Sweet corn response to combined nitrogen and salinity environmental stresses

To define the nature of the combined response curve of sweet corn (Zea mays L.) plants to nitrogen and salinity, a lysimeter study was designed to follow water and solute budgets with combinations of the two variables over wide ranges of 0.5–7.5 dS m-1 and 0–150% of local N-fertilization recommendations. Patterns of water-use efficiency, N content, N uptake, and shoot dry-matter yield indicated the predominance of environmental interactions over Cl-nitrate physiological antagonism. At low salinities, the leaf N content, N uptake, and yield increased with increased N fertilization up to 45% of local N-fertilization recommendations, nitrogen was efficiently stripped from the percolating water and practically no nitrate was leached. At higher N fertilization the amount of leached N increased linearly with increased N input, and N uptake and yield were independent of N rates, levelling off at increased values for decreased salinities. The Liebig–Sprengel and Mitscherlich–Baule models were evaluated against measured data; both achieved similar values for the system's inherent N, the salinity level corresponding with zero-yield, and the predicted yields, which were highly correlated with the experimental data (R2 > 0.9). It is suggested that both models can be used successfully in mechanistic-based plant–soil solution models to predict yield, water and nutrient needs, and the resulted N leaching.