Sustainable Options for Soil and water salinity management in date palm production Nazir Hussain, Osman El-Sharief Abdalla, Muhammed Salem Al-Bakri Al-Yafai and Talaat Ahmed Section of Agricultural Research and Extension Department of Agricultural Affairs Ministry of Environment Doha, State of Qatar drnazirhussain@gmail.com

Components of my discussion Date palm production and yields, the past and present Future climatic changes with respect to salinity/ sodicity and date palm production Extent of salinity in major date palm producing countries Management strategies for soil and water salinity Conclusions

Average yield (T ha-1) of date palm of the top 10 Countries during the last five decades 2010 2005 2000 1990 1980 1970 1961 Countries 6.277 5.850 6.200 5.496 7.444 7.137 7.720 World 32.255 33.428 34.736 24.842 22.300 16.950 23.950 Egypt 4.608 8.080 8.473 4.412 - Iraq 6.334 4.054 4.088 6.385 9.194 12.500 12.000 Saudi Arabia 4.181 6.056 7.793 6.838 8.044 8.503 8.270 UAE 5.815 Pakistan Compiled from FAOSTAT Data by the Authors

Average yield (T ha-1) of date palm of the top 10 Countries during the last five decades (contd.) 2010 2005 2000 1990 1980 1970 1961 Countries 4.002 3.491 3.652 2.618 2.996 2.477 2.500 Algeria 6.533 4.173 4.707 4.339 3.049 3.875 3.841 Iran 11.905 9.764 9.495 7.0097 10.004 6.000 6.023 Sudan 8.816 7.886 4.800 3.482 3.462 3.077 Oman 5.367 5.357 5.000 4.933 - Libya Compiled from FAOSTAT Data by the Authors

The Causes of Diminishing Yields Deficiency of irrigation water of good quality and appropriate irrigation system Soil and water salinity Low yielding cultivars Insect and disease attack Poor agronomic techniques practiced by the farmers Harvesting losses and post harvest cares Poor awareness of the date palm growers, need of training and hampered technology transfer to the end users

Future Global climatic changes to be expected Rise in temperature and evaporation The hydrological cyclones and floods Excessive or meager rainfall Increase in droughts Rising of mean sea level Melting of ice Dry regions of the world would become still more drier It may become more difficult for water scarce countries to cope with natural conditions with lesser water than what is now available (Bino, 2008). Most of the above happenings, if not all, are expected in date palm growing countries

Expected climatic changes and salinity Soil and water salinity are the problems of arid and semi arid regions because these are directly associated with levels of precipitation and temperature More use of saline water under lesser rainfall and subsequent drought The salts added/ recycled through irrigations remain in the profile and come to the surface or subsurface with the capillary movement of soil water when dry conditions coupled with high temperature persist The water evaporates and leaves dissolved salts on the surface or just underneath When such a process continues for longer periods the consequence is salinization (accumulation of salts) followed by sodication (Substitution of Ca + Mg by sodium on the clay complex) Thus, increase in impact of salinity/ sodicity is expected under the scenario of such climatic changes

GLOBAL SCENARIO OF THE SALINITY PROBLOM Soil salinity and sodicity are the global problems that encompass all the continents except Antarctica. World soil map prepared by FAO/UNESCO indicated that total saline lands occupy 397 million ha while sodic lands are spread on an area of 434 million ha. Out of the current 230 million ha of irrigated land of the world, 45 million ha (19.5 %) are salt affected. Salt affected area within dry land agriculture has been reported as 32 (2.1 %) out of total 1500 million ha.

