Evaluation of fertigation. Wetting pattern of a drip system on different soil types. Design of a fertigation system

Transcription

1 Evaluation of fertigation Nutrient solution aquaous solution of mineral salts that are essential for plant nutrition Fertigation simultaneous application of water and nutrients via the irrigation system (mainly micro-irrigation) fertilisation irrigation fertigation (fertirrigation) Area of micro-irrigation in the world: M ha, M ha, M ha, M ha, ,3 M ha (45 countries) which is about 5% of the irrigated area In Hungary ha, 3,2% (????) ICID data; Reinders 2006 Wetting pattern of a drip system on different soil types Advantages and disadvantages of fertigation + Precise (quantity, distribution) and conitnuous application of nutrients + Amount, concentration, composition can be adjusted to crop requirements better yield and quality + Increased nutrient and water use efficiency (WUE, NUE) reduced leaching and fertilizer need + Reduced energy use + Soil conservation (less erosion, compaction, etc.) Expensive Requires more technical knowledge Requires good water quality Risk of clogging of emitters Risk of local salt accumulation Reduction of root volume Design of a fertigation system water fertilizers well Necessary materials and instruments stock solution stock tank(s) pump, injector nutrient solution filter 2 pressure reducing valve filter 1 controller (automation) micro-irrigation system nutrient solution 1

2 Irrigation water Physical characteristics: Temperature Total floating sediments Chemical characteristics: ph: 5,6-6,2 soilless system, 6,2-6,8 on soil EC (ms/cm or ds/m) total dissolved salts (TDS) Rate of harmful ions (Na+, Cl-, HCO3-)(B, F) Rate of matter causing clogging (Fe, Mn) Biological characteristics: Number of bacteria Quality improvement: Acid treatment Removal of Fe and Mn (aeration and depositing) Desalinisation (reverse osmosis) Deionisation Water quality requirements for drip irrigation in Hungary characteristic risk of clogging any moderate high total floating sediments(mg/l) < >100 ph <7,0 7,0-8,0 >8,0 manganese (mg/l) <0,1 0,1-1,5 >1,5 iron (mg/l) <0,1 0,1-1,5 >1,5 hidrogen sulfide (mg/l) <0,5 0,5-2,0 >2,0 number of bacteria (thousand/l) < >50 (29/2006 FVM directive) Ion K + Ca 2+ Mg 2+ Na + NO 3 - Cl - HCO 3 - mg/l 1 51,5 41,7 9,7 5,1 15,6 370,2 molar weight mmol/l 0,02 1,29 1,81 0,46 0,08 0,4 6,07 meq/l 0,02 2,58 3,62 0,46 0,08 0,4 6,07 nutrient solution 0,5 1,0 1,5 fertilizer Σ 6,68 6,55 predicted EC = ((meq cation + meq anion)/2)/10 predicted EC = ((6,68 + 6,55)/2)/10 = 0,66 EC = 2,0 total diddolves salts (TDS) = 495 (mg/l) predicted EC = TDS (mg/l) / 640 predicted EC = 495 / 680 = 0,73 ACTUALLY MEASURED EC = 0,57 1,5 1,0 0,5 irrigation water Water quality requirement of the different systems closed (recycled) soilless production quality open (run-off drainage) soilless production fertigation traditional irrigation 2

3 oldhatóság Solubility (g/100g) Solubility oldhatóság (g/100g) Fertilizer Oldhatóság Solubility at 2020 C C-on Important requirements, characteristics: Solubility perfect, free from insoluble materials NH 4 NO 3 Urea KCl Dissolution quick Residual salt content low Nutrient content high Absence of toxic materials Should not make chemical reaction with the Price (NH 4 ) 2 SO 4 (NH 4 )H 2 PO 4 KNO 3 K 2 SO KCl KNO3 20 K2SO Water vízhőmérséklet temperature ( C) ( C) Types: Straight NH 4 NO 3, KNO 3, Ca(NO 3 ) 2, Mg(NO 3 ) 2, (NH 4 )H 2 PO 4, (NH 4 ) 2 HPO 4, (NH 4 ) 2 SO 4, HNO 3 KH 2 PO 4, H 3 PO 4, (NH 4 )H 2 PO 4, (NH 4 ) 2 HPO 4, K 2 SO 4, KCl, KNO 3, KH 2 PO 4, MgSO 4, (CaCl 2 ), Ca(NO 3 ) 2, Mg(NO 3 ) 2 micro-element compounds, microelement chelates (e.g. EDTA, DTPA) compound/complete fertilizers balanced e.g. 15:15:15 N:P 2 O 5 :K 2 O N heavy(?) e.g. 24:8:16 P heavy e.g. 15:30:15 K heavy e.g. 14:11:25 Stock solution Stock solution: concentrated solution of fertilizers (nutrients) Its concentration is (-200) times more than that of the optimum nutrient solution (0,15-0,3%) Its composition defines the nutrient ratio, and the rate of its dilution defines the concentration of the nutrient solution Should be used up within a few days Precipitation should be avoided Tanks Plastic, fiberglass, (concrete) Protection against direct light and contamination Single tank systems 1 nutrient solution tank direct nutrient solution preparation 1 stock solution tank divided fertigation Dual tank (A, B) system A tank: Ca, nitrates, Mg, Fe, micro-element chelates, nitric acid B tank: sulphates, phosphates, phosphoric acid, complete fertilizers, nitrates, nitric acid, chelates Two tanks + acid tank Acid tank: nitric acid, phosphoric acid One tank per fertilizer (min. 5-6 tanks) 3

