###### Abstract  
Salt-affected soil reclamation provides opportunities for crop production and carbon sequestration. In arid regions such as Pakistan, limited studies have been reported involving soil reclamation and crop production under wheat- maize rotation, but no study has reported predictions on long-term carbon sequestration in reclaimed soils for the treatments used in this study. Thus, a field-scale fallow period and crop production experiment was conducted for wheat-maze rotation on salt-affected soils in Pakistan for 3 years to check the effectiveness of organic amendments for reclamation of the salt-affected soils, carbon sequestration and food grain production. Treatments used were the control (with no additional amendments to reduce salinity), gypsum alone and gypsum in combination with different organic amendments (poultry manure, green manure, and farmyard manure). The treatment with gypsum in combination with farmyard manure was most effective at increasing soil carbon (+169% over the three-year period of the trial). The maximum wheat yield was also recorded in year 3 with gypsum in combination with farmyard manure (51%), while the effect of green manure combined with gypsum also showed a significant increase in maize yield in year 3 (49%). Long-term simulations suggested that the treatments would all have a significant impact on carbon sequestration, with soil C increasing at a steady rate from 0.53% in the control to 0.86% with gypsum alone, 1.25% with added poultry manure, 1.69% with green manure and 2.29% with farmyard manure. It is concluded that food crops can be produced from freshly reclaimed salt-affected soils, and this can have added long-term benefits of carbon sequestration and climate change mitigation. s 29 December 202292010 January  
insecurity associated with both climate change and the increasing population is a major challenge to be addressed [6; 7]. Reclaiming soil affected by salinity will play a major role in meeting this challenge. Soils affected by salinity can be reclaimed by the addition of gypsum (CaSO4- 2H2O). This replaces Na+ in the cation exchange sites with an easily accessible supply of Ca2+. The Na2 SO4 formed by the exchange is easily removed from the soil profile, either by downward leaching or by absorption by halophytic grasses [8]. Unlike in the EU, where reduction in coal-burning power plants is likely to result in future shortages of gypsum [9], gypsum in Pakistan is mined and readily available at less than a dollar per 50 kg bag of gypsum, with no prospects of future shortages [10]. Soils affected by salinity can also be reclaimed by the addition of different organic amendments, which also improves crop production by increasing the organic matter content, available nutrients and biological activity of the soil [11; 12; 13; 14; 15]. A productive soil requires a sufficient concentration of organic matter [16], but salt-affected soils usually contain less than 1% organic matter and, thus, require extra organic inputs [17]. Carbon (C) sequestration in soils also helps to mitigate climate change [18; 19], and the increased soil organic matter (SOM) content can enhance soil fertility, nutrient availability and water holding capacity [20; 21]. As Pakistan lies in a semi-arid zone, it suffers from large-scale soil salinization. Of the irrigated area, 25% is affected by salinity (6 \(\times\) 10\({}^{6}\) ha), which is equivalent to 3.9% of the total salt-affected soils worldwide [22; 23]. Reclaiming salt-affected soils could provide a significant contribution to reducing food insecurity in Pakistan [24]. Many papers have reported the use of organic and inorganic amendments, and their combinations, for the reclamation of saline soils (e.g., [25; 26; 27; 28; 29]). Other work has assessed the use of reclaimed soils for wheat and rice crop production (e.g., [27; 28; 30; 31; 32; 33]). In Pakistan, previous studies have demonstrated the potential of combined gypsum and organic amendments to reclaim salt-affected soils and crop production [27; 30].