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By Edward H. Faulkner With a Foreword byS. Graham Brade-Birks M.Sc. (Manc.), D.Sc. (Lond.), of the SouthEastern Agricultural College (University of London), Wye, Kent
First published 1945

Traditions of the Plough

Continued from Issue 1 of Direct Driller

Ploughing done when the furrow slice is plastic creates clods; every clod is so much soil mustered out of service for the season. The tremendous pressure necessary to separate the furrow slice from its base compresses effectively any soil that is moist enough to be plastic; and a moderate amount of clay in plastic soil serves to harden the mass upon drying so that adobe-like clods result. Smoothing implements may reduce the size of these lumps, but as clods they are likely to remain aloof from the rest of the soil throughout most of the growing season.

Such evidence of damage done by the mouldboard has passed unnoticed by farmers as well as by most other people. Several reasons may be given to account for the public’s blindness to obvious faults of the mouldboard plough.

To begin with, conditions such as modern farmers face were remote indeed when the plough was first used with a crude mouldboard attachment. The land that had been cleared of trees still was not very well subdued, for it was a hopeless task to try to keep the soil free from competing weeds and shrubs while a crop was growing. The forest was forever trying to recover the lost ground, and the only really effective tools farmers had against encroaching saplings, perennial weeds, and other unwanted growth were crude hoes, mattocks, and spades. Such ploughs as they had threw the soil both to the right and to the left.

They did not cover rubbish very well, much less uproot permanently the wild growth which cumbered the ground. To-day the “bull tongue” plough of the South of the United States of America is of somewhat the same design as most of the ploughs which preceded the mouldboard.

Into such an environment the mouldboard was introduced. It was a godsend. Pulled by an ox, or even by men, this plough would actually lift and invert the soil. This made it possible, by careful work, to eliminate completely the perennial weeds and some of the smaller shrubs. And, what was more important, the farmer who previously could manage only a few square rods now could raise food on an acre or more. Such an invention at a time when England was never far from actual starvation captured the imagination of rural people everywhere.

It was electric in its effects upon contemporary thought. The population now could eat regularly and well, provided enough farmers could have mouldboard ploughs. Inventions did not occur often in those far-off days. New aids to living were rare indeed. The mouldboard plough, destined to revolutionize the living conditions of world populations, marked the beginning of a new era. So completely did it fill the greatest material need of a poorly nourished mankind that it was accorded a place in people’s thoughts such as is usually reserved only for saints and priests. The plough had saved humanity almost literally.

When we come to the eighteenth century we find that in England and America alike, the farmer had more trouble keeping unwanted things from growing than in getting his crops to grow. For him, then, the use of the plough was excellent strategy, because temporarily, at least, conditions were created which made it impossible for the weeds to grow. This gave the farmer time to get his root and grain crops started before the wild vegetation recovered from the setback caused by the ploughing. Once his crops were well started, the incomparable richness of the soil kept them well ahead of the weeds.

Now that the richness has completely disappeared from most land in the United States, our proper strategy may well be the exact opposite of what was advantageous then. His ploughing, even though it covered a lot of organic matter, could not create for him the sandwich, organic matter profile (OMP), for there was too much depth of blackness in the soil. The crude mouldboards of the eighteenth century could not be favourably compared with the burnished products of today’s factories. Hammered out by hand at forges erected at or near the ore mines, they could become smooth only through much use. 

They were designed by guess after many trials and did not become stabilized to dependable shape until a century after farmers began to use them generally. Despite its shortcomings – much easier to appraise from our perspective than from that of the contemporary farmer — the plough was, even in its crude state, the greatest invention of the age. It dispelled hunger as the first oil lamp dispelled darkness. Aladdin’s lamp could not have been more wonderful. When in the middle of the nineteenth century the first experiment station was established at Rothamsted, England, no one seems to have raised a question whether the neat work done by the mouldboard plough might be responsible for the trouble farmers were beginning to have growing crops.

The men of science who manned that first station, as well as those in charge of the state experiment stations later established in the United States, inherited an unquestioning reverence for the plough. The doctrine of the Divine Right of Ploughs passed down from generation to generation, so that the possibility that the plough might account for the waning fertility of the soil never seriously occurred to anybody along the line.

