The first attempts were made during the fifties, by Ralph M. Parsons. (1955) in Erbil ...... normal irrigation system) depending on Firman and Kraus (1965). On the ...
Study of water quality and its effect on nutrients availability for corn in Sulaimani region A THESIS SUBMITTED TO: THE COUNCIL OF THE COLLEGE OF AGRICULTURE UNIVERSITY of SULAIMANI AS A PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN
AGRICULTURE SOIL SCIENCE (SOIL CHEMISTRY) BY GHAFOOR AHMED MAM RASUL B.Sc. AGRICULTURE IN SOIL SCIENCE SULAIMANI UNIVERSITY 1979-1980
SUPERVISOR Dr. AKRAM OTHMAN ESMAIL LECTURER OCTOBER 2000
GALAREZAN 2700K
RAJAB 1421 H
DEDICATION I dedicate this to my ... ... - Father’s virtuous spirit. - Pia mater. - Brothers and Sisters. - Partner Nishteman. -
Sons,Rand, Rawaz and Aran.
Ghafoor
ACKNOWLEDGMENT I wish to express thanks and gratitude to the presidency of Sulaimani University, especially to the deanery of the college of Agriculture. Sincere thanks and appreciation are extended to Dr. Akram Othman Esmail for suggesting this subject and for his supervision which helped me very much in completing this thesis. Thanks are also extended to Dr. Tariq H. Karim, Assistant Professor, for reading the manuscript and for his constructive criticism. Thanks are extended to Dr. Ra’ad George Mikha, Head of Soil Science Department for his keen interest in this research. The author is deeply indebted to Mr. Nizar Abdulkadir, head of the computer center for his multifarious help during the preparing a computer program for this investigation. My thanks are due to Sulaimani Environmental Protection Center, Sulaimani Water Sewerage Laboratory, Branch of Computer Press of Sulaimani University, Mr. Matty Derman Khammo FAO, Coordination Librarian and Translator in Erbil and FAO, Sulaimani Meteorological Office for their help in completing this research. I also wish to thank the staff member of the Soil Science Department for their valuable advice and suggestions. Many thanks to the ones who gave me their help and I forget to mention them.
Ghafoor
SUMMARY AND CONCLUSION This study was conducted during the hydrological year from October 1998 to September 1999, to study the effect of water quality on nutrients availability for corn in Sulaimani region. For this purpose, water of twenty locations within and around of Sulaimani city which includes (7) karizes, (8) springs and (5) wells were taken and sampled monthly to determine the concentration of cations and anions, electrical conductivity and pH. The type and amount of ion- pairs and ion activity for these waters were calculated by using a computer program which was prepared for this purpose. The water had been evaluated depending on some regional and world classification. The effect of ion - pairs and ionic activity on the classification of these waters and some statistical relationships between some scientifical concepts were studied. For this purpose, the pot experiment was conducted at the meteorological station / College of Agriculture / University of Sulaimani in Bakrajo, during the spring of growing season 1999 (from 28 - 3 - 1999 to 15 -7 1999). Eight water qualities which had a different ionic composition, the range of Mg/Ca ratio (0.17 - 0.27) and electrical conductivity (0.37 - 0.94 dS.m-1) were used for irrigating Zea mays plant (variety Gambier) using complete randomized design (CRD) with four replications. Complementary intervals were defined after depletion 50 – 60 % of available water depending on the gravimetric method and tensiometer reading. The plants were harvested at three different times (80, 95, 110) days after planting. Dry matter weight was determined on the base of (g pot-1). Some of cations and anions were determined in the leaves and stem of the plant at three different times. Moreover, the electrical conductivity, pH, soluble cations and anions, exchangeable cations and cation exchange capacity (CEC) were I
determined at the end of the experiment for soil. Effect of ion pairing and activity on some statistical relationships between some scientific concepts was studied. The main conclusions could be summarized as follows: 1- It was found that all locations have water of class (C2 - S1), except (Shekh Latef, Mawlana, and Shekh Abas Karizes) having the class (C3-S1) according to Richards (1954). While depending on Ayers & Westcot (1985) the water of all locations was suitable for irrigation. The water of all locations was excellent for irrigation (Don, 1995). 2- Correcting ion pair + activity caused a change in the relationship between (Adj. SAR) and (Adj. RNa) and also between electrical conductivity and ionic strength in both water and soil; therefore, it’s necessary to avoid the using of these relationships at all if the ionic composition was not taken into account. 3- Correcting SAR value for ion pairs and ion pairs plus activity caused an increase of SAR value in an average (1.03, 1.14), (1.055, 1.17) times for water and soil respectively. 4- The dominance was for sulphate and bicarbonate ion pairs (CaSO4)o, (CaHCO3)+, (MgSO4)o, (MgHCO3)+, the contribution of other ion pairs were less than 0.004 (mmol L-1). 5- The concentration of cations and anions, electrical conductivity and sodium adsorption ratio in soil saturated extract were increased with increasing their concentration in irrigation water at the end of growing season. 6- There were significant differences among the water qualities for affecting on the concentration of exchangeable Ca, Mg and Na of the soil at the end of the growing season. 7- There were no any significant differences between treatments for affecting on the cation exchange capacity (CEC) of the soil except (1)st, (6)th and (8)th treatments which have a significant effect on (CEC). II
8- The quality of irrigation water affected significantly the concentration of cations and anions in the leaves and stem at three different sampling times, while the dry matter weight was not affected by different water qualities. 9- The potassium adsorption ratio (KAR) of the soil was affected significantly by ionic composition of irrigation water; it may decrease the availability of potassium if the irrigation continued for many years. 10-The increase in individual ionic concentration doesn’t cause an increment in their concentration in the dry matter; this explains the importance of ionic activity. 11-There is a significant difference between the concentrations of some nutrients (K, N, P, Cl, etc.) in plant irrigated with water having the same concentration of these ions; it explains the role of ionic composition and activity in nutrient availability for plants.
III
LIST OF CONTENTS PAGE NO. SUMMARY AND CONCLUSIONS
I
LIST OF CONTENTS
IV
LIST OF TABLES
VIII
LIST OF FIGURES
X
LIST OF APPENDIXES
XIII
1-INTRODUCTION.
1
2-LITERATURE REVIEW.
