Amelioration of a saline‐sodic soil with low applications of calcium and nitrogen amendments

The effect of low rates of gypsum combined with ammonium nitrate on the soil properties of a saline‐sodic Solonetzic soil (Natriboroll), and growth and mineral nutrition of bromegrass (Bromus inermus L.) was evaluated in a 6‐year field experiment. Annual applications of gypsum (2.24 t ha−1), at a fraction of the soil gypsum requirement, and ammonium nitrate (80 kg N ha−1) reduced the SAR of the B horizon from 29.0 to approximately 15 to 1.7 after 3 to 6 years, respectively. After 6 years the ECt of the B horizon was reduced from 5.5 to 1.4. Improvement of the soil condition was associated with a reduction in soluble Na and enrichment of the soil solution with Ca. In consequence the Ca concentration and ratio of K/Na in the foliage of the bromegrass was increased. The study demonstrates that the combination of perennial grasses and relatively low Ca and N amendments can accelerate the natural process of solodization as characterized by Na leaching and build up of Ca.