P uptake, root properties and biomass of six cover-crops

Phosphorus (P) is an essential and limited nutrient. To avoid shortages in the coming decades, P recycling and efficiency of P use will have to be enhanced. Cover crops may help to transform less available P forms into bioavailable P forms. The aim of this investigation was the comparison of P uptake with root traits of six cover crops. Root and shoot biomass was analysed for P content. Root hair length and root length was measured on the basis of 6400 dpi root scans using ImageJ and WinRhizo. In addition, the root hair cylinder was calculated. P uptake was found to be strongly correlated with the root hair cylinder and the total crop biomass.Keywords: cover crops, phosphorus uptake, root hair cylinder, root length, root hair

Abschätzung des Risikos einer Schwermetall-Akkumulation in Böden durch längerfristige Anwendung von Recycling- Phosphor-Düngemitteln

In order to assess the risk of the use of recycled phosphorus (P) fertilisers for organic farming, the potential accumulation of heavy metals in soil after a 200-year fertilizer application equivalent to 11 kg P ha-1 yr-1 was calculated in a mass balance approach. Both fertilizers currently allowed in organic farming and recycled P fertilizers were regarded. For heavy metals, four scenarios with two soil pH levels (pH 5 and pH 7) and two precipitation excess levels (F 0.1 and F 0.3 m yr-1) were calculated. Recycled P fertilizers like struvite, meat- and bone meal, ashes, sewage sludge and digestate, as well as phosphate rock and triple superphosphate had a higher P content and a lower heavy metal-to-P ratio than composts. Consequently, compost application was associated with the highest pollution risk. Only the Cd accumulation with TSP was higher than that with compost. Model calculations do not indicate a significant risk of heavy metal accumulation in soil compromising food quality or soil fertility after longterm application for the assessed recycled P fertilizers

Akkumulation von Schadstoffen in europäischen Böden durch alternative Phosphordünger

Der Vorsorgewert wurde nur von Cr überschritten. Es zeigt sich, dass das Verhältnis von Schadstoff zu Phosphor eine wichtige Rolle spielt. Von Düngern mit einem geringen P-Gehalt, wie den Komposten, muss eine größere Menge ausgebracht werden, was in dieser Berechnung zu einer höheren Schadstoffanreicherung führte. Grüngutkompost hatte das höchste Akkumulationspotenzial für alle Schwermetalle, nur bei Cadmium wurde er von Triplesuperphosphat übertroffen. Vermutlich ist die atmosphärische Schermetallbelastung von Grünschnitt in Städten und entlang von Straßen besonders hoch und konzentriert sich im Kompost. Die Schadstoffgehalte der Dünger können, je nach Ausgangssubstraten, unterschiedlich sein. Als Phosphordünger eingesetzt, hatten Struvite, Fleisch- und Knochenmehl und Aschen das geringste Schadpotential. Die Schadstoffe, auch bei geringer Anreicherung im Boden, stellen eine Belastung des Wassers, des Staubs und der Kulturpflanzen darstellen dar

Long-term soil accumulation of potentially toxic elements and selected organic pollutants through application of recycled phosphorus fertilizers for organic farming conditions

The pollutant input and the risk of contamination by long-term application of recycled P fertilizers (RPFs) in European agricultural soils were estimated by a mass balance approach. Calculations based on literature data were carried out for the potentially toxic elements (PTEs) Cd, Cr, Cu, Ni, Pb, Zn and for the persistent organic pollutants (POPs) PCBs, PAHs and polychlorinated dibenzo-dioxins and -furans. The PTE accumulation estimation during 200 years of fertilizer application, equivalent to 11 kg P ha-1 year-1, the mean P export via harvested products on European stockless organic farms, regarded soil background concentrations and proposed threshold concentrations. For PTEs, inputs were fertilizer application, atmospheric deposition and liming, output processes were leaching and crop harvest. The effect of varying site conditions was assessed by considering two precipitation excess (F) values and two soil pH values. For POPs, fertilizer application and the half-life time were considered. The PTE accumulation risk was low for most RPFs. For the analysed POPs no accumulation was found. The highest accumulation was found for all PTEs at pH 7 and F = 0.1 m year-1, the lowest at pH 5 and F = 0.3 m year-1. A high P concentration in fertilizers resulted in a low PTE flow per unit of P. composts had the highest PTE accumulation risk due to lowest P contents. Struvite, meat and bone meal, digestate of catering waste, ash and biosolids would be better suited as P fertilizers. The use of fertilizers should be regulated based on their pollutant-to-nutrient ratio

NEED FOR PHOSPHORUS INPUT IN AUSTRIAN ORGANIC FARMING?

