Nurit Agam

Nurit Agam
Ben-Gurion University of the Negev | bgu · Jacob Blaustein Institutes for Desert Research

Professor

About

94
Publications
39,100
Reads
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5,092
Citations
Citations since 2017
38 Research Items
3458 Citations
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Introduction
My main research theme is the exchange of heat, water, and momentum through the soil-plant-atmosphere continuum in natural and agricultural systems. Through understanding of these exchange processes in agricultural systems I seek to develop insights for practical strategies to improve water use efficiency. In natural environments my focus is on dew and water vapor adsorption in arid and semi-arid regions and their role in the local hydrological cycle and ecological functioning.
Additional affiliations
July 2017 - July 2022
Ben-Gurion University of the Negev
Position
  • Associate Professor
January 2013 - July 2017
Ben-Gurion University of the Negev
Position
  • Senior lecturer
January 2008 - December 2012
Agricultural Research Organization ARO
Position
  • Research Associate
Education
October 1999 - September 2005
Ben-Gurion University of the Negev
Field of study
  • Micrometeorology
October 1996 - September 1999
Ben-Gurion University of the Negev
Field of study
  • Micrometeorology
October 1992 - September 1995
Ben-Gurion University of the Negev
Field of study
  • Geography and Environmental Development

Publications

Publications (94)
Article
Full-text available
Efforts to apply gridded root-zone soil moisture (RZSM) products for irrigation decision-support in vineyards are currently hampered by the difficulty of obtaining RZSM products that meet required accuracy, resolution, and data latency requirements. In particular, the operational application of soil water balance modeling is complicated by the diff...
Article
Full-text available
In agriculture, leaf area index (LAI) is an important variable that describes occurring biomass and relates to the distribution of energy fluxes and evapotranspiration components. Current LAI estimation methods at subfield scale are limited not only by the characteristics of the spatial data (pixel size and spectral information) but also by the emp...
Method
Accurate leaf area index (LAI) estimation through machine learning (ML) algorithms is a channel for better understanding and monitoring the existing biomass and it relates to the distribution of energy fluxes and evapotranspiration partitioning. In order to support the ML algorithm for accurate LAI estimation, the supporting data (or features) gain...
Article
The extent of the vertical microclimate heterogeneity inside a greenhouse is mostly unknown, and it can strongly affect plant production and yield quality. Tomato crop was grown in a semi-closed greenhouse equipped with horizontal ventilation and sidewall curtains, which were only opened depending on microclimate conditions; and a naturally ventila...
Article
The Namib Sand Sea is a hyper-arid coastal fog desert, with limited vegetation scattered across the extensive sand dunes. Minimal and unpredictable rainfall, along with proximity to the ocean, make non-rainfall water inputs (NRWIs), i.e. fog, dew and water vapor adsorption, an important part of the ecohydrology. We studied water accumulation across...
Conference Paper
Full-text available
Accurate quantification of the partitioning of evapotranspiration (ET) into transpiration and evaporation fluxes is necessary to understanding ecosystem interactions among carbon, water, and energy flux components. ET partitioning can also support the description of the atmosphere and land interactions and provide unique insights into vegetation wa...
Article
Partitioning of evapotranspiration (ET) into soil water evaporation and transpiration allows separate assessment of soil and plant water, energy, and carbon exchange. Remote sensing-based models are ideally suited to monitor ET over large areas, but ET partitioning estimates vary widely. The objective of this study was to evaluate the two-source en...
Article
Full-text available
Global climate change and the expected increase in temperature are altering the relationship between geography and grapevine (V. vinifera) varietal performance, and the implications of which are yet to be fully understood. We investigated berry phenology and biochemistry of 30 cultivars, 20 red and 10 white, across three seasons (2017–2019) in resp...
Article
Micro-catchment systems (MCs) are designed to harvest and utilize rainwater, with the aim of supporting crop growth in arid regions. While MCs were traditionally built with shallow infiltration basins, recent research indicates that MCs with deeper basins lose less water to the atmosphere than MCs with shallower basins. Consequently, we can expect...
Article
Full-text available
Most soil hydraulic information used in Earth System Models (ESMs) is derived from pedo-transfer functions that use easy-to-measure soil attributes to estimate hydraulic parameters. This parameterization relies heavily on soil texture, but overlooks the critical role of soil structure originated by soil biophysical activity. Soil structure omission...
Chapter
Reactive nitrogen compounds (Nr, which include NOx (i.e., NO+NO2), N2O, ammonia, and HONO) have a large impact on atmospheric chemical composition and, thus, on climate. Nitric oxide (NO) is a chemically reactive trace gas that reacts with ozone (O3) to form NO2 (Crutzen 1979). The formation of O3 depends on a sensitive relationship between NOx (NO...
Article
Full-text available
