N uptake by barley related to malting quality

Abstract

Between 1987 and 1990, crops of barley at Rothamsted were frequently sampled in order to study the influence of husbandry factors upon malting quality.

Studies during the four years of the project showed that the majority of the nitrogen contained in the grain of both winter and spring barley at harvest is taken up before anthesis, whilst the majority of the carbohydrate is produced after anthesis. The project has demonstrated how husbandry factors such as previous crop, rate and timing of nitrogen fertiliser and disease control, as well as weather conditions, can affect the balance between the processes of nitrogen uptake and translocation and carbohydrate production affecting both yield and malting quality.

In six of the nine field experiments studied, ear nitrogen concentration fell after anthesis and then rose until maturity, in two it rose steadily, and in one it fell steadily during this period. This variability means that prediction of final grain quality from measurements made earlier in the season is unlikely to be feasible.

The final experiment of the project was carried out in 1989-90, when winter barley was grown after winter barley, winter oats, winter beans, oilseed rape or potatoes, with a range of nitrogen fertiliser rates, in order to test whether malting barley could be successfully grown after a break crop, providing that nitrogen rates were suitably reduced.

The highest yields were obtained after potatoes, the lowest after barley. The largest amounts of nitrogen which could be applied without grain nitrogen concentration exceeding 1.8% N were 75, 125, 100, 50 and 50 kg N ha-1 after barley, oats, beans, rape and potatoes respectively. The highest margins over nitrogen cost were obtained after oats or beans.