How low can we grow?

Whatever industry you are in, reducing carbon and improving sustainability remains a priority. The horticulture sector is no different. Adrian Tatum reports on recent developments across the UK.

As the UK heads faster towards a low carbon future, the horticulture sector has been ahead of the game over the last few years with growers reducing their carbon footprints and improving the sustainability of their businesses on a consistent basis.

The NFU’s document: Delivering Clean Energy From the Land, sets out a role for agriculture in general in helping delivery challenging reductions. The NFU says: “Agriculture has a unique role to play in implementing the historic 2015 Paris Agreement on climate change. Our industry supplies food, stores carbon and generates renewable energy, but farming is also on the frontline of climate change impacts, being particularly vulnerable to extreme weather events. However, British agriculture can address the challenge of producing for the future as well as tackling climate change. Our declaration prior to the Paris Summit included a key ask on mobilising the huge potential of land-based renewables to deliver clean energy, contribute to national energy security, diversify farm businesses and bring additional benefits to the environment.”

Matthew Simon, Technical Manager at Glinwell and Chair of the British Tomato Growers Association says glasshouse growers have always been proactive at reducing carbon and improving energy efficiency and waste. “Glasshouse growers have almost been ahead of the time with their work to minimise greenhouse cases and look towards implementing renewable energy sources and improve recycling,” he tells The Commercial Greenhouse Grower. “In works both ways. If you are not being proactive with energy efficiency, you are adding costs to the business anyway. The fact that we are drawing C02 and using it to pump back into the crop, implementing new infrastructure such as CHP units and more efficient boilers means that we must be putting less CO2 up the chimmey than most average households.”

Glinwell has been involved with a number of initiatives including re-cycling of water and the Rockwool it uses as growing medium. The company has been working with Grodan on a project that sees used Rockwool now being used to make bricks. Grodan has also produced a next generation substrate-with NG2.0 technology. This technology enables propagators and growers to produce more while using less water, nutrients and space. It creates optimal growing conditions for a whole season, and allows roots to make better use of the entire substrate.

Continuous growth of new roots in both block and slab result in a healthy and vigorous crop throughout the growing season.  These benefits translate to higher yields, improved fruit quality and reduce the sensitivity of the crop to diseases. After a phased introduction, this technology is now worldwide available and covers the complete product range of Grodan.

A joint trial at the Improvement Center, in which the Grotop Master (10 cm high) was used with NG2.0 technology, demonstrated water savings of 15% compared with various other irrigation regimes. In particular, more precise irrigation is possible during the winter months.

According to Dr Phil Morley, Technical Officer at the British Tomato Growers Association, energy efficiency has contributed significantly to carbon reduction and improving the sustainability of growers’ businesses.

“Growers are contributing all the time through energy efficiency. They are using only waste heat and CO2 from other sources including CHP electricity production which is fed either by natural or bio-gas. More efficient growing techniques are ensuring maximum benefit from all inputs so increasing quality and yields per unit of (any) input. They are also redeveloping older glasshouses and constructing newer and more efficient structures. The use of LED lighting to further optimise the uptake and utilisation of CO2 in the crop as well as getting more outputs per unit of inputs is slowly starting to take off in the sector though the initial investment is very high,” he says.

“The focus for tomato growers at the moment is optimisation in use of all natural and other input resources is as ever a priority and new methods and technologies continue to evolve to help with water, fertiliser and energy efficiency,” he adds. “One of our growers (APS Produce-part of the APS Group-see below) is developing a fully tomato based packaging system sourced from tomato plant by products (leaf and stem) and using a bio-digestion process delivering a plastic free punnet and film. This is truly sustainable.”

He says that work is on-going to improve water storage facilities for collecting rainwater from glasshouse roofs as well as re-circulation of nutrient solution in hydroponic systems ensuring optimal use of applied fertilisers.

“Pesticide free production has also been achieved through understanding and nurturing glasshouse ecosystems and where used, soil biomes. And of course ‘reduce, re-use’ re-cycle’ mantra is as strong as ever alongside ‘innovate’. Alongside established funding streams and applied research streams (AHDB funded) we are trying to get growers to research ideas themselves using funding through the excellent ‘Innovative farmers’ initiative also,” says Dr Morley.

“Sustainability is one of the highest priorities for all British Tomato Growers’ not simply a ‘nice to do’ attention to these details is becoming a business critical approach to growing,” he adds. “The carbon foot-printing methods from the past were a little inaccurate and perhaps now out-dated. That being said, efficient use of carbon in the whole process and substitution where possible is very much on growers’ agendas both in terms of ‘doing the right thing’ though also for staying in business, a ‘sustainable business’ is one that is progressive and innovative, such business models are indeed common in the Tomato grower world. The wonderful efficiencies protected crop growers have achieved over the past decades can be seen as a positive case study for other production systems and perhaps the primary research at this point is to ‘join the dots’ and get growers to share best practise as happens in the tomato grower world.”