A spatially distributed land surface temperature is important for many studies. The recent launch of the Sentinel satellite programs paves the way for an abundance of opportunities for both large area and long-term investigations. However, the spatial resolution of Sentinel-3 thermal images is not suitable for monitoring small fragmented fields. Th...
Poster
Full-text available
Solar irradiance and air temperature are the major environmental factors leading to seasonal and regional differences in the composition of grapes. Nevertheless, these factors change dramatically in the course of a day and across a single grape cluster. To date, the consequences of these spatiotemporal fluctuations on the corresponding variability...
Article
Full-text available
Vineyards’ canopy architecture and row structure pose unique challenges in modeling the radiation partitioning and energy exchange between the vine canopy and the interrow area. The vines are often pruned and manipulated to be strongly clumped, while mechanical harvesting requires wide rows, often with vine height to vine spacing ratio > 1. This pa...
Article
Full-text available
Water-limiting conditions in many California vineyards necessitate assessment of vine water stress to aid irrigation management strategies and decisions. This study was designed to evaluate the utility of a Crop Water Stress Index (CWSI) using multiple canopy temperature sensors and to study the diurnal signature in the stress index of an irrigated...
Article
Full-text available
In vineyards, hourly soil heat flux (SHF) may account for as much as 30% of net radiation. Therefore, inaccurate estimates of SHF may lead to non-negligible errors when quantifying the surface energy balance. The typical canopy height to width ratio of two along with widely spaced rows (row spacing exceeding canopy height), and leaf biomass concent...
Article
Solar irradiance and air temperature are characterized by dramatic circadian fluctuations and are known to significantly modulate fruit composition. To date, it remains unclear whether the abrupt, yet predictive, diurnal changes in radiation and temperature prompt direct metabolic turn-over in the fruit. We assessed the role of fruit insolation, ai...
Article
Full-text available
Particularly in light of California’s recent multi-year 1 drought, there is a critical need for accurate and timely evapotranspiration (ET) and crop stress information to ensure long-term sustainability of high-value crops. Providing this information requires the development of tools applicable across the continuum from sub-field scales to improve...
Article
Full-text available
Warm viticulture regions are associated with inferior wines, resulting from the interaction between microclimate and fruit biochemistry. Solar irradiance triggers biosynthetic processes in the fruit, and dominates its thermal balance. Therefore, deciphering its impact on fruit metabolism is pivotal to develop strategies for fruit protection, and am...
Article
Non-rainfall water inputs (NRWI) are a significant water source in drylands. Small latent heat flux (λE) involved in the formation and evaporation of NRWI presents measurement challenges. Microlysimeters (MLs) are a point measurement that was previously shown to be accurate for detecting NRWI. In an attempt to upscale these measurements, two turbul...
Article
Advection of hot air from a warmer to a cooler surface is known to enhance evaporation through additional supply of energy, provided that water is readily available. This study investigated advection in an isolated irrigated vineyard in the Negev desert, over a period of several months under changing plant cover and environmental conditions, and fo...
Article
Full-text available
To use VRI systems, a field is divided into irrigation management zones (IMZs). While IMZs are dynamic in nature, most of IMZs prescription maps are static. High-resolution thermal images (TI) coupled with measured atmospheric conditions have been utilized to map the within-field water status variability and to delineate in-season IMZs. Unfortunate...
Article
Full-text available
Vineyards are characterized by their large spatial variability of solar irradiance (SI) and temperature, known to effectively modulate grape metabolism. To explore the role of sunlight in shaping fruit composition and cluster uniformity, we studied the spatial pattern of incoming irradiance, fruit temperature and metabolic profile within individual...
Article
Accurate measurement of soil temperature gradients is important for the estimation of soil heat flux and latent heat flux, both major components of the surface energy balance. Soil temperature gradients are commonly measured using heat-pulse sensors equipped with thermistors. In this study, individual thermistors showed absolute temperature differe...
Article
In this study ground measured soil and vegetation component temperatures and composite temperature from a high spatial resolution thermal camera and a network of thermal-IR sensors collected in an irrigated maize field and in an irrigated cotton field are used to assess and refine the component temperature partitioning approach in the Two-Source En...
Article
We tested the hypothesis that whole-tree water consumption of olives (Olea europaea L.) is fruit load-dependent and investigated the driving physiological mechanisms. Fruit load was manipulated in mature olives grown in weighing-drainage lysimeters. Fruit was thinned or entirely removed from trees at three separate stages of growth: early, mid and...
Conference Paper
Full-text available
Accurate partitioning of the evaporation (E) and transpiration (T) components of evapotranspiration (ET) in remote sensing models is important for evaluating strategies aimed at increasing crop water productivity. A two-source energy balance (TSEB) model designed for row crops solves the energy balance of the soil-plant canopy-atmosphere continuum...
