Importance of fertigation scheduling Mr. C K Patel Sr. Manager Agronomy Ck.patel@netafim.com SBU-WEST-NETAFIM 9687696657
Proper fertigation scheduling can maximize the fertilizers use efficiency & Crop yield Different factors affecting the fertigation scheduling Scheduling must be based on law of Minimum Essential elements for plant Crop growth stage Nutrients uptake by various crops Cation exchange capacity Soil fertility & texture Soil PH & EC Salt tolerance of crops Fertilizers compatibility soil temperature 2
The Law of Minimum 3 The element which is in shortest supply (in this case, K) limits the yield Justus von Liebg 1840
Essential elements for plant Mn B Mo Micro Nutrient Fe Zn Cu Ca Mg S Secondary Nutrient N P K C H O Cl Primary Nutrient Natural 4
NPK daily uptake rate (kg ha -1 day -1 ) Fertigation scheduling V/S Crop growth stage NUTRIENTS APPLICATION ACCORDING TO THE UPTAKE RATE OF THE CROP 5 4 Broccoli N P spoon feeding 3 K 2 1 0 0 50 100 150 K N P Days after emergence or transplanting 5
Nutrient Uptake by various crops Nutrient Uptake Soil analysis Available nutrients in soil LAI Plant density Crop growth phase Targeted yield/variety Efficiency factors Fertilizers nutrients requirement 6
Cation Exchange Capacity Soil Texture CEC Range ( meq /100gm soil ) Organic soils > 50 Fine (clay) 25-50 Medium (silt) 8-30 Coarse(sand) 5-15 7
8 Fertigation scheduling on the basis of soil fertility & texture
Influence of soil ph on the availability of plant nutrients Optimal ph value: 5 6 Maximal nutrient availability High ph values: Reduced nutrient availability Low ph values: Reduced nutrient availability Toxic levels of Al, Mn 9
Only Fertigation grade Nitrogen - N Fertilizers Grade Formula ph (1 g/l at 20 o C) Urea 46 0 0 CO(NH 2 ) 2 5.8 Potassium nitrate 13 0 46 KNO 3 7.0 Ammonium sulfate 21 0 0 (NH 4 ) 2 SO 4 5.5 Urea ammonium nitrate 32 0 0 CO(NH 2 ) 2. NH 4 NO 3 Ammonium nitrate 34 0 0 NH 4 NO 3 5.7 Mono ammonium phosphate 12 61 0 NH 4 H 2 PO 4 4.9 Calcium nitrate 15 0 0 Ca(NO 3 ) 2 5.8 Magnesium nitrate 11 0 0 Mg(NO 3 ) 2 5.4 10
Phosphorous-P Fertilizers Grade Formula ph (1 g/l at 20 o C) Phosphoric acid 0 52 0 H 3 PO 4 2.6 Monopotassium phosphate 0 52 34 KH 2 PO 4 5.5 Mono ammonium phosphate 12 61 0 NH 4 H 2 PO 4 4.9 Urea Phosphate 17-44-00 2.5 11
Potash - K Fertilizers Grade Formula ph (1 g/l at 20 o C) Other nutrients Potassium chloride Potassium nitrate Potassium sulfate Potassium thiosulfate Monopotassium phosphate 0 0 60 KCl 7.0 46 % Cl 13 0 46 KNO 3 7.0 13 % N 0 0 50 K 2 SO 4 3.7 18 % S 0 0 25 K 2 S 2 O 3 17 % S 0 52 34 KH 2 PO 4 5.5 52 % P 2 O 5 12
