New management systems are needed that enhance the sustainability of crop residue harvesting for use as feedstock in the emerging biofuel industry. We investigated whether a novel perennial cover crop management system, designed to overcome yield drag, would enhance sustainability of maize (Zea mays L.) residue harvesting. Overall the perennial cover crop treatments [Kentucky bluegrass (Poa pratensis L.) (BG) and creeping red fescue (Festuca rubra L.) (RF)] increased the soil potential mineralizable N (8.5%), decreased the loss of total soil organic C (10.1%) and N (6.5%) relative to the no-cover crop controls [with (RR) and without (RS) removal of crop residues]. Respired CO₂, measured during 28 day incubations, decreased in the following order: RF > RS ≈ BG > RR for both in-row and in-between-row samples implying high microbial activity under cover crop treatments. SPAD readings, growth stage, and end of season maize-stalk nitrate test results varied by site-year but were consistent with soil NH₄⁺/NO₃⁻ dynamics. Results indicate that competition between the maize and perennial cover crops for water and N resources was weather dependent. Although previous research documented that the management system employed was able to overcome the yield drag associated with perennial cover crops, in our study maize yields for the perennial cover crop treatments were only one-third the yields for the controls. Overall, we conclude that the perennial cover crop system is capable of enhancing the sustainability of maize residue harvesting, but more work is needed to overcome the yield drag which may be caused by perennial cover crops under some conditions.

中文翻译：

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多年生覆盖作物对土壤碳，氮和玉米生产力的影响

需要新的管理系统来增强作物残渣收获的可持续性，以用作新兴生物燃料行业的原料。我们调查了旨在克服产量拖累的新型多年生覆盖作物管理系统是否会增强玉米（Zea mays L.）残留物收获的可持续性。总体而言，多年生覆盖作物的处理[肯塔基州蓝草（Poa pratensis L.）（BG）和爬行红羊茅（Festuca rubra L.）（RF）]增加了土壤潜在矿化性氮（8.5％），减少了土壤总有机质的损失相对于无覆盖作物的对照[带（RR）和不带（RS）的农作物残留去除率]，C（10.1％）和N（6.5％）。呼吸的CO ₂在28天的培养中测量的，按以下顺序降低：对于行内和行间样品，RF> RS≈BG> RR暗示在被覆作物处理下微生物活性较高。SPAD读数，成长阶段，并通过网站，年变化季玉米秆硝酸盐测试结果的结束，但均与土壤NH一致的₄ ⁺ / NO ₃ ^-动力学。结果表明，玉米和多年生覆盖作物之间争夺水和氮资源的竞争取决于天气。尽管先前的研究表明使用的管理系统能够克服与多年生覆盖作物相关的产量拖累，但在我们的研究中，多年生覆盖作物处理的玉米产量仅为对照产量的三分之一。总的来说，我们得出的结论是，多年生覆盖作物系统能够增强玉米残渣收获的可持续性，但是还需要做更多的工作来克服在某些情况下多年生覆盖作物可能造成的单产拖累。