2
2-1-Factors influencing ionic composition of water:
2
2-2-Ion pairing:
4
2-3-Ion activity:
6
2-4-Statistical relationship between ionic strength (I) and electrical conductivity (EC):
8
2-5-Importance of ionic composition in limitation of water quality for irrigation:
8
2-5-1-Importance of sodium in evaluation of irrigation water quality: 9 2-5-2-Importance of carbonate and bicarbonate in evaluation of irrigation water quality:
12
2-5-3-Importance of chloride and sulphate in evaluation of irrigation water quality:
12
2-6-Classification of irrigation water:
13
2-6-1-The first attempt for classification:
13
2-6-2-Wilcox classification (1948):
13
2-6-3-US Salinity Laboratory classification (1954):
14
2-6-4-Doneen classification (1954):
16
2-6-5-Wilcox classification (1955) (depending on, RSC):
16
2-6-6-Wilcox classification (1955) (depending on, Na% and EC):
16
IV
2-6-7-Thorne and Peterson classification (1955):
17
2-6-8-Fireman and Kraus classification (1965):
17
2-6-9-Todd classification (1966):
18
2-6-10-USSR classification (1970):
18
2-6-11-Rijtema classification (1981):
19
2-6-12-Ayers and Westcot classification (1985):
19
2-6-13-Rhoades et al., classification (1992):
21
2-6-14-Don classification (1995):
21
2-7-Effect of ionic composition of irrigation water on some chemical properties of the soil:
22
2-7-1-Cations and anions:
23
2-7-2-Cation ratio:
23
2-8- Effect of ionic activity on solubility of CaCO 3.
24
2-9-Effect of ionic composition of irrigation water on nutrient availability for plant:
24
2-9-1-Effect of ratio between cations on availability of nutrient for plant:
26
2-9-2-Effect of ion activity and ion pairs on availability of nutrients:
27
3-MATERIALS AND METHODS.
28
3-1-Sampling methods (water sampling):
28
3-2-Water chemical analysis:
28
3-2-1-Electrical conductivity (EC):
28
3-2-2-pH:
28
3-2-3-Cations and anions:
28
3-3-Pot experiment:
30
3-3-1-Packing the soil in pot:
30
3-3-2-Planting:
34
3-3-3-Fertilization:
34
3-3-4-Irrigation:
34
3-3-5-Plant sampling:
34 V
3-3-6-Soil sampling:
34
3-3-7-Soil physical and chemical analysis:
34
3-3-8-Plant analysis:
35
3-3-9-Statistical analysis:
36
3-4-Climatological data:
36
4-RESULTS AND DISCUSSION.
37
4-1-Evaluation of water for irrigation:
37
4-2-Effect of ion pairing and ion activity on the (SAR) values:
40
4-3-Effect of irrigation water quality on some chemical properties of the soil:
48
4-3-1-Electrical conductivity (EC):
48
4-3-2-pH:
48
4-3-3-Soluble cations:
51
4-3-4-Effect of correcting ion pairs and ion pairs + activity on soluble cations:
53
4-3-5-Soluble anions:
55
4-3-6-Sodium adsorption ratio (SAR):
55
4-3-7-Effect of ion pairing and ion pairing + activity on some statistical relationships:
58
4-3-8-Effect of irrigation water on exchangeable cations and cation exchange capacity (CEC) of the soil: 4-4-Effect of water quality on dry matter weight:
63 65
4-5-Effect of irrigation water quality on the chemical composition of the plant leaves:
66
4-5-1-Cation concentration:
66
4-5-1-1-Calcium concentration:
66
4-5-1-2-Magnesium concentration:
69
4-5-1-3-Sodium concentration:
69
4-5-1-4-Potassium concentration:
70
4-5-2-Anion concentration:
72 VI
4-5-2-1-Nitrogen concentration:
72
4-5-2-2-Phosphorus concentration:
74
4-5-2-3-Chloride concentration:
74
4-6-Effect of irrigation water quality on the chemical composition of the plant stem:
76
4-6-1-Cation concentration:
76
4-6-1-1-Calcium concentration:
76
4-6-1-2-Magnesium concentration:
76
4-6-1-3-Sodium concentration:
78
4-6-1-4-Potassium concentration:
78
4-6-2-Anion concentration:
80
4-6-2-1-Nitrogen concentration:
80
4-6-2-2-Phosphorus concentration:
80
4-6-2-3-Chloride concentration:
82
5-Recommendations:
84
References:
85
VII
LIST OF TABLES TABLE NO. 1.
TITLES
PAGE NO.
Some chemical properties of irrigation water used in a pot experiment.
2.
Effect of ion pair and ion activity on the (SAR) in irrigation water used in a pot experiment.
3.
32
The concentration of ions contributed in ion pair in irrigation water used in a pot experiment.
4.
31
32
Some physical and chemical properties of soil used in the pot experiment.
5.
33
Some chemical properties of groundwater, at each location over the hydrological year (1998,1999). 38
6.
Classification of water for irrigation depending upon different systems of classification.
7.
39
Effect of correcting ion pairs and ion pairs + activity on (SAR,Adj.SAR and Adj.RNa) the value of irrigation water. 41
8.
Some chemical properties of groundwater, after correcting ion pairs at each location over the hydrological year (1998, 1999).
9.
42
Some chemical properties of groundwater, after correcting ion pairs + activity, at each location over the hydrological year (1998, 1999).
43
10.
Concentration of ions contributed in ion pairs (mmol L-1).44
11.
Mean of EC, pH, cations and KAR before and after correcting ion pairs and ion pairs + activity, in the soil saturated extract after harvesting.
12.
Effect of ion pairing on the ratio between soluble cations after harvesting.
13.
49
54
The amount of ions contributed in ion pairing in soil saturated extract.
54 VIII
14.
Mean of anions (meq L-1) before and after correcting ion pairs and ion pairs + activity, in the soil saturated extract after harvesting.
15.
56
The ratio between soluble ions in soil extract and irrigation water.
16.
56
Effect of ion pairs and ion pair + activity on the (SAR) the value in the soil saturated extract after harvesting.
17.
Effect of ion pairs and ion pairs + activity on the ionic strength of soil extract.
18.
58
61
Mean of exchangeable cations and cation exchange capacity (C E C) of soil after harvesting.
IX
65
LIST OF FIGURES FIGURE NO.
TITLES
PAGE NO.
1.
Map of Sulaimani city with sampling locations.
2.
The relationship between Adj. SAR and Adj. RNa in irrigation water.
3.
45
Relationship between Adj. SAR* and Adj.RNa* in irrigation water after calculating ion pairs.
4.
47
Effect of ion pairs on the relationship between EC and ionic strength in irrigation water.
7-
50
Effect of water quality on the concentration of cations in the soil saturated extract after harvesting.
10.
57
The relationship between Adj. SAR and Adj. RNa in the soil saturated extract after harvesting.
