Cropping sequence effects of four broadleaf crops on four cereal crops in the Northern Great Plains

The productivity and cropping sequence effects of broadleaf crops are not well known within no-till systems in the semiarid northern Great Plains. We compared productivity of cool- and warm-season broadleaf crops with spring wheat (Triticum aestivum L.), measured cropping sequence effects of broadleaf crops on subsequent cereal crops, and tested if different cereal crops interacted with previous crops. During 1999-2001 we conducted 2-yr cropping sequence experiments at five sites in Montana under climatic conditions ranging from severe drought to average rainfall. Grain yield and quality were measured for chickpea (Cicer arietinum L.), flax (Linum usitatissimum L.), pea (Pisum sativum L.), proso millet (Panicum miliaceum L.), sunflower (Helianthus annuus L.), and wheat in Year 1. In Year 2, four cereal test crops [barley (Hordeum vulgare L.), durum (Triticum durum L.), spring wheat, and winter wheat] were grown following the Year I crops and a fallow control to measure cropping sequence effects. Comparative productivity varied among crops by site, affirming that crop diversity mitigates production risk. Under average rainfall, the cereal test crop yields following flax, pea, and chickpea ranged from 84 to 101% of the fallow control and were greater than that following wheat in seven of nine cases. However, yields following sunflower were equal or less than those following wheat. Under severe drought, cereal test crop yields following broadleaf crops ranged from 21 to 41% of the fallow control and were equal or less than those following wheat. Previous crops affected four cereal test crop species similarly.