Improvements to the accuracy of modelled soil water content from the Second Generation Prairie Agrometeorological Model

2010 ◽  
Vol 90 (3) ◽  
pp. 523-526 ◽  
Author(s):  
M. Gervais ◽  
P. Bullock ◽  
M. Mkhabela ◽  
G. Finlay ◽  
R. Raddatz
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Second Generation ◽  
Regional Scale ◽  
Canadian Prairies ◽  
Growing Seasons ◽  
Crop Development ◽  
Plant Available Water ◽  
Water Values

The direct measurement of soil water on a regional scale is often not practical due to large instrumental and labour requirements. Alternatively, soil water estimates can be derived using models. The Second Generation Prairie Agrometeorological Model (PAMII) models soil water, crop development and evapotranspiration (ET) in order to derive an estimate of crop water use. The objective of this study was to validate, and if necessary modify, the soil water component of PAMII using weather and soil water data collected from several spring wheat trials in Saskatchewan and Manitoba during the 2003 though 2006 growing seasons. Comparison of modelled and measured soil water values yielded a RMSE of 62 mm. For most site-years, PAMII overestimated soil water during the second half of the growing season, which was caused by an increase in modelled canopy resistance (rc) before the crop experienced water stress. The rc function was thus modified so that rc would not increase until the soil water content was < 0.5 of plant available water. Overall this modification reduced the RMSE from 62 to 56 mm. In addition, modelled soil water was underestimated during periods that experienced consecutive days of precipitation. This was because the model stopped infiltration when the top-zone reached saturation. When modified to allow infiltration to continue independent of the top-zone’s water content, the RMSE was further reduced to 53 mm. Overall, both modifications reduced the RMSE of modelled soil water by 9 mm, and this reduction was highly significant (P < 0.01). Key words: Prairie Agrometeorological Model (PAMII), soil water modelling, evapotranspiration, Canadian prairies

Evaluating Soil Water Content in a WRF-Noah Downscaling Experiment

2013 ◽  
Vol 52 (10) ◽  
pp. 2312-2327 ◽  
Author(s):  
Peter Greve ◽  
Kirsten Warrach-Sagi ◽  
Volker Wulfmeyer
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Land Surface ◽  
Root Zone ◽  
Regional Scale ◽  
Land Surface Model ◽  
Surface Model ◽  
Flux Partitioning

AbstractSoil water content (SWC) depends on and affects the energy flux partitioning at the land–atmosphere interface. Above all, the latent heat flux is limited by the SWC of the root zone on one hand and radiation on the other. Therefore, SWC is a key variable in the climate system. In this study, the performance of the Weather Research and Forecasting model coupled with the Noah land surface model (WRF-Noah) system in a climate hindcast simulation from 1990 to 2008 is evaluated with respect to SWC versus two reanalysis datasets for Europe during 2007 and 2008 with in situ soil moisture observations from southern France. When compared with the in situ observations, WRF-Noah generally reproduces the SWC annual cycle while the reanalysis SWCs do not. The biases in areal mean WRF-Noah SWCs relate to biases in precipitation and evapotranspiration in a cropland environment. The spatial patterns and temporal variability of the seasonal mean SWCs from the WRF-Noah simulations and from the two reanalyses correspond well, while absolute values differ significantly, especially at the regional scale.

Analysis of Water Budgets in Semi-Arid Lands from Soil Water Records

1995 ◽  
Vol 31 (2) ◽  
pp. 131-150 ◽  
Author(s):  
C. J. Pilbeam ◽  
C. C. Daamen ◽  
L. P. Simmonds
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Surface ◽  
Total Evaporation ◽  
Growing Seasons ◽  
Neutron Probe ◽  
Unsaturated Hydraulic Conductivity ◽  
Probe Measurements

SUMMARYFour components of the water budget for a growing season, namely storage, drainage, transpiration and direct evaporation from the soil surface, were estimated using a suite of techniques. The only data requirements were rainfall, neutron probe measurements of soil water content and microlysimeter measurements of evaporation from the soil. Data from four growing seasons at Kiboko, Kenya between 1990 and 1992 were used to provide examples of the estimations. Drainage was significant (about 10% of rainfall) in one season only; in the other seasons, total evaporation comprised at least 95% of the seasonal rainfall.Drainage was determined using a relationship between unsaturated hydraulic conductivity and soil water content that was determined during the early part of the rainy season when water was penetrating to depth. This analysis made it possible to identify a critical water content at the base of the soil profile, above which there would be significant drainage. However, there are large errors associated with estimation of drainage if significant drainage occurs.Estimates of direct evaporation from the soil surface were used as the basis of distinguishing transpiration from total evaporation. Microlysimetry was used to develop a model of evaporation from these sandy soils, which was based on the assumption that the evaporation from the soil surface following heavy rainfall is a unique function of time from rainfall, and little influenced by the presence of a sparse crop. This method showed that direct evaporation from the soil accounted for between 70 and 85% of total evaporation in seasons when total evaporation estimates ranged from 150 to 325 mm.