For decades, to my own personal knowledge, men have sensed that the ploughing in of a layer of organic matter at the ploughsole must of necessity interfere with capillary movement; but the subconscious feeling that The Plough Can Do No Wrong apparently prevented anybody from doing anything about it. The result is that, although we have had experiment stations in America for more than three-quarters of a century, no one of them conducted tests, before 1937, designed to compare directly the effects of ploughing, on the one hand, with the surface incorporation of all organic matter on the other.

opening of the present century, it is difficult to avoid assessing blame, on the score of carelessness, against those who did not look beyond their immediate data to the established data gained from ploughing. This is almost implicit in the following:

The Yearbook of the United States Department of Agriculture for 1903 carries this statement on page 284: “Decayed organic matter, by itself or in combination with mineral soil, absorbs moisture much more rapidly than soil containing little or no organic matter; hence, the greater the amount of leaf mould and other litter, the more rapidly will the rain be absorbed. Rapidity of absorption is also influenced by the degree of looseness of the mineral soil. In the forest the mulch of leaves and litter keeps the mineral soil loose and in the best condition for rapid absorption.”

If such a statement seems sufficiently old for its validity to be questioned, compare it with the following, taken from pages 609-10 of the Yearbook of the same department for the year 1938: “Forest litter — the carpet of dead leaves, twigs, limbs, and logs on the forest floor — serves in several ways. Water falling as rain on bare soil dislodges silt and clay particles by its impact. These are taken into suspension and carried into the tiny pores and channels between the soil particles as the water makes its way downward. Very shortly the filtering action of the soil causes the openings to be clogged by the particles; water can no longer move downward through the soil, so it flows over the surface carrying with it the dislodged silt and clay; and erosion is actively under way. A protective layer of litter prevents this chain of events by absorbing the impact of the falling drops of water. After the litter becomes soaked, excess water trickles gently into the soil surface, no soil particles are dislodged, the water remains clear, pores and channels remain open, and surface flow is eliminated except in periods of protracted heavy rains.”

I can detect no significant difference in the meaning of the two quotations. The latter gives a more intimate picture of the processes involved, but it fully confirms the less graphic description in the earlier statement. Moreover, every intelligently conducted experiment so far undertaken in this direction confirms the truth presented.

A paragraph from a letter dated February, 1940, should be interesting in this connection: “The Department of Agriculture has long been interested in developing new methods of soil treatment which will maintain and build up the organic matter content of the soil. Studies carried out by the Soil Conservation Service at a number of locations have already produced unusually outstanding results along this line. At Statesville, North Carolina, for example, it has been found that several inches of pine needles spread over the soil surface reduced the loss of soil by erosion to a point almost beyond measurement. There was also a considerable increase in the organic matter content of the soil and indications point to a worthwhile increase in crop yields. In Nebraska subsurface tillage, which leaves straw and other litter undisturbed on the soil surface, has proved remarkably effective in reducing soil and water losses and in preliminary experiments has led to a material increase in the yield of several crops tested.” This was signed by the Assistant to the Secretary of the United States Department of Agriculture. It may be said that my letter, to which this was the reply, had mentioned and asked for comment on the fact that the mouldboard plough had never been put to test for validation. No mention of the matter was made in the official reply.

Failure to do this has definitely handicapped the development of basic soil information which might easily have prevented the debacle toward which American soils have been drifting.

The failure to harmonize the implications of ordinary observations with really scientific information may be the result of historical lag, or an attitude of mind, or mere carelessness, or, finally, a combination of all three. If we consider the published recognition given to the importance of organic material in the soil surface, especially since the The fact that no advance whatever is apparent, when the statement of 1903 is compared with those of 1938 and 1940, indicates that effort to implement the earlier findings into general farm practice has been neglected. The statements from the yearbooks refer to forest soils, of course; but that fact must not obscure the larger fact that the findings discussed concern principles of universal application. Principles which are valid in the forest are valid in the field, always; so it seems that researches into the importance of organic matter on the surface of crop land should have been started as soon as the earlier announcement had been made. If any such work was begun earlier than 1937, I have been unable to find any record of it.

By Thierry Stokkermans

There is one country where some contractors seed 3000 hectares per year with a 3 metre wide drill, and it is New Zealand. It is not a country of wide plains… most paddocks have odd shapes. How do they do this?

New Zealand has a mild oceanic climate and numerous mountains. Their climate allows the grass to grow all year long. They stock sheep and cattle, for the meat and the milk. There is some cash cropping but arable farms are uncommon, most farms are all grass or mixed. In this pedo-climatic environment and with this farming industry, it is possible to establish new crops 10 months a year. The limitation is a winter break of about 2 months. The NZ seeding calendar is the following:

• Towards the end of winter, farmers will seed spring barley, spring peas and some pastoral mixes such as plantain-clover.

• During the spring, they seed grassing crops to get through the following winter such fodder beet, kale and turnip. This is followed by corn seeding.

• Through the spring, temperatures are getting warmer and seeding get higher and enters mountainous areas.

• Early summer, the high pastures (up to 1000 metres) are reseeded with pluriannual plants such as clover and ryegrass.

