Assessing changes in spatial and temporal patterns of cropping sequences in northeast Montana
Initiatives to mitigate the effects of climate change have focused largely on the reduction of greenhouse gas production and on carbon capture and storage technologies. Changes in agricultural management practices have shown the ability to sequester carbon by increasing soil organic carbon and include reduced tillage intensity, decreased fallow, and changing from monoculture to rotational cropping. All have become more common in portions of the Northern Great Plains; but, despite the growth of these practices, it is unknown to what extent farmers have adopted particular cropping sequences or how they have spread temporally or spatially. My purpose here was to investigate the patterns of changing agricultural practices in northeast Montana during 2001-2012 by focusing on the increased adoption of cereal-pulse sequences and the adoption of block-managed cereal-based sequences in lieu of continuous strip-cropping. A method to identify crops via geospatial data and Landsat imagery was developed, and annual crop maps were created. Crop classifications were extracted from the maps for each field to create a 12-character string for the temporal sequence of crops, and specific 2- and 3-yr sequences were identified with a string-matching algorithm. Finally, I examined the observed spatial patterns of sequence adoption to determine if observed spatial patterns were random or were they consistent with the spread and adoption due to social interaction as described in innovation diffusion theory, adoption based on environmental factors, or neither. The major findings were: (1) cereal-fallow rotations, whether managed in blocks or by strip-cropping, no longer dominate the region; (2) there has been a substantial increase in the adoption of cereal-pulse sequences; (3) producers did not adhere strongly to specific sequences; (4) using 3-yr sequences added no additional information than 2-yr sequences; (5) the adoption of these practices was not randomly located but clustered; and (6) the adoption of these practice are not well-explained by innovation diffusion theory, although social interactions might have played a role in the early stages; the patterns are more consistent with suitability of the physical environment since available water was strongly associated with whether or not a field was managed with either practice.