Constraints to the sustainability of a stockless arable rotation

The sustainability of an organic stockless arable rotation on a fertile soil in eastern England was assessed from 1990 to 2005. The good water and nutrient holding characteristics of the silty clay loam soil were well suited to a stockless organic rotation. Fertility-building clover crops were the most difficult to establish, and failed completely in some years despite one or two re-sowings. Crop yields were good, particularly for cereals, with an average for winter wheat of 7 t ha-1. Crop yield did not show any particular trend with time; there was no evidence of either a post conversion adjustment period, or a fall in yield due to declining fertility. High organic crop prices in the 1990s, resulted in significantly higher gross margins than from comparable non-organic farms. However, falling organic crop prices from 2000 resulted in profitability only similar to non-organic. Supply of N, P and K was probably not a major limitation to crop growth and yield. However, in the longer term, additions of sustainable sources of plant-available phosphorus and potassium would be necessary, even on the nutrient retentive and potassium rich soil. Effective mechanical weeding was difficult on the silty soil. The rotation favoured perennial weeds, particularly creeping thistle which increased progressively despite efforts at control with mechanical and hand weeding

Testing the sustainability of stockless arable organic farming on a fertile soil (OF0145)

This is the final report of Defra project OF0145. If organic farming is to expand in the arable east of England, where the knowledge, infrastructure and capital for livestock are not available, viable stockless systems will be needed. The aim is to maximise economic performance and in turn encourage conversion. Project OF0112 showed that a stockless arable rotation was consistently more profitable that a comparable conventional rotation on the fertile silty clay loam at ADAS Terrington. Project OF0145 researched challenges to sustaining that level of performance into the second crop rotation. The project was a combination of systems comparison, replicated experiments and monitoring of commercial farms. The core of the project was an unreplicated systems comparison with field-scale plots to allow meaningful study of patchy problems such as perennial weeds and give confidence to farmers that the system could work on a farm scale. Conversion was completed in 1995 and the rotation has since been clover, potatoes, winter wheat, spring beans, undersown spring barley. The greatest agronomic challenges continued to be with the establishment of fertility-building legumes. Despite these problems, crop yields have been maintained with good rolling average yields of 25 t/ha for potatoes, 7.5 t/ha for winter wheat, 3.5 t/ha for spring beans and 4.1 t/ha for spring cereals. Disease levels in cereals have remained low and posed minimum threat to yields. Slugs and blight have affected potatoes in wet years; control of these is particularly difficult in an organic system leading to greater yield variability than would be expected in a non-organic rotation. Calabrese has grown and yielded well with few problems but weed control in onions proved both difficult and expensive and they have been dropped in the successor project OF0301. Weighted rolling-average gross margins show a consistent and large advantage to organic (£912/ha conventional, £1757/ha stockless with potatoes and £1148/ha stockless with vegetables). The advantage to organic has increased with time as yields and prices have been maintained whilst conventional crop prices have fallen. Soil fertility as measured by carbon and nitrogen contents has shown little change since the start of conversion in 1990. Soil available P and K have remained at ADAS Index 1 to 2 despite continued crop offtakes. However both are showing a slow progressive decline, less so with P, perhaps partly due to the rotational applications of Aluminium Calcium Phosphate. Annual weeds are proving relatively easy to control, being worst where crop growth is poor for reasons such as compaction on headlands. However, the perennial weeds couch grass, creeping thistles and docks are an increasing problem. Hand pulling of thistles and docks is containing the problem but the cost of this has risen dramatically in the last two years. The distribution of potato cyst nematodes (PCN) was mapped within all five plots in January 1998, 1999 and 2000. Sampling was in 25 m x 25 m sub-plots. In January 2000 viable cysts were found in 7.6 % of sub-plots, all at fewer than 10 eggs per g of soil. There was no evidence of a significant multiplication of PCN following potatoes. Growing a variety other than the resistant Sante may have allowed multiplication. A manure utilisation booklet was compiled in association with Elm Farm Research Centre. The text was agreed with MAFF in May 2001 and it should be published by July 2001. Specific challenges deserving further study include: • The ecology of perennial weeds and agronomic strategies for their control. • Quantification of net nitrogen fixation by legumes and subsequent release to crops. • The impact of potato cultivar on PCN multiplication. • Better and more reliable grain quality. • Control of slugs and potato blight. The development of companion and bi-cropping systems for arable rotations (linked to results from OF0181 and OF0173)

Effect of mowing a legume fertility-building crop on shoot numbers of creeping thistle (Cirsium arvense (L.) Scop.)

