Fertigation. Dr. Juan Enciso Associate Professor BAEN Department Texas Agrilife Research and Extension Texas A&M University System

Transcription

1 Fertigation Dr. Juan Enciso BAEN Department Texas Agrilife Research and Extension

2 Objectives 1. Importance of Irrigation Uniformity on Fertigation 2. Inyector and inyection rates 3. Rules of injection

3 Irrigation systems in the LRGV Earth ditches 33% Drip 3% Sprinkler 2% Gated pipe 10% Laser levelled 67% Poly-pipe 52%

4 Subsurface drip irrigation Requires filtering system

5

6 Wetting pattern shapes and fertilizer extraction Loam

7 Fertigation requires high irrigation uniformity

8 Center pivot Uniformity over 95%

9 Side roll-lateral movement Uniformity 80%

10 Surface irrigation

11 Earth ditches versus poly-pipe Uniformity 50-75%

12 Surge irrigation Cotton and sugarcane

13 Border irrigation-graded border Uniformity 50%-70%

14 Big gun- traveler High Energy cost Very portable

15 Venturi injectors require a pressure differential. A booster pump is recommended fertilizer Fertilizer + water

16 Venturi

17 Acid injection Inject acid to lower ph to Water high in bicarbonate

18 Controlling the inyected amount. Hose on the suction of the fertilizer tank

19 Rules of injection Check for mixing and compatibility Jar test Best to make a small quantity to test fertilizer before preparing large batches

20 Plugging potential of irrigation water Physical Suspended solids

21 Plugging potential of irrigation water Chemical Manganese-iron oxides sulfides Calcium and magnesium precipitation

22 Plugging potential of irrigation water Biological Bacteria Algae Root intrusion - buried emitter

23 Plugging potential of irrigation water

24 Plugging potential of irrigation water Chemical ph Low Moderate Severe < >8.0 Bicarbonate (ppm) < Iron (ppm) Sulfides (ppm) < > 1.5 < > 2

25 Common constituents of irrigation water Cations Amonium NH 4 Calcium Ca Anions Bicarbonate HCO 3 Carbonate CO 3 Hidrogen H Nitrate NO 3 Magnesium Mg Sodium Na Potasium K Phosphate PO 4 Sulfate SO 4

26 Plugging prevention (chemicals used) Chlorine Acid Sulfuric Phosphoric Urea-sulfuric (NpHuric) Citric acid

27 Calcium and magnesium precipitation Carbonate precipitation Plug emitter Use of ACID to LOW ph to 6.5 Sulfuric or white phosphoric Last third of the irrigation set time

28 Acid injection Inject acid to lower ph to Water high in bicarbonate

29 Rules of injection Inject acids downstream Inject other chemicals upstream of the filter ---- discontinue the application during the flushing process

30 Calcium and magnesium precipitation If there are more than 50 ppm of Ca Phosphoric acid should not be injected

31 Rules of injection Only fertigate during the middle half of the irrigation set 1/4 1/2 1/4

32 Chlorine Low concentration (1 to 5 ppm) Act as bactericide Oxidizer of iron High concentration ( 100 to 1000 ppm) Oxidizing agent for organic matter Disintegrate organic matter

33 Monitoring soil moisture and fertilizer movement

34 Future studies 1 ft 1 ft

35 Extraction tubes - monitor leaching, soluble elements

36 Arroyo Colorado 2202

37 Mixing rules # 1 ALWAYS fill the mixing container with 50-75% required water When used in the mix of dry soluble fertilizers

38 Mixing rules # 2 ALWAYS add the ingredients slowly with circulation or agitation to prevent of large, insoluble or slowly lumps

39 Mixing rules # 3 ALWAYS put acid into water Not water into acid Water can boil and spit dangerously

40 Mixing rules # 4 DO NOT COMBINE Phosphoric acid with any calcium fertilizer Calcium phosphates Plug the irrigation system

41 Mixing rules # 5 DO NOT mix sulfate with calcium Insoluble calcium will form

42 Mixing rules # 6 Extreme hard water (Ca and Mg) Phosphates and sulfates Insoluble compounds

43 Mixing rules # 7 NEVER mix or store acids and chlorine together A toxic chlorine gas will form

44 Mixing rules # 8 ALWAYS check with supplier about insolubility and incompatibility

45 Estimated Daily Water Use for Grain Sorghum Inches Leaf Rapid growth Boot Days after planting Bloom Grain fill Drying

46 Cation-Anion Balance Total number of cations = Number of anions Source of nutrition Cations NH NH 4 + Anions 4 K + 9 H 2 PO 4-1 Ca 2+ 3 SO Mg 2+ 1 Cl - Sum of charges

47 Cation-Anion Balance Source of nutrition Cations Anions NO NO K + 5 H 2 PO Ca 2+ 1 SO Mg 2+ 1 Cl - Sum of charges

48 Irrigation controller

49 Irrigation controller with solar panel

50 END