Effectiveness And Mechanism On Phosphogypsum Amending Coastal Saline Soil

There is a lot of coastal saline soil in Jiangsu where plant can not adapt to grow. It could become a perspective farming resource after well-improving. In the current work, greenhouse pot experiments and field experiments were conducted to amend coastal saline soil in Rudong county by phosphogypsum-based conditioner. Besides we have also investigated the interactive influence of different soil water content on wheat growth under phosphogypsum, key results are shown as below:1. Pot experimentsTotal nitrogen, available nitrogen, available phosphorus have been improved, especially available phosphorus in the soil treat with phosphogypsum. Compared to CK2(30%compound fertilizer900kg/hm2),the biggest increment of total nitrogen, available nitrogen, available phosphorus in soil was obtained in amendment5(30%compound fertilizer900kg/hm2+phosphogypsum amendment45000kg/hm2),which was56%,186.6%,411.5%respectively.With the increasing of phosphogypsum,the sodium content was gradually reduced which the lowest was amendment5. While the content of potassium and calcium were gradually increased with increment magnitude of300%and1688.5%respectively. Little significant rise of magnesium content was observed. The content of carbonate and bicarbonate was gradually decreased and the lowest was obtained in amendment5while the content of sulfate was gradually raised, which was increased by214.3%compared with CKl(no compound fertilizer,no phosphogypsum amendment), indicating that the best was amendment5..Phosphogypsum can effectively reduce the soil pH and promote the wheat growth, which the biggest decrease extent was amendment5, fall of13.7%in comparison with CK1.2.Field testThe nutrient content in wheat blade was increased in all treatment with phosphogypsum in field experiment. The highest of total nitrogen and total phosphorus was observed in field treated with phosphogypsum amendment4(30%compound fertilizer1050kg/hm2+phosphogypsum amendment11250kg/hm2),26.21%and35.97%of increment was obtained compared to CK2(30%compound fertilizer1050kg/hm2). Potassium content in amendment3(30%compound fertilizer1050kg/hm2+phosphogypsum amendment2250kg/hm2)was increased by186.25%compared with CK2.Wheat height, one-thousand-grain weight and wheat yield were increased in fields treated with phosphogypsum. The highest wheat height was in treatment amendment5(30%compound fertilizer1050kg/hm2+phosphogypsum amendment22500kg/hm2),a rise of19.04%as to CK2,while the highest one-thousand-grain weight and wheat yield were in treatment of amendment3,an increase of19.36%and45.26%contrast to CK2respectively.Little significant increase of soil organic matter was caused by phosphogypsum amendments,while soil pH was significantly reduced by the amendments, where5.04%of pH was decreased in amendment6(30%compound fertilizer1050kg/hm2+phosphogypsum amendment45000kg/hm2)compared to CK2.The sodium content of soil was gradually reduced with phosphogypsum-dependent manner, the lowest was exhibited in amendment6with a fall of89.8%compared with CKl(no compound fertilizer, no phosphogypsum amendment), while the content of potassium and calcium were gradually increased where the highest content was amendment6,with an increase of384.90%and1977.72%respectively, little rise of magnesium was found. The content of carbonate was gradually decreased and the lowest was in amendment6. Little fall of chlorine was shown while sulfate was gradually raised, the highest content was in amendment6,with an increase of1597%as to CKl,overally indicating the best amendment was amendment6.3.Soil moisture testThree kinds of plant protective enzyme(POD、CAT、 SOD)activity were increased with a manner of soil-moisture-reduction-dependent, the biggest increment magnitude was found in treatment7(30%compound fertilizer900kg/hm2+phosphogypsum amendment45000kg/hm2+30%field moisture capacity)with a rise of55.10%,171.43%and116.86%,respectively compared to treatment1(30%compound fertilizer900kg/hm2+phosphogypsum amendment45000kg/hm2+90%field moisture capacity),demonstrating that wheat seedlings was stressed by water. Furthermore, an increase of two sorts of dry adaptive regulator, soluble sugar and soluble protein,showed water stress of wheat seedlings. Finally, the increasing of content of malondialdehyde in wheat leaves indicated substantial damage was found in wheat leaves cell, where98.37%of increment in treatment7was obtained in comparison with treatment1. It demonstrated that suitable soil moisture needed while phosphogypsum was recycled and reused to amend soil to obtain a maximal benefit.In the present study, phosphogypsum solid waste could be reused and recycled to amend coastal saline soil significantly to desalt and stimulate plant growth.