[טז:כ] :צֶדֶק צֶדֶק תִּרְדֹּף לְמַעַן תִּחְיֶה וְיָרַשְׁתָּ אֶת הָאָרֶץ אֲשֶׁר יְהֹוָה אֱלֹהֶיךָ נֹתֵן לָךְ
Rabbi Samson Raphael Hirsch explains the difference between צדק and צדקה as follows. צדק, the masculine form, represents Hashem's righteousness, which is perfect and all-encompassing. צדקה, the feminine form, represents human righteousness, which is limited (Horeb Chapter 44, paragraph 327).
Accordingly, we can explain this pasuk as a command to constantly strive for perfect צדק, even while we recognize that its ultimate attainment is beyond us.
Indeed, the striving for perfect צדק is what merits us life and the inheritance of our land. We are not to become complacent and settle for “pretty good” justice and righteousness, but constantly seek to improve the state of affairs.