Arable and field veg: improving yield through better soil management
(Jointly organised with IOTA)
Chair: Elizabeth Stockdale (Newcastle University)
Francis Rayns (Garden Organic): Yield response from using green waste compost and manures
Francis is currently Horticulture Research Manager at Garden Organic (formerly known as HDRA). He has been involved in a large number of projects (funded by Defra, HDC, WRAP, the EU and private companies) concerned with fertility management, particularly in organic field vegetable systems. This has included studies of the effects of a range of green manures, composts, animal manures and other soil amendments. He has worked to develop computer models for rotational planning and has been responsible for long term experiments to compare the effects of different rotations on soil quality and crop performance.
Presentation - Yield response from using green waste compost and manures
Peter Mejnertsen (Knowledge Centre for Agriculture, Denmark): Managing manure: experience and ideas from Denmark
Presentation - Managing manure: experience and ideas from Denmark
Steve Wilcockson (Nafferton Ecological Farming Group): Effects of manure application and rhizobia inoculation on yield
Steve is a Senior Lecturer in Crop Production at Newcastle University. He is a founder member of the Nafferton Ecological Farming Group (NEFG) established in 2001 and the NEFG Crop Production team. He co-ordinated the EU’s Blight-MOP 2001-2006 project :Development of a systems approach for the management of late blight in EU organic potato production and the agronomy programme of the Sustainable Arable LINK/HGCA BOB (Better Organic Bread) project: Improving fertility management and disease control in organic and low input production systems for bread making wheat (2005-2010). Steve is leader of the BSc in Agriculture with Honours in Agronomy; a member of NEFG’s team teaching the new MSc in Ecological Farming and Food Production Systems and Chairman of the University of Newcastle Agricultural Society.
Presentation - Effects of manure application and rhizobia inoculation on yield
Thomas Döring (ORC): Nitrogen supply characteristics of ley and green manure species and mixtures
Dr Thomas Döring has joined the Organic Research Centre in April 2009 as Leader of the Crops Programme. After a degree in ecology he graduated with a PhD in organic agriculture from the University of Kassel, Germany, and worked as postdoctoral researcher in the area of insect pest behaviour at Imperial College London.
Presentation - Nitrogen supply characteristics of ley and green manure species and mixtures
Session Summary -
The session kicked off with Francis Rayns from Garden Organic, who gave a good overview of the various options available for organic soil amendments, including farm yard manure, slurry, composted farm wastes, green waste composts, digestate from anaerobic digestion and sewage sludge. In addition to providing plant nutrients, these amendments can also help improve soil structure, modify the availability of nutrients, and provide a means for disposing of waste products. Francis highlighted the limitations of many trials of soil amendments which tend to be time limited and so lack information on long-term effects of repeated applications. GO trials comparing application of FYM, green waste compost and poultry manure over four years found that all amendments increased nitrogen availability immediately after application, with increased nitrogen concentrations lasting for around 5 months. The effects on soil organic matter were less pronounced with only a slight increase in soil carbon after four annual applications, except at high compost input (500-750 kg/ha). Effects on yields varied depending on soil types and veg species, with FYM increasing parsnip yields on a sandy loam. Francis concluded that while manure and composts can provide a valuable source of OM and plant nutrients, there can be pollution problems associated with overuse and a range of issues when amendments are brought onto the farm from outside sources.
Peter Mejnertsen from the Knowledge Centre for Agriculture, Denmark, provided recommendations on the application of ammonia on the basis of the previous crop in cereals, reporting on 35 trials that took place between 1999 and 2000. Yield response to ammonia was optimised at 110-120 kg NH4-N/ha, with the economic optimum (70-85 kg NH4-N/ha) dependent on the price of manure and grain. Spring cereal crops following clover grass showed no response to ammonia applications so Peter advised saving your manure. Winter cereals had the same response to ammonia, independent of the previous crop. Peter stressed the need for prioritizing manure applications to high value crops. In Denmark, most slurry is spread in the spring, with some to grass in summer following the first cut. Application is usually by trailing hoses but these now have to be replaced by direct injection, which has been found to increase N use efficiency by the crop.
Steve Wilcockson from Nafferton Ecological Farming group reported on the variety and fertility trials that were part of the Better Organic Bread project, with a focus on the effects of manure application and rhizobia inoculation on yields of spring wheat. Yield responses to fertility treatments varied across sites and seasons, with no consistent responses identified across all sites. Pre-crop treatment with rhizobia inoculants produced no clear yield advantages, except on one site for winter wheat, and there was no rhizobium x FYM interaction. Summing up, Steve suggested that fertility management responses depend on a range of interacting factors including inherent soil fertility, previous management, the amount of readily available N, and the potential for mineralization of soil N, with cumulative effects building up so that crops later in the rotation benefit from current fertility inputs.
Thomas Döring from ORC discussed N supply characteristics of a wide range of ley and green manure species. There are a number of interacting factors that affect the establishment and biomass production of these species, including management practices, water availability, soil characteristics and the weed and rhizobia communities, and these can vary from species to species. N levels in plant residues also vary by species, with lucerne and clover residues highest, and lupin and vetch species containing just 30-60% that of lucerne. However, this ranking changes when considering the N effect to the next crop; and again when looking at the N fixing ability, contributing to the significant variability in the value of green manure species. The LegumeLINK project which is investigating ley species mixtures recorded considerable variation in biomass production of a range of legume and grass species when grown as monocultures; however, overall biomass production of the All Species Mix was much more stable, indicating that using a diversity of species is a better approach than relying on a single species monoculture.