To mitigate the effect of salt stress and excess B in soil and consequently increase crop yield and improve the behaviour of cv. "Poncho Negro" there are low-cost strategies such as the application of organic amendments. This study aimed at remediating excess salt (150 mM NaCl) and B (20 mg L-1 B) in soil using organic matter treatment (4% and 6%). Stress was supplied by irrigation. The rate of net CO2 assimilation, B, Na+, K+ and Ca2+ content, soluble sugars and proline were measured. All growth parameters measured were higher with 6% organic matter (MO) in soil than with 4% MO, including salinity treatments and excessive B, while Na+ and B concentrations were reduced in leaves and roots. The photosynthesis rate was maintained at the level of control plants with 6% OM applied in soil in treatments with salinity alone and with excess B. In the salinity alone treatment there was a marked increase in the content of compatible solutes, but with the application of 6% MO their content was reduced by more than 100%. The remediation of salt and boron-affected soil by addition of organic matter (6%) is an effective way to improve the behaviour of tomato.