分次施用碱性肥料对土壤pH及土壤镉有效性的影

为探究碱性肥料治酸改土的效果,以碱性肥料为供试肥料,以湖南松柏村典型镉污染农田土为供试土壤,以镉高累积菜心"特青四号"及镉低累积菜心"绿宝"为供试作物,设置不施氮对照CK、碱性肥料及尿素三个处理,研究盆栽条件下,分次施用碱性肥料对土壤pH及土壤镉生物有效性的影响。结果表明:分次施用碱性肥料能在移栽后65 d内使土壤pH维持在较高的水平,特青四号盆栽施用碱性肥料处理土壤的pH分别比尿素及CK处理的高出0.61个及0.20个单位,绿宝盆栽施用碱性肥料处理土壤的pH分别比尿素及CK的高出0.36个及0.12个单位;分次施肥65 d内,各取样时期施用碱性肥料处理土壤的有效镉含量均显著低于CK。而65 d时,特青四号及绿宝盆栽碱性肥料处理的有效镉含量与施用尿素处理相比分别降低了0.11 mg·kg^-1和0.08 mg·kg^-1;与CK相比,尿素及碱性肥料均能显著提高菜心氮量;分次施肥条件下,施用尿素及碱性肥料均能显著降低菜心镉含量。研究表明,在镉污染农田土壤中施用碱性肥料,不仅能提高菜心生物量,保证土壤供氮,还能长效提高土壤pH并降低土壤有效镉含量。

Influences of alkaline fertilizer application on soil pH and soil available cadmium

To study the effects of alkaline fertilizer (a new type of fertilizer) on reduction of soil acidity and cadmium pollution, a pot experiment was conducted using cadmium-contaminated soil from Zhuzhou, Hunan Province, and two varieties of flowering Chinese cabbage, which had either high (Te Qing 4) or low (Lv Bao) cadmium accumulation. The experiment included the following three treatments:alkaline fertilizer, urea, and no nitrogen (CK) treatment. Sixty-five days after transplanting (DAT), the soil pH value in the alkaline fertilizer treatment was 0.61 and 0.20 units higher than that in the urea and CK treatments with Te Qing 4, respectively, whereas the soil pH in the alkaline fertilizer treatment was 0.36 and 0.12 higher than that in the urea and CK treatments with Lv Bao, respectively. The results implied that application of alkaline fertilizer could improve the soil pH over an extended period. The available cadmium content of the soil treated with alkaline fertilizer was significantly lower than that with CK in each sampling period, and the available cadmium content in the urea treatment was 0.11 and 0.08 mg·kg^-1 of Te Qing 4 and Lv Bao pots higher than that in the alkaline fertilizer treatment at 65 DAT. Compared with CK, urea and alkaline fertilizers significantly increased the nitrogen content of flowering Chinese cabbage. Furthermore, urea and alkaline fertilizers significantly reduced the cadmium content of cabbage. Based on these findings, application of alkaline fertilizer in cadmium-contaminated farmland soil can not only ensure cabbage biomass and soil nitrogen supply but also continually reduce soil acidity and available cadmium content.