• During summer, the seeders will follow the combine harvesters to seed fodder crops in the stubbles and produce a maximal amount of feed for the winter.

• Towards the end of the summer, Oil Seed Rape (OSR) might be seeded but it is a marginal crop in this country and many farmers will reseed older pastures to gain productivity and maximise fodder production the following years.

• Finally, during the autumn, cereals crop will be established and the last fodder crops will be seeded in newly available land such as corn stubbles for example. 

Due to its mild climate, its crop diversity and the landscape, crop establishment jobs are spread over the year and a large number of contractors offers custom-seeding to their customers. Some contractors seed a few hundred hectares with a single machine, other seeds more than a thousand hectares and several seed 3000 hectares with a single 3 meters wide rigid drill. A 3m machine travelling at 12- 13km/h can easily cover 3 hectares per hour. But when the field has an odd shape or the slope is so steep that it is only possible to seed it downhill, the productivity drops quickly. And after adding the road time, the maintenance and talking time with the customer, the tractor will operate about 1500 hours a year in front of the seeder, keeping one man busy all year round.

Many contractors seeding more than 2000ha per machine per year focus on two elements: agronomic support and quality of seeding. The contractor frequently visits their fields when plants are emerging – it is an agronomic and customer relationship task they commit to. This has several positive points: observing successes and problems; sharpening agronomical knowledge; improving the quality of their work; and getting to know the customer and gain their confidence. After a while, the farmer sees its contractor as an expert and a consultant in seeding and, in this livestock farming country, they can give them the role of decision maker for crop establishment.

Those contractors work under no-tillage regime and operate Cross Slot seeders. In New Zealand, some farmers plow, other do alternative tillage (e.g. min-till) and a number goes no-till. Looking at the machinery, the market offers the same seeders as in Europe such as John Deere, Great Plains or Aitchison (the last one is a kiwi manufacturer). Some contractors propose a complete tillage process, some offer no-till with a John Deere or an Aitchison. But the only one who managed to use their seeder 1000 hours per year and more are short frame Cross Slot seeder owners.

The main reason is the Cross Slot capacity to pass all year round in all terrains and, therefore, to allow a high fodder and dry matter productivity. The pro of a short frame on a Cross Slot is that the two seeding beams are close together which make it easier to seed travelling sideways on a slope. Indeed, when seeding across a slope, the tractormachine combination tends to walk sideways (a bit like a crab), therefore a shorter machine often keeps working for longer and keeps providing good performances.

As a comparison, a contractor from the Waikato region owning a 6 meters wide John Deere 750A only uses its seeder on smooth fields in the autumn. The shorter vertical travel of the opener does not allow him to seed in older pastures which have bumps and holes. And the quality of the seed environment only allows for autumn seeding. Indeed, in New Zealand like in France, the autumn crop establishments are the easiest to succeed in no-tillage. In New Zealand like in Europe, the Cross Slot opener is heavy to pull.

Furthermore, to pull the machine on a mountain slope, it is important to upsize the tractor and the power. Kiwis mostly use 6 inches row spacing (or 150 mm). A 3 meters wide seeder has 20 openers. On a sandy plain, this will take a 120hp. Working heavy clay on the level it will take up to 200 hp. But New Zealand is a mountainous country and the tractor for such seeder is about 280hp. To provide good traction, the tractor has a decent set of tyres and is ballasted up to 45- 50 kg/hp. This adds up to a tractor weighing 14 tonnes – a weight that could give goose bumps but less scary than some of the fields where seeding is only possible travelling downhill.

The invoicing of a Cross Slot seeding operation is about 200 New Zealand dollars ($NZ) per hectare. It varies from 180 up to 220 $NZ depending on the area and the contractor. And for the jobs with extremely low productivity, such as tiny field and downhill only seeding, some contractors invoice the worked time (hours) instead of the area (hectare). Seeding operations with an Aitchison or a John Deere are half price. It shows that the difference in cost for the client is justified by the versatility, the seeding quality, the productivity gain and the agronomic support.

Looking at the financial investment, a brand-new tractor + seeder combination with 3m working width cost about 600 000 $NZ. The seeder costs as much as the tractor (or the opposite). To quickly find the efficiency of an investment, kiwi contractors apply the rule of the third: to be profitable, the yearly invoicing has to be at least a third of the investment. For the above investment, contractors will have to invoice at least 200 000 $NZ/year which is about 1000ha/year. 

