INTRODUCTION

Efficient use of plant nutrients through chemical
fertilizers and organic manures is a good means for
increasing agriculture productivity and profitability. Cost of
fertilizers has gone up and, hence, their optional use in
required quantity mainly depends on resources available to
farmers. Imbalanced use of chemical fertilizers results in
lower nutrient use efficiency and restricts utilization of the
genetic potential of a crop to its maximum. The most
comprehensive approach of fertilizer application by
incorporating soil test values, nutrient requirement of the
crop, contribution of nutrients from soil manures fertilizers
and fixing yield-targets is possible only through Soil Test
Crop Response (STCR) approach. Therefore, this study was
undertaken to develop targeted yield equations for carrot
crop in red soils of Gandhi Krishi Vignyan Kendra (GKVK),
Bangalore.

MATERIAL AND METHODS

A field experiment was conducted on carrot crop
during kharif 2008-09 under red soils (Kandic paleustalfs)
of Zonal Agricultural Research Station (ZARS), GKVK,
Bangalore to develop targeted yield equations following the

Development of fertilizer prescription targeted yield-equation for carrot crop based
on soil test values

P.K. Basavaraja, P.N. Narasimha Reddy, N.L. Rajesh and K.B. Apoorva
AICRP on STCR, Department of Soil Science and Agricultural Chemistry
University of Agricultural Sciences, GKVK, Bangalore – 560 065, India

E-mail:pujarikbraj@gmail.com

ABSTRACT

A field experiment was conducted on red soils (Kandic paleustalfs) of Zonal Agricultural Research Station, GKVK,
Bangalore during kharif 2008-09 to develop a targeted yield equation for carrot crop. After developing three levels of
fertility gradient with respect to available NPK in soil, the main experiment was conducted by taking carrot as a test
crop. Initial soil data, carrot root yield and NPK uptake by carrot crop were used for obtaining four important basic
parameters, viz., nutrients required to produce a quintal of carrot roots (NR%), contribution of nutrients from
fertilizers (CF%), contribution of nutrients from soil (CS%) and contribution of nutrients from organic matter
(%C-OM). These parameters were used for developing fertilizer-adjustment targeted yield equation. Comparison of
the present soil testing laboratory method with Soil Test Crop Response approach of fertilizer recommendation
clearly indicated superiority of STCR targeted yield approach for efficient and economic use of fertilizers to attain
the required yield target.

Key words: Carrot, red soils, basic parameters, targeted yield equation

procedure of Ramamoorthy et al (1967). Three strips of
fertility gradients, viz., low, medium and high (with respect
to available nitrogen, phosphorus and potassium) were
developed taking fodder maize as the exhaustive crop.
Thereafter the main experiment was conducted by dividing
each strip into three blocks of FYM taking seven different
NPK combinations + 1 Absolute Control. So thus, a total of
21 treatments of NPK combinations and 3 Controls were
imposed in each strip. Similarly, the same NPK treatment
groups in each FYM block were randomized in the other
two gradient strips to a total of 72 treatments. The following
NPK and FYM levels in different combinations were tested
in this experiment.

Nutrient levels tested

FYM (tha-1) N P
2
O

5
K

2
0

kgha-1

0 0 0 0

25 5 0 3 2 2 5

30 7 5 6 4 5 0

- 100 9 6 7 5

J. Hortl. Sci.
Vol. 6(1):33-36, 2011



34

Before applying FYM and NPK, soil samples (0-20
cm deep) from all the 72 plots were collected and analyzed
for available nitrogen, by the alkaline permanganate method
(Subbaiah and Asija, 1956); for available phosphorus, by
Bray’s method and for available potassium, by the
ammonium acetate method (Hanway and Heidal, 1952) as
described by Jackson (1973). After imposing all the
treatments, carrot crop was sown at 22.5cm x 10cm spacing
and recommended package of practices were followed.

