Red clover increases micronutrient concentrations in red clover

Foraeg crops provide micronutrients as well as energy, protein and fibre to ruminants. However, the micronutrient concentrations of forage plant species differ, legumes generally having higher concentrations than grasses. In addition to that there are also strong effects of soil type. Typically, the concentrations of one or several micronutrients in forage are too low to meet the nutritional requirement of dairy cows. We hypothesized that the overall micronutrient (Co, Cu, Fe, Mn, Mo, Zn) concentrations of forage mixtures are affected by the red clover dry matter (DM) proportions and site effects. This hypothesis was tested at three contrasting sites. The results showed that increased red clover proportion increased the overall concentrations of several micronutrient in the mixtures at all sites. At the site with the widest range of red clover proportion (0-70 %) in the mixture, the Co, Cu and Fe concentrations more than doubled between the lowest and highest red clover DM proportions. At the other two sites a smaller increase in red clover proportion(from 10 % to 25 % or from 25 % to 50 %) also increased the overall concentrations of Co by up to 80 % but less for other micronutrients.  One of the sites generally had higher micronutrient concentrations in the crop and removed larger amounts of micronutrients with the harvested biomass compared to the other two sites.This could be explained by differences in pH and micronutrient concentrations of the soils at the sites. We conclude that increased red clover proportion in the sward has the potential to increase tha overall micronutrient concentrations but that the effect of the soil is also a controlling factor

The Updated version of SF Box: A method for soil quality classification as a basis for applicable site-specific environmental risk assessment of contaminated soils

This technical note summarises major changes in the updated version of SF Box, which is part of the SCORE – the Multi-Criteria Decision Analysis method for decision support in soil remediation projects. SCORE stands for the Sustainable Choice Of REmediation and SF Box stands for Soil Function toolBox. The SF Box tool has been developed for soil function assessment to complement environmental risk assessments, in order to increase awareness of decision-makers for inherent soil qualities other than concentration of contaminants and their availability/mobility, which are critical for proper soil functioning, e.g. availability of water and nutrients for soil organisms, but often ignored in remediation projects (driven by protection of the soil environment with ambition to recover ecosystem functions) in Sweden. The tool is based on a scoring method using soil quality indicators (SQIs) for assessing (I) the soil’s capacity to perform its functions in its own reference state of being ‘clean’, i.e. “what can this soil do and can it perform its functions well, assuming that it is free of contaminants?”, and (II) the effects of the remedial actions themselves on soil functions, i.e. “can the remediated soil continue to perform these functions well?”. The earlier version of SF Box addresses the soil functions associated with Primary Production. By (i) taking into consideration the perspectives of soil microbiology, soil fauna and vegetation, (ii) slightly modifying the set of SQIs (consisting of soil texture, content of coarse material, organic carbon/matter, available water, C/N ratio, pH and available phosphorus), and (iii) revisiting the curves for scoring of soil performances on each SQI, the SF Box tool has been updated to assess the soils’ capacity to function as a basis for Life and Habitat of flora and fauna. This updated version is therefore aimed to provide an improved basis for site-specific environmental risk assessment by means of (1) differentiating between the effects of contamination on soil biota and the effects of soil capability to function as a host to these species in its own reference state free from contaminants, and (2) classification of the soils (usually characterized by heterogeneity at contaminated sites) in accordance with their overall performance on the selected SQIs for further analysis of ecotoxicological risks in each soil class

Effect of wood ash and crushed rock soil amendments on red clover growth and dinitrogen fixation

The fertiliser effect of adding wood ash or crushed rock to a low-fertility soil, compared with an unamended control, was assessed in a pot experiment with a perennial ryegrass-red clover mixture. Dinitrogen (N2) fixation by the clover and translocation of fixed N to the grass were determined using 15N natural abundance. The wood ash produced the highest accumulated clover biomass over two cuts, followed by the crushed rock. Chemical analyses suggested that the increase was due to K supply by the amendments. The wood ash also led to larger amounts of fixed N compared with the control. However, N2 fixation was not increased as much as biomass amount, leading to dilution of plant N. There were minor or no treatment effects on mineralisation from soil N pools. This indicates that good-quality wood ash can be successfully used as a multi-element soil amendment to enhance clover growth on low-fertility soils

