Abstract:

Mulching is one of the commonly used measures for water conservation in arid and semi-arid regions. Mulching coal gangue with different thicknesses and particle sizes can promote soil moisture infiltration and inhibit evaporation, whereas its influence on soil chemical characteristics has been unknown. In the study, raw soil and coal gangue in the mining area were used as test materials, and the indoor soil column infiltration and leaching method was adopted. In 90 days, soil pH, nutrients and salt characteristics at depth of 0-5 cm in the column were measured in order to probe the influence of coal gangue mulching with different thicknesses (4 cm, 16 cm) and particle sizes (0 cm<P₁≤0.5 cm, 0.5 cm<P₂≤1 cm, 1 cm<P₃≤2 cm and 2 cm<P₄≤4 cm) on soil chemical characteristics. The aim was to provide data reference and theoretical basis for the resource utilization of coal gangue and vegetation restoration in coal mining area. The results showed that the mulching thickness, particle size and their interaction had significant effects on the soil chemical characteristics. According to the F value of the two-way ANOVA, it can be known that soil pH, water-soluble carbon, total nitrogen, water-soluble nitrogen and readily available potassium content were more affected by the mulching thickness, while the content of soil organic carbon and available phosphorus were more affected by the particle size. The pH of the soil treated with mulching thickness of 4 cm (T1) ranged 7.81-8.38, which was significantly lower than that of the control, whereas the soil pH with mulching thickness of 16 cm (T2) was in the range of 9.08-9.11, which was significantly higher than that of the control. The larger the mulching thickness and the smaller the particle size, the higher the soil organic carbon, water-soluble carbon, total nitrogen, water-soluble nitrogen and readily available potassium content, but the lower the soil available phosphorus content. The cluster analysis showed that the mean content of soil organic carbon, water-soluble carbon, total nitrogen, water-soluble nitrogen and readily available potassium of category Ⅲ (including T1P1, T2P2 and T2P4) increased by 124.42%, 142.01%, 66.67%, 99.58% and 49.12%, respectively, compared with the control. The salt composition of the soil and coal gangue was mainly Na₂SO₄. Soil total salt content of the mulching treatments was significantly higher than that of the control, but mulching coal gangue did not cause salt damage to the soil. In practical applications, we suggest that the coal gangue with a thickness of 16 cm and a particle size of 1-4 cm should be preferentially used for mulching the soil in the mining area.

Key words: coal gangue, mulching thicknesses, particle sizes, nutrient characteristics, salt characteristics, pH

摘要：

覆盖是干旱和半干旱地区常用的保水措施之一,不同厚度及不同粒径的煤矸石覆盖能促进土壤水分入渗并抑制蒸发,但其对土壤化学特征的影响还未见报道。以矿区土壤和煤矸石为试验材料,通过室内土柱浸润淋溶的方法,培养90 d后测定土柱中0—5 cm土层样品的pH、养分及盐分特征指标,以探究不同厚度（4、16 cm）和不同粒径（0 cm<P₁≤0.5 cm、0.5 cm<P₂≤1 cm、1 cm<P₃≤2 cm和2 cm<P₄≤4 cm）的煤矸石覆盖对矿区土壤化学特征的影响,旨在为煤矸石的资源化利用及矿区植被恢复提供数据参考和理论依据。研究结果表明：煤矸石的覆盖厚度、粒径及其交互作用均显著影响土壤的pH和养分含量。根据双因素方差分析的F值,土壤pH、水溶性碳、全氮、水溶性氮和速效钾含量受覆盖厚度的影响较大,而有机碳和有效磷含量则受煤矸石粒径的影响较大。覆盖厚度为4 cm（T1）时,土壤pH的范围为7.81—8.38,较对照显著降低;覆盖厚度为16 cm（T2）时,土壤pH的范围为9.08—9.11,较对照显著升高。覆盖厚度越大且粒径越小,土壤有机碳、水溶性碳、全氮、水溶性氮和速效钾含量越高,而有效磷含量则越低。聚类分析统计结果显示,类别Ⅲ（包含T1P1、T2P2和T2P4）的有机碳、水溶性碳、全氮、水溶性氮和速效钾含量均值较对照分别提高124.42%、142.01%、66.67%、99.58%和49.12%。该研究中矿区土壤与煤矸石的盐分组成特征均以Na₂SO₄为主,虽然覆盖处理的土壤总盐量显著高于对照,但煤矸石覆盖未对土壤造成盐害。在生产应用中,可优先考虑应用厚度为16 cm、粒径为1—4 cm的煤矸石覆盖矿区土壤。

关键词: 煤矸石, 覆盖厚度, 粒径, 养分特征, 盐分特征, pH