University of Extremadura, Forestry School of Plasencia The role of trees for Nitrate leaching after Organic and Mineral fertilization ML López-Díaz, G Moreno, V Rolo

Introduction Underground water Agriculture Nitrate leaching Directive 80/788/CEE Directive 91/676/CEE Fertilization rate Irrigation systems

Introduction PROBLEM Nitrate leaching SOLUTION Agroforestry Systems Organic Fertilization Tree – pasture root systemGradual N mineralization LIXIVIATED NITRATE

Soil NitratePasture Fertilization Treatments Tree Aims

Materials and Methods Systems D  Bare soil P  Pasture S  Tree SP  Tree & pasture Fertilization NF  No fertilize L  Sewage Sludge M  Mineral Greenhouse experiment n = pots: 20 cm Ø, 120 cm height Soil: pH 4.7; 1 g N kg -1 ; 10 g Organic C kg -1

Materials and Methods Parameters analyzed Tree Basal DiameterPasture Production Nitrate Lixiviated Profile of Nitrate Content Rooting profile

Results & Discussion NO 3 - Content in the Soil Profile NO 3 -, mg / Kg soil Depth, cm Systems D  Bare soil P  Pasture S  Tree SP  Tree & pasture Depth, cm NO 3 -, mg / Kg soil Fertilization Treatments NF  No fertilize M  Mineral L  Sewage Sludge

Results & Discussion Nitrate Lixiviation and Fertilization Rates Fertilization Nitrate, g /m 2 Fertilization Treatment Date Nitrate, g /m 2 Fertilization Treatments NF  No fertilize M  Mineral L  Sewage Sludge

Nitrate Lixiviation and Systems Results & Discussion System Nitrate, g /m Fertilization Date Nitrate, g /m 2 Systems D  Bare soil P  Pasture S  Tree SP  Tree & pasture

Results & Discussion Root system Tree Pasture

Results & Discussion Production

Conclusions The use of agroforestry systems are a good tool to control the nitrate leaching adjusting properly the fertilization rate to minimize the competitive effect between vegetation layers

THANKS FOR YOUR ATTENTION Victor Rolo