Economic assessment of three long-term tillage systems for rainfed cereal and legume production in semiarid central Spain

Rainfed crop yields in central Spain are low because precipitation is limited and highly variable. Further, farmers must minimise production costs to offset the continuous decline in price of the commodities produced. The objective of this 16-year work was to assess the economic feasibility of rainfed reduced (CP) and no-tillage (NT) systems compared to conventional-tillage (MP) for a winter wheat (Triticum aestivum L.)–vetch (Vicia sativa L.) rotation (WV) and a winter barley (Hordeum vulgare L.) monoculture (BM) system on a loam soil (Vertic Luvisol). The economic analyses compared gross margins in each rotation and tillage system and assessed the economic performance of a standard rainfed farm enterprise in central Spain based on 2001 input costs and product prices. Although statistically similar, average gross margin for WV was 16% higher than for the BM rotation. Tillage method had no influence on gross margins when averaged across years and rotations; however, gross margins tended to be higher for NT and CP than for MP. Significant differences were observed for the tillage method by crop rotation interaction. The highest gross margin was earned with NT in WV, followed by CP and MP in the same rotation. The lowest gross margins were earned with NT and MP in the BM rotation; whereas, gross margin for CP in BM did not differ from those earned with MP and CP in WV. On an annual basis, gross margins were significantly higher for WV than for BM in 5 of 16 years, similar in 9 years, and lower in 2 years. The breakeven size of farm enterprise was 103, 93 and 105 ha for MP, CP and NT, respectively. The tillage system with the lowest profitability threshold was CP and that with the highest was NT. MP and NT had lower variable costs associated with machinery operation, but NT also had higher herbicide costs. In relation to total costs, machinery costs accounted for 19% in MP and for 16% in NT, while herbicide costs increased from 4.9% in MP to 8.8% in NT. Income variability or risk was similar or the three tillage systems. The most marked difference among tillage systems was in the land area that a farmer can manage, which was four times greater with NT compared to MP, and 1.5 times greater with CP.