4 Making a set composition from straight fertilizers In order to form a nutrient solution with 1 : 0,4 : 1,8 : 0,2 N:P 2 O 5 :K 2 O:MgO composition, in what ratio the following fertilizers should be put into the stock solution? ammonium-nitrate (NH 4 NO 3 ) 34:0:0 mono-potassium-phosphate (KH 2 PO 4 ) 0:52:34 potassium-nitrate (KNO 3 ) 13:0:46 magnésium-nitrate (MgNO 3 ) 11:0: MgO 1 : 0,4 : 1,8 : 0,2 0,4 unit P 2 O 5 0,4/0,52 = 0,77 unit KH 2 PO 4 0,77 unit KH 2 PO 4 0,77 x 0,34 = 0,26 unit K 2 O 1,8 0,26 = 1,54 unit K 2 O is still needed 1 : ready : 1,54 : 0,2 1,54 unit K 2 O 1,54/0,46 = 3,35 unit KNO 3 3,35 unit KNO 3 3,35 x 0,13 = 0,44 unit N 1 0,44 = 0,56 unit N is still needed 0,56 : ready : ready : 0,2 0,56 : ready : ready : 0,2 0,2 unit MgO 0,2/0,15 = 1,33 unit MgNO 3 1,33 unit MgNO 3 1,33 x 0,11 = 0,15 unit N 0,56 0,15 = 0,41 unit N is still needed 0,41 : ready : ready : ready 0,41 unit N 0,41/0,34 = 1,2 unit NH 4 NO 3 ready : ready : ready : ready ready : ready : ready : ready 1 : 0,4 : 1,8 : 0,2 NH 4 NO 3 : KH 2 PO 4 : KNO 3 : MgNO 3 1,20 : 0,77 : 3,35 : 1,33 ammonium-nitrate (NH 4 NO 3 ) 1,20 unit mono-potassium-phosphate (KH 2 PO 4 ) 0,77 potassium-nitrate (KNO 3 ) 3,35 magnesium-nitrate (MgNO 3 ) 1,33 Altogether 6,65 unit E.g. 100 l volume of stock solution with 10% concentration 10 kg fertilizer is put into the stock solution 1 unit = 10 / 6,65 = 1,5 kg Make a 1:0,33:1,5:0,16:0,66 N:P 2 O 5 :K 2 O:MgO :CaO composition nutrient solution from the following fertilizers: complete 14:11: MgO potassium-nitrate 13:0:46 magnesium-sulphate 16 MgO calcium-nitrate 15:0: CaO ammonium-nitrate (NH 4 NO 3 ) mono-potassium-phosphate potassium-nitrate (KNO 3 ) magnesium-nitrate (MgNO 3 ) 1,20 x 1,5 = 1,80 kg 0,77 x 1,5 = 1,16 kg 3,35 x 1,5 = 5,03 kg 1,33 x 1,5 = 2,00 kg 4

