Development of elephant grass in response to irrigation with different levels of domestic sewage

ABSTRACT The agricultural use of alternative water sources of inferior quality, such as reusing the water from domestic sewage, is seen as one way of increasing water availability, in addition to allowing the reuse of nutrients and organic matter, thereby helping to maintain the fertility and productivity of the soil. The aim of this study, therefore, was to evaluate growth, productivity and nutrition in elephant grass irrigated with different combinations of treated domestic effluent and well water. The experimental design was of randomised blocks, with six treatments and four replications, containing 10 plants in each plot. The treatments comprised five combinations of treated domestic effluent (TDE) and well water (WW): T1 (100% WW), T2 (25% TDE + 75% WW), T3 (50% TDE + 50% WW), T4 (75% TDE + 25% WW), T5 (100% TDE), and an additional treatment (T6) of 100% well water + a mineral fertiliser (NPK) recommended for elephant grass. The following variables were analysed: number of leaves, stem diameter, number of tillers, plant height, leaf area, fresh and dry weight of the leaves and stems, fresh and dry weight production, and the macronutrient content of the aerial part of the plant. The treatments applying the greatest levels of TDE had the closest mean values to those obtained under the conventional treatment, while the treatments applying 50% or more TDE were statistically equal by Tukey’s test (p < 0.05) to the conventional treatment.摘要 采用生活污水再生水等劣质替代水源开展农业灌溉，既是提升水资源可用量的有效途径之一，同时可实现养分与有机质的循环利用，有助于维持土壤肥力与生产能力。因此，本研究旨在评估采用不同比例生活污水处理出水（treated domestic effluent, TDE）与井水（well water, WW）组合灌溉时，象草的生长状况、生产性能与营养品质。本实验采用随机区组设计，设置6个处理组与4次重复，每个小区种植10株象草。处理组共包含5种TDE与WW的配比组合：T1（100% WW）、T2（25% TDE + 75% WW）、T3（50% TDE + 50% WW）、T4（75% TDE + 25% WW）、T5（100% TDE），以及额外设置的T6组：100% WW + 象草推荐施用的氮磷钾（NPK）矿质肥料。本实验测定的指标包括：叶片数、茎秆直径、分蘖数、株高、叶面积、茎叶鲜重与干重、总产量鲜重与干重，以及植株地上部分的大量元素含量。结果显示，施用高比例TDE的处理组，其各项指标均值与常规处理组最为接近；而Tukey检验表明，TDE施用比例≥50%的处理组与常规处理组无统计学差异（p < 0.05）。