Carrot root and leaf yield were recorded separately,
and samples were taken for estimation of NPK uptake by
the crop (which was computed using plant analysis as well
as yield data). Initial soil data, yield and uptake were used
for obtaining NR (Nutrient Required to produce a quintal of
carrot roots), %CS (Contribution of nutrients from Soil),
%CF (Contribution of nutrients from Fertilizers) and C–OM
(Contribution of nutrients from Organic Matter), as illustrated
below (Ramamoorthy et al, 1967)

Nutrient uptake (NPK) (kgha-1) by grain + straw
      NR (kg q-1) = ———————————————————————

  Grain yield or any economic produce (q ha-1)

 Nutrient uptake (kgha-1) by grain + straw in Control plot
%CS =    —————————————————————————— X 100

Soil test values (Av. NPK) in Control plot (kgha-1)

These basic parameters were transformed into
simple, workable fertilizer adjustment equations for
calculating any yield target based on soil test values following
the procedure of Ramamoorthy et al (1967).

RESULTS AND DISCUSSION

Highest carrot root yield of 132.47q ha-1 was recorded
in the high-fertility strip (L

3
), where 2-2-2 levels of NPK

were applied along with 25t ha-1 FYM (F
2
). In the low-

fertility strip (L
1
) higher root yield of 118.53q ha-1 was

obtained in 3-1-1 levels of NPK without FYM (F
1
), whereas,

in the medium-fertility strip (L
2
), higher yield of carrot root

(115.58 q ha-1) was noticed in 3-2-3 levels of NPK along
with 30t ha-1 of FYM (F

3
).

Nutrient uptake by
grain + straw in

treated  plot

Soil test values
 in treated plot

%Contribution
(NPK) from soil

X

%CF = ————————————————————————  X 10
Nutrient dose applied in treated plot (kg ha-1)

%C-OM =  —————————————————————————
                Amount of nutrients (NPK) added through OM

[Nutrient uptake by
 grain + straw in

OM  plot ]

[Soil test values
 in OM plot]

 [Mean % Contribution
 (NPK) from   soil]

--

X--

In Control plots, the highest root yield of 93.51q ha-1

was recorded in the high-fertility strip (L
3
) in which 25t

ha-1 FYM (F
2
) had been applied; whereas, the lowest yield

of 51.08q ha-1 was obtained in low-fertility strip (L
1
) where

no FYM (F
1
) had been applied (Table 2).

The basic data, when computed, clearly indicated that
nutrients required to produce a quintal of carrot root are:
0.76 kg nitrogen, 0.42 kg phosphorus and 0.78 kg potassium
(Table 1).

Nutrient-contribution from fertilizer was maximum
(72.37% N, 84.24% P

2
O

5
 and 90.24% K

2
O) for attaining

maximum yield of carrot, whereas, contribution from soil
was slightly lower (28.55% N, 36.56% P

2
O

5
 and 59.29%

K
2
O). Contribution from organic matter was very low

(0.16% N, 0.12% P
2
O

5
 and 0.46% K

2
O). These findings

are in close conformity with those reported by Velayutham
(1979) and Santhi et al (1999).  By using these basic
parameters, targeted yield equation for carrot crop was
developed with respect to fertilizer nitrogen, phosphorus and
potassium requirement (kg ha-1). The equations are as
follows:

F.N.*    = 1.04 T** - 0.39 STV***-N - 0.23 OM

F.P
2
O

5
 = 0.49 T - 0.43 STV-P

2
O

5
 - 0.14 OM

F.K
2
O  = 0.87 T - 0.66 STV-K

2
O - 0.51 OM

* F.N. = Fertilizer Nitrogen (kg ha-1);  F.P
2
O

5
 = Fertilizer

Phosphorus  (kg ha-1);

F.K
2
O = Fertilizer Potassium (kg ha-1)

** T = Yield target (t ha-1)

*** STV = Soil test values (kg ha-1)

Using these equations, a farmer-friendly ready-
reckoner was developed (following the procedure of
Ramamoorthy et al, 1967), which clearly indicates the
quantity of fertilizer nitrogen, phosphorus and potassium
needed to be applied to get a fixed yield-target based on soil
test values.

Table 1. Basic data on nutrient requirement of carrot crop and
contribution of nutrients from different sources

N P
2
O

5
K

2
O

NR (kgq-1) 0.76 0.42 0.78

CS  (%) 28.55 36.56 59.29

CF  (%) 72.37 84.24 90.24

C-OM (%) 0.16 0.12 0.46

Basavaraja et al

J. Hortl. Sci.
Vol. 6(1):33-36, 2011



35

Table 2 indicates the amount of fertilizer nitrogen,
phosphorus and potassium required, along with 10t ha-1 FYM
or without FYM for a fixed yield target of 20t ha-1, based on
soil test values. If this yield target is modified, the amount
of fertilizer nutrient required will change. Similarly, if the
soil test values change, the amount of NPK required to attain
a fixed-target will also get modified.

