1. Departamento de Química y Análisis Agrícola, E.T.S.I., Agrónomos, U.P.M. , Ciudad Universitaria , s/n. 28040 , Madrid , Spain;2. Instituto de Ciencias Medioambientales del C.S.I.C , Madrid , Spain
Abstract:
The aim of the present paper is to assess the efficiency of several experimental fertilizers in a soil-plant system. The laboratory-prepared fertilizers consisted of granular urea coated with Kraft pine lignin. Five fertilizers were used with coatings differing in thickness and/or the addition of linseed oil as a sealing agent. The experiment was carried out in pots inside a glasshouse. The crop used was rye-grass. Results were compared with those from a urea control treatment without coating and a soil without fertilizer application. The dry matter yield and the N uptake by the plant were higher in the treatments with coated controlled release fertilizers (CRF) than in those with uncoated urea. There was a lower nitrogen loss through leaching when using CRF (34 to 68%) was used than when using uncoated urea (over 74%) was used. The N use efficiency was lower for urea than for coated fertilizers. This index increased with the thickness of the coating and the addition of the sealing agent.