Perennial leys for dairy cows: soil and plant attributes, yield and botanical composition with long-term low and high N input

Soil chemical properties, plant nutrient concentrations, yields and botanical composition were studied in a high (mimicking conventional) and low nitrogen (N) input (mimicking self-sufficient organic) farming system over 7 years in a field experiment in Tingvoll, Norway. We compared digested and undigested manure from organically managed dairy cows with two application rates, 110 and 220 kg total N ha-1 yr-1. All, treatments and control, were cultivated with perennial grass-clover ley, re-established once during the study period. In this paper, treatments with high N input are combined to represent conventional farming systems, while low N input treatments represent organic farming systems. After 7 years, AL-extractable phosphorous (P) and potassium (K) concentrations in soil were significantly (p=0.002) higher in the "conventional" treatments than in the "organic" treatments. Despite the double amount of manure, cumulative ley yield (2011-18) was only 17% higher (p<0.001) in the conventional treatment. In 2018, concentration of P in the aboveground plant material was significantly higher in all fertilised treatments than in the control (p=0.041), and significantly higher in the conventional than in the organic treatment (p<0.001). N use efficiency (NUE% = N removed (in ley yields) / N applied (manure) x 100)ranged from 102-163% for the organic treatment, suggesting that more N was removed by ley yields than it was applied with manure. This N may derive from soil or biological N fixation. The conventional treatment had a NUE between 59 and 96%. Low NUE% indicates excessive use of fertiliser that may cause environmental pollution. Botanical composition of the grass-clover ley (2015) was affected by N application rates, with significantly less clover (p=0.008) and more grass (p=0.003) in the high N input treatments. Overall, our findings indicate that in the long-term high N input farming systems do not necessary translate in significant gains of ley yield production when comparing to low N input systems. NUE and clover content of the ley will be reduced with higher N input

Karboninnhold i jord, hva kan vi?

En oppsummering av flere prosjekter om karboninnhold i jord

Hvordan virker biorest på jordhelsa?

En oppsummering av effekten av biorest for jordhels

Farm level management of phosphorus (P): organic farmers need recycled fertilisers

Several organic farming systems are in risk of soil P depletion. E.g. at Tingvoll farm (NW Norway), with organic milk production, topsoil P was reduced by about 50% over 25 years, from 203 mg P-AL/kg soil in 1989 to 100 in 2015. In a field experiment on this farm, applying 30 or 60 tons of slurry per hectare and year to a low-P soil since 2011, soil P increased only slightly. From a starting value of 26, in 2018 the value had decreased to 23 with no manure application in the control treatment. With low application, it was still 26, and with high application it had increased to 35. In 2018, struvite corresponding to 40 kg P/ha was applied to half the experimental plots, and P was analysed in the grass crop. With no manure, it was 0.15% P (% of DM), increasing to 0.19% with low and 0.21% with high manure application. With struvite, these numbers increased to 0.24, 0.22 and 0.23%. Struvite also increased soil P significantly. The slow increase in soil P with high manure application shows that enhancing soil fertility may not be easy, since applied P may be taken up in the crop canopy instead of enriching the soil. Organic farmers should monitor their soil regularly. Too high P concentrations should be avoided, to reduce negative effects from leaching and runoff on waterbodies (eutrophication). However, when soil P decreases below a medium level, actions should be taken to avoid a further decrease. In Norway, 70 mg P-AL kg-1 soil is considered as optimal. Traditionally, rock phosphate has been the solution to P depletion in organic farming. However, the dissolution of phosphate from this material occurs very slowly. Animal-derived fertilisers, such as meat and bone meal, and various type of manure, have a higher P availability, but are often from non-organic production and hence impacts the integrity of the organic farming system. Recycled fertilisers may be a better option, to close the currently widely open nutrient gaps from agricultural land towards more closed cycles between farms and the surrounding societies. Compost and digestates are well established soil amendment products made from organic waste. Compost from park and gardening residues is a fertiliser which most consumers easily accept, whereas digestate can only be applied with restrictions and hence is not so commonly used in organic growing. However, composting implies large losses of greenhouse gases. From this perspective, anaerobic digestion is a better solution. A drawback is that this technology is much more advanced and costly to establish and manage than a compost plant, hence forcing centralisation. Further, microplastic pollutions may be at least as difficult to control in digestates as in composts. A large proportion of P available for recycling is found in human urine and faeces (HUF). Current regulations, e.g. in the EU, do not allow the use of HUF-derived products, but EGTOP proposed in 2016 that struvite and calcined P will be included in Annex 1. Struvite has many benefits and could be an excellent tool to close current P and N gaps. With a content of 5% ammonium (NH4+) following the 13 % of P, it challenges the ban on mineral nitrogen fertilisers. Stakeholders on organic regulations should find a way around this challenge, for the best of the environment and the long-term fertility of organically managed soil

