scholarly journals A Hydraulic Model Is Compatible with Rapid Changes in Leaf Elongation under Fluctuating Evaporative Demand and Soil Water Status

2014 ◽  
Vol 164 (4) ◽  
pp. 1718-1730 ◽  
Author(s):  
Cecilio F. Caldeira ◽  
Mickael Bosio ◽  
Boris Parent ◽  
Linda Jeanguenin ◽  
François Chaumont ◽  
...  
Keyword(s):  
Soil Water ◽  
Water Status ◽  
Hydraulic Model ◽  
Leaf Elongation ◽  
Evaporative Demand ◽  
Soil Water Status ◽  
Rapid Changes

Accuracy of soil water budgets based on a range of relationships for the influence of soil water availability on actual water use

1975 ◽  
Vol 26 (5) ◽  
pp. 871 ◽  
Author(s):  
GG Johns ◽  
RCG Smith
Keyword(s):  
Soil Water ◽  
Water Use ◽  
Water Status ◽  
Surface Zone ◽  
Evaporative Demand ◽  
Water Budgets ◽  
Soil Water Status ◽  
Complex Functions ◽  
Simple Ratio ◽  
Water Values

The accuracy of six published functions for deriving dryland water use from evaporative demand and soil water status was assessed by incorporating them in water budgets which were used to estimate dryland soil water status from actual climatic records. Budget-derived estimates were compared with values actually measured under improved pastures in the field over an 842 day period. The root mean square (RMS) of the differences between computed and observed soil water values was used to evaluate the various functions. RMS values were found to vary from 8.1 to 29.5 mm for the various functions tested. Soil water estimations made by using a simple ratio function were generally as good as or better than those made by using more complex functions. The sensitivity of the various functions to changes in their input assumptions was tested. The results of these tests will facilitate the selection of the optimum functions for conditions other than those encountered in this study. Reduced accuracy of soil water prediction resulted from the use of functions to set water use equal to the potential rate, regardless of the overall dryness of the soil profile, whenever recent rainfall was calculated to have made water available in the surface zone.

Optimisation of fertigation scheduling based on indicators of soil water status in melon growing in semi-arid areas

2021 ◽  
Author(s):  
Sandra María Martínez-Pedreño ◽  
Pablo Berríos ◽  
Abdelmalek Temnani ◽  
Susana Zapata ◽  
Manuel Forcén ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Soil Water ◽  
Water Status ◽  
Total Phenolic ◽  
Crop Water ◽  
Soil Water Status ◽  
Significant Difference ◽  
Irrigation Time ◽  
Crop Cycle ◽  
Semi Arid

<p>In water scarcity areas, it is necessary not only reducing the water applied as much as possible, but also optimizing nutrients application to avoid soil salinization and aquifers pollution because of leaching bellow the root zone. Increasing the sustainability of fertirrigation needs technology to adjust the irrigation time, knowing more precisely the soil water retention capacity and facilitate water absorption by the crop. The aim of this trial was to establish protocols for sustainable fertirrigation in melon crop under semi-arid conditions, both at an environmental and economic level, based on the use of soil water status indicators measured by sensors that allow us to increase the irrigation water use efficiency. Two irrigation treatments were established: i) Control (CTL), irrigated to satisfy the water requirements of the crop, according to the farmer's criterion throughout the crop cycle and ii) DI, deficit irrigation, irrigated to allow a maximum soil water depletion of 20%, with respect to field capacity throughout the crop cycle, from sensors located below the 20 cm depth horizon, in order to limit water leaching into the soil. An experimental design was established with 4 repetitions per treatment distributed at random, with 5 plants per repetition. Macro and micronutrients concentration of soil solution, leaves and fruits were analysed. The crop water status was determined fortnightly by measurements taken at solar midday of stem water potential, net photosynthesis, evapotranspiration rate and leaf conductance. Whereas photosynthetically active radiation absorption, basal stem and fruit equatorial diameters were determined to estimate plant and fruit growth. The physical (longitudinal and equatorial fruit diameters, fruit weight, pulp width and firmness) and chemical (titratable acidity, pH and total soluble solid of the juice, total phenolic content, total antioxidant capacity and total ascorbic acid) characteristics of harvested fruits were determined. Total water applied in CTL treatment was 3,254 m<sup>3</sup> ha<sup>-1</sup> throughout the crop cycle whereas DI received 2,284 m<sup>3</sup> ha<sup>-1</sup>, a 29.8% lower. In both cases, the volume of water applied was lower than recommended by FAO. The regulation of the irrigation time in the DI treatment respect to the CTL promoted a reduction of the soil water content from 30 cm depth, mitigating the water loss below the root system, along with a lower contribution of nutrients, around of 43, 41.8 and 22% of N, P and K, respectively, and less salinization of the soil profile. No significant difference between treatments was detected in the concentration of these nutrients at leaf level. No difference was observed at harvest, with 0.53 and 0.59 g fruit g<sup>-1</sup> total dry mass of harvest index in CTL and DI, respectively. Fruit quality was not negatively affected in DI but improved since ascorbic acid was higher. This means that DI treatment not only did not negatively affect the crop water status and the amount and quality of the yield, but also improved its biochemical quality while reducing water and nutrients use and leaching.</p>

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