For those contractors, the clients have different profiles and have different strategies. Some are engaged in Conservation Agriculture and want to improve their soil. Other wants to maximise short term profitability and get the pastures grazed until the roots (see picture). As any service business: taking the job means bring satisfaction to the customer. Those contractors understand this to the full extent and they are working for and with their customers. To maximise the return on their tractor-seeder combination investment, they are available and mobile. Working on Sundays is common practice. Most of their customers are within half an hour driving from the contractor shed but, sometimes, 2 hours of driving are required to visit a remote customer.

For reference: the current exchange rate is 1.93 NZ$ to 1 GBP£.

You can read Thierry’s blog online at: https://thierrystokkermans.wordpress.com/

GPS and other modern technologies, along with thorough trial protocols, can make farm trialling straightforward and routine. Decisions and innovations can then become thoroughly validated and tailored to real farming conditions.

This useful guide from ADAS outlines processes leading to successful farm-trialling and how to avoid the pitfalls. The guide covers trials conducted with ADAS Agronōmics support, trials using yield mapping technology without ADAS support, and trials where the yields are assessed by weighbridge.

Firstly – What Question are you asking?

• What decision do you want to test? E.g. rotations, cultivations, varieties, fertiliser rates, new products, application timings? Does the importance of this decision merit the effort invested in a trial?

• Most questions have been asked and many answered already. Check with an expert (or search the internet) to see what research has already been done.

• Share your plans: several farms doing the same trial and getting the same results will make the conclusions much more trustworthy and valuable. • Define the control or ‘standard’ practice with which you want your new idea to be compared.

• For any question posed, you need an answer that you can use in future. So ensure that the results will be relevant to your farm and unaffected by expected future changes on farm.

• Average farm trials can ‘prove’ grain yield differences of 0.3-0.5 t/ha. Only the very best farm trials can ‘prove’ differences as small as 0.1 t/ha. Think about what difference you expect and what imprecision you can tolerate.

Secondly – Is your Farm set up for a Trial

Fields

• Do you have fields with the right crop which are big enough, square enough and even enough?

Equipment

• How easily can you apply the different treatments that you want to test?

• How will yields be measured: using yield mapping or a weighbridge? This will affect trial design and management.

• If using yield mapping, do you know how to retrieve and process the data?

• Can you geo-locate tramlines, treatments and yields accurately? Mobile phone precision is crude (>5m). RTK gives the best GPS accuracy (<1m).

• Can you acquire other useful measures? E.g. soil maps, crop sensing, satellite imagery, or drone photos.

Attitude

• Will you be willing to put up with extra hassle at harvest?!

• If using a contractor, are they fully on board?

Designing the Trial & Choosing the Field

Split fields versus Replicated Trials

• With split fields it is difficult to tell if any effect is real, or simply due to underlying variation. At the least, test any new treatment in a block with standard on either side, then gauge the variability between standard areas to judge your confidence in the treatment effect.

• Applying treatments in replicated plots takes more effort, but allows greater confidence in the results.

Designing your trial

• There is no single ‘best design’.

• First set the plot size according to the bout widths of treatment machinery, and your attitude to hassle at harvest.

• Plots should be two or more spreader bouts wide when testing fertiliser applications by spinning disc.

• Wider plots are necessary if you want to view treatments with satellite imagery.

• Rotational or cultivation comparisons (e.g. cover crops) normally need larger plot sizes than spray treatments, and are more hassle to replicate.

• Replicate your farm standard treatment at least twice, and ideally replicate all your treatments. The more replication, the more sure you will be of your result.

• Only test the number of treatments that allows sufficient replication within the uniform area available within the field. Avoid testing more than four treatments per trial.

Design of yield-mapping trials

• Plan your harvesting procedure before you finalise your plot size and layout. Aim for at least two full harvest swaths per plot. Wider plots are best if a precise harvesting plan cannot be guaranteed.

Choosing the right field and area

• Choose a field which is big enough, square enough, and even enough. 

• Choose a field with suitable soil type, previous crop, variety, etc. 

• Avoid fields and areas with recent differences in management e.g. fields previously split (see example below). 

• Avoid areas with known problems of drainage or weeds (unless central to your question). 

• Exclude headlands and areas which include trees, telegraph posts, etc. 

• The trial area should be wide enough to accommodate the trial; using a thin field will limit the number of comparisons that can be made.

• The trial area should be long enough for sufficient yield measurements (ideally >200m) and to maximise the area over which the comparison(s) will be made. 

Laying Out the Plots Fairly

Fit with prior patterns of field variation

• Note that ‘natural’ within-field variation in yield will almost always exceed the expected effects of your treatments, so you need to locate your plots very carefully to be as fair as possible.

• Inspect available satellite images (e.g. on Google Earth) and past maps of yield, soil conductivity, nutrients and NDVI, if available.