Boron fertilisation of organically managed grass-clover swards on coarse-textured soils: effects on botanical and element composition

Three trials were performed on two organic farms with dairy and suckler cows and using home-produced forage and feed crops, predominantly grass-clover ley, in order to determine whether boron (B) is a limiting factor for legumes on coarse-textured soils in an area predisposed to low B soil concentrations. The effects of B fertilisation (applied as sprayed liquid) on biomass yield, botanical composition and plant macro- and micronutrient concentrations relative to soil concentrations and livestock requirements were investigated. Boron fertilisation (i) did not affect any yield, (ii) increased the white clover percentage significantly in forage on one farm and (iii) increased B concentrations in plants and soil on both farms, and (iv) did not affect concentrations of other nutrients in forage on either farm. Thus, B was not an obvious limiting factor on these farms. Effects of management practices on interactions and ratios between B, calcium (Ca), potassium (K), magnesium (Mg) and sodium (Na) and their implications are discussed

Revisiting herbage sample collection and preparation procedures to minimise risks of trace element contamination

A renewed interest in trace elements (TE), as micronutrients as well as potentially toxic elements, and new options for multi-element analysis has led to an increased number of scientists engaging in TE studies. Accreditation, certification and quality control of TE analyses often applies only to the last step in the sample chain when prepared samples are sent to the laboratory for digestion/extraction and subsequent analysis. However, all stages of the chain from initial sampling to final analysis require an understanding of the specific challenges involved in TE studies and an awareness of the contamination risks as well as approaches to limit these. Contamination can potentially be introduced during all stages of handling and preparation of plant samples, e.g. through dust and the materials that make up the different work surfaces, tools and containers used. Milling devices originally used during preparation of two sets of archived herbage samples were tested to indicate the degree of contamination that can arise from milling. For example, some of the milling devices tested showed effects on several TE concentrations while also increasing the variability between samples. A titanium knife mill which was included for comparison gave the best results, showing no measurable contamination by TE of primary interest, while it allowed a high throughput of samples. To enhance the quality of data on TE in bulky plant material such as herbage and to ensure future usability of newly archived samples, we suggest that field handbooks and sample preparation protocols (where needed) are revised to include precautions against TE contamination in all handling steps. This will ensure reliable data on concentrations of micronutrients and potential toxic TE in plant material

Predicted long-term effects of decomposition of leaf litter from Pinus taeda, Eucalyptus cloeziana and deciduous miombo trees on soil carbon stocks

Decomposition rate of leaf litter in native miombo and in Pinus taeda and Eucalyptus cloeziana plantations was measured in the Inhamacari forest research area, Manica province, Mozambique. The Q-model and a simple first-order exponential decomposition model (K-model) were used to predict long-term accumulation of carbon (C) in the litter layer and in soil 34 years after plantation establishment and at steady-state. Measured litterfall from the study plots was used to estimate litter inputs for prediction of C stocks. The results were compared with measured C stocks when stand age in the first-rotation plantation stands was approx. 34 years.At the end of the one-year decomposition study, about half or less of the initial litter mass remained. Leaf litter of the miombo species Brachystegia spiciformis decomposed faster than leaf litter of non-native Eucalyptus cloeziana and Pinus taeda, and a representative mixture of leaf litters of dominating miombo trees decomposed faster than P. taeda, but not E. cloeziana.Measurements indicated higher soil temperatures, and thus higher microbial growth rate, in miombo than in plantation stands. Estimates of initial leaf litter quality indicated higher decomposability of mixed litter substrates of miombo stands than P. taeda needles.Assuming current measured litterfall, the accumulated C stocks predicted by the Q-model were higher than measured C stocks in the litter layer. A major cause of the discrepancy between predicted and measured C stocks in the litter layer of miombo stands was probably frequent ground fires and probably also the influence of termites and other modes of transport into the soil profile.Previously measured increase in C stocks in the soil (0–50 cm) and the litter layer of first-rotation stands of P. taeda and E. cloeziana plantations were much larger than the Q-model predicted soil C stocks at steady-state, indicating that this increase cannot be explained by leaf litter input only. Keywords: Brachystegia spiciformis, Forest degradation, Litterfall, Mozambique, Q-model, Uapaca kirkian