On organic farms, phosphorus (P) balances are often negative because no or little P is imported into the farms. Negative P balances may deteriorate P availability over time. We calculated P balances of the main farm production types in organic farming for the main Austrian production areas. Using data from various data bases and expert knowledge, we applied the sustainability assessment tool REPRO for calculations. The P balances were balanced to slightly deficient for organic forage dairy farms, cash crop farms and permanent crop farms, and slightly to highly surplus on organic refinement, pig producing farms. Deficient P balances, mainly on organic cash crop farms, call for P input especially on farms where available P fractions in the soil are very low and / or P stocks in the soils are low, i.e. on sandy soils and on some calcareous soils. Possibilities for enhancing P mobilisation are discussed. There is an urgent need to close nutrient cycles on the farm and regional scale and to substitute P from rock phosphate reserves by alternative P fertilisers also in organic farming

LCA and Risk Assessment of Recycled Phosphorous Fertilisers

An efficient phosphorus (P) recycling from urban areas is becoming an increasing issue due to the scarcity of natural P deposits. In order to assess the environmental performance of different approaches of P recycling, a LCA assessment and risk assessment studies were carried out. Generally, we found the supply of recycled P-fertilisers (RPFs) to be competitive as compared to conventional sources in terms of LCA results analysed in this contribution: per kg P and with exclusion of infrastructure processes, the highest abiotic depletion potential is shown for conventional mineral fertilisers based on phosphate rocks due to the finite mineral P resources. For fossil primary energy demand, the recycled fertilisers (struvites and an ash-based fertiliser analysed) had highest impacts per kg P. Relatively high acidification and eutrophication potentials from the supply of P-fertilisers are related to composts, triple-superphosphate and struvites. For the global warming potential per kg P, compost presents the worst results again. However, if co-products of organic fertilisers are considered (i.e. N- and K-contents and the humus sequestration potential), most organic fertilisers are in advantage for a number of indicators – with the exception of conventional composting. The low emission compost and the stabilised sewage sludge present moderate to good overall results. The best relative results for all indicators were found for biogas digestate. To assess the risk of soil contamination related to the long-term application of RPFs, accumulation scenarios in soil were calculated with a mass balance approach for the potentially toxic elements (PTEs) Cd, Cr, Cu, Ni, Pb, and Zn and for the persistent organic pollutants (POPs) polychlorinated biphenyls (PCB), polycyclic aromatic hydrocarbons (PAH) and polychlorinated dibenzodioxins and dibenzofurans (PCDD/F) in composts, digestates and other RPFs derived from sewage sludge For all calculations, a fertiliser application over 200 years equivalent to 11 kg P ha-1 yr-1 was assumed. Dependent on PTE mobility in soil due to pH and precipitation excess F, an accumulation or depletion compared to the soil background values was found. Highest accumulation was found in scenario pH 7 F 0,1 m yr-1, lowest in scenario pH 5 F 0,3 m yr-1. Fertilisers like composts, with low P content compared to PTE load, had a higher accumulation potential than fertilisers like struvite, meat and bone meal, sewage sludge ash, sewage sludge and digestates, rock phosphate and triple super-phosphate. Only Cd accumulation with TSP was higher than that with compost. For POPs no accumulation risk in soil was found

Vergleich von Treibhausgasemissionen unterschiedlich wirtschaftender Modellbetriebe im Alpenvorland

