INFLUENCE OF SOIL MOISTURE ON COLD TOLERANCE OF ALFALFA

1980 ◽  
Vol 60 (1) ◽  
pp. 139-147 ◽  
Author(s):  
ROGER PAQUIN ◽  
GUY R. MEHUYS
Keyword(s):  
Soil Moisture ◽  
Soil Water ◽  
Sandy Loam ◽  
Freezing Process ◽  
Plant Survival ◽  
Hardening Process ◽  
Ap Horizon ◽  
Soil Water Holding Capacity ◽  
Water Treatments ◽  
Water Holding

Drought stress applied to alfalfa seedlings (Medicago media Pers.) grown at 20–22 °C by reducing soil moisture from 100 to 30% of soil water holding capacity prior to freezing increased their LT50 by 4–7 °C. The tests were performed in 12-cm pots containing either a greenhouse sandy loam potting mixture or material sampled in the Ap horizon of several soils of varying texture. Similar increases were obtained when identical soil water treatments were applied to plants hardened for 2 or 4 wk at 1 °C. Both stresses, drought and low temperature, have additive influences on plant survival following freezing. Low soil moisture increased both the level of cold hardening achieved and plant survival to freezing, but it had a larger effect on the freezing process than on the hardening process. Freezing tests carried out with insulated pots, in order to simulate field conditions where frost comes from above, did not affect the survival of alfalfa in spite of a delay in the cooling of the soil. Differences in cooling rates during freezing could not be correlated with the higher mortality observed with moist soils.

scholarly journals Estimation of soil water holding capacity with Random Forests for drought monitoring

2021 ◽  
Author(s):  
Yves Tramblay ◽  
Pere Quintana Seguí
Keyword(s):  
Soil Moisture ◽  
High Resolution ◽  
Soil Water ◽  
Random Forests ◽  
Land Surface ◽  
Water Holding Capacity ◽  
Drought Monitoring ◽  
Soil Maps ◽  
Soil Water Holding Capacity ◽  
Water Holding

Abstract. Soil moisture is a key variable for drought monitoring but soil moisture measurements networks are very scarce. Land-surface models can provide a valuable alternative to simulate soil moisture dynamics, but only a few countries have such modelling schemes implemented for monitoring soil moisture at high spatial resolution. In this study, a soil moisture accounting model (SMA) was regionalized over the Iberian Peninsula, taking as a reference the soil moisture simulated by a high-resolution land surface model. To estimate soil water holding capacity, the parameter required to run the SMA model, two approaches were compared: the direct estimation from European soil maps using pedotransfer functions, or an indirect estimation by a Machine Learning approach, Random Forests, using as predictors altitude, temperature, precipitation, evapotranspiration and land use. Results showed that the Random Forest model estimates are more robust, especially for estimating low soil moisture levels. Consequently, the proposed approach can provide an efficient way to simulate daily soil moisture and therefore monitor soil moisture droughts, in contexts where high-resolution soil maps are not available, as it relies on a set of covariates that can be reliably estimated from global databases.

scholarly journals Comparison of three models fitting the soil water retention curves in a degraded alpine meadow region

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Tao Pan ◽  
Shuai Hou ◽  
Yujie Liu ◽  
Qinghua Tan
Keyword(s):  
Soil Water ◽  
Water Retention ◽  
Alpine Meadow ◽  
Soil Depth ◽  
Water Holding Capacity ◽  
Curve Shape ◽  
Soil Water Retention ◽  
Soil Water Holding Capacity ◽  
Water Holding ◽  
Gardner Model

