Talking to growers during and after the winter barley harvest, a big discrepancy in yields was evident in 2017. It would seem that actual field yields varied from around 2.5t to 4.8t/ac.

There may be many reasons for this, but in practical terms it is excessive. My conversations would indicate that very many of the higher yields in this range came from fields that were either on heavier land or being actively managed to improve soil health through the additions of different forms of organic matter over time.

In this regard, I would love to have access to yield and field information for a large spread of these yields, along with the associated details of how the higher-yielding fields were managed in 2017 and in previous years.

Our natural reaction is to look for one specific spray or a disease such as BYDV to explain away the differences, but I fear we would be looking in the wrong place.

Winter barley has produced mainly good yields in recent years, but the crop does not have a track record of continuing to do this over time.

The crop has always been that bit more sensitive to stresses such as waterlogging and drought but crop genetics have improved in this regard. It was also not a fan of high temperatures during grain fill but the fact that many growers averaged well over 4t/ac must mean that modern genetics can cope better with higher temperatures.

Because of these things one is forced to look back to individual field management and performance. And, as indicated previously, two comments seem synonymous with higher winter barley yields in 2017 – heavier land and managed soil health.

You can’t do anything about the texture of your land, so what have some growers done about soil health. I spoke to three specific growers who averaged over 4t/ac; one had applied chicken litter intermittently in recent years, another had applied pig slurry at sensible rates on a regular basis in recent years, the third has been incorporating straw for many years with occasional use of poultry litter.

All three of these averaged well above 4t/ac at low moistures. I am sure there are exceptions to these comments also, in that many good yields were recorded in fields where no organic matter had been used and there will inevitably be others who had applied organic manure in 2017 or previous years, where there was no evidence of a big yield kick.

Health is critical

I believe soil health is key to these findings. And it is not just important for the level of yield produced from a field, but to the very survival of a grower in the business.

About eight years ago, I said at a meeting that I believed that growers had about 10 years to get their soils into good working order for yield generation or the consequences could be serious.

Eight years have passed. Those who are actively and continuously trying to improve their fields are seeing the benefits. Many of those who have done nothing to worn land are seeing the consequences.

Soil health is the consequence of optimising the physical (soil structure), chemical (soil fertility) and biological (soil organisms including earthworms) elements of a soil.

The theoretical benefits of improved soil health include higher yield potential, increased nutrient mineralisation, increased water infiltration, improved soil structure, reduced draught and cultivation costs, improved moisture retention on lighter soils and decreasing soil cultivation costs over time.

When these benefits can all be combined in the same field, one of the knock-on benefits is a wider working window for planting in particular. A second might be lower nitrogen application levels.

Treatment over time will result in improved soil structure, greater resilience in that structure and improved water infiltration or absorption. These things together provide increased workability in soils to give the wider working window where seedbeds can be produced with less cultivation and direct drilling can become a realistic option.

All these benefits tend to be associated with higher soil biological activity, including earthworm numbers and microbial biomass.

That said, the benefits associated with adding organic matter to soils are not equally apparent every year or at every site.

What is definite is that the land we farm today in tillage, much of which comprises the same fields that we farmed in the mid-1980s, is less productive today than back then. In the 1980s most land, but not all, was much closer to grassland and naturally more productive relative to the genetics of the day.

Since then, our land base has been heavily beaten up by powered cultivation equipment, continuous tillage and much heavier equipment.

Our genetics can deliver well over 6t/ha of winter wheat, over 5t/ac of winter barley and over 4t/ac of spring barley. The economics of crop production demand these output levels, but they are very seldom achieved. I believe that it is the poor condition of our soil health that is limiting this potential for output.

One other well-accepted benefit of improved soil health is the ability of land to cope with variable environmental conditions such as either excessive wet or even drought.

Healthy soils can cope much better with this variability, but the benefits may be much less apparent in years where growth conditions are good all through the season. But reducing yield variability from year to year is also a key component of farm management for farm profitability.

In 2017, many crops suffered from lack of moisture in April and May. In winter barley, some fields lost a lot of fertile tillers during this period, leaving lower yield potential. This was actually measured at some experimental sites and was often characterised by lower straw yields with good grain quality.

My guess is that fields that had organic matter added in recent years had lower risk of being affected by this in 2017, but the underlying cause would not have been noticed in the kinder growing seasons of 2015 and 2016.

Research on soils is challenging

A recent research report from the AHDB in the UK has attempted to look at the science of organic matter addition to different soils. To say that this is conclusive in its findings would be a gross exaggeration of the truth.

On balance, or on mature reflection as might be said in Ireland, the findings agree in principle with many of the theories associated with the addition of organic matter sources, or amendments as they are called in this report.

However, the research report, entitled Improvement of soil structure and crop yield by adding organic matter to soil, produced different and sometimes contradictory findings in similar experiments in different fields or soil types, or even establishment systems.

Perhaps this is to be expected, given the very variable nature of soil even within a field. Things like texture, compaction or historic management practices can leave adjacent areas hugely different in their response.

There were many different experiments involved in the report. Most were field-based but some glasshouse-based. The experiments looked at many different types of amendment and attempted, over time, to measure their consequences on a whole range of soil factors.

The consequence for yield was among the most important factors to be measured, but the researchers then attempted to understand the basis for any yield increase by measuring a range of variables, such as soil structure, soil porosity, earthworm numbers, soil microbiology, etc.

A quick summary of the results concurred that yield will generally be increased, but seldom before the second year of treatment. This might not be the experience of some Irish growers who have used poultry litter to great effect and recorded yield increases in the first year of application.

However, the vast majority of the amendments tested in this report were low-nutrient options, such as straw, compost, etc, and these should take longer to show benefit.

As we move into the spring barley harvest, it is notable that the yield benefit from any of the amendments is regarded as being greater or more common in spring crops than in winter crops.

It is also noteworthy that the yield benefit is generally faster and bigger on lighter soils than on heavier soils with higher clay content. It is also noteworthy that the benefits of any amendment extend for up to five years beyond the ending of treatment.

One last point to mention here is that the affect on earthworm numbers was less clear-cut in some experiments than might have been expected across the different trials.

It was not clear why this was the case, but the impact on either earthworm numbers or the total mass of earthworm biomass in the soil were affected to a greater or lesser degree by all the amendments used. Sometimes it was how this was presented that made the difference.

Action is essential

While current science appears to have a limited ability to explain the benefits of adding organic matter to our worn soils, the fact is the benefits are real and big and they extend long beyond the year of application. The nature of the organic matter used will influence all aspects of a soil but green vegetation or manures will contribute more in time in terms of crop nutrition via mineralisation.

With harvest now well under way, many growers will be looking towards catch crops to help harvest nutrients that might otherwise be lost over winter but this same vegetation will prove extremely useful in time in increasing soil biological activity and earthworms in particular. And given that straw is valuable and that vegetation might be a preferable feed source, benefits to a soil might be produced even faster.

Whatever the action, the improvement of soil health must be seen as essential for those who wish to have a future in tillage. Postponing any such action will mean that one is committed to lower yields and higher costs in the interim.

Good farming must involve care for the soil but also action to ensure its improvement over time. Our future in tillage depends on it.

Next week I will bring more details from the findings of that AHDB report. There are many points from within this that may in some way benefit different growers.

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