12.
52
Effect of water quality on the concentration of anions in the soil saturated extract after harvesting.
11.
47
Effect of water quality on EC value of the soil saturated extract after harvesting.
9.
47
Effect of ion pairs + activity on the relationship between EC and ionic strength in irrigation water.
8.
45
Relationship between EC and ionic strength in irrigation water.
6.
45
Relationship between Adj. SAR** and Adj.RNa** in irrigation water after calculating ion pairs + activity.
5.
29
63
Relationship between Adj. SAR* and Adj.RNa* in the soil saturated extract with calculating ion pairs after harvesting.
13.
60
The relationship between Adj. SAR** and Adj. RNa** in the soil saturated extract with calculating ion pairs+ activity after harvesting.
60 X
14.
Relationship between EC and ionic strength in the soil saturated extract after harvesting.
15.
62
Relationship between EC and ionic strength in the soil saturated extract after calculating ion pairs after harvesting.
16.
62
Relationship between EC and ionic strength in the soil saturated extract after calculating ion pairs + activity after harvesting.
17.
62
Effect of water quality on the exchangeable cations of the soil after harvesting.
18.
64
Effect of water quality on the value of CEC of the soil after harvesting.
64
19.
Effect of water quality on the dry matter weight.
67
20.
Effect of irrigation water composition on Ca2+ concentration in plant leaves after (80, 95, 110) days from planting.
21.
68
Effect of irrigation water composition on Mg2+ concentration in plant leaves after (80, 95, 110) days from planting.
22.
68
Effect of irrigation water composition on Na+ concentration in plant leaves after (80, 95, 110) days from planting.
23.
74
Effect of irrigation water composition on K+ concentration in plant leaves after (80, 95, 110) days from planting.
24.
71
Effect of irrigation water composition on nitrogen concentration in plant leaves after (80, 95, 110) days from planting.
25.
73
Effect of irrigation water composition on phosphorus concentration in plant leaves after (80, 95, 110) days XI
from planting. 26.
73
Effect of irrigation water composition on chloride concentration in plant leaves after (80, 95, 110) days from planting.
27.
75
Effect of irrigation water composition on Ca2+ concentration in plant stem after (80, 95, 110) days from planting.
28.
77
Effect of irrigation water composition on Mg2+ concentration in plant stem after (80, 95, 110) days from planting.
29.
77
Effect of irrigation water composition on Na+ concentration in plant stem after (80, 95, 110) days from planting.
30.
79
Effect of irrigation water composition on K+ concentration in plant stem after (80, 95, 110) days from planting.
31.
79
Effect of irrigation water composition on nitrogen concentration in plant stem after (80, 95, 110) days from planting.
32.
81
Effect of irrigation water composition on phosphorus concentration in plant stem after (80, 95, 110) days from planting.
33.
81
Effect of irrigation water composition on chloride concentration in plant stem after (80, 95, 110) days from planting.
83
XII
LIST OF APPENDIXES APPENDIX NO. 1.
TITLES
PAGE NO.
Monthly variations in the pH of water for allocations under the study from Oct.1998 to Sept.1999.
2.
Monthly variations in the EC at 25oC of water for all locations under the study from Oct.1998 to Sept.1999.
3.
97
97
Monthly variations in the Ca2+ concentration of water for all locations under the study from Oct. 1998 to Sept. 1999.
4.
98
Monthly variations in the Mg2+ concentration of water for all locations under the study from Oct.1998 to Sept. 1999.
5.
99
Monthly variations in the Na+ concentration of water for all locations under the study from Oct.1998 to Sept. 1999.
6.
100
Monthly variations in the K+ concentration of water for all locations under the study from Oct.1998 to Sept.1999.
7.
101
Monthly variations in the SO42- concentration of water for all locations under the study from Oct.1998 to Sept. 1999.
8.
102
Monthly variations in the Cl- concentration of water for all locations under the study from Oct.1998 to Sept.1999.
9.
103
Monthly variations in the HCO3- concentration of water for all locations under the study from Oct.1998 to Sept.1999.
10.
104
Monthly variations in the Phosphorus concentration of water for all locations under the study from Oct.1998 to Sept.1999.
105 XIII
11.
Ion pair program steps.
106
12.
Average monthly data of maximum and minimum temperatures, Relative humidity and rainfall from October (1998) to September (1999).
113
13.
Ion pair value in water for all locations under the study. 114
14.
Simple correlation coefficient (r) between ions concentration in irrigation water and their concentration in dry matter of leaves at different sampling times.
15.
115
Simple correlation coefficient (r) between ions concentration in irrigation water and their concentration in dry matter of stem at different sampling times.
XIV
115
1-INTRODUCTION The world population was 2.5 billion in 1950; 4.9 billion in 1985, and 5.3 billion in 1990. It is expected to be 6.3 billion in 2000, and 8.5 billion in 2025 (U.N., 1991). These increases in world population will require an increase in agricultural production to maintain the present level of food intake, and also require an increase in suitable water for irrigation. Groundwater is an important part of the national water wealth; its importance can be clearly realized in areas with poor surface resources like Kurdistan region of Iraq. Dependence upon groundwater was increased with advancement in technology for drilling wells to arrive large deep aquifers to obtain large quantity and good quality of water. Many studies have been done on the quality of groundwater in Kurdistan region. The first attempts were made during the fifties, by Ralph M. Parsons (1955) in Erbil plain and Altun Kupri plain. Most of these studies do not include ionic composition and activity, on the other hand, all chemical, physicochemical and biological processes that take place in the (Soil - Water - Nutrient) system, as well as the nutrient uptake by the plant, depend on the activity rather than concentration (Esmail, 1992). Therefore the aim of this study is to: 1. Find out the effect of ionic activity and ion pairing in groundwater on water classification and its suitability for irrigation. 2. Evaluate the effect of ion activity and ion pairing on the availability of some nutrients and some chemical properties of the soil.