AbstractSoil water retention curve (SWRC) plays an important role in simulating soil water movement and assessing soil water holding capacity and availability. Comparison of fitness between different models to determine the best SWRC model of specific regions is required. In this study, three popular models, van Genuchten, Brooks Corey and Gardner model, were selected for comparing in a degraded alpine meadow region on the eastern Tibetan Plateau. Fitness, error distribution along with key parameters were compared. For each soil horizon, the soil moisture content at all soil water potentials decreased consistently with degradation, thereby integrally moving the SWRCs of all soil depths downward with degradation. The differences in SWRCs across various degradation degrees diminished along with soil depth and soil water potential. The Adj.r2 values of van Genuchten, Brooks Corey and Gardner models ranged in 0.971–0.995, 0.958–0.997, and 0.688–0.909, respectively. The van Genuchten and Brooks Corey models significantly (p < 0.05) outperformed the Gardner model, and have no significant differences in fitness. The fitness of all three models showed no significant changes with degradation. Regardless of degradation degree and soil depth, the fitting error of van Genuchten and Brooks Corey models was mainly distributed in the higher (from –100 hPa to –500 hPa) and lower (below –10000 hPa) potential sections. With regard to the parameters of van Genuchten and Brooks Corey models, the field capacity (θs), and permanent wilting moisture were highly coherent with Adj.r2 values of higher than 0.98, while the curve shape parameter (θr), and air entry pressure of the Brooks Corey model were much lower than those of the van Genuchten model with Adj.r2 values of lower than 0.91. The SWRCs with varying degrees of degradation are best fitted by both van Genuchten and Brooks Corey models but cannot be fitted by Gardner model. Soil water holding capacity decreased with degradation especially in the top soil (0 cm to 30 cm), but the curve shape of all SWRCs did not change significantly with degradation.

scholarly journals Analysis of soil and vegetation patterns in semi-arid Mediterranean landscapes by way of a conceptual water balance model

2008 ◽  
Vol 12 (3) ◽  
pp. 899-911 ◽  
Author(s):  
I. Portoghese ◽  
V. Iacobellis ◽  
M. Sivapalan
Keyword(s):  
Water Balance ◽  
Soil Water ◽  
Water Holding Capacity ◽  
Sensitivity Analyses ◽  
Vegetation Types ◽  
Study Region ◽  
Mediterranean Landscapes ◽  
Soil Water Holding Capacity ◽  
Water Holding ◽  
Semi Arid

Abstract. This paper investigates the impact of various vegetation types on water balance variability in semi-arid Mediterranean landscapes, and the different strategies they may have developed to succeed in such water-limited environments. The existence of preferential associations between soil water holding capacity and vegetation species is assessed through an extensive soil geo-database focused on a study region in Southern Italy. Water balance constraints that dominate the organization of landscapes are investigated by a conceptual bucket approach. The temporal water balance dynamics are modelled, with vegetation water use efficiency being parameterized through the use of empirically obtained crop coefficients as surrogates of vegetation behavior in various developmental stages. Sensitivity analyses with respect to the root zone depth and soil water holding capacity are carried out with the aim of explaining the existence of preferential soil-vegetation associations and, hence, the spatial distribution of vegetation types within the study region. Based on these sensitivity analyses the degrees of suitability and adaptability of each vegetation type to parts of the study region are explored with respect of the soil water holding capacity, and the model results were found consistent with the observed affinity patterns.

An empirical model for drainage from soil under rain fed conditions

Soil Research ◽  
1977 ◽  
Vol 15 (3) ◽  
pp. 205 ◽  
Author(s):  
AR Aston ◽  
FX Dunin
Keyword(s):  
Soil Moisture ◽  
Soil Water ◽  
Empirical Model ◽  
Sandy Loam ◽  
Empirical Relationship ◽  
Field Conditions ◽  
Natural Field ◽  
Moisture Contents ◽  
Weighing Lysimeter

An empirical relationship was derived for drainage from a podzolic sandy loam using a weighing lysimeter at Krawarree, N.S.W. The form of the equation was similar to those used to describe drainage following irrigation. The agreement between computed and measured soil moisture contents over a period of five years was good, and indicated the usefulness of such an approach to characterize drainage of soil water under natural field conditions.

