Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2024
Forfattere
Jens Leifeld Brieuc Hardy Alice Budai Lars Elsgaard Sonja Keel Florent levavasseur Zhi Liang Claudio Mondini Cesar Plaza Leonor RodriguesSammendrag
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Forfattere
Cornelya Klutsch Seniczak Anna Holovachov Oleksandr Juho Vuolteenaho Torbjørn Ekrem Snorre HagenSammendrag
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Soil pH is one of the soil properties that determines the levels of bioavailability of macro and micronutrients for plant roots. Apple rootstocks are the medium by which these nutrients are absorbed and shuttled to grafted scions. Our experiment was aimed at understanding the phenotypic and underlying genotypic variation of apple roots interacting with the same soil amended to five pH levels (4.5, 5.5, 6.5, 7.5 and 8.5) by monitoring growth and leaf nutrient concentrations (Ca, Cu, Fe, K, Mg, Mn, Na, P, S, Zn, and Ni) of one year old Golden Delicious trees grafted on 28 different apple rootstocks. Data was analyzed as a full factorial of pH and rootstock type. Soil pH amendment was successful as least squares means for the pH main effect displayed expected nutrient content curves for Mo (increasing with higher pH) and for Mn (decreasing with higher pH). ANOVA showed significance for main effects (pH and Rootstock Type) while the interaction (pH × Rootstock Type) was significant only for Mo. Both main effects were significant for Mn, P, and Ca whereas pH was significant for Fe and rootstock type was significant for Cu, Zn, and S. No significant effects were observed for Na, Ni and K. Multivariate analyses using rootstock genotype LS means revealed diverse correlation (pairwise Pearson) patterns when the data were analyzed as a whole or split by pH treatment levels. For example, the genotypic similarity (Pearson pairwise) between K and Mo was not significant at pH level 4.5 (r=-0.342 and p=0.109) whereas at pH 8.5 such relationship was highly correlated (r=-0.547 and p=0.006). Similar results were observed among other nutrients. Dual hierarchical clustering (Ward) displayed different number and composition of clusters according to pH where two main clusters were observed for pH 4.5 and three main clusters for the other pH levels. Rootstocks G.41, G.890, MM.111 and G.935 were tightly clustered at pH 7.5 whereas at pH 5.5 they all fell into different clusters. These results suggest the individuality of the interaction of each rootstock with pH levels with implications on fertilizer management practices and optimum pH and planting amendments specific for rootstock type.
Forfattere
Thiago InagakiSammendrag
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Till SeehusenSammendrag
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The evolution of soil structure in agricultural soils is driven by natural and anthropogenic factors including inherent soil properties, climate and soil management interventions, all acting at different spatial and temporal scales. Although the causal relationships between soil structure and these individual factors are increasingly understood, their relative importance and complex interactive effects on soil structure have so far not been investigated across a geo-climatic region. Here we present the first attempt to identify the relative importance of factors that drive the evolution of soil structure in agricultural soils as well as their direction of effect with a focus on the temperate-boreal zone. This was done using a random forest (RF) approach including soil, climate, time, and site factors as covariates. Relative entropy, as quantified by the Kullback-Leibler (KL) divergence, was used as a quantitative index of soil structure, which is derived from the particle-size distribution and soil water retention data, and integrates the effects of soil structure on pores from the micrometre-scale to large macropores. Our dataset includes 431 intact topsoil and subsoil samples from 89 agricultural sites across Sweden and Norway, which were sampled between 1953 and 2017. The relative importance of covariates for the evolution of soil structure was identified and their non-linear and non-monotonic effects on the KL divergence were investigated through partial dependence analysis. To reveal any differences between topsoils (0–30 cm; n = 174) and subsoils (30–100 cm; n = 257), the same analysis was repeated separately on these two subsets. The covariates were able to explain on average more than 50% of the variation in KL divergence for all soil samples and when only subsoil samples were included. However, the predictions were poorer for topsoil samples (≈ 35%), underlining the complex dynamics of soil structure in agricultural topsoils. Parent material was the most important predictor for the KL divergence, followed by clay content for all soil samples and sampling year for only subsoil samples. Mean annual air temperature ranked third and annual precipitation ranked fourth for subsoil samples. However, it remains unclear whether the effects of climate factors are direct (e.g., freezing and thawing, wetting and drying, rainfall impact) or indirectly expressed through interactions with soil management. The partial dependence analysis revealed a soil organic carbon threshold of around 3% below which soil structure starts to deteriorate. Besides this, our results suggest that subsoil structure in the agricultural land of Sweden deteriorated steadily during the 1950′s to 1970′s, which we attribute to traffic compaction as a consequence of agricultural intensification. We discuss our findings in the light of data bias, laboratory methods and multicollinearity and conclude that the approach followed here gave valuable insights into the drivers of soil structure evolution in agricultural soils of the temperate-boreal zone. Theses insights will be of use to inform soil management interventions that address soil structure or soil properties and functions related to it.
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