Wins for Bracebridge Heath, Grantham and Bourne – with all three taking 20 points – retained the status quo at the top of the table.
Fourth-placed Woodhall Spa also claimed a maximum, leaving them 16 points behind Bourne.
Sleaford moved up to sixth with victory over Grimsby who remain bottom but are now only one point behind Spalding.
On what proved to be the bowlers’ day, Dan Freeman took seven wickets for Grantham while Bourne’s Tom Dixon took six as did Joe Irving for Woodhall, Grimsby’s Neal Snell and Jonny Miller for Lindum.
At home to Bourne, Louth had 101 on the board before the first wicket fell – Laurence Scott for 62.
John Medler went on to make 48 but wickets then fell steadily 42 and the innings ended on 171.
Arran Brindle took a wicket with the first ball of the Bourne innings to get rid of Jack Berry.
But Jordan Temple (60) and Sam Evison (33) put on 68 as Bourne claimed a four-wicket win.
Irving put in a man-of-the- match performance for Woodhall Spa, hitting 59 runs and taking 6-16.
They recorded the day’s highest total of 237-8 before bowling Spalding out for 75.
Lindum were restricted to 176-8 at Market Deeping.
The home side looked comfortable on 67-2 when Miller joined the attack to take six wickets for 10 runs in his seven overs and leave Deeping all out for 95.
Deeping are now four points up on Spalding and only two behind Louth and six behind eighth-placed Alford.