5 : CaO 1 : 0,33 : 1,5 : 0,16 : 0,66 0,33 unit P 2 O 5 0,33/0,11 = 3,0 unit complete 3,0 unit complete 3,0 x 0,14 = 0,42 unit N 1 0,42 = 0,58 unit N is still needed 3,0 unit complete 3,0 x 0,25 = 0,75 unit K 2 O 1,5 0,75 = 0,75 unit K 2 O is still needed 3,0 unit complete 3,0 x 0,02 = 0,06 unit MgO 0,16 0,06 = 0,1 unit MgO is still needed : CaO 0,58 :ready: 0,75 : 0,1 : 0,66 : CaO 0,58 :ready: 0,75 : 0,1 : 0,66 0,1 unit MgO 0,1/0,16 = 0,62 unit MgSO 4 : CaO 0,58 :ready: 0,75 : ready : 0,66 0,75 unit K 2 O 0,75/0,46 = 1,63 unit KNO 3 1,63 unit KNO 3 1,63 x 0,13 = 0,21 unit N, 0,58 0,21 = 0,37 unit N is still needed : CaO 0,37 :ready: ready : ready : 0,66 : CaO 0,37 :ready: ready : ready : 0,66 0,37 unit N 0,37/0,15 = 2,47 unit calcium-nitrate 2,47 unit calcium-nitrate 2,47 x 0,26 = 0,64 unit Ca : CaO ready :ready: 0,75 : ready : 0,02 3,0 : 1,68 : 0,62 : 2,47 complete potassium-nitrate 3,00 unit 1,63 unit magnesium-sulphate 0,62 unit calcium-nitrate 2,47 unit Altogether 7,72 unit From that the ratio of calcium-nitrate is 2,47 / 7,72 = 32% in a one-tank system it is reasonable to provide the nutrients in three portions: in one occasion the calcium nitrate, in the two other occasions the rest of the fertilizers is provided A tank fertilizer unit Ca(NO 3 ) 2 2,47 KNO 3 1,39 3,86 B tank fertilizer unit complete 3,00 MgSO 4 0,62 KNO 3 0,24 3,86 Devices for adding fertilizers to the With gravitation from nutrient solution tank Fertilizer tank Venturi pump Piston pump - working with the energy of Fertigation machine - sophisticated equipment (enclose a computer), needs other energy source 5

6 Evaluation of the different devices Fertilizer tank Venturi pump Fertigation machine Price low medium high Solid fertilizer Liquid fertilizer Know-how low medium high Quantity control good medium good Concentr. control nil medium good Pressure loss low high nil Automation nil medium high Nutrient solution Stock solution Irrigation water Control of irrigation (fertigation) Manual Water meter Automatised (needs hydraulic solenoid valves) Based on time Based on volume volumetric control valve Based on volumetric water capacity of soil/substrate (usually at 60-70%) Based on drainage, plant, substrate weight Based on radiation (2-3,5 ml/m 2 volume for 1 J, e.g. start when a 60 J unit accumulated) Setting a fertigation machine controlled on the base of global solar radation How many Joul is the radiation setpoint if there is a sweet pepper crop in May with 3 plants/m 2 density, and we want to provide 80 ml/plant nutrient solution at one occasion? volume of nutrient solution (ml/m 2 ) = plant density (plant/m 2 ) x solution volume per plant (ml/plant) 3 plant/m 2 x 80 ml/plant = 240 ml/m 2 Looking up water loss via transpiration(?): 2,3ml/J/m 2 radiation (J) = volume of nutrient solution (ml/m 2 ) / water loss via transpiration(ml/j/m 2 ) 240 ml/m 2 / 2,3 ml/j/m 2 = 104 J Hónap Paprika Paradicsom Uborka január 3,5 3,8 3,8 február 2,1 2,4 2,6 március 3,1 3,4 3,5 április 2,5 2,8 3,0 május 2,3 2,6 2,8 június 2,7 3,0 3,2 július 2,6 2,9 3,1 augusztus 2,7 3,0 3,0 szeptember 2,4 2,7 2,9 október 2,3 2,4 2,5 november 2,3 2,4 2,5 december 2,3 2,3 2,5 How much nutrient solution should be provided at one occasion in a tomato crop with 2,5 plant/m 2 density in April, if we want to set the radiation setpoint at 100 J? Looking up water loss via transpiration: 2,8ml/J/m 2 volume of nutrient solution (ml/m 2 ) = irrigation treshold (J) x water loss via transpiration (ml/j/m 2 ) 100 J x 2,8 ml/j/m 2 = 280 ml/m 2 solution volume per plant (ml/plant) = volume per area (ml/m 2 ) / plant density (plant/m 2 ) 280 ml/m 2 / 2,5 plant/m 2 = 112 ml/plant 6

7 Control of irrigation (fertigation) Manual Water meter Automatised (needs hydraulic solenoid valves) Based on time Based on volume volumetric control valve Based on volumetric water capacity of soil/substrate (usually at 60-70%) Based on drainage, or plant and substrate weight Based on radiation (2-3,5 ml/m 2 volume for 1 J, e.g. start when a 60 J unit accumulated) Based on information of plant sensors Filters Role: preventing clogging of emitters Tíypes: Hydrocyclone (centrifugal) filter Gravel filter Net filter (mesh) Ring filter mesh how many lines are there in 1 inch = 2,54 cm Pressure reducing valve Function: automatically cuts off the flow of a liquid (e.g. nutrient solution) at a certain pressure. 7