施用钾明矾和白云石对设施农业土壤磷形态转化的影响

    Variation of soil available P and P transformation with alum and dolomite applications in agricultural facility soils

    • 摘要: 中国设施农业中高量灌溉施肥所导致的磷淋溶损失较为突出,可能增加设施周边水体富营养化的风险。施用磷吸附材料可能固持高磷土壤中的活性磷,降低表层土壤磷素向下移动。但是,不同磷吸附材料作用下土壤磷素形态转化和剖面移动特征尚不清楚。因此,该研究通过连续3 a田间试验,结合Hedley连续浸提磷分组方法和磷K边同步辐射(XANES)技术,探究施用钾明矾、白云石以及钾明矾和白云石的混合物(质量比= 1:2)对作物生长及土壤剖面活性磷、磷组分及其磷形态转化的影响。结果表明,连续3 a累积施用8 100 kg/hm2的钾明矾、白云石和钾明矾与白云石的混和物处理对蔬菜产量无显著影响。与对照相比,钾明矾、白云石和钾明矾与白云石混合处理土壤0~30 cm的CaCl2-P含量(质量分数)分别降低了24.98%、8.39%和11.13%,而土壤0~90 cm的Olsen-P含量无显著性差异。Hedley磷分组表明,连续3 a施用磷吸附材料后,相比于对照处理,钾明矾、钾明矾和白云石混和物处理的土壤0~30 cm总磷含量分别显著提高了5.62%、8.82%,而白云石处理土壤0~30 cm的总磷含量则降低了0.57%。土壤磷素组分结果也发现,HCl-P是土壤磷组分中占比最高的组分,占土壤总磷的56%以上;施用磷吸附材料后0~60 cm土层中稳态磷(NaOH-P)的含量均高于对照处理,说明土壤中的活性磷和土壤中的铁铝发生了结合。磷K边同步辐射进一步表明,Ca-P是石灰性土壤中的主要成分,占总磷的比例72%以上。与对照相比,钾明矾、白云石与钾明矾和白云石的混和物处理的二水磷酸铁的含量分别提高了1.55%、5.68%和5.88%;另外,钾明矾、钾明矾和白云石混合物处理提高了羟基磷灰石含量。土壤性质结果表明,单独施用钾明矾显著提高了土壤M3-Fe、M3-Al、M3-P和EC值,并降低了土壤pH值;而施用钾明矾和白云石的混合物对土壤理化性质影响无明显变化,这说明在高磷设施土壤中施用二者混合物较为合适。本研究为减少设施土壤磷流失提供了适用的磷吸附材料,对降低农田面源污染具有一定的参考价值。

       

      Abstract: Leached phosphorus (P) losses from protected vegetable field soils (PVFs) due to frequent irrigation and high fertilizers input is a big issue in China, which may negatively affect the quality of connected surface and subsurface water bodies. The in-situ stabilization of soil P through P sorption materials (PSMs) application in P-enriched soils may reduce the downward movement of P. However, the transformation and mobility of soil P with different PSMs application are still unclear. In the present study, a three-year field experiment was conducted to investigate the effects of applying alum, dolomite, and the mixture of alum and dolomite (MAD, mass ratio = 1:2) on crop growth, soil available P, P fractions, and P transformations in PVFs by using the Hedley P sequential fraction method and the sequential chemical extraction and P K edge X-ray absorption near-edge structure (XANES) spectroscopy. Results showed that the cumulative application of 8 100 kg/hm2 of alum, dolomite, and MAD for three years had no significant effect on vegetable yield. Compared with the control treatment, the soil CaCl2-P contents(mass fraction) in 0~30 cm soil depth in the alum, dolomite and MAD treatments decreased by 24.98%, 8.39% and 11.13%, respectively. On the contrary, there were no significant difference of soil Olsen-P content in the 0~90 cm soil depth among these treatments. Hedley P fractions showed that after 3 years of application of PSMs, the soil total P contents in the 0~30 cm soil depth in the alum and MAD treatments were significantly increased by 5.62 % and 8.82 % compared with the control treatment, while the soil total P contents in the 0~30 cm soil depth of application of dolomite decreased by 0.57 %. The results of soil P fractions also showed that HCl-P was the highest proportion of soil P fractions, accounting for more than 56 % of the soil total P. The content of NaOH-P in the 0~60 cm soil depth after the application of PSMs was significantly higher than that of the control treatment, indicating that the active phosphorus in the soil and the iron and aluminum in the soil were combined. The X-ray absorption near-edge structure (XANES) spectroscopy further showed that Ca-P was the main component in calcareous soil, accounting for more than 72 % of the soil total P. Compared to the control, the treatments of alum, dolomite, and MAD increased the content of iron phosphate dihydrate by 1.55 %, 5.68 % and 5.88 %, respectively. In addition, the treatment of alum and MAD increased the content of hydroxyapatite. The results of soil physicochemical properties showed that the alum treatment significantly increased soil M3-Fe, M3-Al, M3-P and EC values, and decreased soil pH value. The MAD treatment had no significant change on the physical and chemical properties of the soil. This demonstrated that it was more suitable to apply the MAD in P-enriched soil. This study provides applicable PSMs for reducing leached P losses in PVFs, which is of great fundament to curtail farmland non-point surface pollution.

       

    /

    返回文章
    返回