<p style='text-indent:20px;'>A recent result of Frantzikinakis in [<xref ref-type="bibr" rid="b17">17</xref>] establishes sufficient conditions for joint ergodicity in the setting of <inline-formula><tex-math id="M1">\begin{document}$ \mathbb{Z} $\end{document}</tex-math></inline-formula>-actions. We generalize this result for actions of second-countable locally compact abelian groups. We obtain two applications of this result. First, we show that, given an ergodic action <inline-formula><tex-math id="M2">\begin{document}$ (T_n)_{n \in F} $\end{document}</tex-math></inline-formula> of a countable field <inline-formula><tex-math id="M3">\begin{document}$ F $\end{document}</tex-math></inline-formula> with characteristic zero on a probability space <inline-formula><tex-math id="M4">\begin{document}$ (X,\mathcal{B},\mu) $\end{document}</tex-math></inline-formula> and a family <inline-formula><tex-math id="M5">\begin{document}$ \{p_1,\dots,p_k\} $\end{document}</tex-math></inline-formula> of independent polynomials, we have</p><p style='text-indent:20px;'><disp-formula> <label/> <tex-math id="FE1"> \begin{document}$ \lim\limits_{N \to \infty} \frac{1}{|\Phi_N|}\sum\limits_{n \in \Phi_N} T_{p_1(n)}f_1\cdots T_{p_k(n)}f_k\ = \ \prod\limits_{j = 1}^k \int_X f_i \ d\mu, $\end{document} </tex-math></disp-formula></p><p style='text-indent:20px;'>where <inline-formula><tex-math id="M6">\begin{document}$ f_i \in L^{\infty}(\mu) $\end{document}</tex-math></inline-formula>, <inline-formula><tex-math id="M7">\begin{document}$ (\Phi_N) $\end{document}</tex-math></inline-formula> is a Følner sequence of <inline-formula><tex-math id="M8">\begin{document}$ (F,+) $\end{document}</tex-math></inline-formula>, and the convergence takes place in <inline-formula><tex-math id="M9">\begin{document}$ L^2(\mu) $\end{document}</tex-math></inline-formula>. This yields corollaries in combinatorics and topological dynamics. Second, we prove that a similar result holds for totally ergodic actions of suitable rings.</p>