A review of soil carbon change in New Zealand's grazed grasslands. Issue 2 (3rd April 2017)

• Record Type: Journal Article
• Authors: Schipper, Louis A.; Mudge, Paul L.; Kirschbaum, Miko U. F.; Hedley, Carolyn B.; Golubiewski, Nancy E.; Smaill, Simeon J.; Kelliher, Francis M.
• Is Part Of: New Zealand journal of agricultural research. Volume 60:Issue 2(2017)
• Page Start: 93
• Page End: 118
• Publication Date: 2017-04-03
• Subjects: Carbon -- soil -- pasture -- management -- land use -- New Zealand -- grazed; Agriculture -- Periodicals; Agriculture -- New Zealand -- Periodicals; Animal culture -- Periodicals; Animal culture -- New Zealand -- Periodicals; 630.99305
• DOI: 10.1080/00288233.2017.1284134
• Languages: English
• ISSNs: 0028-8233

Abstract

ABSTRACT: Soil organic matter is a potential sink of atmospheric carbon (C) and critical for maintaining soil quality. We reviewed New Zealand studies of soil C changes after conversion from woody vegetation to pasture, and under long-term pasture. Soil C increased by about 13.7 t C ha −1 to a new steady state when forests were initially converted to pasture. In the last 3–4 decades, resampling of soil profiles demonstrated that under long-term pasture on flat land, soil C had subsequently declined for allophanic, gley and organic soils by 0.54, 0.32 and 2.9 t C ha −1 y −1, respectively, and soil C had not changed in the remainder of sampled soil orders. For the same time period, pasture soils on stable midslopes of hill country gained 0.6 t C ha −1 y −1 . Whether these changes are ongoing is not known, except for the organic soils where losses will continue so long as they are drained. Phosphorus fertiliser application did not change C stocks. Irrigation decreased carbon by 7 t C ha −1 . Carbon losses during pasture renewal ranged between 0.8 and 4.1 t C ha −1 . Some evidence suggests tussock grasslands can gain C when fertilised and not overgrazed. When combined to the national scale, different data sets suggest either no change or a gain of C, but with large uncertainties. We highlight key land-use practices and soil orders that require further information of soil C stock changes and advocate for a better understanding of underpinning reasons for changes in soil C.