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首页> 外文期刊>Agriculture, Ecosystems & Environment: An International Journal for Scientific Research on the Relationship of Agriculture and Food Production to the Biosphere >Soil profile carbon and nutrient stocks under long-term conventional and organic crop and alfalfa-crop rotations and re-established grassland.
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Soil profile carbon and nutrient stocks under long-term conventional and organic crop and alfalfa-crop rotations and re-established grassland.

机译：长期常规和有机作物以及苜蓿作物轮作和重建的草地下的土壤剖面碳和养分储量。

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Soil carbon stocks are useful indicators of both C sequestration capacity and sustainability of agricultural systems. Yet, most investigations have only studied the effects of agricultural management on soil carbon in surface layers (<0.3 m). Current soil organic carbon (SOC), total soil nitrogen (TN) and plant available phosphorus (POlsen) to a depth of 1.2 m was measured at two long-term (9 and 18 years) farming systems experiments in southern Manitoba, Canada. Both experiments compared an annual-crop rotation, an alfalfa (Medicago sativa L.)/crop rotation and re-established perennial grassland. At one site the two cropping systems were managed conventionally as well as in adherence to organic farming guidelines, but without manure additions. Due to higher net primary productivity and higher carbon inputs, particularly below ground, SOC stocks (0-120 cm) were 21-65 t C ha-1 higher under the re-established grassland than cropping systems at the clay soil site after 18 years, but not at the site with sandy loam soil after 9 years. On the clay soil, 30-40% of the additional C in the soil profile under the re-established grassland was found below 30 cm indicating the capacity of deep plant roots to sequester C in the sub-soil. Using alfalfa cut for hay in crop rotations did not increase SOC or N stocks compared to annual crop rotations, but plant-available P concentrations were depleted, especially under organic management. SOC was 25-30 t C ha-1 lower under organic than conventionally managed cropping systems, due to lower inputs of plant C (0.8 t C ha-1 yr-1) over the life of the experiment. This highlights that without additional C inputs organic management can reduce SOC compared to conventional cropping systems unless C inputs are maintained which may require manure or compost additions.CAS Registry Numbers 7723-14-0
机译：土壤碳储量是固碳能力和农业系统可持续性的有用指标。但是，大多数研究仅研究了农业管理对表层土壤碳（<0.3 m）的影响。在两个长期（9年和18年）耕作系统中测量了当前土壤有机碳（SOC），土壤总氮（TN）和植物有效磷（P Olsen ）的深度为1.2 m在加拿大曼尼托巴南部进行实验。两个实验都比较了一年生作物轮作，紫花苜蓿（Medicago sativa L。）/作物轮作和重建的多年生草地。在一个站点上，按照常规方式以及遵守有机耕作准则的方式对这两种耕作系统进行了管理，但没有添加粪肥。由于较高的净初级生产力和较高的碳输入量，尤其是在地下，因此，重建后的草地上，SOC储量（0-120厘米）比种植系统高21-65 t C ha -1 18年后为黏土，但9年后不为沙壤土。在粘土土壤中，在重建后的草地下，土壤剖面中30％至40％的C被发现在30 cm以下，这表明深层植物根系吸收C在地下土壤中的能力。与年度轮作相比，在轮作中使用苜蓿切花干草不会增加SOC或N量，但可利用的P含量却减少了，特别是在有机管理下。由于有机碳的投入量较低（有机碳0.8 t C ha -1 yr > -1 ）。这突出表明，与常规种植系统相比，无需额外的C投入，有机管理就能降低SOC，除非保持C投入，这可能需要添加肥料或堆肥.CAS注册号7723-14-0

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