Some facts about salinity in Arab World and GCC countries UAE 0.400 mha KSA 5.641 mha Oman 9.442 mha Qatar 70124 ha Bahrain 41000 ha Kuwait 85000 ha Yemen 0.483 mha Salt affected area in Arab world is 82.7 mha (42 % of arable land that is 14.1% of total) Egypt 3.5 mha Iraq 43.5 mha Sudan 4.8 mha Tunisia 1.5 mha Algeria 0.350 mha Morocco 1.00 mha Libya 0.7007 mha

Effects of salinity on plants 1. OSMOTIC EFFECTS Loss of turgor Reduced water uptake even in the presence of water Reduced uptake of nutrients 2. SPECIFIC ION EFFECT Toxicity of chlorides and sulphate of Na. Toxicity of Boron and Mg. Plant functions (Photosynthesis, respiration and photophosporylation etc.) Membrane leakage Inhibition of enzyme activities

Effects of salinity on plants NUTRITIONAL IMBALANCE More uptake of Na, Ca , Mg, Cl and SO4 Less uptake of K and P Reduced availability of K, P, N, B, Zn, Cu, Fe FINAL EFFECTS General paleness Reduced or stoppage of growth Partial or total death of Plants More sterility Low or no yields

Tolerance of Date palm to salinity (EC dS/ m) 0% yield 50% yield 75% yield 100% yield Type of sanity 21.0 12.0 7.3 2.7 Water salinity (Ayers and Westcot, 1985) 32.0 18.0 11.0 4.0 Soil salinity (Ayers and Westcot, 1985 Growth of seedlings - 9.0 3.0 Water salinity in sandy loam soil (Al-Rasbi et al., 2011)

Date Palm Orchard Affected by Salinity in Oman

Date Palm Orchard Affected by Salinity in Oman

Causes of salinity in the region Climatic conditions: Low rainfall and high temperature results in surface and subsurface accumulation of salts (Salinization) Nearness to sea: Seawater sprays, floods and intrusions Secondary salinity mostly emerging from consistent use of saline water, presently it is the major source of development of salt affected soils in the region Blind and unforeseen pumping of groundwater resulting in destroying the balance (of centuries) existing between recharge and stored good quality water Mismanagement of irrigation water and salt affected soils

Negative effect of saline water on plant parameters of date palm (% decrease over control = 3 dS/ m) Trunk girth Leaf length Number of fronds Plant height Water EC ds/ m - 3 11 8 12 18 6 17 27 28 9 21 32 36 40 29 39 46 15 48 53

Precautionary Measures Safe usage of brackish water through appropriate management strategies in order to control secondary salinity Plowing of lands to break the capillaries and keeping boundaries of fields strong, especially before starting of monsoon season and occasional deep plowing Mulching to decrease evaporation and resultant salt accumulation Green manuring/ composting and addition of organic matter Scheduling of irrigations Addition of amendments (Gypsum, sulphuric acid etc.) if the irrigation water is sodic as well

Safe utilization of saline water Utilization of saline water continuously for longer periods causes salinization and deleterious effects appear on Crops Soils Environment Therefore, management of saline water is highly important In fact, salinity management depends upon management of saline waters Under the prevailing conditions of Arabian Peninsula, appropriate and important strategies are: 1. Leaching fractions 2. Cyclic use 3. Application of organic matter 4. Mulching

Leaching Fractions The EC of water and its used quantity Salts can accumulate slowly and gradually depending upon The EC of water and its used quantity Rainfall and temperature Soil parameters like texture and drainage Leaching of salts can only occur if additional water over and above the consumptive water of various crops is applied This additional water is called leaching fraction (LF) or leaching requirement This is the only solution when saline water is solely available Investigations in Oman indicated partial success of the technique (When EC of water is not too high = 9 dS/ m or above)

Role of leaching fractions in improvement of growth character of date palm seedlings when irrigated with saline water

Effectiveness of leaching fractions in controlling increase in soil EC during irrigation with saline water

Application of organic matter Low organic matter is the peculiarity of soils of arid and semiarid regions but it is very particularly true for Arab Peninsula Soils are mostly sandy and have high drainage that does not permit holding water for longer periods The applied irrigation water disappears in couple of days leaving the lands dry and plants to suffer for water Organic matter is the only rescue of such conditions because soil physical properties including water holding capacity are improved due to its application Manuring and surface mulching indicate significantly higher soil moisture content requiring less irrigations Resultantly, there will be less addition of salts when water is saline and lesser salinization Organic matter of plant residues or from animals may be the best option.

