The advantage of holding this lea land did not end, however, with the fact that a few additional horses or cows could be kept on the grass which sprang up. This was undoubtedly of some value, but the greatest advantage lay in the fact that this land gradually recovered its strength. When the strips which were kept under cultivation finally produced in their turn so little that they had to be abandoned, the tenant who had access to land which had been laid to grass years before could plow this instead, for it had regained its fertility and had improved in physical quality. Fitzherbert recommends a regular interchange between "Reyst" ground and arable land which had become exhausted. When the grass strips become mossy and make poor pasture, plow them up and plant them; when arable strips fail to produce good crops, lay them to grass. Lea ground, "the whiche hath ben errable land of late" should be plowed up. And if a man haue plentie of suche pasture, that wil be mossie euery thyrd yere, lette hym breake vp a newe piece of gronde, and plowe it and sowe it (as I haue seyde before), and he shal haue plentye of corne, with littell dongynge, and sow it no lengar thu it will beare plentye of corne, without donge, and it will beare much better grasse, x or xii yere after.... Reyst grounde if it be dry, will bringe much corne, for the mosse will rotte, and the moll hillockes will amende the ground wel.[105] Tusser's references to the practice of plowing up lea ground and laying other land to grass are so incidental as to be good evidence of the fact that this was not merely the recommendation of a theorist, but a common practice, the details of which were familiar to those for whom he intended his book. A passage in which he refers to the laying to grass of land in need of rest has already been quoted.[106] In discussing the date at which plowing should take place he mentions the plowing up of lea land as well as of fallow.[107] The superior value of enclosed pasture to open-field leas, and of enclosed arable to open-field arable, is not only asserted by Fitzherbert and others who are urging husbandmen to enclose their land, but appears also when manorial surveys are examined. It would seem, therefore, that the tenants would have been anxious to carry the process to an end and enclose their land. Undoubtedly the larger holders were desirous of making the change, but as long as the rights of the lesser men were respected, it was almost impossible to carry it out. The adjustment of conflicting and obscure claims was generally held to be an insuperable obstacle, even by those who urged the change most strongly, while those who on principle opposed anything in the way of enclosure took comfort in the fact that holdings were so intermixed that there was little prospect of accomplishing the change: