Yield advantage and water saving in maize/pea intercrop

Intercropping is a well-established strategy for maximization of yield from limited land, but mixed results have been obtained as to its performance in terms of water use efficiency. Here, two maize/pea intercrop layouts were studied in comparison to sole maize and sole pea with and without plastic cover on maize to reduce evaporation. Growth patterns over time and yield were determined. Profiles of soil water content over depth and across rows in the intercrop were measured at three times to quantify water extraction and its spatial and temporal distribution. Several indices were calculated to characterize the efficiency of land and water use of intercrops as compared with sole crops of maize and pea. Land equivalent ratio ranged from 1.18 to 1.47, indicating that intercropping was an effective strategy for maximizing land use efficiency. Water equivalent ratio, WER, defined to characterize the use efficiency of the water resource in intercropping, in analogy with LER, ranged from 0.87 to 1.16, and ΔWU, the relative departure of actual water use in intercropping from expected use, ranged from −13.7% to 19.8%, indicating variability in the effect of intercropping on water use efficiency. Plastic film in maize increased yield and water use efficiency, but did not significantly affect LER or WER, indicating that intercropping advantage was not affected by plastic film mulch, and the advantages of film mulch were conserved under intercropping. A cropping system of 4 rows maize with 4 rows peas, with 30 cm between maize rows and 20 cm between pea rows, was superior in yield and water use efficiency to a system with 2 rows maize and 4 rows of pea with 40 cm between maize rows and 20 cm between pea rows. It is concluded that intercropping of maize and pea enhances land use efficiency compared to growing them as sole crops. Film mulch saves water in sole crops as well as intercrops.

► Intercropping of maize and pea enhances land productivity.
► Water use efficiency of intercropped maize is increased in correspondence with a decrease in water use efficiency of field pea.
► Yield and water use advantages of film mulch in monoculture are conserved under intercropping.