If the soil test value with respect to available nitrogen
is 290kg ha-1, the amount of fertilizer nitrogen required to
obtain carrot root yield of 20tha-1 is 72kg ha-1 with 10t
ha-1 RYM (Table 2). However, for the same soil-test values
and the same yield target, 94.7kg ha-1 of fertilizer nitrogen
is required when no FYM is applied. Similarly, if the available
phosphorus content of soil is 23kg P

2
O

5
ha-1, the amount of

phosphatic fertilizer required for the same yield-target (20t
ha-1) is 74.5kg P

2
O

5
ha-1 and 88.9kg P

2
O

5
ha-1 with and

without FYM application, respectively. If the soil test value
for potassium is 160kg ha-1, the amount of fertilizer potassium
required for a target yield of 20t ha-1 without FYM is 69.0kg
ha-1, whereas, with FYM just 18.3kg of fertilizer potassium
is required.

Fertilizer use following these equations is more
economical and environment friendly. For example, to obtain
yield target of 20t ha-1 carrot roots, fertilizer nitrogen required

is only 75.0kg ha-1 even if the soil test value ranges from
260kg N ha-1 to 580kg N ha-1, as per soil testing laboratory
(STL) recommendation (Table 3); whereas, in STCR
approach, fertilizer N required for the same yield-target (20t
ha-1) at lower soil nitrogen level (260kg N ha -1) is 106.5kg
fertilizer nitrogen. At higher soil test value of 480kg soil
nitrogen, just 19.7kg of fertilizer nitrogen is needed to achieve
the same yield target.

Similarly, for soil test values of 23.0kg P
2
O

5
ha-1 to

52.0kg P
2
O

5
ha -1, amount of fertilizer phosphorus

recommended as per STL is 63.0kg ha-1;. But, in the STCR
approach, 88.9kg of fertilizer phosphorus is recommended
(Table 3) when soil test value is 23.0kg P

2
O

5
ha-1; whereas,

at 52.0kg ha -1 of available phosphorus, 76.3kg of fertilizer
phosphorus is required to get a yield target of 20t ha-1 carrot
roots. Similarly, 50.0kg ha-1 potassium fertilizer is required
to produce 20t ha-1 of carrot root, when the soil test values
ranges from 125kg K

2
O ha-1 to 300kg K

2
O ha-1, as per STL

recommendations. However, if one follows the STCR
approach of fertilizer application, 92.0kg ha-1 of potassic
fertilizer needs to be added when the soil test value is 125kg
K

2
O ha-1. But, when the soil test value is 300kg K

2
O ha-1,

no potassium fertilizer is needed to achieve the yield target
of 20t ha-1.

Table 2. STCR fertilizer prescription ready-reckoner for carrot root yield target of 20t ha-1*

STV Only FYM STV Only FYM STV Only FYM
KMnO

4
 - N inorganics (10t ha-1) Bray’s P

2
O

5
Inorganics (10t ha-1) K

2
O inorganics (10t ha-1)

F. N Req. F. N Req. F. P
2
O

5
 Req. F. P

2
O

5
 Req. F. K

2
O Req. F. K

2
O Req.

(kg ha-1)

250 110.4 87.7 15.0 92.4 78.0 110 101.8 51.2
260 106.5 83.8 17.0 91.5 77.1 120 95.2 44.6
280 98.6 75.9 19.0 90.6 76.2 125 92.0 41.3
290 94.7 72.0 21.0 89.8 75.3 130 88.7 38.0
300 90.7 68.0 23.0 88.9 74.5 140 82.1 31.5
320 82.8 60.1 25.0 88.0 73.6 150 75.5 24.9
340 74.9 52.2 30.0 85.8 71.4 160 69.0 18.3
400 51.3 28.6 32.0 85.0 70.6 170 62.4 11.7
440 35.5 12.8 35.0 83.7 69.3 180 55.8 5.2
480 19.7 0.0 38.0 82.4 68.0 200 42.7 0.0
520 3.9 0.0 41.0 81.1 66.7 220 29.5 0.0
560 0.0 0.0 44.0 79.8 65.4 240 16.4 0.0
600 0.0 0.0 46.0 78.9 64.5 260 3.3 0.0