Soil water holding capacity under four typical ecosystems in Wuyunjie Nature Reserve of Hunan Province

2012 ◽  
Vol 32 (2) ◽  
pp. 538-547 ◽  
Author(s):  
潘春翔 PAN Chunxiang ◽  
李裕元 LI Yuyuan ◽  
彭亿 PENG Yi ◽  
高茹 GAO Ru ◽  
吴金水 WU Jinshui
Keyword(s):  
Soil Water ◽  
Nature Reserve ◽  
Water Holding Capacity ◽  
Hunan Province ◽  
Soil Water Holding Capacity ◽  
Water Holding

Soil water drying and recharge rates as affected by tillage under continuous barley and barley-canola cropping systems in northwestern Canada

2001 ◽  
Vol 81 (1) ◽  
pp. 45-52 ◽  
Author(s):  
R H Azooz ◽  
M A Arshad
Keyword(s):  
Soil Moisture ◽  
Soil Water ◽  
Sandy Loam ◽  
Time Domain Reflectometry ◽  
Sandy Loam Soil ◽  
Soil Conditions ◽  
Silt Loam ◽  
Silt Loam Soil ◽  
Loam Soil ◽  
The Impact

In areas of the northwestern Canadian Prairies, barley and canola are grown in a short growing season with high rainfall variability. Excessively dry soil in conventional tillage (CT) in dry periods and excessively wet soil in no-tillage (NT) in wet periods could cause a significant decrease in crop production by influencing the availability of soil water. The effects of CT, NT and NT with a 7.5-cm residue-free strip on the planting rows (NTR) on soil water drying (–dW/dt) and recharge (dW/dt) rates were studied in 1992 and 1993 during wet and dry periods to evaluate the impact of NTR, NT and CT systems on soil moisture condition. The soils, Donnelly silt loam and Donnelly sandy loam (both Gray Luvisol) were selected and soil water content by depth was measured by time domain reflectometry. Water retained at 6 matric potentials from –5 to –160 kPa were observed. In the field study, –dW/dt was significantly greater in CT than in NT in the silt loam for the 0- to 30-cm layer during the first 34 d after planting in 1992. The 0- to 30-cm soil layer in CT and NTR dried faster than in NT during a period immediately following heavy rainfall in the silt loam in 1993. The drying coefficient (–Kd ) was significantly greater in CT and NTR than in NT in the silt loam soil in 1993 and in the sandy loam soil in 1992 in the top 30-cm depth. The recharge coefficient (Kr) was significantly greater in NT and NTR than in CT for the silt loam soil. The NTR system increased the –dW/dt by 1.2 × 10-2 to 12.1 × 10-2 cm d-1 in 1992 and 1993 in the silt loam soil and by 10.2 × 10-2 cm d-1 in 1993 in the sandy loam soil as compared with NT. The dW/dt was 8.1 × 10-2 cm d-1 greater in NTR in 1992 and 1993 in the silt loam soil and was 1.9 × 10-2 greater in NTR in 1992 than in CT in the sandy loam soil. The laboratory study indicated that NT soils retained more water than the CT soils. The NTR practice maintained better soil moisture conditions for crop growth than CT in dry periods than NT in wet periods. Compared with NT, the NTR avoided prolonged near-saturated soil conditions with increased soil drying rate under extremely wet soil. Key words: Water drying, water recharge, water depletion, wet and drying periods, hydraulic properties, soil capacity to retain water

scholarly journals Mapping soil water holding capacity over large areas to predict potential production of forest stands

Geoderma ◽  
2011 ◽  
Vol 160 (3-4) ◽  
pp. 355-366 ◽  
Author(s):  
Christian Piedallu ◽  
Jean-Claude Gégout ◽  
Ary Bruand ◽  
Ingrid Seynave
Keyword(s):  
Soil Water ◽  
Water Holding Capacity ◽  
Forest Stands ◽  
Potential Production ◽  
Soil Water Holding Capacity ◽  
Water Holding
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