Conference Paper
Accurate partitioning of the evaporation (E) and transpiration (T) components of evapotranspiration (ET) in remote sensing models is important for evaluating strategies aimed at increasing crop water productivity. A two-source energy balance (TSEB) model designed for row crops solves the energy balance of the soil-plant canopy-atmosphere continuum...
Conference Paper
Full-text available
Olive, considered to be moderately salt tolerant, is commonly irrigated with marginal or low quality water. Exposure to relatively high salinity is detrimental to tree health and production. It was hypothesized that physiological response of olive trees to salinity leads to increased relative canopy temperature and thus is identifiable by means of...
Article
Full-text available
This study compares evapotranspiration (ET) measurements from eddy covariance (EC), lysimetry (LY), and water balance using a network of neutron probe (NP) sensors and investigates the role of within-field variability in the vegetation density in explaining the differences among the various techniques. Measurements were collected over irrigated cot...
Article
Full-text available
Land surface emissivity (LSE) in the thermal infrared depends mainly on the ground cover and on changes in soil moisture. The LSE is a critical variable that affects the prediction accuracy of geophysical models requiring land surface temperature as an input, highlighting the need for an accurate derivation of LSE. The primary aim of this study was...
Article
Full-text available
Evaporation from the soil surface (E) can be a significant source of water loss in arid areas. In sparsely vegetated systems, E is expected to be a function of soil, climate, irrigation regime, precipitation patterns, and plant canopy development, and will therefore change dynamically at both daily and seasonal time scales. The objectives of this r...
Article
Full-text available
Vineyards in the southeastern United States face challenges including poor internal soil drainage, high precipitation, and warm temperatures. This environment causes elevated humidity, creating ideal conditions for fungal diseases. Maintaining tall fescue (Schedonorus arundinaceus Shreb) and resident vegetation ground cover in vineyard inter-rows i...
Article
Full-text available
The two-source energy balance (TSEB) model calculates the energy balance of the soil-canopy-atmosphere continuum, where transpiration is initially determined by the Priestley-Taylor equation. The TSEB was revised recently using the Penman-Monteith equation to replace the Priestley-Taylor formulation, thus better accounting for the impact of large a...
Article
Vineyards in the southeastern United States face challenges including poor internal soil drainage, high precipitation, and warm temperatures. This environment causes elevated humidity, creating ideal conditions for fungal diseases. Maintaining tall fescue (Schedonorus arundinaceus Shreb) and resident vegetation ground cover in vineyard inter-rows i...
Article
Full-text available
Cloud cover drastically and instantaneously reduces net radiation and available energy. Appearance of clouds will therefore alter the surface energy balance and elicit response of plant canopy temperature (T C). The attenuated shortwave radiation and altered T C during the presence of clouds may subsequently affect the crop water stress index (CWSI...
Article
Full-text available
Information regarding tree water status in irrigated olive orchards is essential for managing growth to optimize yields and olive oil quality. One management practice option is to monitor or sample individual trees and use this information for orchard-scale management. This study assessed the ability of thermal imaging to provide the spatial distri...
Article
Agricultural productivity has increased in the Texas High Plains at the cost of declining water tables, putting at risk the sustainability of the Ogallala Aquifer as a principal source of water for irrigated agriculture. This has led area producers to seek alternative practices that can increase water use efficiency (WUE) through more careful manag...
Article
Spatial and temporal variability in soil heat flux (G) under sparse/clumped vegetation conditions is significant and has been studied. However, little attention has been devoted to evaluating the variability of G with respect to row crops, particularly with respect to row direction. The variation in G for row crops is related to the effect of diffe...
Conference Paper
Irrigators of modernized olive orchards are challenged to determine regional and cultivar specific water regimes that increase yield while not jeopardizing olive oil quality. We have investigated olive irrigation regimes, including severe deficit strategies, on two Israeli cultivars (‘Souri’ and ‘Barnea’) in a two year field experiment. Trees recei...
Article
Full-text available
Leaf turgor pressure provides a very sensitive indicator of plant water status. Diurnal changes in turgor pressure of olives were measured over several months with a novel leaf patch clamp pressure (LPCP) probe. The LPCP probe is user-friendly, non-invasive, online-monitoring, robust and versatile, and is characterised by high precision, low-cost a...
Article
Drainage-weighing lysimeters allowed monitoring of water balance components of non-bearing olive (Olea europaea cv Barnea) trees over a 3-month period including short-term events of controlled but severe water stress. The objective of the study was to evaluate a variety of soil and plant-based water status and drought stress monitoring methods on t...