1
2-LITERATURE REVIEW In determining groundwater suitability for irrigation, information is required on both the quantity and quality. The suitability of water for irrigation is determined not only by the total amount of salt present but also by the kind of salt (ionic composition), (Ayers and Westcot, 1985). On the other hand, ion activity depends on kinds of ions and their participation in ion pairing (Radstake et al., 1988 and Esmail, 1992). Therefore, it is necessary to throw light on the factors affecting the ionic composition of irrigation water. 2-1- Factors influencing ionic composition of water: There are many factors that influence water composition and they are as follows: 1- Mineral composition of contact rocks with water: The weathering of parent material or solid rocks which are in contact with groundwater is the primary source of salt in irrigation water, (Davis and Dewiest, 1966; Paliwal, 1972). 2- Ionic composition of aquifer: An aquifer is a saturated bed formation or a group of formations which yield water in sufficient quantity to be of consequence as a source of supply. Its mineral composition affects the chemical composition of groundwater. (Al Sayyab et al., 1983). Dance and Reardon (1983) indicated that cation exchange processes of aquifers have the great effect on the chemical composition of groundwater. 3- Climate: Evapotranspiration and rainfall are two main climatic elements to be considered in evaluating the suitability of water for irrigation (Van Horn,1970). Al Sawaf (1973) has shown that the solubility of CaSO4 in the natural water increases with increasing of water temperature, which causes an increment in Ca2+ and SO42- concentration.
2
Radstake et al. (1988) concluded that the major change in chemical composition of the irrigation water occurs in the soil during the concentration of salt by evapotranspiration. This triggers some hydrochemical reactions. Paliwal (1972) noted the decrease in value of sodium adsorption ratio (SAR), chloride content and increase in the concentration of calcium and magnesium in well water in some regions of India under high rainfall condition. Shalhevet and Yaron (1973) found the fluctuation of groundwater table in some regions of Arbil plain depends upon the rate of rainfall, which affects the ionic composition of various soil horizon and groundwater. Peck and Williamson (1987) regarded the fluctuation of groundwater table depending upon the amount of rainfall and aquifer transmissivity. The coastal water table elevation varies in the order of 0.l to 0.2m between raining and non-raining seasons. (Moore et al., 1992; Stoessell et al., 1993). Bender (1995) noticed a rise of 2m in groundwater table one day after the severe rainfall. 4- Effect of deep percolation: A portion of irrigation water applied to agriculture land filters through the surface soil carrying with it dissolved substance. Rhoades et al. (1988) have shown that deep percolation causes an increase in dissolved salt in substrate and transport to groundwater or surface water which affects its ionic composition. During abnormally severe rain the salt accumulated in the unsaturated zone will be dissolved and washed down to the groundwater (Bender, 1995). 5- Pumping period: The ionic composition of groundwater usually changes with a period of pumping which is depending upon hydrodynamic changes from aquifers system (Gaona - Uzcayno et al., 1985). Ayob et al. (1985) found significant changes in the ionic composition and electrical conductivity value of groundwater of JOLACK Basin at different pumping periods. 3
6- Well properties: George and Wierenga (1987) noticed the small variation in ionic composition and electrical conductivity values of water in deep wells in comparison with shallow wells. 7- Geochemical cycle between groundwater and surface water: The geochemical cycle will affect the ionic composition and electrical conductivity values of groundwater through some processes which take place in this cycle, like (evaporation, solubility, precipitation, ion exchange phenomena, oxidation, reduction, evapotranspiration, and runoff ... ..., etc.) (Maletic,1973). Hydrologic processes will affect directly or indirectly on the quality of groundwater (Bender, 1995). 2-2- Ion pairing: Ion-pairing plays a vital role in describing equilibrium in solvents. Although complete ionic dissociation applies to many salts dissolved in water, it is not a rule of universal validity. For example, a large fraction of the cations and anions of certain strong electrolytes are so attracted to one another in a solution that they behave as if un- ionized. Ions associated in this manner are called “ion-pairs” (Adams, 1971). Bohn et al. (1985) have shown that some soluble anions and cations in water or solution will approach to each other for a distance less than 5 Angstrom, in this case, connect ions which are different in charge by columbic force while each ion keeps its hydration shell this phenomenon means ion pairing. The ion-pairs charge depends upon valence of contributed anion and cation in ion-pairs, if the ions are of equal but opposite charge the ion pair will be uncharged like (CaSO4)o and (MgSO4)o ion-pairs, if the ions are of unequal charge, the ion-pair will have a charge like (KSO4)- and (CaHCO3)+ ion-pairs, (Adams, 1971). The stability of ion-pair depends upon its equilibrium constant. The ionpair, which has a low value of the equilibrium constant, will exit readily. For defining ion pairs equilibrium constant supported (Kb) which is defined 4
depending on dissociation reaction of ion pairs, for example, the ion pair CaSO4o dissociation reaction is written as: CaSO4o = Ca2++SO42and
Where: parentheses denote activity. Kb = The equilibrium constant for the ion pair If (pkb) or (-log kb) increase, the constant of ion pair will increase, and it will decrease with decreasing of pkb (Bohn et al., 1985). Emara et al. (1984) found that the stability of calcium ion-pairs is more than magnesium ion pairs for every legend this is due to the higher enthalpy value of Ca2+ in comparing with Mg2+. The general principles of ion pairing are summarized by Adams (1971) as follows: a- There is no ion-pairing of cations with Cl-. b- Ion-pairing of cations with NO3- is small enough to be neglected. c- Ion-pairing with SO42- is general; it is slight with univalent cations but extensive with multivalent cations. d- Ion-pairing with H2PO4- or HPO42- is only slight for univalent cations and can be ignored; ion pairing between H2PO4- and multivalent cations is significant but not extensive; ion-pairing between HPO42- and multivalent cations is extensive. e- Ion-pairing between HCO3- and univalent cations is in significant; ionpairing of multivalent cations with HCO3- is significant at high pH or at above normal CO2 pressure. Adams (1971) concluded that the necessary data analysis for calculating ion-pairing are followed: a- Those ions that affect ionic strength. 5
b- Those ions that pair significantly. c- Those ions of special interest probably all soil solutions should be analyzed for H, Ca, Mg and K ... ... etc. 2-3- Ion activity: Ion connection with expanded research on the forecasting of water - salt and nutrient - system. Orlov (1967) raised the question of choosing a quantitative measure for describing the chemical, physicochemical and biochemical processes in soil. Since all the reactions that take place in soils, as well as the consumption of nutrients by plants, depend on the activity rather than the concentration of the ions (Pakshina and Rabochev, 1987). At the same time activity is linked to concentration via the activity coefficient (Sparks, 1999) which is defined by: a= * c Where:
a = ion activity = activity coefficient c = ion concentration.
