Abstract:
Brinjal cultivation in Thenmaradchi area of Jaffna district involves indiscriminate
application of large quantities of fertilizers and pesticides. The overuse of fertilizer
pollutes the water bodies in Thenmaradchi. It leads to health problems and also reduces
the net profit of the farmers. The objective of this study was to determine the fertilizer
requirement for maximum yield of brinjal cultivation in Thenmaradchi through field
survey and examine the extent of overuse of fertilizer. For this study, data were
collected from randomly selected 228 brinjal cultivators in this area. A quadratic form of
multiple regression model for brinjal yield were developed using inorganic, organic
fertilizers and interaction term of these fertilizers. Results of this study indicated that
amounts of N, P and K significantly contribute to the brinjal production and also it
showed that there is a significant interaction effect of organic manure and chemical
fertilizer on the brinjal production. Farmers are averagely getting 1072 kg of brinjal from
one lacham. Brinjal farmers in this division are applying 3.7 kg of N, 2.4 kg of P, 2 kg of K
and 0.4 load of organic manure per lacham on average. When farmer applies one more
load of organic manure per lacham, while applying the average level of inorganic
fertilizer, brinjal production per lacham will averagely increase by 796 kg. When farmer
applies one more kg of N per lacham, while applying the average level of organic
manure and other inorganic fertilizer, brinjal production per lacham will increase by 195
kg. There is a significant negative interaction effect of inorganic N fertilizer and organic
manure on yield. When farmer applies one more kg of K, while applying the average
level of organic manure and other inorganic fertilizer, brinjal production per lacham will
increase by 104 kg. There is a significant positive interaction effect of inorganic K
fertilizer and organic manure on yield. The negative effect of inorganic P fertilizer
indicates that most of the farmers apply P more than the optimal level.
