Target Yield Concept
(i) Wheat
The fact that the fertilizer are becoming a constraint in agricultural production due to energy crisis particularly in developing countries such as ours,
it is of great benefit to work out the most economical dose of this input based upon target yield approach in which the efficiency of a nutrient from
soil and fertilizer sources is taken into consideration to complete fertilizer doses for attaining desired yield level of a particular crop in a given soil system.
Such an information has been generated for wheat crop being grown on the acid soils of Himachal Pradesh. The information is as follows:
| Nutrient |
N |
P2O5 |
K20 |
| Nutrient requirement (kg) to produce 1 q of wheat grain |
2.35 |
0.63 |
1.66 |
| Per cent contribution from available nutrient from soil |
6.0 |
41.6 |
12.8 |
| Per cent contribution from applied fertilizer |
47.8 |
8.0 |
68.3 |
(b) Computation of fertilizer dose based upon the basic information :
Fertilizer dose (kg/ha) = (Constant1) X (T) -(Constant2) X (STV (kg/ha))
Where T = Yield target (q/ha)
STV = Soil test value (kg/ha)
Constant1 = {(Nutrient required (kg)to produce 1 q grain) / (% contribution from fertilizer)}
Constant2 = {(% contribution for soil) / (% contribution for fertilizer (kg/ha))}
Soil Analysis
| pH |
OC |
Texture |
Available nutrient (kg/ha) |
| N |
P |
K |
| 5.7 |
0.63 |
CL (Clayloam) |
600 |
30 |
95 |
(c) Transformation of the data (b) into fertilizer equations to achieve specified yield target for wheat :
FN = 491 T-0.124 SN
FP2O5 = 7.86 T-5.16 (SP)
FK2O = 2.44 T-0.187 (SK)
(ii) Lentil (HPL-5)
FN = 10.53 T-0.40 SN
FP2O5 = 8.77 T-8.62 SP
FK2O5 = 3.26 T-0.13 SK
(iii) Gram (C-235)
FN = 13.35 T-0.46 SN
FP2O5 = 4.56 T-7.02 SP
FK2O5 = 2.12 T-0.09 SK
FN, FP2O5 & K2O stand for fertilizer N,P2O5 and K2O
T - Target yield (q/ha)
NS, SP, SK stand for available N, P and K in the soil.
s
| Treatment |
Yield
target
(kg/ha) |
Fert. dose |
Yield
obtained
kg/ha |
Per cent
Deviation |
Yield
response |
Response
yardstick
kg/ha
NPK |
Price of
add.
Yield
Rs/ha |
Cost of
fertilizer
Rs/ha |
Cost of
Net
profit
Rs/ha |
Benefit
cost
ratio |
| T1* |
-- |
O0P0 |
1343 |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
| T2* |
-- |
N90P90K45 |
3132 |
-- |
1789 |
14.3 |
1376.15 |
779.40 |
596.75 |
0.76 |
| T3 |
2000 |
N16P2K31 |
2032 |
+1.6 |
689 |
14.1 |
895.70 |
119.30 |
776.40 |
6.50 |
| T4 |
2500 |
N41P42K43 |
2597 |
+3.9 |
1254 |
10.0 |
1630.20 |
392.65 |
1237.55 |
3.17 |
| T5 |
3000 |
N65P81K55 |
3110 |
+3.7 |
1767 |
8.8 |
2297.10 |
658.09 |
1639.01 |
2.49 |
| T6 |
3500 |
N90P120K67 |
3546 |
+1.3 |
2203 |
7.9 |
2863.90 |
927.68 |
1936.22 |
2.09 |
| T7 |
4000 |
N114P160K80 |
4125 |
+3.1 |
2782 |
7.8 |
8616.60 |
1198.30 |
2418.22 |
2.02 |
| T8 |
5000 |
N64P238K104 |
4275 |
-14.5 |
2932 |
5.8 |
381.60 |
1737.40 |
2074.20 |
1.19 |
Soil properties
T1* = control Texture O.C% AvN AvP AvK
T2* = yield obtained as per state level dose Clayloam 0.43-0.78 436-698 16-38 80-121
Conclusion: Based upon the benefit ratio, one can conclude that farmers of the region can obtain wheat yields upto 30-40 q/ha if they apply fertilizers in acid soils of H.P. in accordance with the target yield concept.