scholarly journals Effects of constantly high soil water content on vegetative growth and grape quality in Japan with high rainfall during grapevine growing season

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Yuta Kobayashi ◽  
Tetsunan Yamamoto ◽  
Hironori Ikeda ◽  
Ryuzo Sugihara ◽  
Hiroki Kaihori ◽  
...  
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Vegetative Growth ◽  
Growing Season ◽  
Experimental Plot ◽  
Growing Seasons ◽  
High Soil ◽  
Berry Quality ◽  
Vineyard Soil

AbstractExcess water in vineyard soils during grapevine growing season is expected to become a critical issue in Japan. The objective of this study was to investigate the effects of constantly high soil water content which was controlled at constantly more than 20% water content in soil on vegetative growth and berry quality of Cabernet Sauvignon over a 3-year growing season. A wireless sensor networking system for real-time monitoring of soil moisture was used to check that the experimental plot had constantly more than 20% water content in soil. Véraison in the experimental plot controlled at constantly high soil water content started 10 days, 4 days and 1 day later than that in the non-irrigated experimental plot in the 2017, 2018 and 2019 growing seasons, respectively. The constantly high soil water content had no notable effects on berry quality, such as berry characteristics and berry composition, at harvest compared with the non-irrigated experimental plot, although there was a certain tendency that constantly high soil water content decreased anthocyanin contents in berry skins compared with those of non-irrigated grapevines during the three growing seasons. We postulated that waterlogging damage due to the increase in soil water content by frequent rainfall would be minimised by the selection of rootstock that confers tolerance to waterlogging stress for scion cultivars and/or viticultural practices to prevent decrease in soil temperature. Also, the introduction of Internet of Things technology for monitoring water status in vineyard soil is expected to contribute to improving practical approaches to vineyard soil water management.

Modeling effects of plastic mulching on crop yields and water productivity in the middle Heihe River Basin

2020 ◽  
Author(s):  
Wang Zhang ◽  
Chunmiao Zheng
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Global Sensitivity Analysis ◽  
Water Productivity ◽  
Regional Scale ◽  
Canopy Cover ◽  
Heihe River ◽  
Aquacrop Model ◽  
Plastic Mulching

&lt;p&gt;Plastic mulching is an effective field practice to improve crop water productivity (WP), especially widely used in arid and semi-arid areas. The positive effects of soil mulching on crop yield and WP have been studied through numerous field experiments and simulations at the site scale. However, few studies have focused on the mulching effects at the regional scale. Zhangye oasis, a typical arid region in the middle Heihe River Basin, was chosen as the study area. Global sensitivity analysis was applied to determine the most sensitive parameters in AquaCrop model. Based on the results of global sensitivity analysis, soil and crop parameters of AquaCrop model were calibrated and validated using field observations from three stations. The normalized root mean square error (NRMSE) values for soil water content, seed maize canopy cover, aboveground biomass, yield, spring wheat canopy cover, aboveground biomass and yield were 18.7%, 6.7%, 23.5%, 12.5%, 10.7%, 24.2% and 15.0% during the calibration period, and the corresponding values during the validation period were 25.1%, 7.0%, 22.2%, 17.7%, 9.1%, 23.6% and 11.7%, respectively. These values indicated the calibrated model performed well to simulate the soil water content and crop growth. Compared with no-mulching, the average soil water content during the growth period, seed maize yield and WP under mulching had been increased by 8.8%, 3.0% and 3.0%, respectively. The results demonstrated that plastic mulching could effectively improve the yield and WP of seed maize, which not significantly on spring wheat. This study offers a quantitatively analysis for plastic mulching applications at the regional scale.&lt;/p&gt;

Effects of Pre-Sowing Flooding, Rainfall, Irrigation and Surface Drainage on Sesame in the Central Sudan Rainlands

1980 ◽  
Vol 16 (2) ◽  
pp. 137-148
Author(s):  
H. R. B. Hack
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Crop Growth ◽  
Surface Drainage ◽  
Central Sudan ◽  
Run Off ◽  
Four Seasons ◽  
Crop Development

SUMMARYSesame was grown in four seasons in which differences in the distribution of the rains and treatments of pre-sowing flooding, irrigation during crop growth and surface drainage resulted in contrasts in soil water content and crop development. In wet years pre-sowing flooding, absence of surface drainage and premature irrigation gave 32–37% decreases in yield. In a season of low rainfall prevention of surface run-off and one later irrigation gave, in the absence of pre-sowing flooding, a 43% increase in yield over that from plots irrigated only at sowing and with surface drainage. Agronomic applications are discussed.

