Interspecific competitiveness affects the total biomass yield in an alfalfa and corn intercropping system

Little is known about the intercropping of perennial legumes with annual cereals although intercropping system is widely applied and studied. The main objective of this study was to determine the aboveground biomass yield and interspecific competitiveness in an intercropping system of alfalfa (Medicago sativa L.) with corn (Zea mays L.). A 3-year (2007–2009) field experiment was conducted, including four intercropping patterns by alternating alfalfa and corn row ratios of 2:2, 3:2, 4:2 and 5:2. Mono-cultured corn and alfalfa were used as the control. The biomass yield of alfalfa was measured at early blooming, whereas that of corn was at physiological maturity. Competitiveness indices examined were land equivalent ratio (LER), aggressivity (A), relative crowding coefficient (K values) and competitive ratio (CR). The biomass yields of mono-cultured alfalfa and all intercropping patterns increased each year. In all years, the 5:2 intercropping pattern always displayed a biomass yield advantage based on greater LER values. Alfalfa had higher relative crowding coefficients (K values), CR, and A values than corn. The intercropping of alfalfa with corn had yield advantages compared to alfalfa or corn monoculture. The intercropping pattern of 5:2 (alfalfa:corn row ratio) was an optimal pattern in our study. Alfalfa was the superior competitor when grown with corn, and its productivity dominated the total biomass yields. Thus, intercropping of alfalfa with corn has the potential to improve performance with high land-use efficiency.

► We examine the dry matter yield and interspecific competitiveness in alfalfa and corn intercropping systems.
► The component crops competitiveness was determined by relative competitive indices.
► Alfalfa is the superior competitor in alfalfa/corn combination and its productivity dominates the systematic biomass.
► Alfalfa/corn intercropping is a viable way to improve biomass per unit land and land-use efficiency.