scholarly journals Simulation of Long-Term Soil Hydrological Conditions at Three Agricultural Experimental Field Plots Compared with Measurements

Water ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 989 ◽  
Author(s):  
Martin Wegehenkel ◽  
Karin Luzi ◽  
Dieter Sowa ◽  
Dietmar Barkusky ◽  
Wilfried Mirschel
Keyword(s):  
Soil Water ◽  
Measurement Errors ◽  
Goodness Of Fit ◽  
Time Domain Reflectometry ◽  
Hydrological Conditions ◽  
Experimental Field ◽  
Precise Knowledge ◽  
Field Plots ◽  
Water Contents ◽  
Soil Water Contents

Soil hydrological conditions influence crop growth and groundwater recharge and, thus, precise knowledge of such conditions at field scale is important for the investigation of agricultural systems. In our study, we analyzed soil hydrological conditions at three agricultural experimental field plots with sandy soils and different crop rotations using a 22-year period from 1993 to 2014 with daily volumetric soil water contents measured by the Time Domain Reflectometry with Intelligent MicroElements (TRIME)-method and pressure heads determined by automatic recording tensiometers. These measured data were compared with soil water contents and pressure heads simulated by a process-based agroecosystem model. Within this 22-year period, time spans with a better model performance and periods with a lower goodness of fit between simulations and observations were observed. The lower goodness of fit in the summer periods was attributed to inadequate calculations of root water uptake. Measurement errors of the TRIME-probes and differences between soil water contents measured by TRIME and pressure heads observed by tensiometers due to different measurement volumes, precision and measuring principles were identified as further reasons for mismatches between simulated and measured model outputs.

scholarly journals Assessing AquaCrop model to simulate soil water contents under semi arid climate of Central Tunisia

2019 ◽  
Vol 6 (12) ◽  
pp. 203-221
Author(s):  
Hiba Ghazouani ◽  
Basma Latrech ◽  
Mguidich Belhaj Amel ◽  
Cherni Amani ◽  
Boutheina M. Douh ◽  
...  
Keyword(s):  
Soil Water ◽  
Goodness Of Fit ◽  
Field Measurements ◽  
Time Domain Reflectometry ◽  
Growth Duration ◽  
Data Set ◽  
Aquacrop Model ◽  
The Time Domain ◽  
Water Contents ◽  
Soil Water Contents

The objective of the present study was to preliminary calibrate and validate AquaCrop model based on crop conservative parameters from the literature for plant growth and water stress thresholds. In addition, physical soil characteristics, root growth, duration of plant stages and atmospheric demands were introduced according to field measurements. Based on this preliminary calibration, simulated water contents were compared to a measured data set of water contents retrieved from deficit and full irrigation treatments on a potato cropped field during an experimental year of 2015. Statistical indexes were computed and finally this performance in simulating water contents were validated under independent measurements carried out during an experiments campaign on the same field on 2014. Moreover, the paper presents the experimental protocol followed for soil characterization, considered as a milestone component for this soil water contents prediction. Results showed, that under the followed preliminary calibration, the model was able to simulate water contents (0v). In general, values of Root Mean Square Error were lower than 0.03 cm3.cm-3 representing the magnitude of error of the time domain reflectometry probe. Moreover values of Nash coffecients were close to 1 confirming the goodness of fit between measured and estimated water contents. Once assessed, the model could be used to study effects of different irrigation strategies on dynamic of water contents aiming to increase water use efficiency.

scholarly journals Measurement and Simulation of Soil Water Contents in an Experimental Field in Delta Plain

Water ◽  
2017 ◽  
Vol 9 (12) ◽  
pp. 947 ◽  
Author(s):  
Wenjuan Hua ◽  
Chuanhai Wang ◽  
Gang Chen ◽  
Hai Yang ◽  
Yue Zhai
Keyword(s):  
Soil Water ◽  
Delta Plain ◽  
Experimental Field ◽  
Water Contents ◽  
Soil Water Contents

Comparing Heat-Pulse and Time Domain Reflectometry Soil Water Contents from Thermo-Time Domain Reflectometry Probes

2005 ◽  
Vol 4 (4) ◽  
pp. 1080-1086 ◽  
Author(s):  
Tusheng Ren ◽  
Zhaoqiang Ju ◽  
Yuanshi Gong ◽  
Robert Horton
Keyword(s):  
Soil Water ◽  
Time Domain ◽  
Heat Pulse ◽  
Time Domain Reflectometry ◽  
Water Contents ◽  
Soil Water Contents

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

scholarly journals The Effect of Irrigation Rate on the Water Relations of Young Citrus Trees in High-Density Planting

2021 ◽  
Vol 13 (4) ◽  
pp. 1759
Author(s):  
Said A. Hamido ◽  
Kelly T. Morgan
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Soil Salinity ◽  
Planting Density ◽  
Stem Water Potential ◽  
Irrigation Rate ◽  
Biological Stress ◽  
Stem Water ◽  
Water Contents ◽  
Soil Water Contents

The availability and proper irrigation scheduling of water are some of the most significant limitations on citrus production in Florida. The proper volume of citrus water demand is vital in evaluating sustainable irrigation approaches. The current study aims to determine the amount of irrigation required to grow citrus trees at higher planting densities without detrimental impacts on trees’ water relation parameters. The study was conducted between November 2017 and September 2020 on young sweet orange (Citrus sinensis) trees budded on the ‘US-897’ (Cleopatra mandarin x Flying Dragon trifoliate orange) citrus rootstock transplanted in sandy soil at the Southwest Florida Research and Education Center (SWFREC) demonstration grove, near Immokalee, Florida. The experiment contained six planting densities, including 447, 598, and 745 trees per ha replicated four times, and 512, 717, and 897 trees per ha replicated six times. Each density treatment was irrigated at 62% or 100% during the first 15 months between 2017 and 2019 or one of the four irrigation rates (26.5, 40.5, 53, or 81%) based on the calculated crop water supplied (ETc) during the last 17 months of 2019–2020. Tree water relations, including soil moisture, stem water potential, and water supplied, were collected periodically. In addition, soil salinity was determined. During the first year (2018), a higher irrigation rate (100% ETc) represented higher soil water contents; however, the soil water content for the lower irrigation rate (62% ETc) did not represent biological stress. One emitter per tree regardless of planting density supported stem water potential (Ψstem) values between −0.80 and −0.79 MPa for lower and full irrigation rates, respectively. However, when treatments were adjusted from April 2019 through September 2020, the results substantially changed. The higher irrigation rate (81% ETc) represented higher soil water contents during the remainder of the study, the lower irrigation rate (26.5% ETc) represents biological stress as a result of stem water potential (Ψstem) values between −1.05 and −0.91 MPa for lower and higher irrigation rates, respectively. Besides this, increasing the irrigation rate from 26.5% to 81%ETc decreased the soil salinity by 33%. Although increasing the planting density from 717 to 897 trees per hectare reduced the water supplied on average by 37% when one irrigation emitter was used to irrigate two trees instead of one, applying an 81% ETc irrigation rate in citrus is more efficient and could be managed in commercial groves.

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