Ganbare Noukyou Seijo: Seijo no Chii to Kon'yakusha o Ubawareta Reijou no Nougyou Kakumei Nisshi @COMIC

"That love and wisdom of yours can save people, so become the support for their minds and spirits." Having frantically refined her wisdom by following those words from the previous saint, Alicia is a young woman who became the next saint. But all her effort ends up being in vain when her position, her fiancee, and nearly everything else she has is stolen away by her younger twin sister. All she has left is a worn-out book about agricultural science. In the midst of her despair, she jumps at the chance to marry someone else in a faraway land, and it's then that the handsome prince Laurent asks her to reclaim and revitalize the country's land...?! Thus begins the tale of a honest young woman who begins saving a country from ruin using her overwhelming knowledge of agriculture!

Source: TO Books