluxes measured for 20 hours related to the soil water content followed the second order polynomial functions. The maximal values were measured for the soil water content of 0.15 cm3 cm−3 (Haplic Fluvisol with water or solution, Haplic Chernozem with solution) and 0.11 cm3 cm−3 (Haplic Chernozem with water). The ratios between values measured for solution and water at the same soil water contents exponentially increased with increasing SUL concentration in soils. This proved the increasing stimulative influence of SUL on soil microbial activity.

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