The effect of fallowing on yield of wheat. III. The effect on grain nitrogen content

Abstract

The nitrogen content of wheat grain in the South Australian wheat-belt is related to water and nitrogen supply. Grain nitrogen decreased with increasing water supply; it tended therefore to be less in wet seasons, less under fallow because of additional stored water and less on fine-textured soils which also provided more water. Grain nitrogen increased as the nitrogen supply was increased either as additional nitrate due to fallow or as nitrogenous fertilizer.

The effect of fallow on grain nitrogen varied with the season. In dry growing seasons, the grain nitrogen percentage was usually higher on the non-fallow treatment, because of the dominant effect of a lesser water supply. In moist growing seasons, the grain nitrogen percentage was higher on the fallow because of the dominant effect of a better nitrogen supply. Since rainfall is unpredictable, the net effect of fallowing on the grain nitrogen percentage is also unpredictable.