Long-term agricultural experiments reveal cyclical patterns in crop yields, even without fertilization. A decades-long study tracking rye production demonstrates a notable decline in yield following initial high outputs, followed by a period of stagnation and eventual recovery.
Initially, an unfertilized plot yielded 22.7 decitons (dt) of rye per hectare. However, over the subsequent 40 years, yields steadily decreased, reaching a low of 10.7 dt/ha in the 1920s. This reduced yield persisted for approximately four decades,remaining consistently low until the 1960s. From the 1960s onward, a gradual increase in yield was observed, culminating in a figure of 22.2 dt/ha by 2010.
Researchers attribute these fluctuations not to soil depletion, but to evolving experimental practices.Changes in rye varieties and plant protection methods implemented over the years likely influenced the observed yield variations. The data, presented as decadal averages (averages over ten-year periods), highlights the complex interplay between agricultural management and long-term crop productivity.