Beijing Key Laboratory of Farmland Soil Pollution Prevention-Control and Remediation, College of Resources and Environmental Sciences, China Agricultural University, No. 2 Yuanmingyuan West Road, Beijing, 100193, Haidian, China.
Hekou District Agricultural and Rural Bureau, Yellow River Road 164Shandong Province, Dongying City, 257200, China.
Environ Sci Pollut Res Int. 2023 Jun;30(30):75681-75693. doi: 10.1007/s11356-023-27713-8. Epub 2023 May 24.
Soil acidification is a worldwide eco-environmental problem detrimental to plant growth and threatening food security. In this study, calcium poly(aspartic acid) (PASP-Ca) and calcium poly-γ-glutamic acid (γ-PGA-Ca) were obtained through cation exchange and used to mitigate soil acidity owing to high solubility and complexing capability. Three rates at 6.7, 13.4, and 20.1 g kg, denoted as PASP-Ca1, PASP-Ca2, and PASP-Ca3, and γ-PGA-Ca (7.4 g kg) were surface-applied and compared with conventional lime (CaCO, 2.5 g kg) along with control in two soil layers (top soil 0-10 cm, subsoil 10-20 cm). After leaching, various soil properties and aluminum fractions were measured to assess their ameliorative performance and mechanisms. Although lime achieved the highest soil pH (6.91) in the topsoil followed by PASP-Ca and γ-PGA-Ca (pH: 5.57-6.33), it had less effect on subsoil increase (5.3) vs. PASP-Ca and γ-PGA-Ca (pH: 5.44-5.74). Surface-applied PASP-Ca demonstrated efficiency in elevating soil pH and reducing exchangeable acidity, mainly as exchangeable Al, whereas γ-PGA-Ca addition superiorly improved soil pH buffering capacity (pHBC). Moreover, PASP-Ca and γ-PGA-Ca addition improved organic carbon by 34.4-44.9%, available P by 4.80-20.71%, and cation exchange capacity (CEC) by 6.19-29.2%, thus greatly enhanced soil fertility. Ca from polyAA-Ca promoted the displacement of exchangeable Al or H from soil colloid, which were subsequently complexed or protonated and facilitated leaching. Additionally, the transformation into stable organo-aluminum fractions via complexation inhibited further hydrolysis. Under PASP-Ca or γ-PGA-Ca addition, the saturation of aluminum in cation exchange complex was reduced 2.91-7.81% compared to the control without addition amendments. Thus, PASP-Ca and γ-PGA-Ca can serve as potent ameliorants to alleviate soil acidity and aluminum toxicity for sustainable agricultural development.
土壤酸化是一个全球性的生态环境问题，它会损害植物的生长，威胁粮食安全。在本研究中，通过阳离子交换得到了聚天冬氨酸钙（PASP-Ca）和聚γ-谷氨酸钙（γ-PGA-Ca），由于其高溶解度和络合能力，它们被用于缓解土壤酸度。在两个土层（表层 0-10cm 和亚层 10-20cm）中，分别以 6.7、13.4 和 20.1gkg 的 3 种浓度（PASP-Ca1、PASP-Ca2 和 PASP-Ca3）施用并与常规石灰（CaCO3，2.5gkg）和对照进行了表面处理。淋洗后，测量了各种土壤性质和铝形态，以评估它们的改良性能和机制。虽然石灰在表层土壤中获得了最高的土壤 pH 值（6.91），其次是 PASP-Ca 和 γ-PGA-Ca（pH 值：5.57-6.33），但它对亚层土壤的增加（pH 值 5.3）的影响较小，而 PASP-Ca 和 γ-PGA-Ca 的影响较大（pH 值：5.44-5.74）。表面施用的 PASP-Ca 在提高土壤 pH 值和降低可交换酸度方面表现出效率，主要是通过可交换的 Al，而 γ-PGA-Ca 的添加则可以更好地提高土壤 pH 值缓冲能力（pHBC）。此外，PASP-Ca 和 γ-PGA-Ca 的添加分别提高了 34.4-44.9%的有机碳、4.80-20.71%的有效磷和 6.19-29.2%的阳离子交换量（CEC），从而大大提高了土壤肥力。聚天冬氨酸钙中的 Ca 促进了土壤胶体中可交换的 Al 或 H 的置换，随后这些元素被络合或质子化并促进了淋洗。此外，通过络合作用将其转化为稳定的有机铝形态，抑制了进一步的水解。在 PASP-Ca 或 γ-PGA-Ca 的添加下，与不添加改良剂的对照相比，阳离子交换复合体中铝的饱和度降低了 2.91-7.81%。因此，PASP-Ca 和 γ-PGA-Ca 可以作为有效的改良剂，缓解土壤酸化和铝毒性，促进农业可持续发展。