The methods of estimating ion activities have been developed by Pakshina and Rabochev (1987): a- Direct detection of ion activities in soil solutions, natural waters by high sensitive electrodes. b- Conversion of analytically determined ion concentrations into activities. The concept of ionic strength has been a foundation of electrolytic chemistry. It provided the means for calculating ionic activities, whether the salt is in a pure state or the presence of other electrolytes. The major aspect of the ionic - strength principles is that the activity coefficient of an ion is the same in all solutions of the same ionic- strength. The ionic strength, (I) of an electrolytic
6
solution is a measure of the intensity of the electrical field in the solution and is defined as:
Where Ci is the actual molar concentration of each ion in the solution and Zi is its valence. Thus, it is necessary to know the concentration of all ions which will affect ionic strength (I) of the soil solution or irrigation water. When the ionic strength of a solution is known, ion activity coefficients can be calculated by the Debye - Huckel equation and Davies equation (Botler, 1964; Garrels and Christ, 1965; Adams, 1971). The familiar Debye - Huckel equation is:
Where: I is the ionic strength (mol L -1). Zi is the valence. A and B are parameters associated with the absolute temperature and dielectric constant of the solvent. A=0.509, B=0.3285 at 250C. ai is an effective mean diameter of the hydrated ion species. The Davies equation recently used by Sparks (1999) is defined as:
Where A, Zi and I are the same as defined above.
7
2-4- The Statistical relationship between ionic strength (I) and electrical conductivity (EC): Many types of research have been conducted for prediction to ionic strength from electrical conductivity, which was simplifying the conversion of concentration to activity. Ponnamperuma et al. (1966) have shown that a simple linear relation exists between the electrical conductivity of a solution and its ionic strength. Utilizing extracts of flooded soil and an electrolyte solution of ionic strength less than 0.06 (mol L-1) they derived the expression as follow: I = 0.016 EC Where I is the ionic strength in (mol L-1), and EC is the electrical conductance in dS m-1 at 25oC. The relationship between ionic strength and electrical conductance was corrected for ion pair formation by Griffin and Jurinak (1973). The relationship was: I = 0.013 EC Where I is the ionic strength mol L-1, and EC is in dS m-1 at 250C. Pasricha (1987) found the following relationship after correcting ion-pairs: I = 0.012 EC Esmail (1992) found that the relation between ionic strength and EC before correcting ion - pairs was: I = 0.019 EC While the relationship between them after correcting ion-pairs was: I = 0.0138 EC. 2-5- Importance of ionic composition in limitation of water quality for irrigation: Water quality criteria for the agricultural purpose should provide information on the suitability of water for irrigation use. The quality of water used for irrigation can vary greatly in quality depend upon type and quantity of 8
dissolved salts. (Richards, 1954; Todd, 1959; Stevens, 1962; Walton, 1970; Rijtema, 1981; Ayers and Westcot, 1985; Abrol et al., 1988). Richards (1954) found that the important properties for limitation of water quality are electrical conductivity, sodium adsorption ratio, (SAR), boron and bicarbonate concentration. Van Horn (1970) found that the factors which are necessary for studying water quality are total dissolved salts, ionic composition, and concentration of trace elements. Walton (1970) reported that the factors to be considered in evaluating the usefulness of groundwater for irrigation are: The total concentration of dissolved solids, the concentration of individual constituents, the relative proportions of some of the constituents, the nature and composition of the soil and subsoil, the topography of the land, the position of the water table, the amounts of groundwater used and the method of applying it, the kinds of crops grown, and the climate of the area. Hassan (1976) found that water quality depends upon the concentration of cations and anions, total dissolved salts, alkalinity, total hardness and soluble gasses. Rijtema (1981) found that the characteristics of irrigation waters that appear to be most important in determining its quality are; total concentration of soluble salts; chloride concentration; relative proportion of sodium to other cation; concentrations of specific ions that may be toxic to plant. Previous studies conducted by (Esmail, 1986 and 1992; Papadopoulos, 1987; Radstak et al., 1988; Abood and Esmail, 1995; Hummadi et al., 1996; Esmail and Wali, 1999; Esmail et al., 1999) emphasized on the fact that it is necessary to take ion composition into consideration in water classification for irrigation. 2-5-1- Importance of sodium in the evaluation of irrigation water quality: The major problem associated with sodium in irrigation water is related to possible adverse effects on soil structure and permeability caused by the accumulation of sodium ions and calcium plus magnesium ions in the irrigation water. Also, to its impact on soil, sodium has a direct toxic effect on the plant (Rijtema, 1981). Due to the influence of sodium on the soil and plants, sodium is considered to be one of the major factors governing water quality. Several 9
methods were proposed for expressing the sodium hazard. Previous water quality was defined on the basis of its sodium percentage alone. The soluble sodium percentage (S.S.P.) may be calculated by this formula:
* mmol L c
-1 =
meq L-1
Scofield (1935) and Magisted and Christianson (1944) considered water which has S.S.P. value of 60% as a harmful water. Greene (1948) raised this lower limit to 80% for water having a total salt content less than 10 mmolc L-1. The U.S. Salinity Laboratory Staff Richards (1954) has proposed the use of the sodium adsorption ratio (SAR) for classification of irrigation water. It was defined by:
Where: Na+= Sodium concentration in mmolc L-1 Ca2+= Calcium concentration in mmolc L-1 Mg2+= Magnesium concentration in mmolc L-1
Ayers and Westcot (1976) used the adjusted sodium adsorption ratio (adj. SAR) for expressing the sodium hazard, which can be express as follow:
10
pHc= (pK2-pKc) +p(Ca2++Mg2+) +p(Alk) p(K2-pKc)
=
The
tabulated
value
for
sum
concentration
of
(Ca2++Mg2++Na+), mmolc L-1. pKc= The solubility product of CaCO3. pK2= Second dissociation constant of bicarbonate. p(Ca2++Mg2+)= The tabulated value for sum of the concentration of (Ca2++Mg2+) mmolc L-1. p(Alk)= The tabulated value for sum concentration of (carbonate + bicarbonate) mmolc L-1. If pHc is greater than (8.4) the water will dissolve CaCO3 from the soil pass through it, but if pHc value less than (8.4) which indicates the possibility of CaCO3 precipitation in water. Suarez (1981) concluded the new term adj. RNa (adjusted sodium adsorption ratio) for a previous purpose. The equation for calculation of adj. RNa is very similar to the older SAR equation and is:
Where: Na= Sodium in the irrigation water reported in mmolc L-1. Cax= A modified calcium value is taken from table adapted from Suarez (1981), reported in mmolc L-1. Cax represented Ca2+ in the applied irrigation water but modified due to the salinity of the applied water (ECw), its HCO3/Ca ratio (HCO3- and Ca2+ mmolc L-1). Mg2+= Magnesium in the irrigation water reported in mmolc L-1
11
2-5-2- Importance of carbonate and bicarbonate in evaluation of irrigation water quality: Eaton (1950) has shown that the carbonate and bicarbonate anions have a direct effect on irrigation water composition and its limitation for irrigation, through their influence on the precipitation of calcium and magnesium and increase in sodium ratio, Wilcox (1955) confirmed this conclusion. Eation (1950) suggested two terms for studying the relation between (carbonate and bicarbonate) with a concentration of calcium and magnesium: a- Soluble sodium percentage possible (S.S.P.P.):
Where the concentration of cation and anions in mmolc L-1. b- Residual Sodium Carbonate (RSC): It is defined by the following equation: RSC= (CO32-+HCO3-) - (Ca2++Mg2+) in mmolc L-1.
