Centro Universitario de plasencia, Univ. de Extremadura, Avda. Virgen delPuerto, 10600 Plasencia-Caceres, Spain.
J Environ Qual. 2011 May-Jun;40(3):853-9. doi: 10.2134/jeq2010.0165.
New sustainable agriculture techniques are arising in response to the environmental problems caused by intensive agriculture, such as nitrate leaching and surface water eutrophication. Organic fertilization (e.g., with sewage sludge) and agroforestry could be used to reduce nutrient leaching. We assessed the efficiency of establishing trees and pasture species in environmentally sensitive, irrigated Mediterranean grassland soils in controlling nitrate leaching. Four vegetation systems-bare soil, pasture species, cherry trees [ (L.) L.], and pasture-tree mixed plantings-and five fertilization treatments-control, two doses of mineral fertilizer, and two doses of organic fertilizer (sewage sludge)-were tested in a greenhouse experiment over 2 yr. In the experiment, the wet and warm climate characteristics of Mediterranean irrigated croplands and the plant-to-plant and soil-to-plant interactions that occur in open-field agroforestry plantations were simulated. Following a factorial design with six replicates, 120 pots (30-cm radius and 120 cm deep) were filled with a sandy, alluvial soil common in the cultivated fluvial plains of the region. The greatest pasture production and tree growth were obtained with sewage sludge application. Both pasture production and tree growth decreased significantly in the pasture-tree mixed planting. Nitrate leaching was negligible in this latter treatment, except under the highest dose of sewage sludge application. The rapid mineralization of sludge suggested that this organic fertilizer should be used very cautiously in warm, irrigated Mediterranean soils. Mixed planting of pasture species and trees, such as , could be a useful tool for mitigating nitrate leaching from irrigated Mediterranean pastures on sandy soils.
新的可持续农业技术正在出现，以应对集约化农业造成的环境问题，如硝酸盐淋失和地表水富营养化。有机施肥（例如，利用污水污泥）和农林复合可以减少养分淋失。我们评估了在环境敏感的、灌溉的地中海草原土壤中种植树木和牧草品种以控制硝酸盐淋失的效率。在一个 2 年的温室实验中，测试了四种植被系统——裸地、牧草品种、樱桃树（L.）和牧草地-树混植，以及五种施肥处理——对照、两种矿物肥剂量和两种有机肥（污水污泥）剂量。在实验中，模拟了地中海灌溉农田的湿润温暖气候特征以及在开阔地农林复合种植园中发生的植物间和土壤-植物间的相互作用。采用六重重复的析因设计，在 120 个盆（30 厘米半径和 120 厘米深）中装满了该地区冲积平原常见的沙质冲积土。施用污水污泥可获得最大的牧草产量和树木生长。在牧草地-树混植中，牧草产量和树木生长均显著下降。除了在最高剂量的污水污泥施用量下，该处理中的硝酸盐淋失可以忽略不计。污泥的快速矿化表明，这种有机肥在温暖的灌溉地中海土壤中应谨慎使用。在沙质土壤上，种植牧草品种和树木（如）的混植可能是减轻灌溉地中海草原硝酸盐淋失的有用工具。
