Effect of liming and sewage sludge application on the botanical composition of a pasture grown under Pinus radiata

The objective of this experiment was to study the influence of sewage sludge and lime application on the botanical composition of a pasture established under a Pinus radiata D. Don plantation. Organic matter and nutrient sewage sludge content, principally nitrogen, indicated that it can be used as fertiliser. The experiment was conducted in the north-west of Spain. The soil was very acid (pH = 4.5) and had a very low nutrient level. It was sown as a grass mixture (25 kg ha(-1) of Lolium perenne, 10 kg ha(-1) of Dactylis glomerata and 4 kg ha(-1) of Trifolium repens) in autumn of 1997 under a five year old plantation of Pinus radiata at a density of 1,667 trees ha(-1). Treatments were no fertilisation (NF), three sewage sludge doses based on nitrogen contents (L1: 160 kg N ha(-1); L2: 320 kg N ha(-1); U: 480 kg N ha(-1)), with or without lime (2.5 t CaCO3 ha(-1)) and mineral fertilisation usually applied in this area (MIN: 40 kg N ha(-1), 120 kg P ha(-1) and 80 kg K ha(-1)). Fertiliser treatments were applied over a period of three years. Liming and sewage sludge fertilisation increased sown species contribution, especially Dactylis glomerata, due to soil fertility iimprovement. Trifolium repens and Lolium perenne presence was low because of shade conditions. Organic fertilisation reduced senescent material.