Gomez Muñoz, Beatriz4; Hinojosa, M. B.5; García-Ruiz, R.6
1 Section for Plant and Soil Sciences, Department of Plant and Environmental Sciences, Faculty of Science, Københavns Universitet2 Universidad de Castilla-La Mancha3 Universidad de Jaen4 Section for Plant and Soil Sciences, Department of Plant and Environmental Sciences, Faculty of Science, Københavns Universitet5 Universidad de Castilla-La Mancha6 Universidad de Jaen
Olive oil orchard occupies a great percentage of the cropland in southern Spain. Thus, changes in nitrogen (N) fertilization might have a great effect on N dynamics at least at regional scale, which should be investigated for a sustainable N fertilization program. In situ net N mineralization (NM) and nitrification (NN) were investigated during a year in comparable organic (OR) and conventional (CV) olive oil orchards of two locations differing their N input. Soil samples were collected in two soil positions (under and between trees canopy) and both buried-bags and soil core techniques were used to quantify both microbial rates. There were differences in NM and NN between sites mainly due to differences in soil total N (TN), and potential mineralisable N (PMN). In all cases NM and NN were higher in soils under tree canopy. NM and NN were higher in OR than in CV managed orchards in the location with high soil TN. Soil TN and PMN explained together a 50 % of the variability in soil N availability, which suggests that these two variables are good predictors of the potential of a soil to provide available N. The highest rates of soil N availability were found in spring, when olive tree demand for N was at its maximum. Annual soil N availability in olive groves was in all cases higher or similar than tree demand suggesting that soil annual supply of N should be taken into account in order to develop sustainable N fertilisation strategies for olive crops.
Nutrient Cycling in Agroecosystems, 2015, Vol 101, Issue 2, p. 223-239
Fertilisation; N dynamic; Organic and conventional olive crop; Soil N mineralization