An agronomic and economic comparison of a conventional and a low-input cropping system in the Palouse

Abstract

The variable costs and net returns for a conventionally managed rotation and for a low-input, legume-based rotation were compared under 1986 economic conditions in the Palouse region of Washington. The conventional system was a four-year wheat/barley/wheat/pea rotation with fertilizers and pesticide inputs each year. The low-input system was a three-year pea-medic/medic/wheat rotation with pesticide inputs used only on peas. As the biennial medic was allowed to set and drop seed and revolunteer in subsequent stands of spring peas, the system was called the “perpetuating-alternativelegume-system” or “PALS”. Identical wheat yields were assumed between the two systems as field trials showed that wheat which followed medic without fertilizer produced similar yields to wheat after cereals with fertilizer. Pea yields were assumed to be lower under PALS due to competition from the medic. Medic was neither harvested nor grazed. For PALS, herbicides on wheat were replaced by harrowing because trials showed that wheat after medic competed better with weeds than wheat after cereals. Variable costs for PALS were only 44 percent of those for the conventional system ($56.82 versus $129.40/acre/year). Fertilizers, pesticides, and application accounted for 56 percent of the costs for the conventional system, but only 26 percent for PALS. The conventional system generated higher gross returns because a crop was harvested every year. Because of its lower production costs, PALS generated higher net returns when crops were sold for market prices. The conventional system was more profitable than PALS only when wheat and barley were valued at current government target prices. Under high and low yielding conditions PALS was more profitable than the conventional system when wheat prices were lower than $3.50 and $5.36/bushel, respectively. Government target and local market wheat prices in 1986 were $4.38 and $2.40/bushel, respectively. If world market competition and domestic policy pressures reduce crop price supports and grain prices in the future, low-input systems would become more profitable than conventional practices. PALS is promising but requires further agronomic evaluation before recommendations can be made.