The effectiveness of CaO and MgO as soil ameliorants in controlling phosphorus movement

This study examined the effectiveness of Calcium (Ca) and magnesium (Mg) as soil ameliorants in enhancing soil properties for phosphorous (P) retention with an aim to reduce P leaching into water. Leaching of P from amended soil was assessed for P:Ca and P:Mg molar ralios of 1 :0.74, 1:1.11, 1:1.26 and 1:3.55 at pH 8.0, 8.5 and 9.0. The results showed that at low P:Mg ratios Mg is more effective than Ca, with at least a 20% reduclion in P leaching occurring. Both Mg and Ca were not effective at ratio 1 :3.55. These findings indicate Ca and Mg compounds can be utilised to control P runoff into water bodies.