2-5-3- Importance of chloride and sulphate in evaluation of irrigation water quality: Since the chloride ion has no effect on the physical properties of soil and it is not adsorbed on the soil complex, so it has not been included in modern classification systems, it appears, however, as a factor in some regional water classifications (Grillot, 1954). Kovda (1973a) found that the increase of sulphate in water causes precipitation of calcium, this may lead to increase of sodium adsorption ratio (SAR), and an imbalance of nutrient in the plant, and it also will have an effect on the physical properties of soil.
12
2-6-Classification of irrigation water: The main classifications can be summarized as follow: 2-6-1-The first attempt for classification: Many attempts have been done for evaluation of irrigation water. The first classification was demonstrated in 1943 depending on electrical conductivity, boron, sodium and chloride concentration (Doneen, 1954):
Water quality
Measurement
No.
C1
C2
C3
3
1
Electrical conductivity(ECat 250C dS m-1)
2
Boron (ppm).
2
3
Percentage of sodium.
75
4
Chloride (mmolc L-1).
10
C1= first class = excellent - good It is suitable for most plants under any condition of soil and climate. C2= second class = good - harmful It is harmful to some crops under special conditions of soil and climate.
C3= third class = harmful - unsuitable Harmful for most plants and unsuitable for all plants, except those which tolerate. 2-6-2-Wilcox classification (1948): Wilcox (1948) classified irrigation waters based on the total concentration of salts in ppm and soluble sodium percentage (S.S.P.) into four classes: 1. Unsuitable water for irrigation: if the total salt concentration is more than (1800 ppm) regardless of S.S.P. 2. Doubtful water in suitability or unpermissible for irrigation: If the total amount of salts is (1200 - 1800 ppm).
13
3. But if the total amount of salts in irrigation water is less than (900 ppm) it is necessary to take S.S.P. into consideration for limitation suitability of irrigation water as follow: a. If the (S.S.P.) value is more than 97% of total cations, it means that the water is unsuitable for irrigation. b. If the (S.S.P.) in water is 77-97% of the sum of cations this water will be doubtful but it will be used under special conditions. c. If the (S.S.P.) in water is 52-77% of the sum of cations, this water is permissible for irrigation under special conditions. d. If the (S.S.P.) in water is less than 52% of the sum of cations, this water is suitable for irrigation. 4. If the total concentration of salt in water is less than (300 ppm) it is suitable for irrigation when the (S.S.P.) is not more than 72% in the sum of cations. 2-6-3-US Salinity Laboratory Classification (1954): US Salinity Laboratory (1954) classified irrigation water to sixteen classes depending on EC ( mhos cm-1) at 25oC and SAR as follows:
Electrical conductivity in Water classes
mhos cm -1 at 250C 0 < EC 250
C1 low-salinity C2 Medium – salinity
250 < EC 750
C3 high – salinity
750 < EC 2250
C4 Very high – salinity
2250 < EC 5000
14
Water classes
SAR
S1= Excellent
< 10
S2 = Good
10-18
S3 = Fair
18-26
S4 = Poor
>26
A diagram for evaluation of irrigation water on the basis electrical conductivity and SAR suggested by the U.S. Salinity Laboratory staff (1954) is given in the figure below:
C1-S4 C2-S4 C3-S4 C4-S4
C1-S3 C2-S3 C1-S2
C3-S3 C2-S2
C4-S3 C3-S2 C4-S2
C1-S1 C2-S1
15
C3-S1
C4-S1
2-6-4-Doneen classification (1954): Doneen (1954) classified irrigation water to three classes depending on the concentration of chloride, sulphate and soil permeability as follow:
Potential Salinity = (Cl+1/2SO4)mmolc L-1 Water quality
high
Moderate
Low
permeability
permeability
permeability
Good
5
2-6-5-Wilcox classification (1955): Wilcox (1955) classified irrigation water to three classes depending on residual sodium carbonate (RSC) as follow: RSC (mmolc L-1)
Water classes Probably safe
< 1.25
Marginal
1.25-2.50
Unsuitable
>2.50
2-6-6-Wilcox classification (1955): Wilcox (1955) also classified the irrigation water depending on sodium percentage and electrical conductivity into five classes: Sodium percentage
ECx106 at 250C
Excellent
< 20
< 250
Good
20-40
250-750
Permissible
40-60
750-2000
Doubtful
60-80
2000-3000
Unsuitable
> 80
> 3000
Water class
16
2-6-7-Thorne and Peterson classification (1955): This classification proposed by the US Salinity Laboratory in (1954) and was modified by Thorne and Peterson (1955) as follow:
EC mhos cm-1 at 250C
Water classes Low salinity
0-250
Moderate salinity
250-750
Medium salinity
750-2250
High salinity
2250-4000
Very high salinity
4000-6000
Excessively salinity
> 6000
2-6-8-Fireman and Kraus classification (1965): Fireman and Kraus (1965) recommended that water should be divided into four groups, according to chloride content, electrical conductivity, and soil texture as follow:
ECiw
mhos.cm-1at250C
Soil Texture
Cliw mmolc L-1
Sandy
Clay Loamy
< 1200
6
Cl1
Cl1
Cl1
1200-1500
6-7.5
Cl1
Cl1
Cl2
1500-1750
7.5-9
Cl1
Cl1
Cl3
1750-2250
9-15
Cl1
Cl2
Cl4
Cl1= No danger under normal irrigation system. Cl2= Low risk. Cl3= Medium risk. Cl4= Dangerous.
17
2-6-9-Todd classification (1966): Todd (1966) classified irrigation water based on total dissolved salts (TDS), chloride and sodium percent as follow:
Elements
Water Classes Suitable
Moderate
Doubtful
TDS (ppm)
700
2000
> 2000
Cl (ppm)
150
500
> 500
Na %
60
60-75
> 75
2-6-10-USSR classification (1970): USSR classification for irrigation water according to its salinities lies into three categories (Van Hoorn, 1970):
Salt content gm L-1 0.20-0.50
Water Evaluation The water of the best quality.
