Abstract
Soil abiotic and biotic interactions govern important ecosystem processes. However, the mechanisms behind these interactions are complex, and the links between specific environmental ...factors, microbial community structures, and functions are not well understood. Here, we applied DNA shotgun metagenomic techniques to investigate the effect of inorganic fertilizers N, P, K, and NPK on the bacterial community composition and potential functions in grassland soils in a 54-year experiment. Differences in total and available nutrients were found in the treatment soils; interestingly, Al, As, Mg, and Mn contents were variable in N, P, K, and NPK treatments. Bacterial community compositions shifted and Actinobacteria were overrepresented under the four fertilization treatments compared to the control. Redundancy analysis of the soil parameters and the bacterial community profiles showed that Mg, total N, Cd, and Al were linked to community variation. Using correlation analysis, Acidobacteria, Bacteroidetes, and Verrucomicrobia were linked similarly to soil parameters, and Actinobacteria and Proteobacteria were linked separately to different suites of parameters. Surprisingly, we found no fertilizers effect on microbial functional profiles which supports functional redundancy as a mechanism for stabilization of functions during changes in microbial composition. We suggest that functional profiles are more resistant to environmental changes than community compositions in the grassland ecosystem.
This study demonstrated that bacterial community composition but not functions shifted in long-term N-, P-, K- and NPK-fertilized grassland.
This study demonstrated that bacterial community composition but not functions shifted in long-term N-, P-, K- and NPK-fertilized grassland.
•We assess crop-livestock integration beyond the farm scale based on farm surveys and assessment.•Cooperating farms gain access to normally underutilised local resources.•Resources accessed via ...cooperation are mostly used to increase farm production intensity.•Recoupling crops and livestock via cooperation between farms generates few environmental benefits.•Cooperating farms are better equipped to grow in period after milk quota abolition.
The intensification of agriculture in Europe has contributed significantly to the decline of mixed crop-livestock farms in favour of specialised farms. Specialisation, when accompanied by intensive farming practices, leaves farms poorly equipped to sustainably manage by-products of production, capture beneficial ecological interactions, and adapt in a volatile economic climate. An often proposed solution to overcome these environmental and economic constraints is to recouple crop and livestock production via cooperation between specialised farms. If well-managed, synergies between crop and livestock production beyond farm level have the potential to improve feed and fertiliser autonomy, and pest regulation. However, strategies currently used by farmers to recouple dairy livestock and crop production are poorly documented; there is a need to better assess these strategies using empirical farm data. In this paper, we employed farm surveys to describe, analyse and assess the following strategies: (1) Local exchange of materials among dairy and arable farms; (2) Land renting between dairy and arable farms; (3) Animal exchanges between lowland and mountainous areas; and (4) Industrially mediated transfers of dehydrated fodder. For each strategy, cooperating farm groups were compared to non-cooperating farm groups using indicators of metabolic performance (input autonomy, nutrient cycling and use efficiency), and ecosystem services provision. The results indicate that recoupling of crop and dairy production through farm cooperation gives farmers access to otherwise inaccessible or underutilised local resources such as land, labour, livestock feed or organic nutrients. This in turn leads to additional outlets for by-products (e.g. animal manure). Farmers’ decisions about how to allocate the additional resources accessed via cooperation essentially determine if the farm diversifies, intensifies or expands operations. The key finding is that in three of the four crop-livestock integration strategies assessed, these newly accessed resources facilitated more intensive farming practices (e.g. higher stocking rate or number of milking cows per hectare) on cooperating dairy farms relative to non-cooperating, specialised dairy farms. As a consequence, cooperation was accompanied by limited environmental benefits but helped to improve resource use efficiency per unit of agricultural product produced. This article provides a critical step toward understanding real-world results of crop-livestock cooperation beyond the farm level relative to within-farm crop-livestock integration. As such, it brings practical knowledge of vital importance for policy making to promote sustainable farming.
