Planting corn and other crops in a grid rather than in rows may control weeds better, say scientists writing in the journal Weed Research.
C. Marin of Jorge Tadeo Lozano University in Colombia and J. Weiner of the University of Copenhagen report on two years of tests in which maize (corn) was sown in three densities in both grids and rows.
“On average, weed biomass was reduced (by 72 per cent in the first year and 58 per cent in the second year), and grain yield was increased (by 48 per cent and 44 per cent) at the highest density in the grid pattern compared with standard sowing practices (medium density, row pattern),” they write.
The researchers say that several studies over the past decade have shown better weed suppression in wheat through a combination of increased crop density and spacial uniformity. Plants seeded in rows are crowded in one dimension, but farther apart in the other.
“In a uniform pattern, individual crop plants are equally crowded in both dimensions. Intraspecific competition within the crop is delayed, while interspecific competition with weeds begins sooner. This allows the crop population to shade and suppress the weeds,” the article says.
The tests were done over two years in Colombia on six-metre-square plots with three densities — five, seven and 10.5 plants per square metre.
Three varieties were used in the tests, and with some variation of weed suppression among them. The researchers hypothesize that varieties with more uniform leaf characteristics also promote more shading and weed suppression.
“Our results suggest the possibility of developing ‘high-density, weed-suppressing’ varieties of maize and other crops, because attributes that will prove advantageous under such conditions are not those natural selection or plant breeding to date have promoted.”