Subsurface soil acidity is a serious constraint to crop production and is inherently difficult to correct through conventional application of lime. Thus, new approaches to ameliorate subsurface soil acidity are needed. A column leaching experiment was established to determine whether the plant residues, when combined with lime, could facilitate lime dissolution and alkalinity movement down soil columns (10 cm in diameter × 45 cm long) to ameliorate acid subsurface soil layers. Five plant residues from canola (Brassica nappus L.), field pea (Pisum sativum L.), lucerne (Medicago sativa L.), oats (Avena sativa L.) and vetch (Vicia villosa L.) (C/N ratios of 52, 13, 16, 53 and 12, respectively) were mixed with soil (18 g dry matter kg⁻¹) in the top of soil columns (0–10 cm) either limed (target pH 7 in CaCl₂) or non‐limed and incubated for 3 months at 25°C. Soil columns were leached six times over the 3‐month incubation period and destructively sampled at 1 and 3 months for chemical analysis. The soil amended with plant residues created favourable pH gradients and facilitated downward movement of alkalinity when lime was added. However, net increases in pH in the 10–12‐cm layer after 3 months were only observed in two non‐legume residue‐amended treatments (canola and oat residues, 0.22–0.43 pH unit increase), but not in three legume residue‐amended treatments (field pea, lucerne and vetch residues), although those treatments had the greatest pH increase in the short term (1 month). In conclusion, surface incorporation of lime in combination with plant residues accelerated the amelioration of subsurface acidity in the immediate zone (10–12 cm) below the amended layer. Canola and oat residues were superior in terms of increased soil pH over a longer term (3 months), possibly due to their higher C/N ratios.

中文翻译：

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当石灰和植物残渣结合在一起时，在酸性土壤柱上的碱度运动要比单独施用时更快。

地下土壤的酸度严重限制了农作物的生产，并且固有地难以通过常规施用石灰进行校正。因此，需要改善地下土壤酸度的新方法。建立了一个柱浸试验，以确定植物残渣与石灰结合后是否能促进石灰的溶解和碱度在土壤柱（直径10厘米×长45厘米）处向下移动，从而改善酸性地下土壤层。芥花油菜（芸苔属），豌豆（豌豆），卢塞恩（苜蓿），燕麦（燕麦属）和紫v（野豌豆）的五种植物残留L。）（C / N比分别为52、13、16、53和12）与土壤（18 g干物质kg ^-1）混合在石灰柱（目标为0-10 cm）的顶部CaCl _2中的pH 7）或未加热并在25°C下孵育3个月。在3个月的培养期内，对土壤柱进行了六次浸提，并在第1和3个月进行了破坏性采样，以进行化学分析。当添加石灰时，用植物残渣修正的土壤会产生有利的pH梯度，并促进碱度的向下移动。但是，仅在两个非豆科植物残渣改良处理（芥花籽和燕麦残渣，pH值增加0.22-0.43个单位）中观察到3个月后10-12cm层中pH的净增加，而在三个豆科植物残渣中未观察到修改的处理方法（豌豆，紫花苜蓿和紫etch残渣），尽管这些处理方法在短期内（1个月）pH值增加最大。结论，石灰与植物残渣的表面结合可以促进改良层下方紧邻区域（10-12厘米）的地下酸度的改善。在较长的时间（3个月）内，低芥酸菜籽和燕麦残留物在提高土壤pH值方面表现优异，这可能是由于其较高的C / N比。