Changes in soil organic carbon in a clay loam soil following ploughing and reseeding of permanent grassland under temperate moist climatic conditions

Abstract

This study investigated changes in soil organic carbon (SOC) in a poorly drained clay loam soil under (i) permanent grassland (PG) over 7 years and (ii) after PG renovation over 2·5 years. The experimental area was divided into four blocks with four paddocks per block. Composite soil samples from each PG block were taken to 30‐cm depth on five occasions between 2004 and 2011. In June 2008, one paddock per block was renovated by ploughing and reseeding and sampled as above on the latter four occasions. Renovation decreased SOC (P < 0·05) by 32·2 t ha−1 in the 2·5 years following ploughing; the difference developed almost entirely (86%) in the first four months. Renovation had no effect on above‐ground productivity, standing root and stubble phytomass or on dissolved organic matter leaching. Therefore, soil respiration was considered to be a single potential pathway responsible for the SOC loss from renovated grassland. Although a simple linear regression indicated a tendency for PG to accumulate SOC, there was no evidence of recovery in SOC to previous levels following renovation during the study period. These results could have implications for greenhouse gas inventories in countries where PG is an important land‐use type.

Productivity and Topsoil Quality of Young and Old Permanent Grassland: An On-Farm Comparison

“…Besides an economic impact, grassland renewal has an environmental impact. Many studies show an increased emission of the greenhouse gasses N 2 O and CO 2 and leaching of nitrogen after ploughing grassland [8,[56][57][58][59][60][61][62]. Our study confirms that when grasslands contain at least 70% desirable grasses (i.e., Lolium perenne and Phleum pratense), long-term grass productivity does not increase and the NY N0 even decreases as a result of grassland renewal.…”

Grassland renovation has important consequences for C and N cycling and losses

“…Even after 25 years of grassland utilization following renovation, the soil organic C did not fully recover. Other recent experiments on sandy soils did not confirm the findings of Necpalova et al (2014). In experiments by Linsler et al (2013) turning an existing sward by ploughing and reseeding it with a grass mixture did not lead to a reduction in soil organic C in the topsoil layer compared to an untreated control sward.…”

“…Their results suggest that management-induced effects on key soil physical properties may have significantly greater implications for C sequestration in permanent grassland soils than infrequent reseeding events even when related to soil disturbance. After a renovation event with ploughing-up of grassland and immediate resowing, Necpalova et al (2014) found a considerable decrease in soil organic C (20% reduction) within a few months (Figure 3). Even after 25 years of grassland utilization following renovation, the soil organic C did not fully recover.…”

“…For renovation, the paddock was ploughed and reseeded with a perennial ryegrass white clover mixture. Differences between treatments were significant at p = 0.05 (after Necpalova et al, 2014) 0 2 4 6 8 Years after renovation Permanent Renovated Soil organic matter (t ha -1 ) management conditions (e.g., Milimonka & Jänicke, 2003;Müller & Hrabe, 2008;Pierre, Deleau, & Osson, 2013). The extent of the immediate change in vegetation after renovation depends on the amount of sward and topsoil disturbance prior to resowing.…”

Optimizing Iowa land use: Past perspectives for current questions

“…from an extended crop rotation, such as those occurring following multiple years of pasture or reduced tillage (Grandy and Robertson 2007;Necpálová et al 2013;Reicosky et al 1995). Furthermore, tillage generally creates a soil disturbance continuum with more aggressive practices disrupting long-term crop rotation benefits and leaving the soil prone to increased runoff and sediment loss (Reicosky 2015).…”