Diversified arable cropping systems and management schemes in selected European regions have positive effects on crop production and soil organic carbon
Creators: name: Rosa, Francaviglia
name: Jorge, Álvaro-Fuentes
name: Claudia, Di Bene
name: Lington, Gai
name: Kristiina, Regina
name: Turtola Eila
Publisher: name: Zenodo
Year: 2019
Subjects: subject: Diversification
subject: Cropping systems
subject: Tillage
subject: Crop rotation
subject: Organic amendments
subject: Soil organic carbon
subject: 2
subject: 1
subject: 3
subject: 4
subject: 5
subject: 6

description: 1 Introduction<br> Traditional arable cropping systems in the EU have been progressively simplified to monocropping systems,<br> with high external inputs through mineral and organic fertilizers, pesticides and conventional tillage (CT).<br> Thus, various crop diversification strategies such as crop rotation, intercropping and multiple cropping, as<br> well as low-input management practices have been promoted to sustain crop productivity while maintaining<br> environmental quality and ecosystem services. Actually, European arable area has high opportunities for<br> sustainable intensification through crop rotation, conservation tillage (minimum (MT) or no-tillage (NT))<br> and fertilization management. It has been also argued that diversification of production systems can lead to<br> better food security (Scherer et al., 2018) and economic sustainability of farms (de Roest et al., 2018), since<br> it contributes to natural pest control, pollination, nutrient recycling, soil structure and fertility conservation,<br> carbon sequestration, and water provision.<br> In the Diverfarming project (www.diverfarming.eu), the preliminary objective was to identify, with an<br> exhaustive literature review, the best crop diversification systems and farming practices to be tested and<br> validated in the field experiments to be planned in the different European pedoclimatic regions.<br> Understanding the expected effects of diversified cropping systems and management options on the resilience<br> and sustainability of agroecosystems in different regions, may promote the adoption of appropriate practices<br> and help to select a suitable method for each production system and environment, thus improving farm<br> management and increasing revenues.<br> 2 Materials and Methods<br> We conducted a data-analysis to evaluate the expected effects of the existing alternatives for crop<br> diversification and environmentally-sound farming management for arable crops in four selected European<br> pedoclimatic regions (Atlantic, Boreal and Mediterranean North and South), and typical cropping systems<br> (fodder grains, leys and mixtures, autumn-winter and spring-summer cereals). The dataset included sitespecific<br> environmental data (e.g. mean annual temperature and rainfall), soil tillage (e.g. no-tillage, minimum<br> and conventional tillage), fertilization management (none, mineral, mixed, organic), cropping system<br> (monoculture, rotation, intercropping, multiple cropping), crop production e.g. grain in cereals and above<br> ground biomass in fodder crops (CP), soil organic carbon (SOC) concentration at the end of the experiment,<br> and soil texture group according to USDA classification. Data included in the analysis depended on the<br> following general criteria: study period (at least one full year), only field experiments (no laboratory or pot<br> experiments), and neither studies specific for GHGs emissions, soil biological and physical parameters, metaanalyses<br> nor modelling studies were considered. Moreover, studies providing SOC content by soil layers<br> under tillage management were also considered. The final selected comparisons were 1165 from a total of 80<br> references.<br> The diversified (Div) and the control (Cont) treatments of each experiment were evaluated based on the<br> percentage change of the considered response variable, i.e. CP, and SOC. Since we used the ratio between<br> the difference (Div – Cont) and the Cont, we could eliminate the differences due to the different CP levels<br> and SOC analytical methods among studies (Eqs. 1-2):<br> Percentage change (CP) = 100 × (CPDiv – CPCont) / CPCont (Eq. 1)<br> Percentage change (SOC) = 100 × (SOCDiv – SOCCont) / SOCCont (Eq. 2)<br> Changes of CP and SOC were analyzed evaluating the effects of crop diversification, tillage and fertilization<br> management, and further by environmental (e.g. climate) or soil parameters (e.g. texture). Data were<br> represented by Box-Whisker plots (central point means, and 95% confidence interval CI). Responses were<br> considered significantly different if their 95% CIs did not overlap, and significantly different from the<br> controls if the 95% CIs did not overlap with zero.<br> 3 Results<br> Compared to monoculture, diversified cropping systems with longer crop rotations (at least 3 years)<br> significantly increased CP by 12%, while the 2-years rotations showed a not-significant 5% increase. CP for<br> intercropping were 11% higher compared to monoculture, though not statistically different. The average<br> effect on CP of multiple cropping was 1%, close to zero (-0.4%) in the Mediterranean region while ranged<br> from -4.3% to 12.6% in the Boreal region (average 3.9%).<br> SOC increased by 13% as average in diversified systems compared with monoculture, and the introduction<br> of legume crops in the rotations significantly increased SOC by 13%. Average SOC increases were 11%<br> higher in semiarid conditions than in humid and sub-humid climates (about 3%).<br> In relation to conservation tillage, CP was 12% higher in NT compared with CT, and was more effective on<br> CP in silty clay loam soils and in arid and semi-arid climates. In addition, NT was more effective in increasing<br> SOC than MT. Significant SOC increases by conservation tillage management were found with organic and<br> mixed fertilization (27 and 5% respectively) and crop rotations (5%).<br> Results by soil layers showed an average SOC increase ranging from 14 to 45% in the top 15 cm with<br> conservation tillage management compared to conventional deep tillage, while SOC decreased by about 10%<br> as average in deeper soil layers below 15 cm.<br> In relation to fertilization management, organic fertilization with manure or slurry increased CP (37-40%),<br> and mineral fertilization was particularly effective with the introduction of cover crops (56%), combined with<br> crop residues (24%) or with manure and crop residues (41%). Furthermore, CP increased with crop residue<br> incorporation (39%) or mulching under conservation tillage (39%) and longer crop rotations (39%).<br> Compared to the control treatment with mineral fertilization, organic fertilization showed the highest and<br> significant SOC increases (25%). Fertilization average effect on SOC was higher for cereal crops in the<br> Mediterranean region (about 25%) compared to fodder crops in the Atlantic and Boreal areas (about 10%),<br> and in loamy textures (about 23%).<br> 4 Discussion and Conclusions<br> In our data-analysis, longer crop rotations resulted in higher CP compared to monoculture. Intercropping was<br> mainly adopted in the humid conditions of the Atlantic and Boreal regions and showed a general lower effect<br> on CP compared to traditional rotations. Results also showed the need of improvements in the management<br> of multiple cropping systems, as indicated by Bedoussac and Justes (2010). In general, results point to the<br> direction that conversion from the traditional monocropping systems, with intensive tillage and mineral<br> fertilization, to alternative systems based on cropping diversification through the use of crop rotations, notillage<br> and organic fertilization results in a better crop performance and in the accrual of soil C.<br> Diversification with longer rotations, NT and organic fertilization management increased both CP and SOC<br> in European arable systems. Notwithstanding, crop diversification and environmentally-sound farm<br> management strategies are often negatively perceived by farmers for a possible decrease in yields and<br> economic benefits that are often coupled with higher machinery investments. Globally, regional differences<br> related to climate and soil texture specific responses should be considered to target local measures to improve<br> soil management.
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