Intercropping Wheat and Beans: Effects on Agronomic Performance and Land Productivity

Declining land productivity associated with soil degradation is a significant issue for intensive wheat production. An intercropping system combining wheat and grain legumes may provide a farmwide production system that fulfills both economic and environmental concerns. We grew spring wheat (Triticum aestivum L. 'Scarlet') as a monoculture and intercropped with either a common bean cultivar (Phaseolus vulgaris L. 'Red Kidney' or 'Black Turtle') or a fava bean cultivar (Vicia faba L. 'Bell') without fertilizer in rows of wheat/bean 1:1 and 2:1 as well as broadcast arrangements during 2011 and 2012 to assess the impact of different genera (Vicia and Phaseolus) and cultivars (Red Kidney or Black Turtle) on the wheat performance, land productivity, N and C accumulation in aboveground biomass, and soil mineral N balance. As baseline, the monoculture wheat plots yielded 3.2 t ha(-1). However, wheat-fava bean plots displayed higher land equivalent ratio (LER) and total land outputs (TLO) with increased land productivity of 50% in the 1:1 and 32% in the 2:1 arrangements. Intercropped plots in row arrangements also improved wheat biomass nitrogen and grain protein content compared with monoculture plots. Wheat-fava bean in the 1:1 arrangement accumulated the highest N (34 kg ha(-1), i.e., 176% higher) and organic C (2138 kg ha(-1), i.e., 26% higher) in shoot biomass compared with monocultured wheat. Both NH4+ and NO3- pools were higher in intercrop plots with the highest mineral N balance in wheat-fava bean in the 1:1 arrangement (+0.2 mg NH4+ and +1.1 mg NO3- kg(-1) dry soil). This study demonstrates that intercropping wheat with fava bean is an efficient strategy to increase land productivity while also increasing forage and soil quality.