Effect of Row Spacing and Plant Density on Silage Maize Growth, Dry Matter Distribution and Yield

Maize growth in narrow rows provides a more uniform spatial arrangement, but it does not always lead to increasing yield. A four-year study was conducted to investigate the effect of row spacing on silage maize growth and yield during the growing season and at harvest time. A field experiment with conventional (0.70 m) and narrow rows (0.35 m) at a plant density of 92,000 plants ha−1 was evaluated in the years 2011–2014, and the interaction of row spacing × plant density (92,000 and 110,000 plants ha−1) was tested in 2013–2014. The narrow rows clearly demonstrated potential to support plant height and weight development, together with a higher stalk proportion, at around two months after seeding. However, these contrasts were lost in the later stages and at harvest time. Some potential for non-significantly higher dry matter yield (4.6–10.8%) was shown in the narrow rows in three years of the experiment, in association with lower losses in plant numbers, when compared to conventional row spacing. The potential of yield improvement in the narrow rows showed relationships with weather conditions during the second half of the growing season. In summary, under the growing conditions of the study region, narrow row spacing significantly promoted early plant development, but these effects did not persist until harvest, thus resulting in only limited success in yield improvement.