scholarly journals Process-based modelling of NH<sub>3</sub> exchange with grazed grasslands

2017 ◽  
Vol 14 (18) ◽  
pp. 4161-4193 ◽  
Author(s):  
Andrea Móring ◽  
Massimo Vieno ◽  
Ruth M. Doherty ◽  
Celia Milford ◽  
Eiko Nemitz ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Ph ◽  
Regional Scale ◽  
Scale Model ◽  
Nh3 Emission ◽  
Initial Soil ◽  
The Difference

Abstract. In this study the GAG model, a process-based ammonia (NH3) emission model for urine patches, was extended and applied for the field scale. The new model (GAG_field) was tested over two modelling periods, for which micrometeorological NH3 flux data were available. Acknowledging uncertainties in the measurements, the model was able to simulate the main features of the observed fluxes. The temporal evolution of the simulated NH3 exchange flux was found to be dominated by NH3 emission from the urine patches, offset by simultaneous NH3 deposition to areas of the field not affected by urine. The simulations show how NH3 fluxes over a grazed field in a given day can be affected by urine patches deposited several days earlier, linked to the interaction of volatilization processes with soil pH dynamics. Sensitivity analysis showed that GAG_field was more sensitive to soil buffering capacity (β), field capacity (θfc) and permanent wilting point (θpwp) than the patch-scale model. The reason for these different sensitivities is dual. Firstly, the difference originates from the different scales. Secondly, the difference can be explained by the different initial soil pH and physical properties, which determine the maximum volume of urine that can be stored in the NH3 source layer. It was found that in the case of urine patches with a higher initial soil pH and higher initial soil water content, the sensitivity of NH3 exchange to β was stronger. Also, in the case of a higher initial soil water content, NH3 exchange was more sensitive to the changes in θfc and θpwp. The sensitivity analysis showed that the nitrogen content of urine (cN) is associated with high uncertainty in the simulated fluxes. However, model experiments based on cN values randomized from an estimated statistical distribution indicated that this uncertainty is considerably smaller in practice. Finally, GAG_field was tested with a constant soil pH of 7.5. The variation of NH3 fluxes simulated in this way showed a good agreement with those from the simulations with the original approach, accounting for a dynamically changing soil pH. These results suggest a way for model simplification when GAG_field is applied later at regional scale.

scholarly journals CONTEÚDO DE ÁGUA NO SOLO EM CULTIVO DE MILHO SEM E COM COBERTURA MORTA NA ENTRELINHA NA REGIÃO DE ARAPIRACA-AL

Irriga ◽  
2010 ◽  
Vol 15 (2) ◽  
pp. 173-183 ◽  
Author(s):  
Gustavo Bastos Lyra ◽  
José Leonaldo de Souza ◽  
Iedo Teodoro ◽  
Guilherme Bastos Lyra ◽  
Gilson Moura Filho ◽  
...  
Keyword(s):  
Zea Mays ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Grain Filling ◽  
Dry Period ◽  
Traditional System ◽  
Straw Mulching ◽  
Crop Development ◽  
Grain Filling Period

