磷石膏改良滨海盐土效果及对小麦生长的影响

Effects of Phosphogypsum on Coastal Saline-sodic Soil and the Growth of Winter Wheat

江苏滨海盐土(盐碱土)约66.22万公顷,大多未开发利用,主要因为含盐量很高,迫切需要进行改良。本试验采用田间试验方法,利用磷肥厂副产物磷石膏进行盐(碱)土改良试验。试验设置不施肥、不施用磷石膏、单施复合肥、施用复合肥+磷石膏不同用量等8个处理进行。结果表明,施用磷石膏可以降低盐碱土土壤pH,与不施用磷石膏的对照相比,施用磷石膏后表层0~20 cm土壤pH下降0.07~0.40个单位,碳酸氢根离子下降15.81%~43.53%;土壤钠离子浓度下降17.25%~89.83%,土壤钾离子含量增加8.17%~384.90%,土壤钙离子含量增加59.51%~1977.72%,土壤有机质增加4.51%~19.50%。施用磷石膏处理小区小麦叶片全氮含量较不施磷石膏处理增加7.85%~26.21%,叶片全磷含量增加5.02%~35.97%;小麦增产11.41%~45.26%。滨海盐土及盐碱土可以采用磷石膏进行改良,有较好的改良效果。综合考虑,以处理为30%复合肥1050 kg·hm^(-2)+磷石膏1125 kg·hm^(-2)和30%复合肥1050 kg·hm^(-2)+磷石膏2250 kg·hm^(-2)处理效果最好。

【Objective】There are about 0.66 million hectares of coastal saline-sodic soil in Jiangsu that have not been developed and used as arable land for agriculture.This is because the saline-sodic soil has a higher concentration of salt that requires urgent ameliorating.【Method】This study used waste phosphogypsum(PG),a kind of by-product from the phosphate industry,to conduct an amelioration experiment of saline-sodic soil in the field.Eight treatments were employed in the field experiment:no fertilizer and PG,fertilizer but no PG,and compound fertilizer+different amounts of PG.【Result】Results showed that pH was decreased by 0.07-0.40 pH units in the depth of 0-20 cm topsoil treated with PG compared to the control.Soil bicarbonate and sodium ions decreased by 15.81%-43.53%and 17.25%-89.83%,respectively.The concentration of potassium ion,calcium ion,and organic matter in the amended soil treated with PG was increased by 8.17%-384.90%,59.51%-1977.72%,and 4.51%-19.50%,respectively.Also,the amounts of total N and P in the wheat leaves in the PG treatment were increased by 7.85%-26.21%and 5.02%-35.97%,respectively,and the wheat grain yield increased by 11.41%-45.26%.Overall,PG can be used to ameliorate costal saline-sodic soil with better effectiveness.Mechanistically,the increase in calcium ions occurred as PG exchanged with sodium ions adsorbed in soil,and the sodium ions were leached underground during irrigation and rain to decrease the soil pH.Also,some acid-containing groups in PG were able to neutralize the bicarbonate ions to decrease the soil pH.PG increased the N uptake in wheat leaves and the yield of wheat grain due to the increased P from PG which induced a proportionate uptake of nutrients by the plant.Comprehensively,the best performance was the treatments of 30%compound fertilizer(1050 kg·hm^(-2))+PG(1125 kg·hm^(-2))and 30%compound fertilizer(1050 kg·hm^(-2))+PG(2250 kg·hm^(-2)).【Conclusion】The positive effect of PG should not be considered proportional to the amount applied,because trace hazardous elements in PG could accumulate in the soil which will result in environmental risks and grain safety issues.Thus,proper care should be taken when using high doses of PG for soil amendment.