In long-term trials, not only are individual plot errors correlated over time but there is also a consistent underlying spatial variability in field conditions. The current study sought the most appropriate covariance structure of errors correlated in three dimensions for evaluating the...

An assessment of time-trends in yield parameters is essential to the utilization of data from long-term field trials for the comparison of different crop rotations and input regimes, and the identification of sustainable production systems. The barley-vetch rotation established at Breda in...

In long-term field trials comparing different sequences of crops and husbandry practices, the identification and understanding of trends in productivity over time is an important issue of sustainable crop production. This paper presents a statistical technique for the estimation of time trends...