Soil fertility evaluation and fertilizer recommendation

soil fertility evaluation and fertilizer recommendation

1. Soil Fertility Evaluation And Fertilizer Recommendation

2. Soil Fertility Evaluation

3. Approaches for soil fertility Evaluation Soil Analysis Plant Analysis Biological methods Visual symptoms of nutrient deficiency

4. Soil Analysis

5. Rating limits of soil test values Nutrient Low Medium High Organic carbon (%) Below 0.5 0.5 – 0.75 Above 0.75 Avail. N (kg ha-1) Below 280 280 – 560 Above 560 Avail. P (kg ha-1) Below 22 22-56 Above 56 Avail. K (kg ha-1) Below 141 141-336 Above 336 Avail. S (ppm) Deficient < 10 ppm Sufficient > 10 ppm

6. Plant analysis 1.plant analysis is an indirect evaluation of soil 2.plant analyses are interpreted on the basis of critical value approach Two general types of plant analysis are in use. 1. The Rapid tissue test which is customarily made on fresh tissue in the field. 2. Total analysis performed in the laboratory with precise analytical techniques

7. Rapid tissue tests D etermination of nutrient elements in the plant sap of fresh tissue. Plant Part to be Selected : In general the conductive tissue of the latest mature leaf is used for testing .

8. Time of Testing: The most critical stage of growth for tissue testing is at the time of bloom or from bloom to early fruiting stage. Nitrates are usually higher in the morning than in the afternoon if the supply is short. Test for nitrates Diphenylamine Phosphates Molybdate + Stannous oxalate For potassium Sodium cobalti nitrate

9. Total Analysis: Total analysis is performed on the whole plant / plant parts plant material is dried, ground, ashed and used for estimation Precise analytical techniques are used for measurement of the various elements

10. Diagnosis and Recommendation Integrated System It considers nutrient concentration ratios rather than individual element The approach measures the relative balance between nutrients Large number of sites is selected at random Each element in the plant is expressed in as many ways as possible Ex: Nutrient ratios N/P, N/K or products NxP, NxK etc NPK requirement of the crop is diagnosed using DRIS chart

11. Fertilizer Recommendations

12. Approaches Generalized/blanket Recommendations Soil Test Rating and Fertilizer Adjustment Soil test crop response and target yield concept Site specific nutrient management

13. Generalized/blanket Recommendations Uniform application of RDF of a crop. RDF Ex.(N, P 2 O 5 , K 2 O Kg/ha) Rice :- 100:50:50 Maize:- 150:75:40 Red gram:- 25:50:25 Cotton:- 150:75:75

14. Soil Test Rating and Fertilizer Adjustment NUTRIENT Soil Test Ratings Kg/ha LOW MEDIUM HIGH N <280 280-560 >560 P 2 O 5 <22 22-56 >56 K 2 O <141 141-336 >336 S <10ppm 10-20ppm >20ppm

15. RDF (Kg/ha) ADDITION IN RDF AT LOW FERTILITY DEDUCTION IN RDF AT HIGH FERTILITY NITROGEN <50 NO CHANGES NO CHANGES 50-100 +12.5 -12.5 100-175 [phone] +37.5 -37.5 250-325 +50 -50 PHOSPHORUS <25 NO CHANGES NO CHANGES 25-75 +12.5 -12.5 75-125 +25 -25 POTASSIUM <25 NO CHANGES NO CHANGES 25-50 +12.5 -12.5 Changes to be made in RDF

16. Soil test crop response and target yield concept NUTRIENT REQUIREMENT (Kg/q) = TOTAL UPTAKE OF NUTRIENT (Kg/ha) YIELD OF GRAIN (q/ha) %CS = TOTAL UPTAKE OF NUTRIENT IN CONTROL PLOTS (Kg/ha) X 100 AVAILABLE SOIL TEST VALVES OF CONROL PLOTS ( Kg/ha) %CF = TOTAL UPTAKE OF NUTRIENT IN TREATED PLOTS (Kg/ha) --( AVAILABLE SOIL TEST VALVES OF TREATED PLOTS ( Kg/ha) X %CS) X 100 FERTILIZER DOSE APPLIED(Kg/ha)

17. Target Yield Equation Using the Basic Data, Fertilizer Dose Required for specific yield target is calculated by F=(NR *T – CS/100*S)*100/CF F = Fertilizer required kg/ha NR = Nutrient requirement kg/q T = Targeted yield q/ha CS = % contribution of N/P/K from soil S = Soil test value CF = % contribution of N/P/K from fertilizer