66
M. A. S. Abdel Monem and I. A. El Ghandour
rural communities, water harvesting can also be enhanced through the application of
satellite remote sensing.
The soil moisture neutron probe (SMNP) is portable equipment for measuring
periodically soil water content at different depths. Data generated from this monitoring are used to calculate the soil water balance and estimate the total amount of
soil water removed by both soil evaporation and plant transpiration [7–10]. WUE
by crops as measured by the SMNP can be increased by up to 50% by changing
irrigation technologies [11, 12] and/or management practices [13, 14], to improve
groundcover and thus reduce evaporation from the soil surface. For example, approximately 25–50% of irrigation water can be saved by using drip irrigation over the
traditional flood surface irrigation. Such savings also brought about other benefits
including an increase in the efficiency of fertilizer applied to crops to the same extent
(20–50%) and a reduction in nitrogen leaching losses beyond the plant rooting zone.
The measurement of natural variations in the abundance of stable isotopes of
oxygen, hydrogen, carbon and nitrogen in soil, water and plant components can help
to identify the sources of water and nutrients used by plants and to quantify water
and nutrient fluxes through and beyond the plant rooting zone. It also an important
tool in understanding different irrigation and land management practices and their
impact on plant uptake of water and nutrients. The soil surface since the light isotopes (hydrogen-1 and oxygen-16) evaporate more readily than the heavy isotopes
(hydrogen-2 {
2 H} and oxygen-18 {
18 O}). The natural isotopic ratios of hydrogen
(
2 H/
1 H) and oxygen (
18 O/
16 O), which are often expressed as delta units (G
2 H and
G
18 O) in soil water, water vapour within a plant canopy and plant leaves can provide estimates of soil evaporation and plant transpiration [15, 16]. Such information
will enable irrigation and land management practices to be developed to minimize
soil evaporation (the non-productive loss of water) and channel this water for crop
production.
Use of nuclear and isotopic techniques has proved to be invaluable tools for
improving WUE. Stable isotopes of water,
2 H and
18 O, at the natural abundance
level; have provided useful tools for tracking and quantifying water flows within
and beyond the plant rooting zone. These techniques show potential to partition
evapotranspiration into soil evaporation and plant transpiration (the water component
removed by plants for their growth). Data and information obtained from using the
nuclear and isotopic techniques can be used: (i) To evaluate the efficacy of different
irrigation and land management practices that minimize soil evaporation and optimize
plant transpiration, (ii) To locate sources of water use by different plants so as to
develop an integrate tree-crop system for sustainable food production particularly in
drylands environments and (iii) To identify and develop management strategies that
minimize the losses of water and associated fertilizers, pesticides, soils and animal
manure from farmlands. The need to minimize such environmental impact from
agricultural activities is increasingly important to enhance viable and sustainable
agricultural systems. The carbon isotope discrimination has potential as a tool for
screening and evaluating large samples of cultivars with increased WUE under waterlimited conditions https://mirfali.wordpress.com/2013/08/09/page/58/.
M. A. S. Abdel Monem and I. A. El Ghandour
rural communities, water harvesting can also be enhanced through the application of
satellite remote sensing.
The soil moisture neutron probe (SMNP) is portable equipment for measuring
periodically soil water content at different depths. Data generated from this monitoring are used to calculate the soil water balance and estimate the total amount of
soil water removed by both soil evaporation and plant transpiration [7–10]. WUE
by crops as measured by the SMNP can be increased by up to 50% by changing
irrigation technologies [11, 12] and/or management practices [13, 14], to improve
groundcover and thus reduce evaporation from the soil surface. For example, approximately 25–50% of irrigation water can be saved by using drip irrigation over the
traditional flood surface irrigation. Such savings also brought about other benefits
including an increase in the efficiency of fertilizer applied to crops to the same extent
(20–50%) and a reduction in nitrogen leaching losses beyond the plant rooting zone.
The measurement of natural variations in the abundance of stable isotopes of
oxygen, hydrogen, carbon and nitrogen in soil, water and plant components can help
to identify the sources of water and nutrients used by plants and to quantify water
and nutrient fluxes through and beyond the plant rooting zone. It also an important
tool in understanding different irrigation and land management practices and their
impact on plant uptake of water and nutrients. The soil surface since the light isotopes (hydrogen-1 and oxygen-16) evaporate more readily than the heavy isotopes
(hydrogen-2 {
2 H} and oxygen-18 {
18 O}). The natural isotopic ratios of hydrogen
(
2 H/
1 H) and oxygen (
18 O/
16 O), which are often expressed as delta units (G
2 H and
G
18 O) in soil water, water vapour within a plant canopy and plant leaves can provide estimates of soil evaporation and plant transpiration [15, 16]. Such information
will enable irrigation and land management practices to be developed to minimize
soil evaporation (the non-productive loss of water) and channel this water for crop
production.
Use of nuclear and isotopic techniques has proved to be invaluable tools for
improving WUE. Stable isotopes of water,
2 H and
18 O, at the natural abundance
level; have provided useful tools for tracking and quantifying water flows within
and beyond the plant rooting zone. These techniques show potential to partition
evapotranspiration into soil evaporation and plant transpiration (the water component
removed by plants for their growth). Data and information obtained from using the
nuclear and isotopic techniques can be used: (i) To evaluate the efficacy of different
irrigation and land management practices that minimize soil evaporation and optimize
plant transpiration, (ii) To locate sources of water use by different plants so as to
develop an integrate tree-crop system for sustainable food production particularly in
drylands environments and (iii) To identify and develop management strategies that
minimize the losses of water and associated fertilizers, pesticides, soils and animal
manure from farmlands. The need to minimize such environmental impact from
agricultural activities is increasingly important to enhance viable and sustainable
agricultural systems. The carbon isotope discrimination has potential as a tool for
screening and evaluating large samples of cultivars with increased WUE under waterlimited conditions https://mirfali.wordpress.com/2013/08/09/page/58/.