Fig 1.
Temperature and total precipitation recorded at the experimental site from 1982 to 2012.
(A) Monthly averaged 31-year temperature and precipitation and (B) anomalies during summer crop growing season. Deviation from 31-year average from May 1st to November 30th in minimum (MIN), maximum (MAX) and mean (MEAN) temperatures and total precipitation (prec) are shown. Error bars show Fisher protected LSD for total precipitation (32.7mm). Fisher protected LSD for maximum and minimum temperatures were 0.48°C and 0.20°C respectively.
Table 1.
Long-term effects of rotation diversity and tillage on mean and cumulative corn and soybean yields.
Fig 2.
Long term trends in corn and soybean yields under conventional and reduced tillage at Elora.
Yields under (A-B) tillage and (C-D) reduced tillage. Each of the 4-year rotation was duplicated 2 years out of phase so that corn and soybean yields were available yearly (n = 31) and biyearly (n = 16) respectively. Each main rotation plot was split into two levels of tillage. LS means (n = 4) are shown for each rotation. Crop abbreviation: C = corn, S = Soybean, O = Oat, B = spring barley, W = Winter wheat, rc = underseeded red clover, A = Alfalfa.
Table 2.
Effect of rotation diversity and tillage on probabilities of obtaining high and low corn yield based on long-term yield distributions.
Fig 3.
Benefits of diversification under different weather scenarios.
(A-B) Corn yields compared to CCSS rotation (%) obtained for selected cluster in (A) reduced tillage and (B) tilled systems. (C-D) Soybean yields compared to CCSS rotation (%) obtained for selected clusters in (C) reduced tillage and (D) tilled systems. Crop abbreviation: C = corn, S = Soybean, O = Oat, B = spring barley, W = Winter wheat, rc = underseeded red clover, A = Alfalfa. (*) significantly different from high yielding years (cluster E) at p = 0.05.
Table 3.
Corn and soybean mean grain yields per growing season clusters in different tillage systems.
Fig 4.
Yield variation under different weather scenarios.
(A-B) Coefficient of variation for corn yields (CV, %) obtained for selected cluster and on average across the study period in (A) reduced tillage and (B) tilled systems. (C-D) Coefficient of variation for soybean yields (CV %) obtained for selected cluster in (C) reduced tillge and (D) tilled systems. Crop abbreviation: C = corn, S = Soybean, O = Oat, B = spring barley, W = Winter wheat, rc = underseeded red clover, A = Alfalfa.