Jalali Mohsen, Jalali Mahdi
Department of Soil Science, College of Agriculture, Hamadan, Iran.
Department of Soil Science, College of Agriculture, Hamadan, Iran.
Chemosphere. 2017 Mar;171:106-117. doi: 10.1016/j.chemosphere.2016.12.042. Epub 2016 Dec 19.
Accurate estimation of phosphorus (P) leaching is important because excess P may reduce surface and ground water quality. Little attention has been paid to estimate P leaching from soil tests in calcareous soils. The relation between different soil tests P (STP), P sorption index (PSI) and degree of P saturation (DPS) and leaching of P were examined for assessing the risk of P loss from calcareous soils. Columns leaching repacked with native soils were leached with either distilled water or 10 mM CaCl solutions, separately. Four leaching events were performed at four days, and 28.7 mm of distilled water or 10 mM CaCl solutions was applied at each leaching events. Compared with distilled water, CaCl had a small ability to solubilize P from soils. Concentration of P in leachate in both leaching solutions was exceeding 0.1 mg l associated with eutrophication. Cumulative P leached P was ranged from 0.17 to 18.59 mg P kg and 0.21-8.16 mg P kg, when distilled water and 10 mM CaCl solutions were applied, respectively and it was higher in sandy clay loam soils compared with clay soils. Among evaluated environmental soil P tests, P (P extracted by 10 mM CaCl for 3 h), P (P extracted by 10 mM CaCl for 1 h) were more accurate than other soil P tests for predicting P concentration in the leachates in both leaching solutions and accounting for 83% and 72% of variation of P concentration, respectively. The water extractable P (WEP) (r = 0.771) and Olsen-P (P)(r = 0.739) were significantly related to the leached P concentration using distilled water solution in a split line model, with a change point of 27.4 mg P kg and 61.5 mg P kg, respectively. Various DPS were calculated and related to the leached P concentration. Based on P extracted by Mehlich-3 (P) and HCl (P) and PSI, the change point of the relationship between leached P concentration and DPS (P(P+PSI)×100) and DPS (P(P+PSI)×100) for both leaching solutions was approximately the same, thus a mean value of 49% for DPS and 73% for DPS was obtained. Soils were grouped into four categories of increasing P leaching potential based on WEP, P, and DPS. The results indicated that 8.00%-25.50% of the soil grouped in no risk category whereas 8.00%-13.70% of the soils fell into the high risk category.
准确估算磷（P）淋失非常重要，因为过量的磷可能会降低地表水和地下水的质量。在石灰性土壤中，人们很少关注通过土壤测试来估算磷的淋失情况。为了评估石灰性土壤中磷流失的风险，研究了不同土壤测试磷（STP）、磷吸附指数（PSI）和磷饱和度（DPS）与磷淋失之间的关系。用天然土壤重新装填的柱体分别用蒸馏水或10 mM氯化钙溶液进行淋洗。在四天内进行了四次淋洗，每次淋洗施加28.7毫米的蒸馏水或10 mM氯化钙溶液。与蒸馏水相比，氯化钙从土壤中溶解磷的能力较小。两种淋洗溶液中渗滤液中的磷浓度均超过了与富营养化相关的0.1毫克/升。当分别使用蒸馏水和10 mM氯化钙溶液时，累积淋失磷的范围分别为0.17至18.59毫克磷/千克和0.21至8.16毫克磷/千克，并且砂质粘壤土中的累积淋失磷高于粘土。在评估的环境土壤磷测试中，10 mM氯化钙提取3小时的磷（P）、10 mM氯化钙提取1小时的磷（P）在预测两种淋洗溶液中渗滤液的磷浓度方面比其他土壤磷测试更准确，分别解释了磷浓度变化的83%和72%。在分段线性模型中，水提取磷（WEP）（r = 0.771）和Olsen - P（P）（r = 0.739）与使用蒸馏水溶液淋失的磷浓度显著相关，变化点分别为27.4毫克磷/千克和61.5毫克磷/千克。计算了各种DPS并将其与淋失的磷浓度相关联。基于Mehlich - 3提取的磷（P）和盐酸提取的磷（P）以及PSI，两种淋洗溶液中淋失的磷浓度与DPS（P（P + PSI）× 100）和DPS（P（P + PSI）× 100）之间关系的变化点大致相同，因此得到DPS的平均值为49%，DPS的平均值为73%。根据WEP、P和DPS将土壤分为四类，磷淋失潜力逐渐增加。结果表明，8.00% - 25.50%的土壤属于无风险类别，而8.00% - 13.70%的土壤属于高风险类别。
