Interactie tussen boven- en ondergrondse organismen

Herstel van biodiversiteit is een moeilijk proces aangezien lang niet alle onderliggende mechanismen bekend zijn. Zo is niet bekend hoe boven- en ondergronds levende organismen elkaar beïnvloeden in hun interacties met planten en wat het effect daarvan is op de plantendiversiteit. Met behulp van een 'realistische' proefopstelling hebben we daar meer zicht op gekrege

Red clover varieties of Mattenklee type have higher production, protein yield and persistence than Ackerklee types in grass-clover mixtures

Dairy farmers have increased interest in multiyear red clover-ryegrass ley pasture swards because of their high productivity and protein concentration but the adoption of such mixtures has been restricted because of poor persistency of many red clover cultivars currently used. We aimed (i) to assess dry-matter yield (DMY), persistence and nutritive value of four Mattenklee and four Ackerklee cultivars and (ii) to investigate the underlying plant morphological traits. We conducted a 4-year field experiment with red clover-ryegrass mixtures, in combination with a short-term pot experiment in which the red clover cultivars were grown both in monoculture and in mixture with Lolium perenne L. In the field, Mattenklees showed higher production (on average 42% higher) and clover content (on average 34% higher) in the third and fourth year of production compared to Ackerklees. In the fourth year, Mattenklees had slightly lower digestibility and lower protein concentration compared to Ackerklees cultivars; however, the digestible DMY and the protein yield were higher for Mattenklees. Both persistence and nutritive value of the different red clover cultivars were closely correlated with plant morphological traits. For stem length, there was close correlation (r > .77) between the results from the pot experiment and the field experiment, suggesting that stem length may be an important trait for plant breeding.</p

Earthworms increase plant production: a meta- analysis

To meet the challenge of feeding a growing world population with minimal environmental impact, we need comprehensive and quantitative knowledge of ecological factors affecting crop production. Earthworms are among the most important soil dwelling invertebrates. Their activity affects both biotic and abiotic soil properties, in turn affecting plant growth. Yet, studies on the effect of earthworm presence on crop yields have not been quantitatively synthesized. Here we show, using meta-analysis, that on average earthworm presence in agroecosystems leads to a 25% increase in crop yield and a 23% increase in aboveground biomass. The magnitude of these effects depends on presence of crop residue, earthworm density and type and rate of fertilization. The positive effects of earthworms become larger when more residue is returned to the soil, but disappear when soil nitrogen availability is high. This suggests that earthworms stimulate plant growth predominantly through releasing nitrogen locked away in residue and soil organic matter. Our results therefore imply that earthworms are of crucial importance to decrease the yield gap of farmers who can't -or won't- use nitrogen fertilizer

Biochar application differentially affects soil micro-, meso-macro-fauna and plant productivity within a nature restoration grassland

Biochar is proposed as an option to sequester carbon (C) in soils and promote other soil-based ecosystem services. However, its impact on soil biota from micro to macroscale remains poorly understood. We investigated biochar effects on the soil biota across the soil food web, on plant community composition and on biomass production. We conducted a field experiment in a nature restoration grassland testing four treatments: two biochar types (herbaceous feedstock pyrolyzed at 400 °C or 600 °C – hereafter B400 and B600), and a positive (i.e. unpyrolysed biochar feedstock, hereafter Hay) and negative (no addition) control. Responses of plants and soil biota were evaluated one and three years after establishing the treatments. Soil pH and K concentrations increased significantly in the B600 treatment. Mite abundances were significantly higher in B400 whereas nematode abundances were highest in Hay (1st year) and lowest in B400 (3rd year). Other soil fauna groups (enchytraeids and earthworms) varied more between years than between treatments. Legume cover increased significantly in the biochar treatments but this effect was transient. Legumes, grasses and primary productivity also showed a statistically significant Treatment x Year interaction due to transitory effects that were no longer present by the 3rd year. Our results suggest that biochar produced from meadow cuttings and applied at the 10 t/ha rate cause transitory impacts on soil biota abundance and plant communities over the 3-year timeframe used for this experiment. Therefore, this type of biochar could potentially be used for soil carbon sequestration, with minimal impacts on soil biota abundance or diversity, within the groups studied here, or plant biodiversity and productivity. Further research is required to investigate the longer-term impacts of this potential soil C storage sink

Biochar application differentially affects soil micro-, meso-macro-fauna and plant productivity within a nature restoration grassland

Plant science

Soil Quality - a critical review

Sampling and analysis or visual examination of soil to assess its status and use potential is widely practiced from plot to national scales. However, the choice of relevant soil attributes and interpretation of measurements are not straightforward, because of the complexity and site-specificity of soils, legacy effects of previous land use, and trade-offs between ecosystem services. Here we review soil quality and related concepts, in terms of definition, assessment approaches, and indicator selection and interpretation. We identify the most frequently used soil quality indicators under agricultural land use. We find that explicit evaluation of soil quality with respect to specific soil threats, soil functions and ecosystem services has rarely been implemented, and few approaches provide clear interpretation schemes of measured indicator values. This limits their adoption by land managers as well as policy. We also consider novel indicators that address currently neglected though important soil properties and processes, and we list the crucial steps in the development of a soil quality assessment procedure that is scientifically sound and supports management and policy decisions that account for the multi-functionality of soil. This requires the involvement of the pertinent actors, stakeholders and end-users to a much larger degree than practiced to date

Soil-derived Nature's Contributions to People and their contribution to the un Sustainable Development Goals

This special issue provides an assessment of the contribution of soils to Nature's Contributions to People (NCP). Here, we combine this assessment and previously published relationships between NCP and delivery on the UN Sustainable Development Goals (SDGs) to infer contributions of soils to the SDGs. We show that in addition to contributing positively to the delivery of all NCP, soils also have a role in underpinning all SDGs. While highlighting the great potential of soils to contribute to sustainable development, it is recognized that poorly managed, degraded or polluted soils may contribute negatively to both NCP and SDGs. The positive contribution, however, cannot be taken for granted, and soils must be managed carefully to keep them healthy and capable of playing this vital role. A priority for soil management must include: (i) for healthy soils in natural ecosystems, protect them from conversion and degradation; (ii) for managed soils, manage in a way to protect and enhance soil biodiversity, health and sustainability and to prevent degradation; and (iii) for degraded soils, restore to full soil health. We have enough knowledge now to move forward with the implementation of best management practices to maintain and improve soil health. This analysis shows that this is not just desirable, it is essential if we are to meet the SDG targets by 2030 and achieve sustainable development more broadly in the decades to come. This article is part of the theme issue 'The role of soils in delivering Nature's Contributions to People'. © 2021 The Author(s)