This report was presented at the UK Organic Research 2002 Conference. Perennial weeds with spreading root systems, e.g. Cirsium arvense, are difficult to control in organic arable rotations, particularly in those without grazed leys. Competitive crops and repeated mowing are proven methods of control that can be applied to the legume fertility-building crops in stockless rotations. An experiment at ADAS Terrington in 2000 compared a standard treatment of mowing at 45 cm legume height (x4) with mowing every two weeks (x8), and mowing when thistle flower buds were visible (x3). Thistle shoot numbers counted in July 2001 were around 75% less than at start of mowing in April 2000 (mean of 9.5 shoots per m2). The results suggest that achieving and maintaining a dense competitive crop has more influence than mowing frequency on creeping thistle survival under a clover fertility-building crop

Organic Arable Systems at ADAS Terrington OF0112

Project OF0112 contributes to MAFF's main policy focus of encouraging conversion to organic farming methods. It is part of a long term rotational study that began in 1990 as OF0102 and has recently been extended to 2001 as OF0145. The overall objective of these three projects is to evaluate the cost of conversion to organic arable production on a fertile soil, to assess the physical and financial performance of the organic rotation, to identify and overcome limitations to sustainabilty and to compare the results with conventional arable production. The project comprises a field-scale unreplicated systems comparison and associated replicated experiments at ADAS Terrington, and a financial analysis of ten commercial 'linked' organic farms. The silty clay loam soil at Terrington has proved ideal for organic production, primarily because it has very good water and nutrient and retention. As expected, organic crop yields have been less than conventional, averaging 70% for winter wheat; yields have been, on average, double that of the linked farms, and reached a peak of 10 t/ha in 1996. Variable costs have been lower and organic prices have been twice or more that for conventionally grown potatoes and wheat. Crop grossmargins (i.e. the value of the crop harvested minus the drect variable costs of growing it) have been consistently higher from organic than conventional. Even allowing for the lower value of the other three crops in the rotation, i.e. beans, spring cereal and clover (Set aside), overall gross margin from organic was higher than from conventional (average from 1993 to 1997 was 1,878 v 1,290 #/ha). Crop yields and gross margins were generally lower on the linked farms, probably mainly because they were on lighter soils more prone to leaching losses. However, all were viable businesses and had similar profitabilities to conventional farms of their size. The most profitable rotations in cluded potatoes and/or vegetables. In the absence of animal manures and synthetic fertilisers, the main driver of crop yield and key to sucess, will be the fixation of sufficient atmospheric nitrogen by the Rhizobium bacteria in the root nodules of legumes. Replicated experiments comparing a range of species have shown that in terms of gross accumulation of nitrogen in the cut foliage, and in the yield of a following wheat crop, red clover, lucerne and white clover are all very effective fertility builders, with red clover on average just the best. A second experiment has compared wheat, barley and oats as the cover crops for the undersowing of red clover. In 1997 clover dry matter at harvest uder oats was only 4.5kg/ha compared with 88 under wheat and 74 under barley. Baley was also the most profitable crop, however this was affected by relative grain prices which vary between years. A third experiment tested timing of manure application across the rotation. The modest quantity applied (30 t/ha per rotation) was chosen as what could have been produced from animals fed on crops grown within the rotation. There was only one isolated response in crop yield over four different crops. This was probably a reflection of the high inherent fertility and nitrogen retention capacity of the silty clay loam soil at Terrington. There are real current business opportunities for conversion to arable production. The linked farms, mostly with mixed arable livestock rotations, show profitability comparable with conventional; stockless arable production was consistently more profitable than conventional on the fertile nutrient retentive soil at Terrington. However there remain questions about the longer term sustainability of a stockless arable rotation, even on such a well suited soil. The next phase of the project (OF0145), which has just started, will focus on sustainability studying potential threats from perennial weeds, nutrient supply and soil-borne pests and diseases. The use of manure will be discontinued and, in that part of the study area, vegetables will be introduced in place of potatoes to test an alternative rotation

Companion cropping for organic field vegetables (OF0181)

