Key Points
- Plant population is one of a number of factors that affects maize silage yield. Yield is driven by light interception, denser populations intercept more sun light up to the point where shading becomes an issue and the yield increase tapers off.
- In Canterbury, where it is cooler in spring and growers choose shorter maturing hybrids, plant populations could be increased to 130,000 to 150,000 plants/ha and still remain profitable.
- At the trial sites, the calculated economic optimum plant populations ranged from 125,000 to 185,000 plants/ha and produced yields from 19 to 27 t DM/ha. The economic optimum is site specific, also depending on environmental and crop management practices such as hybrid selection and sowing date.
- There are a number of downsides to denser populations; maturity may be delayed, the grain harvest index may be slightly lower and the stem diameter is smaller, increasing the risk of crop lodging.