About 8.8 % (UBA 2010) of the total greenhouse gas (GHG) emissions in Austria are caused by agricultural practices. Besides the release of climate relevant gases, C-sequestration occurs depending on the natural conditions and farming system. The focus of the project was to describe the GHG-emissions and sinks of the most relevant farming types, both organic and conventional, within the main production areas in Austria. Results of an intensively cultivated region in the North-West are presented. Based on the input data, six model-farms were created with the programme REPRO, whereby forage production, cash crops and refinement systems were considered. All systems had a positive humus balance and sequestered carbon in the soil, especially forage production systems. Due to the use of mineral fertilizers, a higher N-balance occurred in all conventional systems. Organic systems on the other hand were able to utilize nutrients to a wider extent. The GHG-potential related to area was at least 29 % higher at conventional compared to organic systems, whereby N2O-emissions, calculated according to IPCC 1997, were most relevant. Differences were reduced and results even reversed calculating the GHG-potential per product unit. When calculating the N2O-Emissions with an increased N2O emission factor of 2.5 % of N input in a scenario, the emissions increased almost proportionally

Impact of reduced tillage on soil organic carbon and nutrient budgets under organic farming

No-tillage (NT) and reduced tillage (RT) systems are well-known management tools for reducing soil erosion and improving soil fertility. NT and RT may improve the environmental and economic performance of organic farming, but they are still not common practice among organic farmers. This paper presents the effects of tillage [RT versus conventional tillage (CT)], fertilization (slurry versus manure compost) and biodynamic preparations (with versus without) on soil fertility indicators such as soil organic carbon (Corg), microbial biomass and microbial activity, soil nutrients and nutrient budgets in an organic farming system during the first six-year crop rotation period of a long-term experiment on a clayey soil in a temperate climate. RT caused stratification of soil organic carbon (Corg), microbial properties and soil nutrients in the soil profile. Under RT, Corg in the 0-10 cm soil layer increased from 2.19 to 2.61% (w/w) from 2002 to 2008, whereas it remained constant under CT. In both tillage treatments, Corg remained constant in the 10-20 cm soil depth. Microbial biomass C increased by 37% under RT in the 0-10 cm soil depth and microbial activity [dehydrogenase activity (DHA)] was enhanced by 57%. Soil microbial biomass C and DHA in the 10-20 cm soil depth were also higher under RT (+10 and +17%, respectively). Soluble soil P and K were 72 and 40%, respectively, higher in 0-10 cm soil depth under RT when compared with CT. Fertilization showed no effects on the measured soil properties. Biodynamic preparations increased solely the Cmic-to-Nmic (soil microbial biomass C to soil microbial biomass N) ratio by 7% in the 0-10 cm soil depth. Nutrient budgets for P were balanced in all treatments, but N and K exports were higher under RT compared to CT. We conclude that RT is a suitable method for increasing indicators of soil fertility in organic farming systems. The combined effects of RT and an organic farming system with a diverse, ley-based crop rotation and organic fertilization merit further promotion and it may be considered for supporting actions by the agricultural policy scheme

Begrenzte Phosphor-Ressourcen

Im CORE Organic Projekt „IMPROVE-P“ werden Strategien für ein nachhaltiges P-Management speziell für den Bio-Landbau entwickelt. Dazu wurden bei einem Workshop anlässlich der BIO AUSTRIA-Bauerntage 2016 Ergebnisse des Projekts zu P-Dünger-Pflanzenversuchen und Risikoabschätzung hinsichtlich Schwermetallen sowie Ökobilanzierung für P-Quellen von den Autoren dieses Beitrags präsentiert

Projektvorstellung: C - Speicherung in Böden landwirtschaftlicher Betriebssysteme Österreichs

Die Projektziele bestehen im Wesentlichen in der Optimierung und Bereitstellung der Daten- und Berechnungsgrundlagen im Bereich Pflanzenbau und Humusgehalte im Boden, um die Profile der treibhausgas-relevanten Emissionen und Senken in landwirtschaftlichen Betrieben Österreichs darzustellen, sowie in der Modellierung treibhausgasrelevanter Emissionen und Senken der wichtigsten landwirtschaft-lichen Betriebstypen Österreichs (Martkfrucht-, Futterbau-, Veredelungs-, Dauerkultur-, Kombinations-, und landwirtschaftliche Gemischtbetriebe) in den Hauptproduktionsgebieten