Typical organic crop rotations are extensive with at least one year in four as a fertility building crop. However, the economic viability of organic systems may be compromised by having 75% or less of the farm productive at one time, limited further by the absence of the Arable Area Payments Scheme, particularly Set-aside, for vegetable crops. In addition, the system gives rise to a high fertility/low fertility sequence which is inefficient in terms of nutrient management (particularly nitrogen). To try to address this, the use of permanent beds of companion crop grown alongside the vegetable crops has been developed under various conditions around the world and is perceived as a possible alternative in organic husbandry. Companion crops also have the potential to reduce the impact of pests and weeds. A potential disadvantage of companion crops is competition with crop plants for space, light, water and nutrients. The companion crop, therefore, is likely to have to be mown or grazed to control competition and encourage nutrient transfer. On the positive side, companion crops have the potential to reduce the impact of pests, and weeds. The challenge is, therefore, to develop appropriate crop layouts and machinery to balance these interactions and result in profitable crop production. Project OF0181 was delivered with Elm Farm Research Centre and was guided by a Steering Group. The core of the project was the further development and evaluation of a seven-crop companion crop system initially developed by Professor Martin Wolfe at Wakelyns Agroforesty, Fressingfield, Suffolk, a Soil Association registered organic farm. The system was based on 1.5 m beds, with three 20 cm vegetable rows alternating with 30 cm leguminous companion strips. Within each bed, there was a seven-course crop rotation: potatoes, alliums, Umbellifers, spring oats, legumes, brassicas and spring wheat. To establish and manage this system, Martin Wolfe and his co-workers (P. J. & M. J. Wards) had by spring 1999 developed a range of purpose-built machinery including a strip rotavator, 3 row precision seed drill, straight tine or L-blade strip cultivator with/without discs, rotary strip mower, strip irrigator and a strip compost spreader. Two large experiments were established at Wakelyns in spring 1999; it was planned that these be continued for the full three years of the project. One experiment compared a factorial combination of a) three companion crops: white clover, vetch and nil, b) companion crop mowings left to fall, or deflected onto the vegetable rows, and c) the presence or absence of added composted manure. A second experiment compared factorial combinations of winter cover crops of rye and vetch grown in the vegetable rows with additional approved inputs of phosphorus and potassium. All seven crops were grown but assessments were made only on brassicas, alliums and carrots. Conclusions Companion cropping has the potential to improve economic viability, and pest, disease and annual weed control in organic cropping systems, particularly in field vegetables which are not supported by the Arable Area Payment Scheme. However, in practice, in project OF0181 these benefits were not realised: • Grass weeds were favoured and were difficult to control once established. • There were problems with seedbed preparation and crop establishment; these may be less on lighter soils. • Some crop species were better suited to companion cropping. In 2000 and 2001, there was: - a high yield in both years from beetroot, spinach, chard and kale; - a high yield in one year from Brassicas (some cabbage, swede, turnip), endive, lettuce, parsley and parsnip; - a low yield in both years from Allium crops (leeks, onions), Brassica (sprouts, some cabbage, calabrese), carrots, celeriac, broad and dwarf beans. • Clover used soil available nitrogen in preference to fixed nitrogen, starving less competitive crops such as alliums of the nutrient and resulting in very low yields. • Even with reliable yields, companion cropping in the form tested may only be suited to small-scale labour-intensive production. A system with greater spatial separation of companion and vegetable crops, with vegetables and companion crops grown alone in separate beds or strips, may give the reported benefits of companion cropping with less competition and be practical for large scale production

The long-term agronomic performance of organic stockless rotations

This report was presented at the UK Organic Research 2002 Conference. Two long-term experiments were established with the aim of evaluating the agronomic and economic performance of organic stockless rotations. In total, four different rotations were evaluated at two sites in the south (Elm Farm Research Centre) and east (ADAS Terrington) of England. All of the rotations included either a one or two-year red clover green manure crop to provide nitrogen for subsequent crops and it was found that this was sufficient to support three or four years of arable cropping. Over a period of eleven years at EFRC and five years at ADAS Terrington, there was no evidence of a decline in crop yield, although there were significant year-to-year variations. Crop yields were generally equivalent to or greater than average organic yields. Levels of soil available P and K was maintained at both sites at non-limiting levels. Pest and diseases were not problematic, but perennial weeds posed the most significant problem

Weak anion-exchange hypercrosslinked sorbent in on-line solid-phase extraction-liquid chromatography coupling to achieve automated determination with an effective clean-up

A mixed-mode polymeric sorbent was on-line coupled to liquid chromatography (LC) for the first time and applied it to the selective solid-phase extract a group of pharmaceuticals in complex environmental water samples. The mixed-mode polymeric sorbent is a high-specific surface area hypercrosslinked polymer resin (HXLPP) in the form of monodisperse microspheres further modified with 1,2-ethylenediamine (EDA) moieties. These properties allows its application as a weak anion-exchange (WAX) sorbent in the on-line solid-phase extraction (SPE) coupling. The on-line SPE-LC method developed using the HXLPP-WAX sorbent was successfully applied to percolate a large volume of ultrapure (500 ml), river (250 ml) and effluent sewage (100 ml) water samples. In all the cases, the HXLPP-WAX resin provided near total recoveries of the most acidic compounds studied and clean chromatograms. This is because the ion-exchange interactions enable a washing step to be added to the SPE protocol that removes the compounds with weak acidic, neutral and basic properties from the sample matrix

A “collective effort to make yourself feel better”: The group process in mindfulness-based interventions.