1-2
Water is causing salinity and alkalinity hazard.
3-7
Water could be used for irrigation only with leaching and perfect drainage.
18
2-6-11-Rijtiema classification (1981): Rijtiema (1981) classified irrigation water according to its sodium adsorption ratio (SAR), salt concentration and soil textures to four categories:
SAR at total soluble salt Danger for
concentration (g m-3)of
Suitability
soil structure Small
Suitable for all soil
Medium
Not
suitable
for
silty
loam,
clay
loam, sandy clay loam,
silty
360
470
1200
8.2
6.1
4.0
8.2-15.4
6.1-12.2
4.0-9.0
15.4-22.6
12.2-18.3 9.0-14.0
clay
loam. High
Only suitable for loamy sand, coarse sandy loam, sandy loam, loamy peat, sandy peat, light peat.
Very high
Not suitable.
> 22.6
> 18.3
> 14.0
2-6-12-Ayers and Westcott classification (1985): The most accepted classification of irrigation water is that proposed by Ayers and Westcot (1985) which depended upon EC value, the permeability of the soil, toxic effect of ions and the side effects of some ions as described below:
19
Degree of Restriction of Potential irrigation problem
use Unit
none
slight to
severe
moderate
Salinity ECw or
dS m-1
3.0
Infiltration SAR
= 0-3 and ECw =
>0.7
0.7-0.2
1.2
1.2-0.3
1.9
1.9-0.5
2.9
2.9-1.3
5.0
5.0-2.9
8.5
Miscellaneous Effects Nitrogen (NO3-N) mg L-1
Bicarbonate (HCO3) mmol L-1 35000
Slightly Saline
Brine
2-6-14-Don classification (1995): Don (1995) classified irrigation water depending up on total salt content, EC, SAR, Na% and pH to five classes as follow:
Electrical
Water
conductivity
Quality
ECx10+3 millimhos cm-1
Excellent
Total soluble salt (ppm)
Sodium content (%salts
SAR
pH
as Na)
0.25
175
20
3
6.5
Good
0.25-0.75
175-525
20-40
3-5
6.5-6.8
Permissible
0.75-2.0
525-1400
40-60
5-10
6.8-7.0
Doubtful
2.0-3.0
1400-2100
60-80
10-15
7.0-8.0
>3.0
>2100
>80
>15
>8.0
Unsuitable
21
2-7- Effect of ionic composition of irrigation water on some chemical properties of the soil: It is important to have a clear understanding of the nature of the reactions which take place when ions are added to soils, of the constituents to which they react, and of the resulting products of the reaction and their relations to the concentration and composition of the soil solution (Stevens, 1962). Ions affect certain soil physical and chemical properties, in turn, may affect the suitability of the soil as a medium for plant growth (Rhoades et al., 1992). The irrigation water which has EC between 0.75 and 3.0 dS m-1 tend to cause an increasing problem in soils by creating a difficulty in the availability of water to the crop. (Ayer and Westcot, 1976). Ayer and Westcot (1976) indicated an increase in soil salinity in the case of using bad water quality, the salinity of soil increases when the water takes by the plant from the soil, and suggested the following equations: 1- ECsw = 3 ECw 2- ECe = 1.5 ECw 3- ECsw = 2 ECe Where: ECw=electrical conductivity value of irrigation water (dS m-1). ECe=electrical conductivity value of saturated soil extract (dS m-1). ECsw= electrical conductivity value of soil solution (dS m-1). Rijtema (1981) showed that an increase in water salinity would cause an increase in osmotic pressure of the soil solution, causing reduces in the availability of water for the plant. Esmail (1986and 1992) noticed the significant correlation (r =0.99**) between EC of irrigation water and soil extract of some calcareous soils. Ayers and Westcot (1985) found that typical pH range for irrigation water is from 6.5 to 8.4; irrigation water with a pH outside the normal range may cause a nutritional imbalance or may contain toxic ions. Many investigators like 22
(Hassan et al. 1983; Esmail, 1986 and 1992; Al-Azawi, 1986; Abdual Amer et al., 1987 and Dohuki, 1997) found that the water quality has not significant effect on the pH value of calcareous soil because of its high buffer capacity. 2-7-1-Cations and anions: Many investigators like (Al-Azawi, 1986; Esmail, 1986 and 1992 and Abdul-Amer et al., 1987) found (from their studies on the effect of quality of irrigation water in Arbil plain on some chemical properties of soil under complementary irrigation condition) the high significant correlations between the concentration of cations and anions in irrigation water and saturated soil extract, the results also showed that the ionic composition of saturated soil is similar to the ionic composition of irrigation water. Kelley (1963) found that if the concentration of Ca2+ in irrigation water is equal or more than 35% of total cations, it will replace sodium on the particle soil surface. Esmail (1992) noticed that the high significant correlation between the concentration of cations and anions in irrigation water and soil extract, the correlation coefficient (r) value was (0.887**, 0.949**, 0.989**) for Ca2+, Mg2+, and Na+ respectively. The presence of bicarbonates in the irrigation water can reduce the concentration of Ca2+ and Mg2+ in the soil solution by precipitating these ions as insoluble carbonates (Nyle and Ray, 1999). Esmail (1992) noticed the high significant correlation between the concentration of sulphate and chloride in soil extract and irrigation water. The correlation coefficient (r) value was (0.970 **, 0.883**) for sulphate and chloride respectively. 2-7-2-Cation ratio: Chemical compounds of any type in irrigation water are very strong reagents, influencing the ratio, quantity, and quality of the cations adsorbed previously by clay minerals and by organic soil colloids. (Rahman and Rowell, 1979). 23
