Agrarian legacy in soil nutrient pools of urbanizing arid lands
Agrarian legacy in soil nutrient pools of urbanizing arid lands
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城市化干旱地区土壤养分库中的农业遗产
DOI：
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
C. Redman
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文献类型：
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作者：
David B. Lewis;J. Kaye;C. Gries;A. Kinzig;C. Redman
当今世界范围内旱地城市的扩张消耗了耕地和本土生态系统，为研究人们现在居住的地方以前的土地使用痕迹提供了实验室。在美国凤凰城周围，我们比较了由农场改建的住宅庭院中的土壤养分库与原生沙漠中开发的庭院中的养分库。以前属于农业的庭院中的有机物、碳 (C)、氮 (N) 和可溶性离子含量是非农业庭院的 2 倍以上。土地转为住宅用途 40 年后，这些水池的水位仍然很高。目前的氮积累量（1.5 g m−2 yr−1）不受先前土地利用的影响，表明住宅施肥率和保留率不受先前土壤肥力的影响。在最近的农业历史中，土壤中生物可利用的无机磷 (Pav) 有所升高，但由于 Pav 在从未耕种过的庭院中积累，这一信号在住宅使用 10-30 年后消失。我们的研究结果表明，这是一种“直接农业遗产”，其中养分库的土地改良经受住了城市化，而不是“间接遗产”，其中当前的土地管理是由以前的土地利用塑造的。因此，旱地农业将物质隔离在土壤中，而且——我们还发现住宅土壤中的物质含量高于当代农业土壤——住宅用地的利用只会增加这些土壤已经承受的农业遗产。人类对干旱土地的密集使用可能会导致土壤物质库的增加，这种情况可能会造成全球后果。
Today's worldwide expansion of dry land cities consumes cultivated and native ecosystems, providing laboratories for investigating imprints of former land use in places where people now live. Around Phoenix, USA, we compared soil nutrient pools in residential yards converted from farms with nutrient pools in yards developed on native desert. Organic matter, carbon (C), nitrogen (N), and soluble ions were >2‐fold greater in yards that were previously agrarian than in yards that were not. These pools remain elevated 40 years after land conversion to residential use. Present N accumulation (1.5 g m−2 yr−1) is not affected by prior land use, suggesting that rates of residential fertilizer application and retention are not affected by antecedent soil fertility. Bioavailable, inorganic phosphorus (Pav) is elevated in soil with a recent agrarian past, but this signal disappears after 10–30 years of residential use owing to an accumulation of Pav in never‐farmed yards. Our results indicate a ‘direct agrarian legacy,’ wherein agrarian amendment of nutrient pools endures urbanization, more so than an ‘indirect legacy,’ wherein present land management is molded by former land use. Agriculture in dry lands thus sequesters material in soils, and—as we also found higher material contents in residential soils than in contemporary agrarian soils—residential land use simply adds to the agrarian legacy these soils already bear. Intense human use of arid lands may cause increases in material pools in soils, a condition with potential global consequence.