Conservation agriculture in North America

Conservation agriculture (CA) is a production paradigm that groups reduced tillage, mulching with crop residues or cover crops, and diversified crop rotations, especially those that incorporate leguminous crops. In North America, reduced tillage is the most widely adopted practice that seeks the ideals of CA and adoption rates are increasing. Cover crops are used on a low percentage of cultivated land in North America, but recent efforts to promote the value of cover cropping have resulted in increased adoption rates. Developing cropping systems that use biomass for biofuel systems has potential for expanding the cultivation of cover crops. This chapter illustrates the diversity in CA adoption in North America by describing CA adoption in contrasting production regions with variations in climate, soil types, and cropping systems. Zero-till adoption has been more popular in regions where growing seasons are not limited by cold conditions and with moderate levels of crop residue. Zero-till adoption has been limited by difficulties in seeding and the development of weed resistance to common herbicides. Strip tillage has evolved as an alternative conservation tillage practice and is being adopted widely across North America. Future CA systems will allow for conservation practices, such as tillage intensity, to be applied in a spatially variable way that matches conservation costs and benefits with specific conditions in fields and watersheds.