Soil phosphorus drawdown by perennial bioenergy cropping systems in the Midwestern US
Soil phosphorus drawdown by perennial bioenergy cropping systems in the Midwestern US
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DOI：
10.1111/gcbb.13020
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发表时间：
2023-02
期刊：
影响因子：
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通讯作者：
M. Z. Hussain;S. Hamilton;G. Robertson
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文献类型：
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作者：
M. Z. Hussain;S. Hamilton;G. Robertson
在不施肥的情况下，多年生生物能源种植系统的收获减少了土壤养分储量，但养分下降的时间过程并不经常被调查。分析了柳枝稷、芒草（Miscanthus × P. maximowiczii）和杂交白杨（Populus nigra × P. maximowiczii）-以及免耕玉米（玉米; Zea mays L.）作为比较，所有这些都种植在美国密歇根州西南部的前农田上。只有玉米得到磷肥。玉米（谷物和秸秆），柳枝稷，芒草每年收获，而白杨收获后6年。土壤测试P（STP; Bray‐1方法）每年在土壤上部25 cm处进行测量。收获磷去除量由组织磷浓度和收获产量（或白杨年木质生物量增加）计算。淋溶估计为总溶解磷浓度在土壤溶液中取样根深度（1.25米），结合水文模型。到目前为止，施肥和收获是玉米磷收支的主导因素，收获磷去除主导了柳枝稷、芒草和白杨的磷收支，而大气沉积和淋溶损失相对不显着。由于显着的磷去除收获，柳枝稷，芒草，白杨的磷平衡是负的，并对应于减少STP，而磷肥补偿收获玉米中的磷去除，导致正的磷平衡。结果表明，不施磷肥的多年生作物收获从土壤中去除了遗留的磷，即使在曾经施过大量磷肥的土壤中，继续收获也会很快将磷降低到极限水平。因此，生物能源作物的广泛种植可能会改变农业景观中的磷平衡，最终需要磷肥，这可以通过从收获的生物质中回收磷来提供。
Without fertilization, harvest of perennial bioenergy cropping systems diminishes soil nutrient stocks, yet the time course of nutrient drawdown has not often been investigated. We analyzed phosphorus (P) inputs (fertilization and atmospheric deposition) and outputs (harvest and leaching losses) over 7 years in three representative biomass crops—switchgrass (Panicum virgatum L.), miscanthus (Miscanthus × giganteus) and hybrid poplar trees (Populus nigra × P. maximowiczii)—as well as in no‐till corn (maize; Zea mays L.) for comparison, all planted on former cropland in SW Michigan, USA. Only corn received P fertilizer. Corn (grain and stover), switchgrass, and miscanthus were harvested annually, while poplar was harvested after 6 years. Soil test P (STP; Bray‐1 method) was measured in the upper 25 cm of soil annually. Harvest P removal was calculated from tissue P concentration and harvest yield (or annual woody biomass accrual in poplar). Leaching was estimated as total dissolved P concentration in soil solutions sampled beneath the rooting depth (1.25 m), combined with hydrological modeling. Fertilization and harvest were by far the dominant P budget terms for corn, and harvest P removal dominated the P budgets in switchgrass, miscanthus, and poplar, while atmospheric deposition and leaching losses were comparatively insignificant. Because of significant P removal by harvest, the P balances of switchgrass, miscanthus, and poplar were negative and corresponded with decreasing STP, whereas P fertilization compensated for the harvest P removal in corn, resulting in a positive P balance. Results indicate that perennial crop harvest without P fertilization removed legacy P from soils, and continued harvest will soon draw P down to limiting levels, even in soils once heavily P‐fertilized. Widespread cultivation of bioenergy crops may, therefore, alter P balances in agricultural landscapes, eventually requiring P fertilization, which could be supplied by P recovery from harvested biomass.