Ecosystem responses to nitrogen (N) additions are manifold and complex, and also affect the carbon (C) cycle. It has been suggested that increased microbial carbon use efficiency (CUE), i.e. growth ...per C uptake, due to higher N availability potentially increases the stabilization rates of organic inputs to the soil. However, evidence for a direct link between altered microbial anabolism and soil organic C (SOC) stocks is lacking. In this study, unfertilized (control) and NPK-fertilized (NPK) treatments of seven temperate grassland experiments were used to test the hypothesis that fertilizer-induced differences in SOC stocks (ΔSOC) cannot be explained by differences in C input alone, but that microbial anabolism plays an important role in C sequestration. At two experimental sites, microbial CUE and related metabolic parameters was determined using an 18O labeling approach at two different incubation temperatures (10 °C and 20 °C). Fertilization effects on the abundance of Bacteria, Archaea and Fungi were also determined using quantitative PCR targeting the respective rRNA genes. Due to the availability of yield and belowground biomass data, the introductory carbon balance model (ICBM) could be used for all seven sites to estimate the contribution of C input to ΔSOC. A significantly higher microbial growth (+102 ± 6%), lower specific respiration (−16 ± 7%) and thus significantly higher CUE (+53 ± 21%) was found for the NPK treatments, which was consistent across experiments and incubation temperatures and correlated with measured root C:N ratios. Growth (+49 ± 5%) and respiration (+70 ± 9%) were increased by a higher incubation temperature, but this was not the case for CUE. The fungi to bacteria ratio changed significantly from 0.18 ± 0.02 (control) to 0.09 ± 0.02 (NPK). On average, only 77% (51% when excluding one extreme site) of observed ΔSOC was explained by C inputs. The optimized humification coefficient h of the model used to fit the observed ΔSOC was strongly correlated to differences in the root C:N ratio between the control and NPK treatments (R2 = 0.71), thus confirming a link between microbial anabolism and substrate C:N ratio. Furthermore, varying h directly by observed differences in CUE improved the model fit at the two sites investigated. This study provides direct evidence that CUE of soil microbial communities is relevant for SOC sequestration, and its dependency on soil N availability or substrate C:N ratio might allow for its inclusion in models without explicit microbial C pools.
•Mineral fertilization increased microbial growth per carbon uptake.•Modeling showed that higher inputs alone cannot explain soil carbon increase.•Optimized humification coefficients correlate with changes in substrate C:N ratio.•N availability increases microbial anabolism which contributes to soil C storage.•Incubation temperature had no effect on microbial carbon use efficiency.
There is an increasing demand for evaluating the impact of specialization in agriculture on soil carbon balance. The main aims of the study were (1) to model the impact of long-term changes in ...agriculture on soil organic carbon (SOC) stocks at regional level using the Rothamsted C model (RothC), (2) validate these results by conventional SOC analysis, and (3) to compare impacts of “as was” and “mixed farming system” scenarios on SOC trends. The study area covered 1800km2 of Dolnoslaskie province, Poland. The significant changes have occurred in this area since 60's. The production system has changed from the mixed crop-animal farming to highly specialized crop production.
We evaluated two scenarios. The starting point for both scenarios was the situation in 1960 (co-existing low intensity crop and animal production). The scenario S-1 reflected recorded changes in agriculture, namely slow transition into specialized and more intensive production with progressive simplification of crop rotation and decline in livestock density. Scenario S-2 constituted hypothetical continuation of the starting situation (i.e. low intensity crop and animal production).
In the period 1960–2014 SOC accumulation was observed in “as was” scenario (S-1) in almost all locations of the area characterized by low initial SOC content. The model outputs were then validated using SOC measurements in samples collected in two periods: 1960–1970 and 2010–2014. The modelled SOC stock explained 56% of variability of the measured SOC stock. Comparison of S-1 and S-2 scenarios revealed that re-introduction of mixed farming with current intensity of agricultural production has capacity for further increasing SOC stocks in the region.