Efficiency of organic matter application in maintaining plant growth parameters during saline water irrigation

Effectiveness of organic matter application for controlling increase in soil EC during irrigation with saline water

Mulching to reduce salinization High temperature generally results in high evaporation which causes twin effect; enormous water losses and enhanced salt accumulation in arid and semiarid regions Providing mulch on the surfaces checks water losses and simultaneous salt concentration The major objective of mulching is conserving moisture after irrigations and thus saving water in the long run, although it subsequently reduces salt accumulation as well The mulch may be plastic, polythene, soil or organic residues Studies on mulching in Oman established its usefulness

Effect of mulching and saline water on soil EC (dS/ m) Means Date palm Residue Plastic cover Control Water Salinity (dS/ m) 2.22 B 1.63 bc 1.06 c 3.98 bc 3 6.39 A 4.35 b 3.27 bc 11.56 a 6 - 2.99 B 2.16 B 7.77 A

Soil Salinity Management Analyzing the specific soil, water and climatic conditions of the region), following techniques can be recommended Application of organic matter (especially composted crop residues and animal manures) that can increase water holding capacity of soil, decrease demands for irrigations and could reduce salt accumulation Leaching of salts through appropriate water quality, quantity and leaching method Selection of suitable varieties that can match salinity level and other soil properties of the growing site (texture, structure, calcareousness, fertility and drainage)

Soil Salinity Management Irrigation system well suited to quality of water, soil texture and drainage, Bubbler is just like flood and may be replaced with subsurface irrigation system Two to three flood irrigations during land preparation before transplantation of date palm saplings and prior shifting to modern/ bubbler irrigation system for leaching down the accumulate salts in the soil surface The above practice can be useful if adopted after every quarter to leach down the accumulated salts and keeping soil EC lower when irrigation water is saline Breaking capillaries by hoeing and mulching to reduce evaporation and accumulation of salts, especially in loam and clay loam soils

LEACHING OF SALINE SOILS The saline soils can be rehabilitated through leaching by good quality water (or at least having lesser EC than the soil). At the steady state the soil will have same EC as that of leaching water provided that soil drainage is good (as existing in Gulf countries). The most appropriate equation to calculate quantity of water required for leaching can be that of Hillel (2000). Of course, salt tolerance of crops to be grown will be important consideration C/ Co = k/ (d/ ds) Where C= Salt concentration to be obtained in the leached soil Co = Initial salt concentration in the soil D = Depth of leaching water Ds = Depth of the soil to be leached k = an empirical coefficient (0.1 for sandy soils)

CONCLUSIONS The management practices that can be adopted are: The success of management of salinity in Arabian Peninsula and other date palm growing countries depends upon minimum possible use of saline water and controlling salt accumulation The management practices that can be adopted are: Matching of salt tolerance of date palm varieties with the salinity status of soil is the key of success. Alternatively, soil salt level must be reduced through leaching with good quality water or at least water having lesser EC than the soil to be rehabilitated The quality of saline water and soil EC must be monitored during date palm growth and site specific measures like; appropriate leaching fractions, application of organic matter/ soil conditioners, mulching and suitable agronomic practices be adopted If saline water is the only option then packages of practices for date palm growing must match site specific conditions of soil, water and climate and the salt tolerance of variety

Future research required Future research in the region on all aspects of salinity should not only be strengthened but also be directed to remove past deficiencies The site specific case studies of leaching fractions for various qualities of saline water to be used for different varieties of date palm are of particular importance Identification/ evolution of salt tolerant varieties/ cultivars is another important area in this regard Management practices like cyclic use of saline and good quality water have to be investigated Interactions of high temperature and saline water irrigation should be of particular interest in the scenario of climatic changes

Policy decisions Wise policy decisions by the respective governments can balance the situation and put date palm farming on the right track which can not only increase regional production (going very rapidly down and down due to salinity) but can also be capable of meeting future challenges Salinity research not only be strengthened but organization should be established at country and regional level which should only be dealing with the salinity subject Universities of the region should play a leading role in this regard and must be provided with finances and the expert manpower