Hayland conversion to wheat production in semiarid eastern Montana: tillage, yield and hay production comparisons

When converting grass- and haylands to cultivated crop production, care must be taken to conserve and maintain soil resources while considering economic issues. Methods of breaking sod can have a bearing on erosivity, physical and chemical properties of soils, and cost of production. Our objective was to compare three methods of converting crested wheatgrass Agropyron desertorum (Fisch. ex Link) Schult.] hayland to wheat (Triticum aestivum L.) production vs. leaving the land for hay production. We initiated a study in 1990 on Dooley sandy loam (fine-loamy, mixed Typic Argiboroll) near Froid in semiarid eastern Montana, USA. Plots, replicated three times, were 12- by 30-m oriented east to west on a north-facing slope. We converted sod to cultivated crop production by: (1) moldboard plow, (2) toolbar with sweeps, (3) herbicides (no-till). Plots were fallowed until spring 1991 and then seeded to spring wheat each of the next four years. All wheat plots were fertilized with 224 kg ha^?1 of 18-46-0 in 1991 and 1992, and 34 kg ha^?1 nitrogen as 34-0-0 in 1993 and 1994. Grass was either fertilized same as wheat or not fertilized. Wheat yields averaged 2540 kg ha^?1 on tilled treatments and 2674 kg ha^?1 on no-till. Fertilized grass consistently out-yielded unfertilized, and averaged 3.2 Mg ha^?1 vs. 1.8 Mg ha^?1. Toolbar with sweeps had highest economic return of US$169.48 ha^?1 to pay for land, labor, and management. Moldboard plow had US$162.05 ha^?1. Because of herbicide costs, no-till only returned US$148.64 ha^?1. Unfertilized grass hay returned US$67.68 ha^?1 and fertilized grass hay, US$97.95 ha^?1. Results may be tempered because our wheat yields were high: a 2016 kg ha^?1 wheat yield would have returned the same as fertilized grass. Before converting grass- and hay-lands to small grains production, consideration must be given to such variables as sod conversion methods, management practices, labor requirements, market conditions, total precipitation and its temporal distribution, soil conditions, growth environment, soil conservation, and economics.