•Soil carbon is accumulated under intensive crop production in low carbon soils.•Mixed farming systems provide potential for higher carbon sequestration.•Combining pedoclimatic and agronomy data enables SOC modelling at regional level.•Roth-C provides reliable long-term projections of SOC changes.
A matter of time Berendse, Frank; Geerts, Rob H. E. M.; Elberse, Wim Th ...
Diversity & distributions,
07/2021, Volume:
27, Issue:
7
Journal Article
Peer reviewed
Open access
Aim
High levels of nitrogen deposition have been responsible for important losses of plant species diversity. It is often assumed that reduction of ammonia and nitrogen oxide emissions will result in ...the recovery of the former biodiversity. In Western Europe, N deposition peaked between 1980 and 1988 and declined thereafter. In a 60‐year experiment in hay meadows, we tested the hypothesis that increasing and declining nitrogen deposition had negative, respectively, positive effects on plant species diversity.
Location
Wageningen, the Netherlands.
Method
Duplicated plots received different fertilization treatments from 1958 onwards (control, Ca, K, P, PK, N, NPK). Productivity, soil pH and species composition were measured at regular intervals. In the control plots, the correlations between N deposition, diversity, production and soil acidification were analysed. Subsequently, we tested whether the treatment effects (e.g. N addition and liming) confirmed the hypothesized interactions.
Results
In the control plots, soil pH, species diversity and the abundance of legumes and short forbs declined between 1958 and 1987 when atmospheric N deposition was high but recovered after 1987 when N deposition decreased. However, also in the N addition plots species diversity recovered partly after 1987, although the soil pH of the acidified soils in these plots did not. In addition, also in the limed plots diversity decreased rapidly during the first 30 years while in this treatment soil acidification was more than compensated.
Main conclusions
We conclude that declining N deposition resulted in the recovery of plant species diversity, but not in recovery of the former species composition. Time appears to be an additional, but crucial factor for the recovery of diverse, flowering meadows. Species not adapted to the new management conditions created at the start of the experiment disappeared during the first decades, while species fit for the new environment needed many years to establish.
Multifunctional land use has become a widely supported pathway for Europe's countryside. Brussels and the national governments stimulate farmers to integrate primary production with non-agricultural ...practices from which they can also benefit. In favour of this development different stakeholders are encouraged to collaborate to produce the so-called farmer-managed public goods. This paper explores critical success factors for the production and maintenance of these public goods. In two Dutch case study regions we show a chronology of major events from 1975 leading to a shift from primary agricultural production towards a successful multifunctional land use. We evaluated which critical success factors crucial for managing public goods manifest themselves in our case study regions. Besides six critical success factors described in literature (Property rights, Asymmetric information, Administrative complexity, Governance, Time lags and Market structure) four other factors appear to be crucial in governing farmer-managed public goods: (1) establishing a system of rewards; (2) a mix of governance forms; (3) visionary leadership with networks in both the public and the private sectors and (4) time for new ideas to mature and to build commitment among the actors.
In Western-Europe, agricultural practices have contributed to environmental problems such as eutrophication of surface and ground water, flooding, drought and desiccation of surrounding natural ...habitats. Solutions that reduce the impact of these problems are urgently needed. Common reed (
Phragmites australis
) is capable of sanitizing surface water and may function as green energy source because of its high productivity. Here, the results of an experiment in a constructed wetland in the Netherlands are presented where two different sanitation treatments were compared. Depending on the residence time and volume per unit area, reed is capable to reduce the total amount of nitrogen in the water with average efficiencies from 32 to 47% and the total amount of phosphorous with 27–45%. Although biomass production still varies largely between different parts of the constructed wetland, a rapid increase in biomass was observed since planting. Constructed wetlands with reed provide opportunities to improve water quality and reed produces enough biomass to serve as green energy source. Moreover, these wetlands also function as a flood water reservoir and are possibly advantageous for biodiversity. The optimal moment of reed harvesting depends on the goal of the owner. This moment should be chosen wisely, as it may have consequences for reed filter regeneration, biomass production, biodiversity, methane emission and water sanitation efficiency.
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