Wednesday 28 September 2016

Tillage: Sludge could be a valuable resource - if it is properly managed

Richie Hackett

Published 14/10/2015 | 02:30

A €7.5 million proposed development to make Johnstown Castle in County Wexford the top visitor attraction in the south east was officially launched by the Minister for Public Expenditure and Reform Brendan Howlin TD, pictured with Teagasc's Dr Noel Cawley and Professor Gerry Boyle. Photo: Dylan Vaughan
A €7.5 million proposed development to make Johnstown Castle in County Wexford the top visitor attraction in the south east was officially launched by the Minister for Public Expenditure and Reform Brendan Howlin TD, pictured with Teagasc's Dr Noel Cawley and Professor Gerry Boyle. Photo: Dylan Vaughan

The harvest has finished up well, with sufficiently long dry spells to harvest the majority of the National acreage. Given the amount of rain that has fallen from July to October, that is a significant achievement. The 2015 season is continuing to be very compliant as it shifts to the 2016 season, as sowing continues apace.

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There may be problems managing these early sown crops into excellent warm seedbeds, but it's preferable to manage difficult crops in the field than look at bags of seed in the shed overwinter.

The main lesson learnt from beans this year is that we don't know nearly enough about the crop in modern day production systems. This is dangerous given the acreage sown last year and hopefully the acreage that will be sustained into the future.

We need more information and again we have been found wanting in terms of providing basic research to grow our crops efficiently in our Irish climate. Too much of our basic information is more than 30 years old, or is taken directly from Britain or, even worse, taken from commercial company information.

Taking beans as a case in point, we don't know the optimum target plant stand, planting system, herbicide mixes, fertiliser level, or a definite answer to the previous no-no: application of nitrogen into the seedbed.

Most have an opinion on these after this year and indeed Oakpark is gathering information on some of these factors. 2015 and 2014 were atypical seasons, so it could be very dangerous to design production systems based on the outcomes of these seasons.

Taking seedbed nitrogen as a case in point, there are reports that seedbed nitrogen had some beneficial effect on some crops this year, but our 50-year-old mantra is that seedbed nitrogen has a negative effect on development the rhizobium bacteria, necessary for nitrogen fixing as the crop grows, but we have no definitive answers.

Taking up the point that my colleague PJ Phelan brought up last week regarding use of sludge on crops, this is another good example, and one of many, where up-stream and down-stream processors push all the risk onto primary producers. We, as primary producers, accept this risk without question.

As part of the programme of water quality improvement and general pollution control, every town and city had to install sewage management facilities over the last few decades, and the net result of these facilities is the production of large volumes of sludge manure, which must be disposed of safely and securely.

If as crop producers, we all refused to take this sludge onto our land - because of the risk it imposes on our businesses, as PJ outlined - this would pose a monumental problem.

The problem would not be for primary producers, but for every town and city in the country who would have to find other outlets for this nutrient, but this point never seems to be made.

Sludge that is properly produced, managed, handled and applied according to well-developed rules and regulations, is a very safe and effective source of nutrient. There are plenty of red herrings thrown about regarding its use, not least of which is the heavy metal content.

There can be elevated levels of heavy metals in the product, measured in grammes per hectare, but the most fertile soils in the country are based on limestone soils and can contain heavy metals measured in tonnes per hectare rather than grammes, with no effect on human or crop safety.

There is also undoubtedly a 'yuck factor' involved, but that is the society we live in today, so there's no real way of overcoming that.

The problem was insurmountable a few years ago when every town and county council had different systems and different delivery systems, and, more importantly, different levels of monitoring and control systems. However, all sludge management is now under the control of Irish Water, which now has full control of every sludge system in the country.

There is now a huge opportunity to standardise the product, standardise the delivery systems, standardise the monitoring and controls, and standardise the treatment of this product by the various schemes.

Chemical fertilisers are produced in far flung places and we have no control over the price and the availability.

As a small island, we should seize the opportunity to standardise sludge management to the benefit of the producers of this sludge and also to growers, who can use this product to improve soil fertility levels.

Dr Richard Hackett is an agronomist based in north County Dublin and is a member of the ITCA and ACA.

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