Russell T Swift^1,2, Jonathan Edward Chambers¹, Tongai Mtangadura³, Elijah Phiri⁴, Innocent Sandram⁵, Philip Meldrum¹, Paul Bryan Wilkinson¹, John Banda⁴, Joseph Chimungu⁵, Charles B Chisanga⁴, Cornelia Inauen¹, Ivy Ligowe⁶, Nellie Magwero⁵, Vengai Mbanyele³, Chawezi Miti⁴, Miyanda Moombe⁴, Patson Nalivata⁵, Pathias N Lubinga⁴, Hatirarami Nezomba³, Keston Njira⁵, Willy Namaona⁵, Paul Mapfumo³, Florence Mtambanengwe³, Toga Mapangisana³, Frédéric Nguyen² and Murray Lark^1,7, (1)British Geological Survey, Keyworth, United Kingdom, (2)Université de Liège, Applied Geophysics, Department ArGenCo, Liege, Belgium, (3)University of Zimbabwe, Harare, Zimbabwe, (4)University of Zambia, Lusaka, Zambia, (5)Lilongwe University of Agriculture & Natural Resources, Lilongwe, Malawi, (6)Department of Agricultural Research Services (DARS), Lilongwe, Malawi, (7)University of Nottingham, Nottingham, United Kingdom