What Calendar did Muslim farmers use for agrarian purposes? Was this an issue that was discussed among muslim majority societies? If a muslim area did adopt a solar calendar would this have been controversial?
I'm not super well-equipped to comment on the specifics of agrarian calendars (suffice it to say, though, that solar calendars were often used for practical purposes—be they pre-existing Christian ones or some of the innovations discussed below), but as for the final part of your question—
If a muslim area did adopt a solar calendar would this have been controversial?
—I can say without a doubt that by the early modern period, at least, it was not unusual for governments to operate on multiple-calendar systems. Perhaps switching entirely to a solar year would have excited controversy, but in these cases the traditional lunar calendar was retained for general use while various solar calendars were adopted for more specialized purposes. In Muslim Spain and North Africa, for example, the tāʾrīkh al-ṣufr was an Islamic version of the era hispanica used for solar dates among the Christian kingdoms of the Iberian peninsula.
The Ottoman financial (maliyye, or rumi) year, too, was based on the Julian calendar. There were a few major differences from the Julian calendar, though: from 1677 on, the year officially began on March 1, and (more importantly), the maliyye year was always* numbered the same as the lunar hijrī year in which it began. (So the maliyye year beginning in 900 AH would be numbered 900 as well, even though it would inevitably spill over into 901 AH.) The ~11-day mismatch between the two systems meant that for every 32 maliyye years, 33 hijrī years had passed: the missing maliyye year, called the sıvış or "skip" year, caused a great deal of issues for the Ottoman administration and has been argued to have been at the root of recurring financial crises until the dual-calendar system was abandoned in favor of the official adoption of the Gregorian calendar in 1918. This is a great example of how a dual-calendar system might not even be controversial in the popular view, but can cause quite a mess for other reasons.
[* always... until maliyye 1287 (1871-2 CE), which should have been followed by mal. 1289 because of the sıvış year issue, but was instead followed by mal. 1288, leading to a permanent offset between maliyye and hijrī dates for the next 45 years.]
Several Iranian rulers also seem to have had a keen interest in solar calendars, initially because a good portion of the Iranian plateau continued to practice Zoroastrianism after the Islamic conquest. (The Zoroastrian calendar is a solar one.) Because the old Persian system gained on the proper solar year by about one day every four years, however, we again see something of a tax crisis: in this case, the issue was that landholders were eventually asked to pay taxes before their crops had ripened. One of the more effective reforms to combat this slippage was the "Jalālī calendar" implemented by the Seljuk ruler Malik-shāh I in 1079 CE, which fixed Nowrūz—and thus tax day—at the spring equinox, and later to 15 March Julian. Nowrūz is still celebrated on the equinox to this day, the most lasting legacy of Malik-shāh's reform, but the Jalālī calendar also laid the basis for two further calendrical reforms: the so-called "Khānī" calendar of the Mongol Maḥmūd Ghazān Khān (beginning on the vernal equinox 12 Rajab 701/March 13, 1302) and the Ilāhī calendar of the Mughal emperor Akbar (beginning on 27 Rabīʿ II 963/March 10, 1556, the date of the vernal equinox following his accession to the throne on 3 Rabīʿ II/February 15). The late-Ilkhanid historian Ḥamd Allāh Mustawfī, writing in the voice of Ghazān, describes the profusion of calendrical systems in use in early fourteenth-century Iran:
Although there is only one shāh in Iran, in the dīvān there is not one calendar. For the start of the year (sar-i sāl), each has a different system by which to date the work of the kingdom. Some choose to keep their records according to the hilālī [the lunar-hijrī] calendar, others reckon according to the kharājī calendar, and others use neither, and calculate the beginning of the year from the month of fūrdīn. The name of this is the New Year system and it dates from the days of Cyrus. Some count by the iskandarī calendar and others calculate by the jalālī. I will cast all these calendars (tārīkhha) aside and make a new one and call it the khānī.
While, again, I'm not super well-equipped on how Muslim farmers specifically used solar calendars, it's worth noting that such agricultural use was of course the major driver for the implementation of solar tax years (from at least the ʿAbbasids onwards). In order to effectively tax agrarian populations, of course, you need to ensure that they have products to tax, so financial administrations as well as the farmers themselves found solar calendars to be rather useful. And of course, since the former have left more written records than the latter, it's a bit easier to explain through that lens.
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If you have institutional access to the Encyclopedia of Islam, its article on "Tāʾrīkh" is a great overview of the various types of calendar systems used in the Islamicate world. [link]
On the sıvış years and their effects on the Ottoman financial system: H. Sahillioǧlu, "Sıvɩş year crises in the Ottoman Empire," in Studies in the economic history of the Middle East, ed. M.A. Cook (London 1970), 230-52.