Karbon i jord

Farmers are supposed to use managment practices that enhance soil organic carbon. Yet, this is easier to say than do it, specially in soils with high initial soil organic carbon content. Here, we presented the main projects on soil organic carbon at NORSØK, with emphasis on the challenges under Norwegian conditions. The projects summarized in this presentation are: MERMOLD, CAPTURE, K-BEP and C-arouNd

Assessing on-farm soil health indicators under Norwegian conditions

Farmers and advisors seek simple methods to monitor soil health. Here, we assessed the performance of different soil health tests on the top soil (0-10 cm) of different agricultural “habitats”, from an organically managed grassland to a conventional potato production in Norway. In each production system, grassland and potato, we selected different areas where variations on soil health were expected. In the grassland, a gradient from cultivated to permanent pasture was selected. In the conventional potato field, plots that received different organic materials (biochar, digestate, farmyard manure) two years prior to the soil assessment, were selected. The tests were performed in early summer 2021 (June) for the grassland, and in summer 2021 (July) after the harvest of early potatoes in the potato field. The tests comprised different aspects of soil health: soil organic matter content (ignition loss), labile soil carbon fractions (Active C), soil biology (microbiology and mesofauna) and soil biological activity (soil respiration and feeding activity) and soil aggregate stability. Test results were used to compare the systems and the areas within the systems. Overall, the tests significantly differentiate between organically managed pasture and conventional potato field, with the first showing better values for soil health. However, the tests did not significantly differentiate between areas/treatments within the production systems. Yet, in the organically managed grassland, permanent pasture showed a trend of better soil health than cultivated areas. In the conventional potato field, selected soil health tests were not sensitive to capture the residual effects of the organic amendments, and untreated and treated soil showed very similar values. To be able to visualize the results together, we normalized the data by diving single values by the maximum value observed for each soil indicator within each system. By doing so, we obtained an overall soil health diagram that can be easily interpreted by farmers and advisors. The use of several simple tests together showed to be valuable also to inform about soil health within the to two production systems. Yet, a visual evaluation of the topsoil and chemical nutrient analysis is recommended to complement these tests. Furthermore, we need more field data to obtain “reference levels” for these tests, that would help with the interpretation of their results in the future

Mer organisk materiale i jord brukt til intensiv potetdyrking

I prosjektet MERMOLD har organisk materiale i kombinasjon med fangvekster blitt tilført jord som brukes til intensiv potetdyrking. Forskerne har undersøkt om dette øker moldinnholdet og hvordan det påvirker jord, potetavlinger og sykdommer på potet

Long-term changes in soil characteristics and ley yields on an organic dairy farm in Norway

Organic milk production was established at Tingvoll experimental farm in 1989, replacing the previous conventional sheep production. Since then, soil nutrient supply has been manure from its own herd, biological nitrogen fixation and liming. Soil samples for concentrations of nutrients and soil organic matter (SOM) have been taken every 5–7-year intervals since 1990, and grass-clover yields have been annually measured since 1991. Overall, changes in SOM concentration and nutrient content in the topsoil (0-20 cm) were greater than in the subsoil (20-40 cm). In the topsoil, in the cultivated areas, SOM concentration and plant-available phosphorus (P-AL), calcium (Ca-AL) and magnesium (Mg-AL), were lower in 2021 than 1991. Potassium (K-AL) content has increased from 1991 to 2021. In permanent pastures, the SOM concentrations were higher than in cultivated areas. Overall, decrease in SOM and soil fertility may be related to the land use change, high initial contents, soil drainage, and climate change. The average air temperature in the growing season has increased about 0.05° C per year during the 30-year period, and three cuts of the ley instead of two cuts per year became more often. The yield of the first cut of the ley has slightly decreased since 1991, but the quality of the ley and the proportion of grass and clover has been stable until the fifth production year within each crop rotation

