Grazed temporary grass‐clover leys in crop rotations can have a positive impact on soil quality under both conventional and organic agricultural systems

Abstract

Soil quality (SQ) is the ability of soil to provide ecosystem functions and services. Implementation of a certain agricultural system can affect SQ and therefore play an essential role in achieving sustainable agriculture. The aim of this study was to explore how agricultural systems (conventional vs. organic), grazing regime (non-grazed vs. grazed) and the different proportions of temporary grass-clover leys in crop rotations (ley time proportion, LTP) affect SQ within a mixed (cropping and pasture/dairy system) commercial farming enterprise in the UK. Seven SQ indicators were evaluated, including chemical (pH; available phosphorus (P); potassium (K)), physical (bulk density, BD; aggregate stability, AS) and biological (total carbon (C); microbial biomass carbon, MBC) sectors. All SQ indicators were measured at three depth intervals (0-0.15, 0.15-0.30, 0.30-0.60 m), except for AS and MBC, which were only considered for the topsoil (0-0.15 m). The findings reflected existing knowledge on the advantages of organic vs. conventional systems for SQ indicators, with the former showing higher MBC and similar K, BD, AS and C in the 0-0.30-m compared to the latter. Lower topsoil available P in organic systems can be related to the lack of measurements in all P pools. When grazing was included: (a) both agricultural systems showed higher topsoil available P, C and MBC; and (b) there was a

Effects of integrating grass‐clover leys with livestock into arable crop rotations on soil carbon stocks and particulate and mineral‐associated soil organic matter fractions in conventional and organic systems

“…The increase in the POM-C with an increased grazed ley time proportion (0-0.15 m) was in line with increases in soil aggregation for the same study sites where the same treatment was implemented (Zani et al, 2020). Even though Zani et al (2020) have also reported increased microbial biomass C with the implementation of grazing, these results altogether suggested that at least part of this POM is not being decomposed, potentially because of spatial constraints (i.e. POM-C is being occluded within soil aggregates).…”

“…For instance, whether a ley is used for hay meadow cutting or livestock grazing (i.e. ICL system) can change its nutrient inputs and dynamics (Zani et al, 2020), soil microbial community size, diversity and activities (Crème et al, 2018) and is therefore likely to affect soil C stocks. Under grazing, extra inputs through forage residues and animal dung, stimulation of root turnover and exudation and changes in plant species and composition, as well as in root growth quantity and dynamics, could enhance soil C stocks throughout the profile, although this is also dependent on several aspects, for example climate, soil type, grass species and/or grazing intensity/management (Assmann et al, 2014;Chen et al, 2015;McSherry & Ritchie, 2013;Pineiro et al, 2010).…”

Nutritional Benefits from Fatty Acids in Organic and Grass-Fed Beef

“…A 2020 Nature article analysing the external climate costs of food determined that external GHG costs are highest for both conventional and organic animal-based products (including eggs, poultry, ruminants and pork) compared to milk and plant-based foods [ 12 ]. Despite this grouping of all animal agriculture as ecologically unsustainable, there are clearly differences in environmental impact between production systems [ 5 , 13 , 14 ], especially when considering impacts beyond emissions, including biodiversity [ 13 , 15 ], soil health [ 13 , 16 ] and energy/land use [ 13 ].…”

The effect of agroecosystem management on the distribution of C functional groups in soil organic matter: A review

“…In a study by Ganjegunte et al ( 2005 ), the distribution of C functional groups in the humic and fulvic acids in soils was not significantly different under either continuous light (0.16–0.23 steers ha −1 ) and heavy grazing (0.56 steers ha −1 ) or no grazing for ~ 20 years; however, the O-alkyl groups were slightly greater in the humic acid fraction of the light grazing treatment compared to both the heavy grazing and grazing-free treatments. Several authors have also found that the more labile SOC fractions (i.e., light fraction C, microbial biomass C, and water-soluble OM) increase under grazing (e.g., Haynes 2000 ; Oduor et al 2018 ; Ruis et al 2017 ; Zani et al 2020 ). This is explained due to increased cycling of plant material and the return of ingested plant material by grazing animals in the form of manure (Haynes 2000 ).…”