caa a22 4500 477112196 CHVBK 20180405111612.0 cr unu---uuuuu 170330e19960501xx s 000 0 eng 10.1007/BF00029050 doi (NATIONALLICENCE)springer-10.1007/BF00029050 Elevated CO2 effects on carbon and nitrogen cycling in grass/clover turves of a Psammaquent soil [Elektronische Daten] [D. Ross, S. Saggar, K. Tate, C. Feltham, P. Newton] Effects of elevated CO2 (525 and 700 μL L−1), and a control (350 μL L−1 CO2), on biochemical properties of a Mollic Psammaquent soil in a well-established pasture of C3 and C4 grasses and clover were investigated with continuously moist turves in growth chambers over four consecutive seasonal temperature regimes from spring to winter inclusive. After a further ‘spring' period, half of the turves under 350 and 700 μL L−1 were subjected to ‘summer' drying and were then re-wetted before a further ‘autumn' period; the remaining turves were kept continuously moist throughout these additional three consecutive ‘seasons'. The continuously moist turves were then pulse-labelled with 14C-CO2 to follow C pathways in the plant/soil system during 35 days. Growth rates of herbage during the first four ‘seasons' averaged 4.6 g m−2 day−1 under 700 μL L−1 CO2 and were about 10% higher than under the other two treatments. Below-ground net productivity at the end of these ‘seasons' averaged 465, 800 and 824 g m−2 in the control, 525 and 700 μL L−1 treatments, respectively. in continuously moist soil, elevated CO2 had no overall effects on total, extractable or microbial C and N, or invertase activity, but resulted in increased CO2-C production from soil, and from added herbage during the initial stages of decomposition over 21 days; rates of root decomposition were unaffected. CO2 produced h−1 mg−1 microbial C was about 10% higher in the 700 μL L−1 CO2 treatment than in the other two treatments. Elevated CO2 had no clearly defined effects on N availability, or on the net N mineralization of added herbage. In the labelling experiment, relatively more 14C in the plant/soil system occurred below ground under elevated CO2, with enhanced turnover of 14C also being suggested. Drying increased levels of extractable C and organic-N, but decreased mineral-N concentrations; it had no effect on microbial C, but resulted in lowered microbial N in the control only. In soil that had been previously ‘summer'-dried, CO2 production was again higher, but net N mineralization was lower, under elevated CO2 than in the control after ‘autumn' pasture growth. Over the trial period of 422 days, elevated CO2 generally appears to have had a greater effect on soil C turnover than on soil C pools in this pasture ecosystem. Kluwer Academic Publishers, 1996 C cycling nationallicence elevated CO2 nationallicence microbial biomass nationallicence N mineralization nationallicence plant decomposition nationallicence soil respiration nationallicence Ross D. Landcare Research New Zealand, Private Bag 11052, Palmerston North, New Zealand aut Saggar S. Landcare Research New Zealand, Private Bag 11052, Palmerston North, New Zealand aut Tate K. Landcare Research New Zealand, Private Bag 11052, Palmerston North, New Zealand aut Feltham C. Landcare Research New Zealand, Private Bag 11052, Palmerston North, New Zealand aut Newton P. AgResearch Grasslands, Private Bag 11008, Palmerston North, New Zealand aut Plant and Soil Kluwer Academic Publishers; gopher://gopher.wkap.nl 182/2(1996-05-01), 185-198 0032-079X 182:2<185 1996 182 11104 https://doi.org/10.1007/BF00029050 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00029050 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Ross D. Landcare Research New Zealand, Private Bag 11052, Palmerston North, New Zealand aut NATIONALLICENCE 700 1- Saggar S. Landcare Research New Zealand, Private Bag 11052, Palmerston North, New Zealand aut NATIONALLICENCE 700 1- Tate K. Landcare Research New Zealand, Private Bag 11052, Palmerston North, New Zealand aut NATIONALLICENCE 700 1- Feltham C. Landcare Research New Zealand, Private Bag 11052, Palmerston North, New Zealand aut NATIONALLICENCE 700 1- Newton P. AgResearch Grasslands, Private Bag 11008, Palmerston North, New Zealand aut NATIONALLICENCE 773 0- Plant and Soil Kluwer Academic Publishers; gopher://gopher.wkap.nl/ 182/2(1996-05-01), 185-198 0032-079X 182:2<185 1996 182 11104 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer