In Mediterranean countries, where rainfall is scarce and irregular, intensive agriculture promotes erosion and nutrient losses from soil, ending eventually in contamination of water bodies. Wild shrubs may protect the soil against the erosivity of raindrops. However, some shrubs such as wild lavender are traditionally harvested by uprooting the entire plant. Thus, we studied here the impact of harvesting only a part of the plant biomass. Cultivating lavender, Lavandula lanata L., in erosion plots in Lanjarón, Granada, Spain, we studied the effect of two harvest intensities of 25% and 50% of the plant biomass, on soil erosion, runoff, nutrient loss (NPK) and soil-water dynamics. Our results show that decreasing the harvest intensity from 50% to 25% reduced soil loss by 67%: from 143 to 46 kg soil ha⁻¹yr⁻¹. Water runoff was also decreased by 59%: from 13 to 5 mm yr⁻¹. These findings demonstrate that the rational harvest of cultivated aromatic plants protected the soil against erosion due to the reduction of soil-particle detachment by raindrop impact, and consequently avoided mechanical soil movement. Further, decreasing the harvest intensity from 50% to 25% reduced N losses by 65%, P losses by 42% and K losses by 64%. Soil-water content at 5, 10 and 20 cm deep was also higher for a harvest intensity of 25% than for a harvest intensity of 50%. In conclusion, this study supports the cultivation of lavender instead of wild harvest, following a rational harvest of biomass for reducing erosion and pollution as well as conserving soil-water content.

中文翻译：

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通过降低在斜坡上生长的薰衣草的收获强度，大大减少侵蚀和养分流失

在降雨稀少且不规则的地中海国家中，集约化农业促进土壤侵蚀和养分流失，最终导致水体污染。野生灌木可以保护土壤免受雨滴侵蚀。但是，传统上通过拔除整个植物来收获一些灌木，例如野生薰衣草。因此，我们在这里研究了仅收获部分植物生物质的影响。在西班牙格拉纳达Lanjarón的侵蚀区种植薰衣草Lavandula lanata L.，我们研究了两种收获强度（分别为植物生物量的25％和50％）对土壤侵蚀，径流，养分流失（NPK）和土壤的影响-水动力学。我们的结果表明，将收获强度从50％降低到25％，可将土壤流失减少67％：从143千克土壤减少到46千克土壤^-1年- ^1年。径流也减少了59％：从13毫米yr ^-1降至5毫米yr ^-1。这些发现表明，由于雨滴的撞击减少了土壤颗粒的分离，合理收获的栽培芳香植物可以保护土壤免受侵蚀，从而避免了土壤的机械运动。此外，将收获强度从50％降低到25％，可将氮损失减少65％，将磷损失减少42％，将钾损失减少64％。收获强度为25％时，深5、10和20厘米处的土壤水分含量也高于50％时。总而言之，这项研究支持在合理收获生物量以减少侵蚀和污染以及保持土壤水分的基础上，进行薰衣草栽培，而不是野生收获。