At last I have understood the problem (thanks to Fahim and Sadia). You have to consider either north-south, or east-west or diagonal straight lines; consider which yields highest amount of crop of a kind instead of all of them together.
More clearly, for first test,

SsS
sSs
SsS

my confusion was

_s_
s_s
_s_
we can get a ring of 4 's' ... so the ans should be
s
4

but later my friends explained consider only one straight line,which ever produces most as
S__
_S_
__S

or
_s_
s__
___

or
___
__s
_s_

Hope my problem helps other.