47.0 78.5 64.1 280 0.0 0.0
50.0 77.2 62.8 300 0.0 0.0
52.0 76.3 61.9 320 0.0 0.0
54.0 75.4 61.0 340 0.0 0.0
58.0 73.7 59.3 440 0.0 0.0
62.0 72.0 57.5

*To increase or decrease yield target by one q ha-1,variations to be made in fertilizer recommendations are as follows:
N = + 1.05kg                                         P

2
O

5 
= + 0.49kg

                                                                         
K

2
O = +  0.87kg

Fertilizer prescription for carrot

J. Hortl. Sci.
Vol. 6(1):33-36, 2011



36

Table 3. STCR  fertilizer prescription ready-reckoner along with STL method of  fertilizer application for carrot root yield target
of 20tha-1

STCR STL STV STCR STL STCR STL
STV KMnO

4
F. N F. N  Bray’s F. P

2
O

5
F. P

2
O

5
STV K

2
O F. K

2
O F. K

2
O

Req. Req. P
2
O

5
Req. Req. Req. Req.

250 110.4 90.0 15.0 92.3 73.0 110 101.8 65.0
260 106.5 90.0 17.0 91.5 73.0 120 95.2 65.0
280 98.6 90.0 19.0 90.6 73.0 125 92.0 50.0
290 94.7 75.0 21.0 89.7 73.0 130 88.7 50.0
300 90.7 75.0 23.0 88.9 63.0 140 82.1 50.0
320 82.8 75.0 25.0 88.0 63.0 150 75.5 50.0
340 74.9 75.0 30.0 85.8 63.0 160 69.0 50.0
400 51.3 75.0 32.0 85.0 63.0 170 62.4 50.0
440 35.5 75.0 35.0 83.7 63.0 180 55.8 50.0
480 19.7 75.0 38.0 82.4 63.0 200 42.7 50.0
520 3.9 75.0 41.0 81.1 63.0 220 29.5 50.0
560 0.0 75.0 44.0 79.8 63.0 240 16.4 50.0
600 0.0 60.0 46.0 78.9 63.0 260 3.3 50.0

47.0 78.5 63.0 280 0.0 50.0
50.0 77.2 63.0 300 0.0 50.0
52.0 76.3 63.0 320 0.0 35.0
54.0 75.4 53.0 340 0.0 35.0
58.0 73.7 53.0 440 0.0 35.0
62.0 71.9 53.0

In comparison to the current soil testing laboratory
(STL) recommendations followed in Karnataka, the STCR
approach of fertilizer application is superior for efficient use
of costly fertilizer nutrients in a balanced way without
accruing any wastage, thereby helping sustaining the soil
productivity for longer period.

REFERENCES

Hanway, J.J. and Heidal, H. 1952. Soil analysis methods as
used in Iowa State College Soil Testing Laboratory.
Iowa State College of Agriculture Bulletin, 57:1-31

Jackson, M.L. 1973. Soil Chemical Analysis. Prentice Hall
of India Pvt. Ltd., New Delhi

Ramamoorthy, B., Narasimham, R.L. and Dinesh, R.S. 1967.
Fertilizer application for specific yield targets of
Sonora – 64 wheat. Ind.Farming, 17:43-45

Santhi, R.,  Selvakumari, G. and Rani Perumal. 1999. Soil
test based fertilizer recommendations under integrated
plant nutrition system for rice – rice – pulse cropping
sequence. J. Ind. Soc. Soil Sci., 47:288-294

Subbiah, B.V. and Asija, G.I. 1956. A rapid procedure for
determination of available nitrogen in soils. Curr. Sci,.
31:196-198

Velayutham, M. 1979. Fertilizer recommendations based on
targeted yield concept – problems and prospects. Fert.
News 24:12-20

(MS Received 20 September 2010, Revised 14 April 2011)

Basavaraja et al

J. Hortl. Sci.
Vol. 6(1):33-36, 2011