Remediation of salt-affected soil by natural and chemical amendments to improve berseem clover yield and nutritive quality

Salinity is a major problem affecting crop production worldwide. The potential of different soil amendments (sulphur, gypsum, compost, and combination of gypsum, compost and sulphur) and two plant-growth stimulators (potassium silicate and calcium carbonate nanoparticles) to alleviate the harmful effects of saline soil on two cultivars of berseem clover (Trifolium alexandrinum L.), one salt tolerant ('Serw-1') and the other high yielding ('Helaly'), was evaluated. Some soil properties were measured before and after treatments. Plant growth parameters, herbage yield, nutritive value and plant metabolites, including photosynthetic pigment and endogenous hormone contents, were also determined. The herbage yield of berseem clover cultivars substantially increased with the application of soil amendments in both years. The greatest yield increase was obtained with the compost application. The highest protein contents in herbage (16.4% in Helaly and 17.2% in Serw-1) were detected in response to composite (compost + gypsum + sulphur) and compost treatments, respectively. Carbohydrate content increased to 9.53% in Helaly and 5.1% in Serw-1 in response to the gypsum and compost treatments, respectively. The composite, compost and gypsum soil amendments were the most effective treatments resulting in the greatest herbage yield and quality values.