Ex-tin mining land is a degraded land with low soil fertility and poor soil physical properties. The research aimed to find the best ameliorant for the improvement of ex-tin mining soil and corn yield. This experiment, conducted in Bangka Belitung Province, Indonesia, used a Randomized Block Design with 7 treatments and 4 replications: control, 20 t ha−1 biochar, 20 t ha−1 cattle manure, 20 t ha−1 mucuna compost, 10 t ha−1 biochar+10 t ha−1 cattle manure, 10 t ha−1 biochar+10 t ha−1 mucuna compost, and 10 t ha−1 cattle manure+10 t ha−1 mucuna compost. The corn variety used was Sukmaraga. The application of ameliorant significantly increased soil chemical properties (pH, potential and available P, potential and exch-K, exch-Ca, exch-Mg, exch-Na, and base saturation) and growth and yield of corn. The corn yield from the 20 t ha−1 biochar treatment was higher than that of the control, but was not significantly different from the other treatments. The single application of 20 t ha−1 biochar and the application of 10 t ha−1 biochar in combination with either 10 t ha−1 cattle manure or 10 t ha−1 mucuna compost resulted in the best soil chemical improvement and crop yields.