Impact of harvest residues, fertilisers and N-fixing plants on growth and nutritional status of young Eucalyptus globulus plantations under Mediterranean conditions

摘要

Growth and nutritional status of young plantsof Eucalyptus were assessed in a field trial, under differentscenarios of harvest residue management and nutrientavailability. Treatments were as follows: incorporation ofharvest residues into the soil by harrowing (I); I with Nfertiliser application (IF); I with leguminous, Lupinusluteus L., seeding (IL); removal of harvest residues (R); Rwith N fertiliser application (RF); R with leguminousseeding (RL); distribution of harvest residues on the soilsurface (S); S with N fertiliser application (SF). Treatmentswere replicated four times in four blocks with a fullyrandomised design. Tree growth (height and diameter atbreast height) was measured and understory biomassdestructively recorded. Tree nutritional status was assessedby foliar analysis (N, Ca, Mg, P, K and leaf area). Significantdifferences in growth between I, R and S treatmentswere only detected at early stage. Intercropping withLupinus decreased tree growth during the early phase, butafter 5 years growth was similar to that measured in the Iand R treatments. Application of fertiliser enhanced treegrowth especially when harvest residues were retained onthe soil surface. Combining incorporation of harvest residueswith fertiliser application (IF) was the best option toincrease tree growth, which was significantly greater thanin the R and S. Initially, leaf N was positively affected bythe leguminous (RL and IL), but, after the first fertiliserapplication (1 year after planting), greater N was observed in the IF, RF and SF, the difference decreasing graduallyover the following years