Passage:
In early medieval Western European agrarian history, historians long believed that the widespread adoption of the heavy three-field crop rotation system in the ninth century directly precipitated an immediate doubling of rural population density. Recent micro-historical analyses of manorial tax rolls from the Seine Basin, however, suggest a more complex timeline. While three-field rotation did increase arable land utilization by leaving only one-third of field acreage fallow each year compared to one-half under two-field systems, the nitrogen-fixing leguminous crops planted during the secondary rotation cycle required significantly higher labor inputs during spring planting. In regions where peasant labor pools were constrained by feudal corvée obligations to noble demesnes, villagers were unable to plant spring pulse crops in sufficient volume to enrich depleted soils. Consequently, yield ratios for staple cereal grains in these constrained manors remained stagnant for nearly two decades following the official adoption of the three-field protocol. It was only after subsequent legal shifts in the late ninth century allowed peasants to commute labor services into cash rents—thereby granting them temporal autonomy over their spring planting schedules—that crop yields and local demographic growth figures experienced their anticipated upward inflection.
Based on the passage, the legal commutation of feudal labor obligations into cash rents in the late ninth century contributed to higher staple cereal yields by enabling peasants to allocate adequate time to spring leguminous crop planting.
Answer: Answer