Avaliou-se a variação do conteúdo de água no solo em diferentes fases de desenvolvimento do milho cultivado sem (Tradicional) e com cobertura morta (Capim) na entrelinha. Observações agrometeorológicas e da cultura foram realizadas na região de Arapiraca, AL (09º38'35" S; 36º40'15" W; 260 m) entre julho e outubro de 2005, na transição do período úmido e seco. Consideraram-se nas análises as seguintes fases de desenvolvimento do milho: inicial (20 d), crescimento (35 d), intermediária (40 d) e final (30 d). A umidade volumétrica do solo foi estimada pelo modelo de van Genutchen em função de medidas do potencial matricial de água no solo. Medidas do potencial foram obtidas por tensiômetros automáticos instalados a 0,15 m de profundidade. O sistema com cobertura morta manteve conteúdo de água no solo superior ao sistema Tradicional em 65,8 % dos dias (75 dias) do ciclo. Contudo, o conteúdo de água no sistema Tradicional sobressaiu-se ao com cobertura morta na maior parte do período de enchimento de grãos (80 %), o que resultou numa maior produtividade de grãos no Tradicional. Na transição entre o período chuvoso e seco da região não é recomendado o uso da cobertura morta na entrelinha durante todo o ciclo do milho, principalmente se o período de enchimento de grãos coincidir com o período seco. Para eventos de chuva de moderado a forte (> 7 mm d-1) a cobertura morta aumenta a capacidade de infiltração da água no solo. Porém, para eventos fracos, a água fica armazenada na cobertura, sendo perdida diretamente para a atmosfera.   UNITERMOS: cobertura morta, movimento de água no solo, semi-árido, Zea mays.     LYRA, G.B.; SOUZA, J.L.; TEODORO, I.; LYRA, G.B.; MOURA FILHO, G.; FERREIRA JÚNIOR, R. A. SOIL WATER CONTENT IN MAIZE CROP WITH AND WITHOUT STRAW MULCHING IN ARAPIRACA  REGION, ALAGOAS, BRAZIL     2 ABSTRACT   The soil water content in different crop development stages of maize cultivated with straw mulching and in traditional system, i.e., bare soil rows, was evaluated. Agro meteorology and crop fields observations were carried out in the Arapiraca region (09º38'35" S; 36º40'15" W; 260 m), state of Alagoas, Brazil, from July through October, 2005, in the transition between humid and dry periods. The following stages of maize development and their lengths (days) were considered: initial (20), crop development (35), mid-season (40) and late (30). The soil moisture was estimated from van Genutchen`s model in function of soil water potential. Potential measurements were obtained from automatic tensiometers, installed at the depth of 0.15 m The soil water content in the mulching system was higher than in the traditional one  in 65.8 % of the cycle (75 days). However, the soil water was higher in the traditional system in the grain filling period (80 % of days); this resulted in higher  grain yield in the traditional system. The use of mulching is not advisable during all maize development cycle in the transition between humid to dry period in that region, mainly if the grain filling period is in the dry period. For moderate to heavy rainfall events (> 7 mm d-1), the infiltration capacity is incremented by mulching. However, for weak events, the rainfall water is stored in mulching and is directly lost to the atmosphere.   KEYWORDS: straw mulching, soil water movement, semi-arid, Zea mays  

scholarly journals Plant available water

1987 ◽  
Vol 6 (3) ◽  
pp. 109-114 ◽  
Author(s):  
P. C. Nel ◽  
J. G. Annandale
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Lower Limit ◽  
Climatic Factors ◽  
Field Capacity ◽  
Threshold Level ◽  
Evaporative Demand ◽  
Available Water ◽  
Plant Available Water

The amount of water in the soil available for plant use, as well as water use efficiency, can be largely influenced by managerial practices. Field capacity is a useful arbitrary upper limit of plant available water (PAW), but factors such as redistribution of soil water, evaporative demand and root distribution may influence it. The lower limit of PAW is often referred to as the wilting coefficient, below which soil water is unavailable to plants. Yield losses occur long before the lower limit of available water is reached. Leaf water potential, transpiration, photosynthesis and various other plant processes are drastically reduced after soil water content has reached a certain threshold level. The presence of this threshold soil water content is being questioned by some researchers. Various soil, plant and climatic factors influence PAW. Laboratory measurements of PAW have a few serious shortcomings. In situ measurements are time consuming and for this reason work is still being done on streamlining laboratory methods.

scholarly journals Ridge–furrow–ridge Rainwater Harvesting System with Mulches and Supplemental Irrigation

HortScience ◽  
2011 ◽  
Vol 46 (1) ◽  
pp. 108-112 ◽  
Author(s):  
Borut Gosar ◽  
Dea Baričevič
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Weed Control ◽  
Rainwater Harvesting ◽  
Echinacea Purpurea ◽  
Plant Production ◽  
Plastic Mulch ◽  
Supplemental Irrigation ◽  
Growing Seasons

New ridge–furrow–ridge rainwater-harvesting (RFRRH) system with mulches has been promoted in agricultural production to improve economic potential for high-value plant production. In this system, plastic mulch covers two ridges and the furrow between them, which serves as the rainwater-harvesting zone. To test this system more effectively, a field study using purple coneflower (Echinacea purpurea Moench) as an indicator crop was conducted to determine the effect of the RFRRH system with or without a covering of two different types of polyethylene mulches and with or without supplemental irrigation on soil water content, crop yield, and time dedicated to weed control during the growing seasons of 2007 and 2008. In the non-irrigated plots, the results showed significantly higher soil water content during dry periods at the beginning of plant growth in the mulch-covered RFRRH system in comparison with the control (uncovered ridges). In comparison with the control, the mulch-covered RFRRH system significantly increased yield and reduced time dedicated to weed control. In the event of a rainfall deficiency, the mulch-covered RFRRH system enabled simple supplemental irrigation, using an agricultural vacuum tanker, by flooding the polyethylene mulch-covered furrow with hardly any ridge erosion. However, in only 1 year did supplemental irrigation significantly increase yield.

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