Burgos Pilar, Madejón Engracia, Cabrera Francisco
Instituto de Recursos Naturales y Agrobiología de Sevilla, CSIC, Seville, Spain.
Waste Manag Res. 2006 Apr;24(2):175-82. doi: 10.1177/0734242X06062876.
Organic wastes can be recycled as a source of plant nutrients, enhancing crop production by improving soil quality. However, the study of the dynamic of soil nutrient, especially the N dynamic, after soil application of any organic material is vital for assessing a correct and effective use of the material, minimizing the losses of nitrate in leachates and avoiding the negative environmental effects that it may cause in groundwater. To estimate the effect of three organic materials, a municipal solid waste compost (MWC), a non-composted paper mill sludge (PS), and an agroforest compost (AC) on the N dynamic of a sandy soil two experiments were carried out: an incubation experiment and a column experiment. The incubation experiment was conducted to estimate the N mineralization rate of the different soil-amendment mixtures. The soil was mixed with the organic amendments at a rate equivalent to 50,000 kg ha(-1) and incubated during 40 weeks at constant moisture content (70% of its water-holding capacity) and temperature (28 degrees C) under aerobic conditions. Organic amendment-soil samples showed an immobilization of N during the first weeks, which was more noticeable and longer in the case of PS-treated soil compared to the other two amendments due to its high C/N ratio. After this immobilization stage, a positive mineralization was observed for all treatment, especially in MWC treated soil. Contemporaneously a 1-year column (19 cm diameter and 60 cm height) experiment was carried out to estimate the nitrate losses from the soil amended with the same organic materials. Amendments were mixed with the top soil (0-15 cm) at a rate equivalent to 50,000 kg ha(-1). The columns were periodically irrigated simulating rainfall in the area of study, receiving in total 415 mm of water, and the water draining was collected during the experimental period and analysed for NO3-N. At the end of the experimental period NO3-N content in soil columns at three depths (0-20, 20-35 and 35-50 cm) was determined. The nitrate concentration in drainage water confirmed the results obtained in the incubation experiment: nitrate leaching was higher in soil treated with MWC due to its higher N-mineralization rate. Nevertheless, the nitrate losses represented a low amount compared with the total nitrogen added to soil. No clear signs of water-draining contamination were observed during the first year after the application of AC and PS; however, the nitrate leaching in soil treated with MWC slightly exceeded the limit allowed for the Drinking Water Directive 98/83/CE.
有机废物可作为植物养分来源进行回收利用，通过改善土壤质量提高作物产量。然而，研究土壤施用任何有机物料后土壤养分的动态变化，尤其是氮素动态，对于评估该物料的正确有效利用、最大限度减少渗滤液中硝酸盐的损失以及避免其可能对地下水造成的负面环境影响至关重要。为了评估三种有机物料，即城市固体废弃物堆肥（MWC）、未堆肥的造纸厂污泥（PS）和农林复合堆肥（AC）对砂质土壤氮素动态的影响，开展了两项实验：一项培养实验和一项柱体实验。培养实验旨在估算不同土壤改良剂混合物的氮矿化率。将土壤与有机改良剂按相当于50,000 kg·ha⁻¹的比例混合，并在有氧条件下于恒定湿度（田间持水量的70%）和温度（28℃）下培养40周。有机改良剂 - 土壤样品在最初几周表现出氮的固定，与其他两种改良剂相比，PS处理的土壤中这种现象更明显且持续时间更长，这是由于其碳氮比高。在这个固定阶段之后，所有处理都观察到了正向矿化，尤其是在MWC处理的土壤中。同时，进行了为期1年的柱体实验（直径19 cm，高60 cm），以估算用相同有机物料改良的土壤中的硝酸盐损失。将改良剂按相当于50,000 kg·ha⁻¹的比例与表层土壤（0 - 15 cm）混合。定期对柱体进行灌溉以模拟研究区域的降雨，总共灌溉415 mm水，并在实验期间收集排水并分析其中的NO₃-N。在实验期结束时，测定了土壤柱体三个深度（0 - 20、20 - 35和35 - 50 cm）处的NO₃-N含量。排水水中的硝酸盐浓度证实了培养实验的结果：由于MWC处理土壤的氮矿化率较高，其硝酸盐淋失量更高。然而，与添加到土壤中的总氮量相比，硝酸盐损失量较低。在施用AC和PS后的第一年，未观察到明显的排水污染迹象；然而，MWC处理土壤中的硝酸盐淋失量略超过了欧盟饮用水指令98/83/CE规定的限值。