• If there is obvious variation, arrange the treatment areas so that comparisons will be fair. Ideally any patterns of variation should run across the tramlines, so that variation is not confounded with the treatments.

• Where the likely pattern of yield variability will run at rightangles to your treatments this can be an advantage, as you can see the effect of the treatment across different conditions e.g. soil zones.

Allocate treatments to plots

• Statisticians prefer treatments to be allocated to plots randomly, within blocks of replicates. This is especially important if there is a spatial trend across the treatment lengths.

• There can however be advantages in systematic designs, not least simplicity. We prefer to alternate the standard treatment with the test treatments as above, so that a good estimate of spatial variation can be made, and good comparisons can be made with the standard.

Applying and Recording the Treatments

Mark and record trial and treatment locations unambiguously

• Make a proper record of which treatments were placed where, ideally using mapping software/ apps, or at least using a sketch on a field map.

• It is also worth marking the locations of the plots in the field using canes or flags.

• Tell all those that might be carrying out field operations about the trial and its requirements.

GPS for yield-mapping trials

• To accurately analyse yield mapping data, GPS positions of plots are essential for yield data to be correctly assigned to treatments.

• Your tramline and treatment locations may be recorded accurately on your tractor, but this is often difficult to extract and share.

• Record the GPS co-ordinates of the centre of the tramlines for all the treatment plots where they meet the headlands at both ends of the field.

• Ideally use a proper GPS device with a correction signal (e.g. RTK or EGNOS) as the accuracy of smart phones and sat navs is typically poor (>5m). GPS locations can be displayed in various websites and apps, including http:// gridreferencefinder.com/

Apply the treatments

• Equipment being used for applying treatments should be calibrated.

• When applying treatments, it is important that only the thing of interest is changed so that you can understand what is having an effect on yield. For example, if you are testing a spray, ensure that the different standard and test treatments are applied within a short time of each other and at the same water volume and pressure.

• Apply all other inputs uniformly over the whole field, so that the comparison of your chosen treatment with the standard is not confounded. It is usually best to avoid variable rate fertiliser applications over the trial area.

Crop Protection

Make explanatory measurements

• Depending on your question, it will usually be worth making some explanatory measures (e.g. of disease or by sampling for nutrient analysis).

• The more measurements you take, the more confidence you are likely to have in the outcome of the comparison you are making.

• Point measurements should be in adjacent positions along the length of each plot, georeferenced if possible.

• Effects ‘to a line’ coinciding with the boundary of a treatment can be particularly convincing. Take photos of any visual effects you can see.

• If you are able, it is often worth getting aerial imagery from a drone or plane.

• It is possible to acquire satellite imagery, though free imagery at 20m resolution is unlikely to show treatment differences unless plots are quite wide.

• Spatially referenced measurements (such as drone images) can be analysed statistically to gauge how much confidence you can place in any comparison.

• Keep a dated record of any visual effects of the treatment, or any spatial differences that could affect the results.

Plan for harvest

• Good harvesting is critical for trials whether you are comparing treatments using yield mapping, weighbridge or a yield monitor. Your optimal strategy will depend on the relative widths of plots and combine header, your willingness to harvest discard areas separately, and harvest logistics, e.g. the need to unload on the move.

• Key factors for success are accurate harvester calibration, ensuring full header widths, not cutting across treatment boundaries, and maintaining consistency between plots. Harvest the whole field with the same combine on the same day.

• Yield mapping gives the best confidence that treatments differences are real rather than from spatial variation.

• Using a weighbridge gives accurate weights, but you need accurate measures of the area to get good yields

• Simply using the combine monitor for separate plots can give instant answers, but will be affected by measuring the area in non-full swaths, start and ends of combine runs and shortwork.

Harvesting – Harvesting your trial

• Harvest the headlands first

• Aim to be as consistent as possible between plots. Inclusion of wheelings in the combine swath can depress reported yield by around 0.5 t/ha.

• If not using yield mapping, you must avoid cutting across the treatment boundary in your yield area. If yield mapping, this data will need to be removed from treatment comparisons.

Harvest of yield-mapping trials

• Calibrate the yield monitor according to the manufacturer’s instructions. Ideally test the yield monitor against harvested grain weights over a weighbridge.

• Keep to a constant speed and try to harvest the whole trial under the same conditions and on the same day.

• Harvest in line with the tramlines.

• Keep the combine header full wherever possible, and aim to cut at least two full header widths per plot. A cut with standing crop on either side of the dividers will be fuller than cuts with an edge or wheeling to one side, even though the widths may be assumed to be the same. For example, a 30cm difference in actual swath width on a 10m header can give a 3% difference in calculated yield, around 0.3 t/ha.

