The influence of nitrogen and sulphur fertiliser on amino acid composition of wheat and barley grain

Improved grain protein quality through fertiliser management has potential benefits for growers and feed processors. Stable high quality grain is demanded by feed processors to facilitate grain handling and to reduce the cost of additives in feed formulation. In this experiment we examine the potential gains from altering grain protein quality with fertiliser management. A factorial experiment was conducted at Lincoln to determine the response of grain yield and quality to nitrogen (N) and sulphur (S) fertiliser treatments. Wheat (Triticum aestivum L. cv. Impact) and barley (Hordeum vulgare L. cv. Dash and an experimental naked barley) were grown under N and S levels ranging from 0 to 150 kg/ha. Amino acid composition of grain was predicted using near infrared spectroscopy. Nitrogen fertiliser consistently increased the concentration of component amino acids in grain. However, S fertiliser had little effect on these components. Higher levels of amino acids in grain were associated with increased levels of N and S taken up by the plants. Regional trials showed that improved grain amino acid profiles could be achieved through fertiliser management and cultivar selection. Sowing date and plant population also had significant effects on amino acid concentration in grain. Additional key words: near infrared reflectance spectroscopy, crop management