|HANSEN, NEIL - Brigham Young University|
|BLACKSHAW, ROBERT - Agri Food - Canada|
|LYON, DREW - Washington State University|
|MACHADO, STEPHEN - Oregon State University|
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 12/1/2016
Publication Date: 1/6/2017
Citation: Hansen, N.C., Allen, B.L., Anapalli, S.S., Blackshaw, R., Lyon, D., Machado, S. 2016. Dryland agriculture in North America. In: Farooq, M., Siddique, K.H.M., editors. Innovations in Dryland Agriculture. Cham, Switzerland: Springer. p. 415-441.
Interpretive Summary: Dryland crop production is important in North America, particularly in the Canadian Prairie, the Great Plains and Inland Pacific Northwest of the U.S. The traditional production system is a wheat-summer fallow rotation with tillage, but soil degradation, erosion, and poor water use efficiency limit its sustainability. No-till adoption is greatest in the northern Great Plains, where systems are being adopted together with more intensive crop rotations that reduce fallow frequency, increase precipitation use efficiency, reduce erosion, and improve soil properties. As adoption of reduced tillage practices has grown, dependence on herbicides for weed control has also increased and led to weed resistance and weed shifts that complicate weed management. Sustainable weed management in dryland wheat production will best be achieved through continued development and adoption of integrated weed management and crop production practices. Wheat is the most common dryland crop in North America, with fewer acres of maize, sorghum, pulses, and oilseeds. In the northern Great Plains, oilseed crops, annual forages and pulse crops in continuous crop rotations without fallow have been successfully integrated into dryland rotations, improving soil health. Soil improvements associated with intensified rotations requires careful management and a period of time for the system to adapt. Use of a cropping system model has been demonstrated as a way to test alternative crops and crop rotations with different environmental conditions. Future research using experimentation and modelling should continue to develop alternative no-till crops and crop rotations that increase precipitation use efficiency, improve soil properties, reduced dependence on N fertilizers, adapt to climate change, and develop alternative markets.
Technical Abstract: Areas of North America with high density dryland farming include the Canadian Prairies, U.S. and Mexican Great Plains, and the Inland Pacific Northwest of the U.S., with wheat (Tritcum aestivum L.) being the dominant crop. Dryland farming is less dense but important in nearly every state in the western U.S. and in northern and central Mexico. In addition to wheat, North American dryland farming is important for the production of maize (Zea maize L.), sorghum (Sorghum bicolor L.), pulses, and oilseeds. The traditional and still prevalent cropping system is a two-year rotation of wheat and summer fallow. In this traditional practice, shallow tillage is used during fallow periods to control weeds and help store moisture in the soil. Sustainability of this practice is limited by soil degradation and erosion and poor water use efficiency. Where adopted, no-till practices improve precipitation storage and use efficiency, which has led to crop intensification and diversification and improvements in soil properties. This chapter highlights some current issues for dryland cropping in North America including integrated pest management for herbicide resistant weeds, diversification of crop rotations, soil carbon dynamics and residue management, and the application of models to aid decision making. Sustaining the dryland cropping systems of North America depends on research and application of practices that reverse past soil degradation, increase cropping system diversity, and apply integrated pest management strategies. Both experimental and modelling approaches are needed to address these challenges.