• Combine direction can also affect measured yield, especially on slopes or in lodged crops. Extract yield data promptly

• Each combine system is different in the types of files used to store data and how these can be transferred and viewed.

• However, most yield data can readily be imported into farm management software such as Gatekeeper. The data are then relatively easy to export for comparison and analysis.

Keep good records

• Record how you harvested the trial, the time and date, and describe any problems.

• Take grain samples from each plot if appropriate, e.g. for grain protein analysis.

Harvest of weighbridge trials

• Accurate measurement of the harvested areas of each plot is essential for accurate calculation of yield. It is best to compare equal lengths of runs of a known harvested width (e.g. two combine runs per plot). Use good quality GPS tools or a measuring wheel to measure the length.

• If weighing grain from different areas of the field, remember that irregular areas are difficult to measure accurately and may compromise your results. 

• If measuring harvested area with the combine yield monitor, avoid non-full headers and adjust width as necessary.

Analysing Yield Mapping Results

Sort out and clean the data

• Remove data from headlands and any values that are clearly aberrant. Various filters are available to remove data where the combine has stopped or changed direction. Also remove data from combine runs that straddled two treatments, or where the header was not full, even if the software has adjusted for width (sometimes an overcorrection is applied).

• Assign the yield data to treatment plots and calculate the mean of the cleaned data for each plot.

• Unfortunately, analysing yield map data from trials is not straightforward in many farm software packages. As an alternative, you can try QGIS mapping software, available free from www.QGIS.org.

Assess treatment effects

• Treatment differences will rarely be visually obvious from the yield maps

• Look at the spatial variation in the field and judge whether this was likely to have affected the comparisons.

• Variation in yields of standard plots can indicate whether treatment differences are real. Any treatment effect needs to be bigger than the difference between standard plots.

• If your treatments were associated with different input costs, you can calculate a gross margin for each plot.

• Remember that an absence of evidence of a treatment effect is not evidence of absence – it may be that your trial was not precise enough to detect the effect.

Drawing Conclusions – Check to avoid false conclusions

• Remember that inherent spatial variation in fields is normally larger than any treatment effect you may have imposed.

• Double-check that yields were assigned to their rightful treatments. 

• Was the yield map similar to previous yield map(s) without treatments?

• Some spatial variation is inevitable, but this must be assessed and compared to gauge how sure you can be that a yield difference was really a treatment effect.

• How well did yields of replicates agree? • Consider the counterfactuals and any possible confounding factors.

• Spatial data from other sources, including in-season images and monitoring, should be used with the trial yield data to gauge how likely it is that treatment effects are real.

Share and discuss your conclusions

• If possible, compare your results with those of others. The same trial conducted on another farm or in the subsequent season can build further confidence in the results.

ADAS’ Agronōmics service

ADAS has d e v e l o p e d a process, software and new statistical p r o c e d u r e s so those c o n d u c t i n g farm trials can reach the right c o n c l u s i o n s quickly and easily. This includes; 

Geoprocessing to define harvest d i r e c t i o n s , combine runs and distances.

Assignation of data to t r a m l i n e s , treatments and headland areas.

Data cleaning and processing to remove e x t r e m e outliers and anomalous runs, filter data anomalies, and correct for any offset between opposing harvest runs.

Spatial analysis to model spatial variation both related and unrelated to treatments, estimating the average treatment effect(s) and their uncertainties.

Reporting, displaying yields as maps with a standardised colour key and providing clear conclusions.

Meta-analysis of trial series.

For further information, and queries about analysing farm trial data using ADAS’s Agronōmics service, contact agronomics@adas.co.uk

This guide was been prepared by ADAS’s Agronōmics team including Daniel Kindred, Sarah Clarke, Susie Roques, Damian Hatley, Pete Berry and Roger Sylvester-Bradley and they can be contacted on +44 (0) 333 142950

Mike Donovan writes…

Joel Williams is a familiar face to many with an interest in soil health and biology, and first spoke to a UK farming audience in 2010. The Australian plant and soil health educator has a global audience and Direct Driller magazine caught him at the Overbury Estate in Worcestershire where he joined the estate manager and no-till enthusiast Jake Freestone and also Simon Cowell, a long term no-tiller who farms heavy land in Essex who was voted Soil Farmer of the Year 2018. The day provided a mass of information both in the field and from the podium for farmers thinking of transitioning to no-till as well as others who have already made the change. The event was superbly organised by QLF, quality liquid feeds, who have developed the foliar product Boost which is used by both featured farmers.

Joel provides workshops and consultation on soil management, plant nutrition and integrated approaches of sustainable food production as well as giving soil-based talks for farmers, advisors and others. At university he specialised in plant and soil dynamics and he has a particular interest in managing soil microbial ecology along with crop & soil nutrition to optimise plant immunity, soil function and soil carbon sequestration.

