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

Abstract

Renewing agricultural grasslands for improved yields and forage quality generally involves eliminating standing vegetation with herbicides, ploughing and reseeding. However, grassland renewal may negatively affect soil quality and related ecosystem services. On clay soil in the north of the Netherlands, we measured grass productivity and soil chemical parameters of ‘young’ (5–15 years since last grassland renewal) and ‘old’ (>20 years since last grassland renewal) permanent grasslands, located as pairs at 10 different dairy farms. We found no significant difference with old permanent grassland in herbage dry matter yield and fertilizer nitrogen (N) response, whereas herbage N yield was lower in young permanent grassland. Moreover, the young grassland soil contained less soil organic matter (SOM), soil organic carbon (C) and soil organic N compared to the old grassland soil. Grass productivity was positively correlated with SOM and related parameters such as soil organic C, soil organic N and potentially mineralizable N. We conclude that on clay soils with 70% desirable grasses (i.e., Lolium perenne and Phleum pratense) or more, the presumed yield benefit of grassland renewal is offset by a loss of soil quality (SOM and N-total). The current practice of renewing grassland after 10 years without considering the botanical composition, is counter-productive and not sustainable.

Nitrous oxide emissions from grass–clover swards as influenced by sward age and biological nitrogen fixation

“…Despite the 2-year-old sward having a higher proportion of L. perenne, grassland renovation did not result in improved yields and forage quality. This is in agreement with several other reported studies of investigated swards where there were only minor signs of deterioration prior to restoration (Iepema et al, 2020;Velthof et al, 2010;Vliegher & Carlier, 2007). Furthermore, yield and quality improvements following grassland renovation are likely to be limited to the more intensively managed systems.…”

De potentie voor koolstofvastlegging in de Nederlandse landbouw

“…Naast het positieve effect op het organischestofgehalte tonen Iepema et al (2020) tevens aan dat het voorkomen van scheuren van grasland een positief effect heeft op de bodemkwaliteit. (Maltas et al, 2018).…”

Extending grassland age for climate change mitigation and adaptation on clay soils

“…The study was conducted in 2014, on marine clay soil (Haplic Fluvisol; FAO, 2015) at 10 dairy farms in the north of the Netherlands. At each farm, a young (5–15 years since grassland renewal) and an old (> 20 years since grassland renewal) grassland were selected and compared with farm as a block factor (for more information about the selected grasslands, see Supplementary Material, Table S1 and Iepema et al, 2020). Grassland age (years since the latest renewal) was recorded by interviewing the farmers, except for two very old (older than 30 years) grasslands where the age was conservatively set at 30 years because the exact year of renewal was not known.…”

“…Adjacent to the non‐fertilized plot, three fertilization subplots of 10 × 3 m were installed to determine grass productivity in relation to chemical soil quality. The results of this experiment were published by Iepema et al (2020) with more details about the selected grasslands.…”

“…In an earlier paper we reported the effects of permanent grassland age on grass productivity in relation to chemical soil quality in an on‐farm experiment (Iepema et al, 2020). Here we report from the same experiment on the effect of permanent grassland age (young versus old grassland) on (1a) carbon stock and (1b) the rate of carbon sequestration on marine clay topsoil (0–10 cm), which can contribute to climate change mitigation.…”