Adapter les pratiques agricoles aux différentes conditions pédoclimatiques : un outil pour agriculteurs et conseillers

Les pratiques agricoles qui réduisent la quantité de carbone dans le sol peuvent perturber son activité microbienne, modifier sa structure, et sa capacité à fournir eau et nutriments aux cultures. Elles peuvent aussi limiter la capacité des sols agricoles à lutter contre le changement climatique. Le projet de recherche européen Catch-C s’est interrogé sur la capacité des pratiques agricoles alternatives à limiter ou contrebalancer ces problèmes. À partir des premiers résultats de l'analyse des effets de différentes pratiques en Europe, cet article nous présente la conception d'un outil d'aide à la décision pour les acteurs du monde agricole qui résume les avantages et inconvénients de ces modèles alternatifs, propose des recommandations validées scientifiquement, pour tendre vers une gestion durable des sols agricoles, sur lesquelles de futures politiques pourront se reposer

Slurry spreading on a silt loam soil : influence of tyre inflation pressure, number of passages, machinery choice and tillage method on physical soil quality and sugar beet growth

Soil compaction forms a major threat to the well-functioning of agricultural soils. This threat is primarily driven by the increasing wheel loads of modern farming machinery and the increased frequency of field operations in periods when the soil is moist to wet and thus more prone to compaction. The application of slurry in early spring can have a highly detrimental impact, certainly for a crop like sugar beet, which is sensitive to soil compaction. A one-year experiment was set up on silt loam soil in the Belgian loess belt to assess the short-term impact of this field operation on soil under conventional ploughing and under non-inversion tillage. Two types of farming machinery were compared: a widely used tractor-trailer combination and a less common self-propelled slurry spreader, with the latter having higher wheel loads. Both machines were operated according to common or standard practice and a practice that aims at preventing soil compaction. For the tractor-trailer, this was with tyre inflation pressure recommended for road traffic and field traffic, respectively, corresponding with high and low tyre inflation pressure. The self-propelled slurry spreader was operated under standard and crab steering, respectively. Lowering the tyre inflation pressure to the recommended level for field traffic limited soil compaction and sugar beet yield loss. Although the effects of crab steering were less pronounced, it lowered the impact on the soil by limiting the number of passages. The overall machinery effect remained limited. The heavier self-propelled slurry spreader did not significantly increase the level of soil compactness and reduce sugar beet yield compared to the more common tractor-trailer combination. Soil under conventional ploughing showed more soil compaction, while the effectiveness of reducing tyre inflation pressure as a prevention strategy was lower compared to non-inversion tillage. The tillage practice, however, did not have any overall influence on sugar beet yield

Short-term effects of cover crops and tillage methods on soil physical properties and maize growth in a sandy loam soil

Soil compaction is a serious threat to agricultural production because of an expanding agricultural mechanization. Conservation tillage and use of pioneer plants can be an environmentally solution to alleviate the adverse effects of soil compaction. Root penetration into compacted soil of two winter cover crops with different rooting patterns, i.e. tap-rooted white mustard (Sinapis alba L.), and fibrous-rooted winter rye (Secale cereal L.), and of maize (Zea mays L.) in the consecutive growing season was assessed. Additionally, the effects of two spring tillage methods were evaluated, i.e. strip tillage and intensive tillage (by mouldboard ploughing). Winter rye showed significantly higher root penetration than white mustard in the top 15 cm, while an opposite trend was observed at 20-45 cm depth. After one season, maize root penetration was significantly greater following white mustard than winter rye at 30-40 cm depth. Strip tillage, like intensive tillage, could sufficiently loosen soil for adequate maize growth even though maize root distribution was restricted to tilled rows in contrast with intensive tillage. In conclusion, white mustard already showed positive short-term effects on maize growth, whereas strip tillage did not negatively affect it. Combining both is a viable option to reduce the negative impact of soil compaction on maize growth

Feedstock mixture composition as key factor for C/P ratio and phosphorus availability in composts : role of biodegradation Potential, biochar amendment and calcium content

Agricultural soils in northwest Europe as well as in parts of the USA have excessive P levels. To meet European environmental standards on nutrient leaching in soils with a high P load, the total P content of manures and composts limits their application rate. The aim of the present study was to determine the effect of feedstock composition on C/P ratio and P availability in mature compost. A functional compost with a high C/P ratio and a high organic matter content is a valuable tool for maintaining soil fertility. We produced composts with C/P ratios of 60-180 and high organic matter contents, i.e., 43-72% on dry matter basis. P concentration in the compost increased and C/P ratio decreased due to mass reduction during the composting process, which was determined by the biochemical composition, i.e., the biodegradation potential of the feedstock mixture. The feedstock selection also had indirect effects on P availability due to its effect on compost characteristics such as pH, which strongly reduced the readily available P concentrations at > 8.5. Compost pH was found to be an important indicator for readily available P concentrations in the studied composts with between 7.1 and 9.4, and was positively related to total Ca content in the compost, indicating an interaction between Ca and P. In contrast, P availability was not related to the organic matter content of the composts. Mixing biochar (pyrolyzed organic matter) into the compost further reduced the readily available P in two types of compost by 10-64%, even after addition of a small amount of additional mineral P. This was observed for two types of biochar with different chemical composition. The reduction was higher for the biochar with the highest Ca, Fe and Al concentrations, indicating the role of these elements for P binding in the biochar-blended compost

Effects of soil wetness and tyre pressure on soil physical quality and maize growth by a slurry spreader system

Slurry spreaders are among the heaviest machines used for farming operations. The effects of soil wetness and tyre pressure on physical soil properties were evaluated by using a (similar to)5 Mg wheel load slurry spreader mounted on a tractor. The impacts were also compared with Terranimo (R) model predictions and X-ray micro-computed tomography (X-ray micro-CT) parameters. In the consecutive maize growing season, soil physical properties, total mineral nitrogen content and maize above biomass were evaluated additionally between in and out track positions. Immediately after traffic, penetration resistance (PR) was significantly higher (P 30 pm) of soil trafficked under moist conditions was different (P 0.05) between in- and out-track positions while above ground dry biomass of maize reduced with (similar to)7% at in-track positions

Assessing the consequences of policy measures on long-term agricultural productivity – Quantification for Flanders

Policy can influence the long-term agricultural resource productivity by stimulating/discouraging farmers to apply certain land use practices (LUP), as LUPs may affect the soil organic carbon (SOC) stock, hence influencing crop productivity. We introduce six policy strategies, each characterized by its own mix of LUPs, for the Flemish agricultural sector. Three strategies reveal the impact of the Common Agricultural Policy (CAP) in the past, while others reflect the potential of the CAP and the application of compost. We use the life cycle impact assessment indicators ‘SOC change’ and ‘biomass productivity loss’, which account for the impact of LUPs on SOC and yield, to assess the effects on long-term productivity. To avoid burden shifting, also the resource footprint is calculated. Several farm management systems (FMS) are distinguished, each characterized by a specific combination of farm type, agricultural region, rotation system and manure type. The results highlight that policies such as the CAP significantly contribute to a better SOC stock and (to a lesser extent) productivity. Furthermore, applying extra compost seems to be promising: it can result in an increasing resource productivity and reduced resource footprint. It is important to consider the resource footprint as only for one strategy the resource consumption outweighs the benefit (i.e. reduction in N fertilizer) in the short or medium term, while also being beneficial in terms of resource productivity. As the results differ per FMS, a differentiated approach is advisable when specific LUPs are stimulated in the context of sustainable farming