Crop residue management in arable cropping systems under a temperate climate. Part 2: Soil physical properties and crop production. A review

Introduction. Residues of previous crops provide a valuable amount of organic matter that can be used either to restore soil fertility or for external use. A better understanding of the impact of crop residue management on the soil-water-plant system is needed in order to manage agricultural land sustainably. This review focuses on soil physical aspects related to crop residue management, and specifically on the link between soil structure and hydraulic properties and its impact on crop production. Literature. Conservation practices, including crop residue retention and non-conventional tillage, can enhance soil health by improving aggregate stability. In this case, water infiltration is facilitated, resulting in an increase in plant water availability. Conservation practices, however, do not systematically lead to higher water availability for the plant. The influence of crop residue management on crop production is still unclear; in some cases, crop production is enhanced by residue retention, but in others crop residues can reduce crop yield. Conclusions. In this review we discuss the diverse and contrasting effects of crop residue management on soil physical properties and crop production under a temperate climate. The review highlights the importance of environmental factors such as soil type and local climatic conditions, highlighting the need to perform field studies on crop residue management and relate them to specific pedo-climatic contexts

Crop residue management in arable cropping systems under temperate climate. Part 1: Soil biological and chemical (phosphorus and nitrogen) properties. A review

Introduction. Interacting soil organisms support biological processes that participate in soil functions, organic matter decomposition, and nutrient cycling. Earthworms and microorganisms play a range of beneficial roles in agricultural systems, including increased organic matter mineralization, nutrient cycling, and soil structure stabilization. Literature. The following aspects of crop residue management effects are examined in this paper: (i) earthworm composition and structure; (ii) soil microbial communities; and (iii) phosphorus (P) and nitrogen (N) element availability and distribution in the soil profile. Conventional tillage (ploughing) is often reported to generate decreased soil organism abundance and diversity, primarily earthworms and microorganisms, as well as a uniform distribution of the nutrients P and N within the ploughed soil horizon. Soil residue incorporation of mineral particles can maintain P and N levels, however returning soil also increases aeration and the activation of microbial activity. Hence, comparisons of tillage effects on soil biological functioning and nutrient cycling remain unclear. Conclusions. This review highlights the challenges in establishing definitive evidence regarding the effects of crop residue management on soil organisms and nutrient dynamics. The studies examined reported variability in soil and climate, and the complexity of soil processes contributed to the absence of clear findings. Further research is required under temperate climate conditions

Distinct communities of Cercozoa at different soil depths in a temperate agricultural field.

Protists are the most important predators of soil microbes like bacteria and fungi and are highly diverse in terrestrial ecosystems. However, the structure of protistan communities throughout the soil profile is still poorly explored. Here, we used Illumina sequencing to track differences in the relative abundance and diversity of Cercozoa, a major group of protists, at two depths; 10-30 cm (topsoil) and 60-75 cm (subsoil) in an agricultural field in Germany. At the two depths, we also distinguished among three soil compartments: rhizosphere, drilosphere (earthworm burrows) and bulk soil. With increasing depth, we found an overall decline in richness, but we were able to detect subsoil specific phylotypes and contrasting relative abundance patterns between topsoil and subsoil for different clades. We also found that the compartment effect disappeared in the subsoil when compared to the topsoil. More studies are now needed to describe and isolate these possibly subsoil specific phylotypes and better understand their ecology and function

Agricultural management and pesticide use reduce the functioning of beneficial plant symbionts

We thank all the farmers and farm managers for allowing us to sample their fields and for completing our detailed questionnaires. We also thank A. Bonvicini, L. Schönholzer, M. Macsai, F. Tamburini, H. Gamper, S. Müller, D. Bürge, M. Zuber, S. Zhao, V. Somerville, A. Brugger, O. Scholz, D. Bugmann, R. Heiz, B. Seitz and M. Roser for help with field work, the design and execution of the greenhouse experiment and lab analyses. We also thank J. Helfenstein and the anonymous reviewers for valuable feedback on the manuscript. The Digging Deeper project was funded through the 2015–2016 BiodivERsA COFUND call for research proposals, with the national funders Swiss National Science Foundation (grant 31BD30-172466), Deutsche Forschungsgemeinschaft (317895346), Swedish Research Council Formas (contract 2016-0194), Ministerio de Economía y Competitividad (Digging_Deeper, Ref. PCIN-2016-028) and Agence Nationale de la Recherche (ANR, France; grant ANR-16-EBI3-0004-01).Phosphorus (P) acquisition is key for plant growth. Arbuscular mycorrhizal fungi (AMF) help plants acquire P from soil. Understanding which factors drive AMF-supported nutrient uptake is essential to develop more sustainable agroecosystems. Here we collected soils from 150 cereal fields and 60 non-cropped grassland sites across a 3,000 km trans-European gradient. In a greenhouse experiment, we tested the ability of AMF in these soils to forage for the radioisotope 33P from a hyphal compartment. AMF communities in grassland soils were much more efficient in acquiring 33P and transferred 64% more 33P to plants compared with AMF in cropland soils. Fungicide application best explained hyphal 33P transfer in cropland soils. The use of fungicides and subsequent decline in AMF richness in croplands reduced 33P uptake by 43%. Our results suggest that land-use intensity and fungicide use are major deterrents to the functioning and natural nutrient uptake capacity of AMF in agroecosystems.BiodivERsA COFUNDSwiss National Science FoundationDeutsche ForschungsgemeinschaftSwedish Research Council FormasMinisterio de Economía y CompetitividadAgence Nationale de la RechercheDepto. de Farmacología, Farmacognosia y BotánicaFac. de FarmaciaTRUEpu