Crop Sequence and Tillage Influences On Long-Term Dryland Spring Wheat Production.

Cropping systems and management practices for spring wheat production have changed during the past half century.  Greater emphasis on soil and water conservation has helped to stabilize crop yields.  Our objectives were to determine the influences of six crop sequences and two tillage practices on spring wheat grain production and N concentration and grain precipitation-use efficiency.  The six crop sequences were:  1) continuous spring wheat, residue left in place (CSW+); 2) continuous spring wheat, residue removed (CSW-); 3) spring wheat – millet; 4) spring wheat – safflower – fallow; 5) spring wheat – safflower – rye partial cover crop; and 6) spring wheat – fallow.  Tillage practices were minimum-till (30 to 60% soil surface covered by residue) and no-till (>60% soil surface covered by residue).