No-Till Farmer reports on research that higher maize (corn) yields in the USA are partly due to modern hybrid varieties taking up more nitrogen after flowering than their older counterparts.
Researchers found that modern hybrids (post-1990) took up 27 percent more total nitrogen from the soil after flowering than pre-1990 corn plants. In fact, nitrogen uptake after flowering in post-1990 hybrids averaged 56 percent of the total grain nitrogen at the end of the season.
Primarily, more grain nitrogen came from new nitrogen uptake from soil during grain filling, as opposed to nitrogen being remobilized from plant leaves and stems. The higher amount and duration of nitrogen uptake contributed to superior grain yields even as actual grain nitrogen concentrations declined.
Optimum nitrogen levels increased plants' abilities to absorb phosphorus, potassium and sulphur. Part of the corn plant's response to receiving adequate nitrogen is that progressively higher percentages of total plant phosphorus, potassium and sulfur end up in the grain fraction at harvest.
Read the full report here.