6. A rectangular piece of land enclosed by fences has a length and width of $52 \mathrm{~m}$ and $24 \mathrm{~m}$, respectively. An agricultural science technician wants to divide this land into several congruent square test plots. The land must be fully divided, and the sides of the squares must be parallel to the boundaries of the land. There are $2002 \mathrm{~m}$ of fencing available. The land can be divided into a maximum of $\qquad$ square test plots.
6.702 pieces.

Assume the land is divided into several squares with side length $x$, then there exist positive integers $m, n$, such that
$$
\frac{24}{x}=m \text{, and } \frac{52}{x}=n \text{. }
$$
$\therefore \frac{m}{n}=\frac{6}{13}$, i.e., $m=6 k, n=13 k(k \in \mathbf{N})$.
Note that when the value of $k$ is as large as possible, the number of experimental plots reaches its maximum. The total length of the fence used to divide the land into several squares with side length $x \mathrm{~m}$ is
$$
L=(m-1) \times 52+(n-1) \times 24=624 k-76 .
$$

Since the maximum length of the fence available is $2002 \mathrm{~m}$. Therefore, we have
$624 k-76 \leqslant 2002$, which gives $k \leqslant \frac{2078}{624} \approx 3.33$.
Thus, $k_{\max }=3$. At this point, the total number of squares is $m n=702$ (pieces).