Short-term effects of grassland renovation on CO<SUB>2</SUB> exchange of grasslands in a temperate humid region

Abstract

To investigate the short-term effects of grassland renovation on carbon dioxide CO 2 exchange of intensively managed grasslands in Japan, we conducted CO 2 flux measurements during the renovation process by using the eddy covariance and closed chamber methods in 2007, 2012, and 2013. The flux measurements were conducted at three grassland fi elds: two fi elds used for cutting, one receiving only chemical fertilizer CF and the other receiving composted cattle manure CM annually, and one fi eld used for grazing GM . Chamber measurements revealed fl ushes of CO 2 after plowing 14.45 -23.94 μmol m 2 s 1 and subsequent disk harrowing 7.36 μmol m 2 s 1 , in CF followed by rapid drops of CO 2 flux, which were local and temporary phenomena. The mean CO 2 losses during renovation periods were calculated as 4.52 -4.74, 6.00 -6.81, and 4.57 g C m 2 d 1 in CF, CM, and GM, respectively; CF and CM calculation is based on eddy covariance measurements, including temporal fl ux variations and representing footprint areas. The amount of carbon input during renovation including non-harvested grass biomass stubble and roots and applied manure was estimated as 2.24 -3.50 and 6.17 -8.77 Mg C ha 1 in CF and CM, respectively. Among them, carbon derived from plowed roots and manure is presumably resistant in soil, contributing to long-term soil organic carbon SOC accumulation. Our results also indicate that grassland renovation work does not affect short-term net CO 2 loss signifi cantly, although it affects CO 2 emissions to a certain extent. We can therefore say that net CO 2 loss during renovation is mainly brought by the absence of vegetation in this site. Grasses contribute SOC accumulation through biomass allocation belowground; and it is thus recommended to shorten grassland renovation period, the duration without photosynthesis, to reduce CO 2 loss associated with grassland renovation.

Effects of farmyard manure application and grassland renovation on net ecosystem carbon balance in a temperate grassland: analysis of 11-year eddy covariance data

“…The same amount of chemical fertilizer was applied to each plot during renovation in both years to ensure adequate initial grass growth. For additional details on the renovation of the plots, see the work of Matsuura et al (2017).…”

“…Journal of Agricultural Meteorology 79 (1) , 2023 − 14 − Several studies have been conducted on the immediate effects (hours to days) of grassland renovation on C dynamics, reporting that CO 2 emissions increase immediately after soil disturbance and decrease only after hours ( Reicosky et al, 1997;Willems et al, 2011;Matsuura et al, 2017). The increased emissions are likely due to the physical release of CO 2 entrapped in soil pores or dissolved in soil water ( Reicosky and Lindstrom, 1995;Reicosky et al, 1997).…”

“…Farmers are advised to renovate grasslands to restore declining productivity based on several regional criteria for soil properties and the degree of weed invasion (Agricultural Production Bureau, 2006). In another study, we collected CO 2 flux measurements around grassland renovation work and found that renovation does not significantly affect immediate (hours to days) net C loss ( Matsuura et al, 2017). However, little is known about the longer-term (months to years) effects of renovation on C dynamics.…”

Greenhouse Gas Emissions from Cut Grasslands Renovated with Full Inversion Tillage, Shallow Tillage, and Use of a Tine Drill in Nasu, Japan

“…The soil is derived from volcanic ash; Kurashima et al [19] previously classified it as a loamy Entic Humudept, mixed, mesic [20]. The annual averages for ambient air temperature and precipitation were 12.2 • C and 1561 mm, respectively [21].…”