The Turks were also encouraged to emigrate from Bulgaria by regulations which affected the cultivation of rice – which was originally introduced to the region by the Turks. This was part of a project to eradicate malaria that included also draining of swamps in the Tundzha, Arda, and Maritsa Basins. The project succeeded in eradicating malaria, however, it also exacerbated droughts in those regions. Rice was a staple crop for the Turks and in its prohibition many of them saw yet another sign of unacceptable Bulgarian domination. An even more important impulse to Turkish emigration was the Bulgarian land tax of 1882. By Moslem law all land was owned by God but after the abolition of feudalism in the 1830s use of that land conferred temporary wardship upon the user, and thus the tithe which had been the main levy on land until 1882 conformed to traditional Moslem codes of thought and practice. The land tax did not. Furthermore, land tax applied to all land in a man's possession not, as under the tithe, merely to that part which had been cultivated. This hit the Turks hard for they customarily left a large proportion, in many cases as much as half, of their land fallow. Taxation now fell on the fallow land too but production and earnings could not be increased by the same proportion and as a result many of the remaining Turkish owners of large estates left Rumelia. Significantly 1882 was the peak year for the sale of larger Turkish properties in Rumelia, though the sale of such properties continued steadily throughout the first half of the 1880s. From the end of the war to the summer of 1880 only six large Turkish chifliks in Eastern Rumelia had been sold but the five years before union with the Principality of Bulgaria in 1885 saw the sale of about a hundred. That most of the larger Turkish owners and many smaller ones left Rumelia was undoubtedly an important factor in the easy attainment of Bulgarian supremacy in Rumelia during the early 1880s.