Plant Functional Diversity Leads to Increased Yields in a Low-input Organic Intercropping System

In multispecies systems, facilitation and complementarity can offset some of the negative effects of interspecies competition. This can lead to more efficient use of resources by the plant community as a whole, resulting in an increase in productivity. Overyielding, a phenomenon whereby plant production in mixture exceeds that of production in monoculture, has been attributed to complementary use of resources by different plant functional types. Different combinations of peanut, watermelon, okra, cowpea and pepper in single crop and various intercropping combinations were investigated in a low-input organic system in Texas. Each species was selected to perform a specific function within the system. Results from land equivalent ratio (LER) and per plant production calculations show that the intercropping combination with peanut, watermelon and okra (W_pwo) and peanut, watermelon, okra and cowpea (W_pwoc) consistently overyielded and performed the best overall in both 2011 and 2012. Planting dates were adjusted in 2012 based on observations from 2011. This did not, however, alter LER values between years as LER’s were 1.17 for both combinations in 2011 and 1.17 and 1.20, respectively, in 2012. Changes in planting dates resulted in a reversal of dominance between watermelon and okra between years. In 2011 when watermelon was the dominant crop, per plant production was highest in the three, four and five species combinations. In 2012 when okra was the dominant crop, per plant production was also highest in the three, four and five species combinations. Peanut per plant production was highest in the three and four species combinations and cowpea and pepper appeared to be negatively affected or in many instances unaffected by intercropping combination with regards to per plant production. These findings suggest three and four species intercropping combinations, whereby each crop is selected to perform a specific function within the system, may provide small-scale sustainably-minded producers a model system that can be utilized in suboptimal conditions and allow them to reduce inputs while increasing overall yields.