Produced Water Quality Limits for Irrigated Agriculture. Robert Flynn, Ph.D. Extension Plant Sciences, NMSU

Transcription

1 Produced Water Quality Limits for Irrigated Agriculture Robert Flynn, Ph.D. Extension Plant Sciences, NMSU

2 Introduction Water Quality Affects Soil Productivity Crop Performance Poor Water Quality Can be managed Can be treated Start with: Irrigation Water Assessment Soil Test

3 What are we looking for? ph Salinity Specific Ion Effects Sodium Bicarbonate Chloride Boron Other

4 ρh = -log(h + ) Water ρh Acidic, Basic, or Neutral Normal Range 6.5 to 8.4 New Mexico (>7 ph <8.4) Best to measure immediately

5 Water Salinity Presence of dissolved salts Cations (Ca ++, Mg ++, K +, Na + ) Anions (HCO 3-, CO 3=, Cl -, SO 4= ) Measured as Electrical Conductivity (e.c.) ds/m or mmhos/cm TDS (mg/l or ppm)

6 EC w Examples Distilled Water 0 Artesia 1.6 Tularosa 2.5 Fort Sumner 4.1 Vinton, TX 4.3 Carlsbad 6.0 Hagerman 6.6 Lake Arthur 8.8

7 Interpreting ec w Degree of restriction on use None Slight - Moderate Severe < > 3.0 UNITS: mmhos/cm

8 Interpreting TDS Degree of restriction on use None Slight - Moderate Severe < > 2000 UNITS: ppm or mg/l e.c. X 640 TDS

9 SAR: Sodium Adsorption Ratio Sodium (Na) Calcium (Ca) & Magnesium (Mg) Na disperses clay particles in soil (bad) Ca & Mg bring clays into aggregates (good)

10 Sodium level (SAR) Both the amount of salts and the kind of salts affect soil structure Dispersed soil Aggregated soil Electrical conductivity (ds/m)

11 Interpreting SAR & EC w Degree of restriction on use None Slight - Moderate Severe SAR = 0 3 & EC w = > <0.2 SAR = 3-6 & EC w = > <0.3 SAR = 6-12 & EC w = SAR = & EC w = SAR = & EC w = > <0.5 > <1.3 > <2.9

12 Specific Ion Effects - SAR Degree of restriction on use None Slight - Moderate Severe Surface Irrigation <3 3-9 >9

13 Specific Ion Effects: Cl - Degree of restriction on use None Slight - Moderate Severe Surface Irrigation (meq/l) < >10 meq Cl - /l = ppm/35.5

14 Irrigation & Na+, Cl Surface Irrigation Most woody species are sensitive to sodium and chloride Most annual species are not sensitive Overhead irrigation + low humidity Na+ and Cl- may be absorbed through the leaves of sensitive plants.

15 Crop Tolerance to Na + & Cl meq/l meq/l >20 meq/l Grape Alfalfa Cauliflower Pepper Barley Cotton Potato Corn Sugarbeet Tomato Cucumber Sunflower Safflower Sesame Sorghum

16 Grape Tolerance to Cl - (meq/l) Grape RS or CV Root Zone Irrigation water Salt Creek, Dog Ridge Thomson seedls Perlette Cardinal Black Rose

17 Specific Ion Effects Boron Degree of restriction on use None Slight - Moderate Severe ppm < >3.0

18 Crop Tolerance to Boron (ppm) Very Sensitive (<0.5) Blackberry Sensitive ( ) Grape Pecan Onion Less Sensitive (0.75 1) Wheat Peanut Moderately Sensitive (1-2) Pepper, red Potato Moderately Tolerant (2 4) Corn Squash Tolerant (4 6) Sorghum Tomato Alfalfa Very Tolerant (>6) Cotton Asparagus

19 Specific Ion Effects Bicarbonate (HCO 3- ) Degree of restriction on use None Slight - Moderate Severe meq/l < >8.5 meq HCO 3 - /l = ppm/61

20 Drip Irrigation Concerns

21 Clogging Hazards Clogging caused by: Physical Chemical Biological

22 Size of selected particles Coarse Sand: mm Fine Sand: mm Silt: to 0.05 mm Clay: <0.002 Bacteria: to Virus: <0.0004

23 Filtration Sized to remove particles 1/10 the size of the smallest emitter opening. Individual silt, clay, and bacteria can pass through filtration and emitters However, conglomeration occurs especially from bacterial glues Can t filter all the particles, so Flushing the system is important

24 Total Suspended Solids (TSS) Level of Concern Low <50 ppm (mg/l) Moderate ppm (mg/l) High >100 ppm (mg/l)

25 Total Dissolved Solids (TDS) Level of Concern Low <500 ppm (mg/l) Moderate ppm (mg/l) High >2000 ppm (mg/l)

26 Chemical Precipitation Hazards ρh Low <7.0 Moderate High >8.0 $12 - $18 $5 - $90

27 Chemical Precipitation Hazards Iron (Fe) Low <0.2 ppm (mg/l) Moderate ppm (mg/l) High >1.5 ppm (mg/l) With sulfide >0.1 mg/l can get a black sand like material.

28 Chemical Precipitation Hazards Manganese (Mn) Low <0.1 ppm (mg/l) Moderate ppm (mg/l) High >1.5 ppm (mg/l) In presence of sulfides can form a black, sand-like insoluble precipitate.

29 Chemical Precipitation Hazards Hydrogen sulfide (H 2 S) Low <0.1 ppm (mg/l) Moderate ppm (mg/l) High >2.0 ppm (mg/l)

30 Chemical Precipitation Hazards Bicarbonate & ph (above 7.5) Low <1.5 meq/l Moderate meq/l High >2.5 meq/l o Can Cause Lime Scale o White film around emitters o White precipitate in flush water

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