Refining Soil Conservation and Regenerative Practices to Enhance Carbon Sequestration and Reduce Greenhouse Gas Emissions

Modern agricultural technology, in all its aspects, has enabled increased agricultural production to meet the growing demand for food and fulfill the Sustainable Development Goals of the UN Agenda 2030. Yet the impact of these achievements on soil degradation and greenhouse gas (GHG) emissions is considerable. Agricultural practices that increase soil carbon stocks and reduce greenhouse gas emissions, as outlined under the international 4per1000 initiative, constitute valuable strategies for mitigating global warming while increasing soil carbon stocks and ensuring soil health. The objective of this proposal is to evaluate the influence of conservationist and regenerative agricultural practices on carbon (C), nitrogen (N) and phosphorus (P) cycling, soil biodiversity and GHG emissions with a particular emphasis on long-term SOC stocks, and processes governing C persistence. This project represents an exploratory effort to couple the stoichiometric drivers to microbial populations related to C, N, and P cycling and stocks, and GHG emission under diverse agricultural practices. To this end, we set up a long-term consortium of field experiments that assess the impact of different cropping systems and agricultural practices on soil properties. The participants from twelve different countries represent a total of 37 field sites with different time sequences and/or contrasting agricultural management. Twenty-six sites have been established for at least ten years. At each site, estimates and modelling scenarios of possible N2O, CO2 and CH4 emissions from crop/pasture/forestry systems will be carried out using best available IPCC or local emission factors and GHG emissions will be measured at a subset of sites. To compare the impact of different climatic and edaphic conditions among sites, we propose a standard soil organic matter (OM) physical fractionation procedure resulting in two contrasting soil fractions including particulate organic matter (POM), which consists mainly of partially decomposed plant residues, and the mineral-associated OM (MAOM), principally of microbial origin. This project will build a worldwide database of C and N stocks, bulk density, soil fertility and GHG emissions across different ecosystems and under differential agricultural management. Moreover, the project will determine the extent to which climatic conditions, net primary production of cropping systems and soil type affect carbon and nitrogen stocks, nutrient dynamics and greenhouse gas emissions. The final product of the project will be to recommend best management practices for production of food crops which would promote soil C accumulation, especially MAOM, without increasing GHG emissions thus contributing to the sustainability and resilience of agriculture

Long-term effects of slurry and anaerobically digested slurry on soil fertility

The global need to substitute fossil fuels, along with rising fertilizer costs, calls for a more efficient use of manure resources in agricultural systems. One option may be to treat more animal manure by anaerobic digestion to produce energy and co- produce an organic fertilizer. Here, we investigated the long-term effects of anaerobically digested (AD) dairy cow slurry on crop yields, soil organic matter (SOM) and chemical soil characteristics. The field experiment was established in a grass-clover ley in 2011 and comprised two fertilizer treatments, non-digested slurry and AD slurry, applied at two rates of total N (110 and 220 kg ha-1 y-1), compared with a non-fertilised control. While the rate of manure application affected soil concentrations of extractable nutrients and pH, these variables were not affected by AD. SOM concentrations (0-20 cm) decreased in all plots, and faster on plots with high intrinsic SOM. The decrease was similar with application of non- digested slurry (US) and anaerobically digested slurry (ADS) and at slow and high application rates. US and ADS gave similar yields of grass-clover ley and whole crop cereal, on average 0.79 and 0.40 kg DM m-2. The proportion of clover in the ley canopy was similar in manured treatments and the nonfertilized control. With respect to crop yields and chemical soil characteristics, longterm (10 years) effects of AD in an organic dairy cow farming system seem to be minor, not compromising grassland productivity or soil quality in the long term. However, with traditional application of the slurry (no incorporation), no yield increase was achieved with AD, as has been found in other studies