Lecture 8: Irrigation Water Quality

Transcription

1 The Islamic University of Gaza- Civil Engineering Department Irrigation and Drainage- ECIV 5327 Lecture 8: Irrigation Water Quality Prepared by Husam Al-Najar

2 Physical Parameters used in the evaluation of agricultural water quality Parameters Symbol Unit Total dissolved solids Electrical conductivity Temperature Color/turbidity Hardness sediments TDS EC T mg/l ds/m o C NTU/JTU mg equivalent CaCO 3 /l g/l NTU/JTU = Nephelometric Turbidity Unit/ Jackson Turbidity Unit

3 Chemical Parameters used in the evaluation of agricultural water quality Parameters Symbol Unit ph Acidity/basicity Type and concentration of anions and cations Calcium Magnesium Sodium Carbonate Bicarbonate Chloride Sulphate Sodium adsorption ratio Boron Trace metals Heavy metals Nitrate-nitrogen Phosphate Potassium Ca Mg Na CO 3 HCO 3 Cl SO 4 SAR B NO 3 -N PO 4 -P K mg/l mg/l

4 Salinity All waters used for irrigation contain varying amount of salts Salinization of soil and water is inevitable in climates where ET > precipitation Thus, drainage, either natural or artificial is essential to manage salts Key to sustainable irrigated agriculture in arid/semi-arid climates Salinity-total salt content Electrical Conductivity (EC w ) Electrical Conductivity of saturated paste extract (EC e or sat)

5 General Irrigation Water EC Classifications Class of Water Class 1, excellent Class 2, good Class 3, permissible Class 4, Doubtful Class 5, Unsuitable TDS (mg/l) < Electrical conductivity (ds/m) Permissible: leaching is needed if used Doubtful and Unsuitable: good drainage needed and sensitive plants will have difficulty obtaining stand.

6 Plants only transpire "pure" water Salinity Impact Salts in irrigation water remain in soil if not leached Plant Physiological drought Increased osmotic potential of soil Specific ion toxicity Leaf burn Nutrient uptake interferences

7 Crop Selection Phaseolus bean Saline sites: salt tolerance genotypic differences in reaction to increasing NaCl supply sugar beet

8 Evapotranspiration vs. Salinity (Gates et al. 2006)

9 Yield vs. Evapotranspiration Schneeklothet al, 2004

10 Relative Yield (%) EC e

11 Relative Yield vs. Salinity (Gates et al 2006)

12 Salinity effects

13 Crops classification according to salinity Salinity rating group Threshold salinity (ds/m) Zero yield salinity Sensitive (almond, apple, apricot, carrot) Moderately sensitive (corn, grape, pepper, tomatoes) Moderately tolerant (olive, barley) Tolerant (cotton, date palm)

14 Sodicity (sodic) -high sodium content SAR: sodium adsorption ratio SAR = Ca Na Mg 2 ++ Where: Na, Ca, and Mg concentrations must be expressed as meq/l

15 Generalized Classification of Salt-Affected Soils Classification EC (ds/m) SAR ph Saline Sodic Saline-Sodic High ph

16 Specific Ion Concerns and Toxicities Sodium (Na + ) Soil sodicity Crusting Reduced infiltration Lower hydraulic conductivity Higher ph impacting nutrient uptake Plant Stunted plants Toxicity and leaf burn potential

17 EC and SAR The hazard of irrigation water sodium on soil infiltration mustbe determined from the SAR/EC interaction. As EC increases relative to SAR, infiltration problems are reduced. Rainfall or sprinkler irrigation with non-saline water on soils previously irrigated with sodic water can increase the infiltration problem. Ayers and Westcott, 1985

18 Chloride (Cl - ) Contributes to EC Essential in low amounts Sensitive crops affected at high concentration Leaf burn potential under sprinkler Burn higher with daytime irrigation

19 Chloride tolerance criteria Chloride (mg/l) < > 350 Effect on crop Generally safe for all plants Sensitive plants show injury Moderately tolerant plants show injury Can cause sever problems

20 Boron (B) Essential in low amounts (alfalfa) Toxic to sensitive crops (>1.0 to 2.0 ppm) Fertility Sufficient in low concentrations

21 The Guidelines for the use of effluent waste water quality in irrigation (Takashi, 1990) Potential irrigation problem unit Degree of restriction None Slight to moderate Sever Salinity EC TDS ds/m mg/l < 0.7 < > 3.0 > 2000 Permeability SAR= 0-3 and EC = Specific Ion toxicity Sodium Surface irrigation Sprinkler irrigation Chloride Surface irrigation Sprinkler irrigation Miscellaneous effects ph Residual chlorine (overhead sprinkler only) ds/m > 0.7 > 1.2 > 1.9 > 2.9 > 5.0 SAR mg/l mg/l mg/l mg/l < 3 < 70 < 140 < > > 100 Normal range < 0.2 < 0.3 < 0.5 < 1.3 < 2.9 > 9 > 350 < > 5.0

22 Management Options Saline sites: management (Jordan valley)

23 Saline sites: plant adaptations- screening for salt tolerance of avocado

24 Field Diagnosis

25 N deficiency symptoms: corn

26 Nitrogen cycle Atmosphere N 2 biological N 2 fixation (N 2 R-NH 2 ) legumes N 2 O, NO x, N 2 denitrification (NO 3- N 2 O, NO x, N 2 ) NO 3 - uptake nitrification (NH 4 + NO 3- ) organic fertilizers organic (manure...) matter mineralization NH 4 + (R-NH 2 NH 4+ ) NH 4 + fertilizers, urea Soil leaching NO 3- fertilizers

27 P deficiency sypmtoms

28 K deficiency symptoms

29 Calcareous sites: B toxicity -soybean

30 Phaseolus bean Saline sites: salt tolerance genotypic differences in reaction to increasing NaCl supply sugar beet

31 Recommended microbiological quality guidelines for wastewater use in agriculture Catego ry Reuse condition Exposed group Intestinal nematodes (arithemetic mean no. of eggs per litre) Fecal coliform (geometric mean no. per 100 ml) A Irrigation of crops likely to be eaten uncooked, sports fields, public parks Workers, consumers public < 1 < 1000 B Irrigation of cereal crops, industrial crops, fodder crops, pasture and tries Workers < 1 No standard recommended C Localize irrigation of crops in category B if exposure of workers and the public does not occur None Not applicable Not applicable

32 Crop type and areas in the Gaza Strip (dunum) Source: Ministry of agriculture, 2004 Crop Type North Gaza Middle Khanyuns Rafah Total Citrus 2,200 5,812 3, ,600 Olives 145 6,200 5,552 8,000 3,000 22,897 Date Palm Only small area remaining Almonds ,750 3,163 Fruits 301 2,992 2,552 3, ,333 Vegetables (protected) 4, ,347 6,470 7,525 21,382 Vegetables 6,756 3,532 5,860 17,376 13,520 47,044 Field crops 2,494 3,423 5,135 21,680 3,830 36,562 Flowers ornamentals Total ,627

33 Palestinian Standards for irrigation and groundwater recharge Parameter Palestinian Standards Irrigation Recharge BOD (mg/l) TSS (mg/l) TDS (mg/l) EC (ms/cm) - - T-N (mg/l) Na (mg/l) Cl (mg/l) SAR 9 - B (mg/l) F. Coliform (MPN/100ml) Nematodes (ovum/l) <1 <1