| The development of coastal beach resources is of great significance to the replenishment of cultivated land area.However,due to the long-term influence of ocean tides,the coastal soil has high salt content and poor soil structure,which is not suitable for planting food crops and causes second-ary waste of cultivated land resources.Therefore,it is of great significance for regional agricultural production to carry out research on the obstacle characteristics and regulation of coastal beach reclamation.Based on coastal tidal flats reclamation farmland soil in fujian province as the re-search object,selecting desulfurization gypsum and biochar amendment,the soil column simulation investigation method,the design of indoor soil column infiltration,evaporation and leaching experiment,the simulation of soil water infiltration,evaporation and salt leaching process,to investi-gate the soil improvement effect of desulphurized gypsum and biochar alone or in combination for coastal beach reclamation.Finally,the opti-mum proportion of desulfurized gypsum and biochar was selected by prin-cipal component analysis.The main conclusions of this paper are as fol-lows:（1）The results of infiltration experiment showed that,compared with the control treatment,all treatments could reduce the infiltration capacity of sandy saline-alkali soil,and treatment F with 100g/kg desulphurized gypsum alone had the greatest inhibition,with the infiltration time reaching26.1 times that of 600min CK.Treatment B with 50g/kg biochar alone had little effect on soil infiltration.Kostiakov model can explain this infiltration experiment well,and the model parameters K range of each treatment is2.9～15.7,which is smaller than CK,which verifies the inhibition effect of desulfurized gypsum and biochar on soil infiltration process.（2）Evaporation experiment results show that all the treatments can promote the evaporation of soil water.Among them,there was little differ-ence between the combined treatments,and the largest cumulative evapo-ration was the F1B2 treatment with 75g/kg desulfurized gypsum+30g/kg biochar,which reached 442mm monthly cumulative evaporation,1.3 times that of CK.Rose evaporation model is suitable for this evaporation exper-iment.（3）The results of leaching experiment show:compared with the con-trol treatment,on the whole,desulphurized gypsum alone or combined desulphurized gypsum and biochar had a significant effect on the change of soil salinity.The addition of biochar alone had little effect on leaching process and physicochemical properties of soil after leaching.The specific performance is as follows:（1）Adding desulphurized gypsum alone or desulphurized gypsum and biochar combined can significantly promote the leaching of salt ions.Es-pecially Ca2+and SO42-leaching.The effect of biochar alone on salt ion leaching is small.（2）Compared with CK,all treatments could significantly increase soil total porosity.F1B2 treatment with 75g/kg desulfurized gypsum and30g/kg biochar had the best effect on improving soil total porosity,which increased by 38.1%compared with CK.All the treatments could signifi-cantly increase the average water content of soil surface and bottom layer.F1B2 and F2B1 mixed treatments had better effect than the single addition treatment,and the water content was increased by 24.8%and 16.3%,re-spectively,with the best water retention performance.（3）The addition of desulphurized gypsum alone or combined with de-sulphurized gypsum and biochar could significantly reduce soil p H and soil sodium adsorption ratio（SAR）,the improvement effect of 0～20cm surface layer was better than that of 40～60cm bottom layer.Biochar alone had little effect on soil p H and sodium adsorption ratio（SAR）.The addition of de-sulphurized gypsum alone or combined addition of desulphurized gypsum and biochar significantly increased soil total salt content,but sodium salt was mainly converted to calcium salt.Biochar alone had little effect on soil total salt content after leaching.（4）Principal component analysis was used to select the treatment of F1B2 as the optimal ratio of desulfurized gypsum and biochar,namely the combined addition of 75g/kg desulfurized gypsum and 30g/kg biochar,had the best improvement effect on the physical and chemical properties of the soil and water and salt transport in this study.In conclusion,the improvement effect of compound addition treat-ment is better than that of the two amendments alone,that is,Under the synergistic action of desulfurized gypsum and biochar,the improvement effect of soil physical and chemical properties and water and salt status of coastal beach reclamation arable soil is better.The optimal ratio was75g/kg desulfurized gypsum and 30g/kg biochar. |
