Tillage and fertilizer effects on yield, profitability, and risk in a corn-wheat-potato-wheat rotation
Reduced tillage results in lower production costs and thus may have economic advantages for farmers. However, yield penalties, specific yield risks, or higher nutrient requirements may counteract the positive effects of reduced tillage. This study investigates long-term tillage effects (moldboard plow, and deep and shallow chisel plow) and their interactions with N fertilizer input on yields and economic performance in a corn (Zea mays L.)-wheat (Triticum aestivum L.)-potato (Solanum tuberosum L.)-wheat rotation in southern Germany. Conventional tillage (CT) and reduced tillage systems provided comparable economic returns. The systems of reduced tillage required higher surface-dribbled urea ammonium nitrate solution (UAN) fertilizer to corn and potato to be as efficient as the CT system. This may have implications for the overall environmental assessment of reduced tillage systems. For moderate- and higher-risk-averse producers, CT with usual fertilizer practice was more efficient than all other management options for the whole rotation. Farmers' risk aversion has no impact on the choice of the most efficient tillage and fertilizer management for potato (CT with usual fertilizer practice) and for corn (reduced tillage with increased fertilizer level). For wheat, the results show a high impact of risk aversion on the optimal choice of the tillage and fertilizer system. With increased energy prices, the economic savings of the reduced tillage systems due to reduced fuel use may be offset by higher fertilizer requirements since nitrous fertilizer prices are highly determined by energy costs.