Because I have seen a farmer selling chemical fertilizer in his yard, the Spring Festival couplets at the gate are "XX chemical fertilizer is good, planting land ensures a bumper harvest."
2. There are many problems if you ask for it from a literary point of view.
1) Spring Festival couplets not only have the same number of words as the upper and lower couplets, but also require the same structure.
The inside and outside of the first part of the couplet belongs to the couplet phrase, and the second part is the partial phrase.
2) The upper and lower couplets are required to be fair and opposite to each other in the same position. If you can't do this, at least "135 doesn't matter, 246 is clear". If it still doesn't work, the most basic requirement is that the ending characters should be flat and relative. In other words, the end of the first couplet is ambiguous, that is, three or four tones, and the end of the second couplet is one or two tones. In fact, it is not difficult to do this. Just turn your couplet upside down.
Nowadays, many merchants send Spring Festival couplets to customers in the New Year, and there are no couplets. Both sentences end in a flat voice. So there is no need to be too strict with yourself.