In the last few years he has been working in the UK and Europe with both conventional and organic farming systems, integrating soil chemical & biological assessments and in addition integrating plant nutritional analyses as a joined-up strategy for managing crop production. In the UK he was a headline presenter at the 2018 Groundswell Show in Herts and in the year did two presentations in Herefordshire and others in Sussex and Derbyshire, Haddington and Perthshire in Scotland, Northumberland , Shropshire and Tullamore, Ireland. He has enthusiastic audiences in Australia, UK, Ireland, Netherlands, Latvia, South Africa, Kenya, Canada and the US.

At the podium Joel is a convincing speaker who talks with his hands, while in the field he is often in the bottom of a soil pit explaining what is revealed to an audience around the edge. Soil, its use and misuse, is his passion but the MSc he is currently doing in Canada is in the wider area of Food Policy, illustrating his belief in the need to acquire a wide knowledge of the whole business of food supply. Joel has a wide understanding of the issues surrounding soil, the way farmers use it its biology and science.

The breadth of knowledge means that he has a suite of soil subjects within his expertise. “We live in exciting times in farming, as the industrial, ecological and agrarian factors of farming overlap to produce production systems, and the question of ecology is introduced at any part of the spectrum.” The third is ecology which is described by diversity conservation and the ecosystem. This is the leg which Joel considers most neglected. While the industrial or conventional farming contributes to the deterioration of soil components, including water quality and sustainability, the agrarian system relies on natural processes. Joel spends time exploring the area between the two, proposing farmers maximise the use of the natural processes which the farmer can harness to substitute for a proportion of artificial inputs.

Plant nutrient sources and supply

There are two basic sources: chemical and natural. Soil health is the provider of natural sources of nutrients, so the farmer who understands the mechanism of soil will have the tools to stimulate natural organisms that improve nutrient production. Soil health equals plant health and vice versa. Plants absorb nutrients fast, foliar feed getting to the roots in about an hour. Farmers using foliar products are advised to spray in the early morning for best take up.

Joel explains that the UK, along with many other countries, has a history of over-application of nutrients, and says this is due to a focus on N, P and K and a disregard micro-nutrients and a casual interest trace elements. He explains that all components are needed if the soil’s potential is to be made available for the crops being grown. Smaller quantities of micro-nutrients may be needed, but their importance is equal to other elements. Healthy soil with adequate supplies of Mo, Fe, Ni and Co are able to feed healthy bacteria that are able to sequester N from the air as well as creating the right growing conditions for N fixing legumes and clovers. The science applies to all plants, and he stressed the importance of molybdenum.

Tissue tests can mislead. Testing for total N doesn’t reveal levels of amino acid and the tests can show an N deficiency when the actual problem is in the trace and micro elements. Adding N from the bag will be far less efficient Soil biology is combined with soil physics and soil chemistry in creating a productive medium for crop growth, and Joel underlines the importance of all three, and explains that each has an influence on the other two. Chemical changes affect the physical structure as well as the biological activities; physical changes like compaction affect the biology and the chemistry… Joel focusses on soil biology because it is less well understood than the others.

Most are aware of the huge number of living organisms, from the primitive algae which are the first form of life, to bacteria and fungi, protozoa (the single-celled microscopic animals, which include amoebas, flagellates, ciliates, sporozoans, and many other forms); nematodes; arthropods which include spiders and other invertebrate insects; other insects like centipedes and others; and earthworms. Soil carries billions of organisms which work together in what is called the soil food web, where carbon is the common denominator. Bacteria and fungi break down the organic matter by feeding on it and incorporate it into their biomass.

Up the chain and the critters are feeding on organic carbon and excreting it, breaking it down. At the top of the chain are creatures which eat each other producing dung for bacteria and fungi to enjoy. Mycorrhizal fungi is of major importance for plants as they are attached to the roots and contribute to plant development by being fed the sugars and carbohydrates which are the product of photosynthesis and in return feeding the roots mineral and organic nutrients needed for plant growth. Mycorrhizal fungi exist in nearly all soils and provide a secondary root system for the plant, a wider and efficient network attached to the plant’s roots with spreading spidery arms extending beyond the plant roots. These fungi can increase the plants access to soil volume from ten to a thousand percent, and so increasing water absorption, plant size and production.

Further up the chain the protozoa

Nematodes are well know to farmers and growers. Root feeding ones feed on the sugars from roots having first punctured the root with a stylus. Beneficial ones scoop up bacteria and feed on it, others feed on fungi having a straw like structure,and others again that feed on other nematodes. Each process excretes waste products which are then available to the the plants. The process creates nutrients which can be measured and analysed. Some nutrients are highly soluble and almost instantly available to the plant once connected to the root structure. Less available are the exchangeable nutrients which will take a short time to become available.

