Comparisons of costs and returns for different cropping and tillage systems are difficult to estimate. There are many different variables of production to consider with the amount and timing of rainfall at a particular farm being the most important. Soil health is also different for each of these alternative tillage and cropping systems.
Six different farmers in southeastern Montana and southwestern North Dakota were interviewed to determine their production methods and costs. Based on these interviews a generic typical farm was developed. This generic farm was used to estimate the different costs and returns for different cropping and tillage systems as well as the soil health associated with each.
The six farmers interviewed had various production practices in their agricultural crop rotations. Conventional till, minimum till and zero till farming were utilized to raise cereal grains, pulse crops and annual and perennial legumes. Clay, clay loam and sandy loam were the three main soil types in the area surveyed. Annual precipitation ranged from 11 to 14 inches.
Depending on precipitation received, all operators had cereal grain acreage where management decisions were made in early July to harvest the crop for hay or leave it for grain. Winter wheat, spring wheat, hay barley, lentils, oats, corn and alfalfa were grown for hay with lentils, hay barley, corn and alfalfa also being used for additional grazing. All but one operation included cattle grazing of standing crop or crop stubble as part of their management practices. The fields grazed one year were rested at least one year prior to grazing again. Oilseed crops grown were safflower, flax, and yellow mustard. Seed crops included winter wheat, winter rye, spring wheat, durum, soft white winter wheat, barley, hay barley, buckwheat, and spring and winter field peas.
Planting equipment included conventional hoe, single and double disc drills and air seeders with single or double disk coulters on 7 to 10 inch row spacing. Seeding rates in pounds per acre ranged from 75 to 90 for winter wheat, 63 to 120 for spring wheat, 120 for durum, 70 to 90 for barley, 30 to 60 for lentils, 22 to 30 for safflower, 80 for peas, 4 for yellow mustard, and 30 for flax. Corn, 80 to 90 day maturity, was planted at 13,000 plants per acre. Reder and McNeal spring wheat, Erhart winter wheat, and Haybet hay barley were the most common varieties of cereal grains planted.
Roundup was used for weed control both in the spring before planting and in the fall after harvest on no-till acres. Surfactant and ammonium sulfate spray adjuvants were always used whenever Roundup was applied. Other herbicides used for weed control were Fargo, Celebrity +, Bison and Everest. One producer noted a possible allelopathic influence from winter rye on the presence of wild buckwheat and wild oat.
The two operators who used conventional till fallow had limited their cultivations to four per year. A chisel/shovel cultivator with a harrow and/or rodweeder attachment was the main piece of tillage equipment used. Use of an offset disc to do one round on strip edges in the fall for sawfly control and for spring cultivation to disc in fertilizer before planting on continuous crop rotations was also implemented.
Granular fertilizer was broadcast in the spring prior to planting or applied at seeding with the drill. Anhydrous ammonia was injected by an anhydrous implement in the fall. The most common granular formulations were 46-0-0 urea and 11-52-0 super phosphate. Annual applications of available nitrogen ranged from 18 to 40 lbs per acre with available phosphate ranging from 3 to 6 lbs per acre.
A Soil Tillage Intensity Rating (STIR) was calculated for each of the different crop rotations and tillage systems used by the six producers. The STIR is used to evaluate the effect of tillage on soil health in each of the different systems. A STIR with a low value has a minimal adverse effect on soil health. Over time a system with a low STIR value will have a minimal adverse effect on soil structure and overall soil health. The low STIR will improve organic matter, fertility, productivity and water holding capacity and soil structure. See Table 1 for the different STIR values for the different crop rotations and tillage systems.