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To establish soil test based balanced fertilizer prescription for ginger variety
Maran in laterite soils of Kerala, an investigation was undertaken at the College of
Horticulture, Vellanikkara. The field study consisted of fertility gradient experiment
and STCR experiment.
The fertility gradient experiment was conducted during March-April 2000 in
the farm attached ,to the College. The desired gradient in soil fertility was created in
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one and the same field by applying graded doses of N, P and K fertilizers and raising
fodder maize var. Co. I.
The STCR experiment was conducted in the same field during May-Nov
2000 using the test crop, ginger variety Maran. The treatments consisted of
fractional factorial combinations of four levels of N (0, 50, 100 and 200 kg ha-I),
three levels of P (0,37.5, 75kg P205 ha-I) and five levels of K (0, 37.5, 75, 150 and
300kg K20 ha-I) along with three levels of farmyard manure (0, 15 and 30 t / ha)
fitted in a response surface desi~n.
Using multiple regression model, the fertilizer adjustment equation for N at
varying soil test values for available N for maximum rhizome yield (t ha-I) of
ginger in laterite soil was derived as FN = 153 - O.28SN where FN is fertilizer N (kg
hal) and SN is soil available N (kg ha-l ).
At varying soil test values for organic carbon % (OC) and Phosphorous kg / ha
the above equations become FN = 312.94 - 518.4 OC and FP = 79.8 - O.94SP for
maximum rhizome yield.

The behaviour of fertilizer K was found to produce responses other than
'normal' and hence optimization could not be done for fertilizer K for maximum
rhizome tuber yield at varying soil test values.
The nutrient requirements of ginger variety Maran were estimated to be 2.1,
0.3, S.6kg N, P20S and K20 respectively to produce one kg of rhizome. In the
laterite soil, the efficiencies of contribution of nutrients from the soil for ginger were
calculated as 10.1,6.9 and 44% N, P20S and K20 respectively. The fertilizer
efficiencies were worked out as 27.3, 10.9 and S3.2% N, P20S and K20
respectively. The efficiencies of contribution of nutrients from farmyard manure
were calculated as 30, 7 and 60% N, P20S and K20 respectively.
From the above basic data, fertilizer prescription equations for specific yield
targets of ginger var. Maran in the laterite soil were derived as given below.
Without FYM
FN =7.8T - 0.37 SN
FP =2 .. 8T - 0.64 SP
FK = 10.6T - 0.833 K
With FYM
FN = 7.8T - 0.37SN - 1.11 ON
FP = 2.8T - 0.64 SP - 0.7 OP
FK = 10.6T - 0.835 SK - 1.13 OK.

Where,
FN, FP, FK - Fertilizer N, P20S, and K20 respectively in Kglha.
T - Target of fresh rhizome yield in t/ha.
SN, SP, SK - Soil available N, P and K in kg/ha respectively.
ON,OPOK - quantities of N, P and K supplied through organic manure in kg/ha.
Based on the fertilizer prescription equations ready reckoners were
developed for different yield targets.
The study has revealed the superiority of fertilizer application over the semi
quantitative approach followed in the soil testing laboratories and the generalized
package of practices recommendation followed in the state for the crop. The
fertilizer dose can be adjusted based or. the specific objective and available
resources of the farmer.
To know the influence of native elements on yield soil and plant samples
were analyzed for micronutrient contents. In soil Ca, Mg and Mn showed positive
correlations and Zn, Fe showed negative correlations with yield.
In plant leaf magnesium and rhizome manganese showed positive correlation
and rhizome iron showed negative correlation. Further path analysis was carried out
to know the nutrient interactions.