There is growing interest in mindfulness-based interventions (MBIs) in the management of multiple physical and mental health issues. Although MBIs utilize a group format, research on how this format impacts teaching and learning mindfulness is lacking. This study aimed to develop a detailed theory of MBI group processes utilizing a grounded theory methodology. This article presents our subsequent model, developed from semistructured interviews conducted with MBI students, teachers, and trainers (N = 12). A core category, the group as a vessel on a shared journey, and three higher-order categories emerged from the data. They illustrate how MBI group processes navigate a characteristic path. Teachers build and steer the group “vessel” in a way that fosters a specific culture and sense of safety. The group is facilitated to share communal experiences that augment learning and enrich mindfulness practice. Limitations and implications for clinicians and researchers are discussed

Energy use in organic farming systems (OF0182)

This is the final report of Defra project OF0182. The attached main report starts with a more detailed Executive Summary, from which most of this text is extracted. One of the possible benefits from organic farming is a reduced, or more efficient, use of energy in agriculture. The main objective and deliverable of study OF0182 was to develop a model of energy inputs in organic farming systems. To illustrate the potential of the model, it was used to contrast organic with similar conventional systems and to highlight important differences. This was presented as a detailed written report (49 pages) to MAFF and is summarised in this document. The report and model were delivered to MAFF in March 2000. A previous study, completed by Phil Metcalfe of ADAS in 1996 for MAFF ARP Division, entitled “A Comparison of Energy use in Organic and Conventional Agricultural Production Systems”, compared direct and indirect energy use in simple individual crop and livestock enterprise models. These were combined to give whole-system models covering dairy, beef and arable farming. These systems were presented as organic conversion scenarios in the MAFF booklet “Organic Conversion Information Service” (1996). Project OF0182 updates the models developed in 1996 and expands the study to include upland beef and sheep, and vegetables. The dairy, vegetables, arable and upland beef/sheep models are based on the MAFF funded studies OF0146, OF0126, OF0145 and OF0147 respectively. The study also included a consideration of food distribution costs and the possible substitution of labour for energy. The data was organised into a system of linked spreadsheets to form the model The dominant energy inputs in conventional agriculture are indirect energy for the manufacture and transport of fertilisers, particularly nitrogen, and indirect energy for the manufacture and transport of pesticides. These together account for around 50% of the total energy input to a potato or winter wheat crop, and as much as 80% of the energy input into some vegetable crops. Organically grown crops require around 50% of the energy input per unit area than do conventional crops, largely because of lower, or zero, fertiliser and pesticide energy inputs. However, the generally lower yields of organic crop and vegetable systems reduce the advantage to organic when energy input is calculated on a unit output basis. In stockless arable crop rotations, the inclusion of fertility building crops and winter cover crops, that have energy inputs but no direct outputs, can result in a lower whole-rotation energy efficiency from organic methods. In livestock systems, where the fall in output may be less than in arable, and there are no dedicated fertility building crops, overall energy efficiency is greater in organic than in comparable conventional systems. These conclusions were made using average yield data in the model and need to be interpreted with caution. On more fertile soil, where the yield difference with conventional arable production is smaller, organic systems would perform relatively better. The converse would occur on poorer soils. Also, in practice, energy inputs for cultivations and weed control will vary with soil type, weather, weed spectrum and population. The average data presented in the report are illustrative and are not definitive. The strength of the model is that it can be used to simulate many different management systems and yield expectations. The models also allowed a range of transport scenarios to be considered. There was little opportunity found for replacing energy with labour resources

Synthesis and application of hypercrosslinked polymers with weak cation-exchange character for the selective extraction of basic pharmaceuticals from complex environmental water samples

The synthesis of high specific surface area sorbents (HXLPP-WCX) in the form of hypercrosslinked polymer microspheres with narrow particle size distributions, average particle diameters around 6 µm, and weak cation exchange (WCX) character, is described. The WCX character arises from carboxylic acid moieties in the polymers, derived from the comonomer methacrylic acid. A novel HXLPP-WCX sorbent with an attractive set of chemical and physical properties was then used in an off-line solid-phase extraction (SPE) protocol for the selective extraction of a group of basic compounds from complex environmental samples, a priority being the clean separation of the basic compounds of interest from acidic compounds and interferences. The separation power of the new sorbent for basic pharmaceuticals was compared to two commercially available, mixed-mode sorbents, namely Oasis WCX and Strata X-CW. Under identical experimental conditions, HXLPP-WCX was found to deliver both higher capacity and better selectivity in SPE than either of the two commercially available materials. In an optimised SPE protocol, the HXLPP-WCX sorbent gave rise to quantitative and selective extractions of low µg l-1 levels of basic pharmaceuticals present in 500 ml of river water and 250 ml of effluent waste water