The third category, the insoluble ones, can move down the soil strata and will, in time, change their nature and become available. When a soil test shows a deficiency of soluble nutrient the temptation to add more from the bag is compelling, but in reality the soil may well have enough nutrient, but lack the means of accessing it. More biological activity would bring the nutrients above the root zone and closer to the surface to allocation where they can be used.

Farm tour of Overbury

The group of 90 toured the higher land at Overbury and Jake Freestone explained that the management moved towards no-till in 2003 and has since taken up cover cropping and companion planting. The first field we saw has been no-till since 2012 and undressed Cruse wheat was coming through well. The crop had some Zn and Mg and 15 t/ha of FYM in addition to the pea residue. Blackgrass populations are in decline and the aim is rouse minimal insecticides. One of the visiting farmers named Ken put forward the idea that their neighbours’ use of the product provides protection, but Jake’s view is that as soil condition improves so the crop condition is raised and so become stronger and more resistant to insect damage. Rotational grass is used to clean land. They use a soil penetrometer to measure soil compaction and provide some comparative data of soil resistance at differing depths, and on the day of the visit we found that there was little difference between measurements in and out of the tramline. They also measure water infiltration using a drain pipe 

The three tractors and tour trailers climbed right to the top of Bredon Hill passing a large area of stoney brash to where the 6m CrossSlot direct drill was parked. Jake explained that the hugely robust machine was designed for New Zealand conditions where farmers were regularly tackling stony ground, and the expense was justified by the expected 20 year lifetime of the machine. The drill can handle four products at a time, with two hoppers with air, so it can do a main crop and granular fertiliser. Two side pods are used for small seeds, slug pellets and other product that is spread at a low rate. The drill weighs 11 tonnes and the tractor 9t, and the fuel is 13 – 15 litres /ha. Jake’s straw policy varies with the field. It is baled and removed before osr because of the slug challenge.

Simon Cowell, judged Soil Farmer of the Year for 2018 provided a fascinating account of working some of the heaviest clay on the Essex coast. His farming has involved working with soil to improve plant performance, and this has involved numerous trials of ideas he thinks might work. The result is that his growing medium has improved hugely. “The soil has lost its stickiness and it is 20 years since we have applied any phosphate. The farm carried a dairy herd and after each grazing we would put on some more nitrogen, just as we were told to do. Grass now grows as well without the top dressing of N.

Simon explained the plant hierarchy and how their nutritional needs change dependent on their place in the list. Moving the soil composition up the scale through the use of compost has resulted in a noticeable reduction in blackgrass which has been a major problem on these bacterial soils. The compost has reduced the germination of weed seeds and has meant that Atlantis is now working again. Simon says that the no-till system keeps the soil aerobic, while working these soils with tines and power harrows breaks the structure and causes slumping.

“I see the compost heap providing an inoculant rather than a fertiliser or soil conditioner. The compost provides a home for good bacteria and fungi which then help feed the cash crop.” The compost is mixed with a bespoke machine rather than a fork and the stirring increases both carbon and nitrogen levels. The heap is kept at 70C and is left to stand for a year. He makes the most of horse compost, ditch soil and plasterboard. Fed this way the crops tend to have stronger straw, deeper roots while plots given regular fertiliser have softer tissue making it easier for destructive fungi and insects to attack.

Every field has a ‘holiday’ by being down to lucerne for three years. The crop goes to local company Dengie crop driers and the plants get a chance to drive their roots deep into the soil – they can go as deep as 45ft and more. While conventional farmers would break up the root network created by these roots, by leaving them well alone Simon preserves the matrix of pores which aid drainage and provide new roots with a highway rich in fungi and bacteria from the rotting roots. The field surfaces are better able to carry farm traffic and the need for ultra flotation tyres is now much reduced. Simon also trialled the effect of fungicides – stopping using them on some fields – and found they were depressing yields. So while they reduced disease they had side effects.

He also has developed his own wheat mix blend, choosing 4 varieties that are unrelated and mixing them prior to drilling. The next year’s crop comes from home saved seed, and this has now continued for five years. He was interested in how this mix compared with seed from KWS and was pleased to see his mix performed well. He has done other trials into N and concludes that often the plant needs a combination of trace elements and bacteria in addition to the N feed. “The processes we are dealing with are far far more complex that is presented in textbooks and by experts.” Simon describes the trials as ‘addictive’ and the information gained is always worth more than the money spend on doing the work.