Divisions for Relative Salt Tolerance(EC) Ratings of Agricultural Crops 100% 90% 75% 50% 0% maximum 3 FIELD CROPS EC e EC w EC e EC w EC e EC w EC e EC w EC e EC w Barley 8 5.3 10 6.7 13 8.7 18 12 28 19 Cotton ( 7.7 5.1 9.6 6.4 13 8.4 17 12 27 18 Sugarbet 7 4.7 8.7 5.8 11 7.5 15 10 24 16 Sorghum 6.8 4.5 7.4 5 8.4 5.6 9.9 6.7 13 8.7 Wheat 6 4 7.4 4.9 9.5 6.3 13 8.7 20 13 Soybean 5 3.3 5.5 3.7 6.3 4.2 7.5 5 10 6.7 Cowpea 4.9 3.3 5.7 3.8 7 4.7 9.1 6 13 8.8 Groundnut 3.2 2.1 3.5 2.4 4.1 2.7 4.9 3.3 6.6 4.4 Rice (paddy) 3 2 3.8 2.6 5.1 3.4 7.2 4.8 11 7.6 Sugarcane 1.7 1.1 3.4 2.3 5.9 4 10 6.8 19 12 Corn (maize) 1.7 1.1 2.5 1.7 3.8 2.5 5.9 3.9 10 6.7 Flax 1.7 1.1 2.5 1.7 3.8 2.5 5.9 3.9 10 6.7 Broadbean 1.5 1.1 2.6 1.8 4.2 2 6.8 4.5 12 8 Bean (Phaseolus vulgaris) 1 0.7 1.5 1 2.3 1.5 3.6 2.4 6.3 4.2 (Source: Mass, 1984) 13
fertilizer compatibility Calcium nitrate + Sulfates CaSO 4 precipitate (gypsum) Calcium nitrate + Phosphates Ca phosphate precipitate Magnesium + di- or monoammonium phosphate Magnesium Phosphate precipitate Ammonium sulfate + KCl or KNO 3 K 2 SO 4 precipitate Phosphorus + iron iron phosphates precipitate Fertilizers mixtures in the tank which reduce the solubility of the mixture due to formation of precipitates 14
Compatibility chart for water soluble fertilizers 15 Source: Marwaha-2003
Effect of temperature on the uptake of nutrients by plant 16
Nitrification NH 4 + nitrification NO 3 - How long it takes? Half life of this process at 25 0 C and Field capacity How long it takes? moisture content is about 1-2 weeks 17
Cotton Fertigation schedule Source: BCI-GGRC 18
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Conclusion Fertigation scheduling with balance nutrients programme, including all criteria like EC,PH, CEC, soil texture, soil fertility status & crop growth stage, can only maximize the crop yield 20
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Fertigation schedule for cotton (one acre) Basal application SSP Micronutrien FYM (t/a) (kg/a) ts (Kg/a) Targeted Yield 6 250 5 1.6 t/a Fertigation (kg/acre) DAS DAYS UREA AS MAP- (12-61-00) MOP MgSo4 CaNo3 Micronutrien ts (g/a) 0-8 8 12 5 8 9-15 7 20 5 8 16-50 35 40 5 17 10 5 100 51-80 30 10 25 5 25 10 5 100 81-110 30 10 25 25 10 5 100 111-140 30 25 25 10 5 100 141-180 40 17 5 Total 180 92 75 20 125 45 20 400 Fertilizer N P K S Mgo Cao SSP 0 40 0 28 Urea 42 AS 15 18 MAP 2 12 MOP 75 MgSo4 4 CaNo3 3 5 Total nutrients k/a 63 52 75 46 4 5 22 Fertilizer Type Qty Price Total Categor % of Total Cost Rs (kg) (Rs/kg) cost Rs y cost FYM Basal 6000 1 6000 SSP Basal 250 8 2000 8250 Basal 56 Micronutrients Basal 5 50 250 Urea Traditional 92 6.34 583 AS Traditional 75 12.7 953 2986 Traditio nal MOP Traditional 125 11.6 1450 20 MAP WSF 20 85 1700 MgSo4 WSF 45 14 630 CaNo3 WSF 20 42 840 3570 WSF 24 Micronutrients EDTA 0.4 1000 400 Total Cost 14806 14806 100