Formula to ignore blank cells

[Dairy]

Hi I have a sheet setup to count and sum the values as below, second is an array formula.

=SUMPRODUCT(('Fert Input'!E$12:E$151=B8)*('Fert Input'!F$12:F$151='Fert Mix'!$V$4))+SUMPRODUCT(('Fert Input'!G$12:G$151=B8)*('Fert Input'!H$12:H$151='Fert Mix'!$V$4))

=SUM(IF('Fert Input'!E$12:E$151=B8,IF('Fert Input'!F$12:F$151=$V$4,'Fert Input'!C$12:C$151,0),0))+SUM(IF('Fert Input'!G$12:G$151=B8,IF('Fert Input'!H$12:H$151=$V$4,'Fert Input'!C$12:C$151,0),0))

These work well but I wish to add a 3rd and 4th formula to count and sum < or = to

=SUMPRODUCT(('Fert Input'!E$12:E$151=B8)*('Fert Input'!F$12:F$151<=$N$1))+SUMPRODUCT(('Fert Input'!G$12:G$151=B8)*('Fert Input'!H$12:H$151<=$N$1))

=SUM(IF('Fert Input'!E$12:E$151=B8,IF('Fert Input'!F$12:F$151<=$N$1,'Fert Input'!C$12:C$151,0),0))+SUM(IF('Fert Input'!G$12:G$151=B8,IF('Fert Input'!H$12:H$151<=$N$1,'Fert Input'!C$12:C$151,0),0))

How might I stop the formulas above counting blank cells it finds in columns F and H?

 

[Robert Mika]

=SUMPRODUCT(ISNUMBER('Fert Input'!F$12:F$151)*('Fert Input'!E$12:E$151=B8)*('Fert Input'!F$12:F$151<=$N$1))+SUMPRODUCT(ISNUMBER('Fert Input'!H$12:H$151)*('Fert Input'!G$12:G$151=B8)*('Fert Input'!H$12:H$151<=$N$1))

 

[Dairy]

=SUMPRODUCT(ISNUMBER('Fert Input'!F$12:F$151)*('Fert Input'!E$12:E$151=B8)*('Fert Input'!F$12:F$151<=$N$1))+SUMPRODUCT(ISNUMBER('Fert Input'!H$12:H$151)*('Fert Input'!G$12:G$151=B8)*('Fert Input'!H$12:H$151<=$N$1))

Yes! works nicely. I can add the ISNUMBER as a third statement to the array formula.

=SUM(IF('Fert Input'!E$12:E$151=B8,IF('Fert Input'!F$12:F$151<=$N$1,IF(ISNUMBER('Fert Input'!F$12:F$151),'Fert Input'!C$12:C$151,0),0)))

Seems to work as well.

Cheers,

Daniel