A substantial proportion of soil carbon (C) is commonly lost following cultivation of soil and in the transition of pastures to crops. Incorporation of plant residues with nutrient addition (nitrogen, phosphorus and sulphur) may reduce these losses. We investigated the impact of initial soil fertility and supplementary nutrient addition on breakdown of sugarcane residue and associated changes in soil C following a pasture to crop transition. The legume-based pasture was previously managed with fertilizer to develop soils with high and low C. The soils were cultivated with sugarcane mulch (10 Mg ha⁻¹), a C4 crop residue that enabled isotopic ¹³C tracking, with or without nutrients and sown to a triticale crop [Triticale (× Triticosecale)]. Higher soil fertility with additional nutrients reduced the decrease in total soil C as a proportion of the initial C (14.9% compared to 21.8% without nutrients) to 100 mm depth. Supplementary nutrient addition also resulted in lower physical recovery of sugarcane mulch after 105 days (38.2% in high fertility with nutrients, compared to 97% recovery in low fertility no-nutrient). A larger decline of ¹³C from the total soil in the high fertility nutrient treatment was similarly observed, compared to low fertility without nutrients (decreases of 47 and 38 mg ¹³C kg⁻¹ soil, respectively). More fertile pastures with tactical nutrient addition was an effective means for reducing the loss of C during transition to crop.

中文翻译：

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残留物掺入后土壤肥力和养分介导土壤碳动态

在土壤耕种后以及从牧场过渡到农作物时，通常会损失大量的土壤碳（C）。将植物残留物与营养物（氮，磷和硫）的掺入可以减少这些损失。我们调查了从牧场开始向作物过渡后土壤初始肥力和添加养分对甘蔗渣分解和土壤碳相关变化的影响。以前使用肥料管理基于豆类的牧场，以发展高碳和低碳土壤。土壤用甘蔗覆盖物（10 Mg ha ^-1）耕种，这是一种能够进行同位素¹³ C追踪的C4作物残渣，有或没有养分，播种到黑小麦作物[小黑麦（×小黑麦属）]。较高的土壤肥力和更多的养分可以减少土壤总碳的减少，降低的比例为初始土壤C的比例（14.9％，而没有养分的21.8％）降至100毫米深度。补充营养元素还导致甘蔗覆盖物在105天后的物理恢复较低（高营养水平下为38.2％，而低营养水平则为97％）。与没有养分的低肥力相比，在高肥力的养分处理中相似地观察到总土壤中¹³ C的下降幅度更大（分别降低47 C和38 mg  ¹³ C kg ^-1土壤）。加上战术营养素的更肥沃的牧场是减少过渡到作物过程中碳损失的有效手段。