Katz (1973) demonstrated that if Mg/Ca ratio in solution is sufficiently low, Mg2+ does not prevent calcite crystallization, even at a level approaching that of the Oceans (108 mmolc L-1). Berner (1975) found that increasing supersaturation at a Mg/Ca ratio of 5can bring about (magnesian) calcite of supersaturation. In a magnesium dominated water (ratio of Ca/Mg 0 And m 0.2 Then fi = (0.509 * Sheets("sheet1").Cells(k - 4, 5).Value * sm) / (1 + 0.329 * Sheets("sheet1").Cells(k - 4, 7).Value * sm) - 0.3 * m 110
f(k) = 10 ^ -fi End If ll: t = Sheets(s1).Cells(k, 3) Rem p(k) = t * f(k) Next k Sheets("sheet4").Cells(18, 4).Value = m Sheets(s1).Cells(6, 4) = p(6) Sheets(s1).Cells(7, 4) = p(7) Sheets(s1).Cells(8, 4) = p(8) Sheets(s1).Cells(9, 4) = p(9) Sheets(s1).Cells(11, 4) = p(11) Sheets(s1).Cells(12, 4) = p(12) Sheets(s1).Cells(13, 4) = p(13) k1 = (p(6) * p(11) / Sheets("sheet1").Cells(14, 2)) / 1000 k2 = (p(6) * p(12) / Sheets("sheet1").Cells(15, 2)) / 1000 k3 = (p(6) * p(13) / Sheets("sheet1").Cells(16, 2)) / 1000 k4 = (p(7) * p(11) / Sheets("sheet1").Cells(17, 2)) / 1000 k5 = (p(7) * p(12) / Sheets("sheet1").Cells(18, 2)) / 1000 k6 = (p(7) * p(13) / Sheets("sheet1").Cells(19, 2)) / 1000 k7 = (p(8) * p(11) / Sheets("sheet1").Cells(23, 2)) / 1000 k8 = (p(9) * p(11) / Sheets("sheet1").Cells(20, 2)) / 1000 k9 = (p(9) * p(12) / Sheets("sheet1").Cells(22, 2)) / 1000 k10 = (p(9) * p(13) / Sheets("sheet1").Cells(21, 2)) / 1000 Sheets(s1).Cells(19, 3) = k1 Sheets(s1).Cells(20, 3) = k2 111
Sheets(s1).Cells(21, 3) = k3 Sheets(s1).Cells(23, 3) = k4 Sheets(s1).Cells(24, 3) = k5 Sheets(s1).Cells(25, 3) = k6 Sheets(s1).Cells(27, 3) = k8 Sheets(s1).Cells(28, 3) = k9 Sheets(s1).Cells(29, 3) = k10 Sheets(s1).Cells(31, 3) = k7 For i = 2 To 250 a = Sheets("sheet3").Cells(2, i) If a > 0 Then GoTo line12 Else GoTo line13 End If line12: Next i line13: Sheets("sheet4").Cells(34, 2) = i - 2 End Sub.
112
Appendix (12): Average monthly data of maximum and minimum temperatures, Relative humidity and rainfall from October (1998) to September (1999). *
Temperature (C)0 Months
Rainfall
R.H.
Max.
Min.
(mm)
(%)
Oct. (1998)
29.3
15.3
0.0
29
Nov. (1998)
24.6
11.5
4.2
39
Dec. (1998)
18.9
7.8
3.8
49
Jan. (1999)
13.2
5.0
87.9
63
Feb. (1999)
14.8
4.2
97.8
62
Mar. (1999)
19.3
7.4
18.7
47
Apr. (1999)
23.9
12.4
17.2
39
May (1999)
31.3
19.9
0.0
29
June (1999)
36.0
24.7
0.0
27
July (1999)
38.7
27.2
0.0
22
Aug. (1999)
40.5
28.5
0.0
24
Sept. (1999)
34.0
21.9
0.0
27
*- FAO, Suleimani Meteorological Office,
113
Appendix (13) Ion-pairs value (mmol L-1) in water for all locations under the study.
Locations
(CaSO4)0
(CaHO3)+
(MgSO4)0
(MgHCO3)+
(NaSO4)-
(NaHCO3)0
(KSO4)-
Ion-pairs types
Dabashan .1
0.042
0.034
0.012
0.008
0.000
0.000
0.000
Dabashan.2
0.059
0.044
0.012
0.008
0.000
0.000
0.000
Kalaken
0.061
0.049
0.012
0.009
0.000
0.000
0.000
Daraban
0.061
0.053
0.012
0.009
0.000
0.000
0.002
Khewata
0.053
0.049
0.012
0.009
0.001
0.000
0.000
Maladawd
0.050
0.036
0.012
0.016
0.001
0.000
0.000
Kany Bardyna
0.069
0.052
0.012
0.012
0.000
0.000
0.000
Parky Azdy
0.143
0.090
0.028
0.025
0.001
0.001
0.001
Majed Beg
0.100
0.062
0.022
0.024
0.001
0.001
0.001
Shekh Latef
0.167
0.111
0.042
0.031
0.001
0.001
0.001
Mawlana
0.187
0.161
0.034
0.022
0.002
0.002
0.001
Shekh Abas
0.160
0.135
0.040
0.022
0.001
0.001
0.001
Kany Garaw
0.049
0.078
0.016
0.016
0.000
0.000
0.000
Zhala
0.061
0.090
0.014
0.010
0.001
0.001
0.001
Kany Sarchawa 0.042
0.051
0.009
0.014
0.000
0.000
0.000
Fateh.1
0.044
0.087
0.008
0.014
0.001
0.003
0.000
Fateh.2
0.055
0.081
0.011
0.015
0.000
0.001
0.000
Wahab
0.049
0.097
0.009
0.016
0.000
0.001
0.000
Honar
0.040
0.081
0.010
0.017
0.000
0.000
0.000
Fayaq
0.033
0.076
0.008
0.016
0.000
0.001
0.000
114
Appendix
(14):
Simple
correlation
coefficient
(r)
between
ions
concentration (mmolc L-1) in irrigation water and their concentration (mg g1
) in dry matter of leaves at different sampling times.
(r) value Ions
1st S. time
2nd S. time
3rd S. time
Caiw – Ca.p.L.
0.69
0.41
0.28
Mgiw – Mg.p.L.
0.82
0.12
0.49
Naiw – Na.p.L.
0.14
0.30
0.72
Kiw – K.p.L.
0.09
0.47
0.21
Piw – P.p.L.
0.56
0.10
0.13
Cliw – Cl.p.L.
0.49
0.77
0.36
Appendix
(15):
Simple
correlation
coefficient
(r)
between
ions
concentration (mmolc L-1) in irrigation water and their concentration (mg g1
) in dry matter of stem at different sampling times. (r) value Ions
1st S. time
2nd S. time
3rd S. time
Caiw – Ca.p.S.
0.16
0.61
0.28
Mgiw – Mg.p.S.
0.14
0.03
0.32
Naiw – Na.p.S.
0.53
0.75
0.13
Kiw – K.p.S.
0.25
0.36
0.19
Piw – P.p.S.
0.37
0.67
0.03
Cliw – Cl.p.S.
0.69
0.32
0.06
iw, p.L. and p .S. indicate the irrigation water, plant leaves and plant stem respectively.
115
