An appraisal of the in situ soil-core technique for measuring nitrogen uptake by a young Pinus radiata plantation

• Published in: Soil biology & biochemistry 1989, Vol.21 (7), p.939-942
• Main Authors: Smethurst, P.J., Nambiar, E.K.S.
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Chemical, physicochemical, biochemical and biological properties; Fundamental and applied biological sciences. Psychology; Organic matter; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Pinus radiata; Soil science
• ISSN: 0038-0717; 1879-3428
• DOI: 10.1016/0038-0717(89)90084-9

N uptake by a weed-free Pinus radiata plantation growing on a sandy podzol between 8 and 37 months after planting was measured by an in situ soil-core technique and by biomass harvesting. As estimated by both techniques, N uptake ranged from 1 kg ha −1 between 8 and 15 months of age, to about 30 kg ha −1 between 26 and 37 months. There was close quantitative agreement between the two techniques for two of the four measurement periods, and reasonable and poor agreement for the other two periods. Over the entire 8–37 months, N uptake was estimated to be 61.6 and 51.2 kg ha −1 for the soil-core and harvest techniques, respectively. An ancillary experiment indicated that the frequency of core sampling (every 4–16 wk) did not greatly affect estimated rates of N mineralization. The in situ soil-core technique is useful for measuring annual N uptake by young P. radiata, but there is uncertainty about its value in estimating seasonal uptake.