The APS Group has been very proactive in its approach to reducing carbon and improving on sustainability. Over the last few years, working with academics and industry experts, the company has developed a unique anaerobic digestion (AD) plant that uses all 3,500 tonnes of the tomato crop’s leaf waste and converts it into valuable by-products that can be used in APS’s tomato growing operation. These include bio-plastics and leaf fibre cellulose, which is used in the manufacture of packaging film and punnets to pack our tomatoes for sale.

The company also uses thermal storage tanks which are used to pump into the glasshouse at night to keep the crop warm without the need to run a boiler. These work well alongside APS’s CHP plant. The waste heat to warm the tomato plants in our glasshouses and waste carbon dioxide produced to help nourish them.

At the company’s Alderley Edge nursery the heat rejected from the packhouse, from cooling the tomatoes, is used to warm the irrigation water. This saves 40% of the electricity normally used to cool the tomatoes, and also saves the fuel normally needed to heat the water, thus improving fruit quality and crop production at the same time.

New glasshouse schemes are also building in more sustainable solutions. A large commercial glasshouse planned for Godmanchester in Cambridgeshire could be the first one in the world to use surplus heat from a sewage works if planning permission is granted later this year.

The scheme would see low-grade heat collected from waste water at the nearby sewage works using ground source heat pumps, which would also help to eliminate carbon emissions.

The planning documentation states that: “Large scale developments of this type make a major contribution towards the production of home grown food, national food security and at the same time significantly reduces associated carbon dioxide levels and food miles. The socio-economic benefits can also be substantial – the proposed facility is expected to create 135 additional full-time jobs once operational and where glasshouses are located they are seen to significantly enhance the local economy.”

It said: “This development represents an excellent opportunity for Huntingdonshire District Council to contribute a reduction in our carbon emissions by 26% by 2020. The concept of the proposed development incorporates a new approach to glasshouse heating, with the aim of reducing and potentially eliminating carbon emissions from the growing process, through the use of heat pumps which would extract the low grade heat embedded within the treated wastewater from the nearby water recycling centre (WRC).”

Changes to the Renewable Heat Incentives (RHI) over the last few years has seen a temporary slow down in the uptake of some renewable energy technologies, but on the whole growers are still positive about making investments when and where appropriate, especially in the area of biomass heating.

The Department of Business, Energy and Industrial Strategy has recently reported that recent figures showed that a peak in RHI applications of biomass systems over 1MW happened in October-a direct result of the alignment of biomass tariffs in September. According to analysis by Farm Energy Centre (FEC), it was noted that there was a slight reduction in the number of applications overall. In terms of anaerobic digestors, RHI changes haven’t been so favourable and there has been a downturn in investments in this area.

Growers such as R& L Holt have successfully combined the use of anaerobic digestors, biomass boilers and use of liquid Co2 giving the company maximum flexibility and the ability to drive further efficiencies in terms of energy costs.

Growers have also been asked to review their water strategies after the heatwave experienced this summer. Technological advances in this area are helping growers become more efficient by the day with their water use. Priva’s water management programme is one example. The system allows you to; treat your entry-level water for an optimum irrigation strategy, administer the right concentrations and ratios of nutrients and determine the time at which watering takes places in the glasshouse. It also allows you to manage the recirculation and discharge water safely and efficiently.

Growing media specialist, Klasmann-Deilmann, has developed a calculating tool for determining the carbon footprint of horticultural businesses. This system discloses not only emissions relating to energy consumption, seed, fertilisers and pesticides, as well as packaging and growing containers, but also the proportion arising from substrate use.

The new calculating tool can be used to determine the CCF for a nursery and the PCF of each crop cultivated there. Firstly, all relevant factors are identified in detail and fed into the calculations. These include consumption of electricity, natural gas, petroleum and coal, the seed used, fertilisers and pesticides utilised, and packaging and growing containers. The use of growing media, including their transport to the nursery, is also factored in.

The CCF subsequently determined by the calculating tool enables a business to develop its own strategy for reducing emissions and to assess this over several years. Potential parameters here may include the business’s heating strategy or the use of substrates with a higher proportion of alternative constituents. Experts at Klasmann-Deilmann provide active, ongoing input into the calculation process for the carbon footprint.

“Sustainability is playing an increasingly important role for the major food corporations,” comments Moritz Böcking, Managing Director of Klasmann-Deilmann. “We are keen to equip not only ourselves but also our customers for the demands of the future. Those able to account for how environmentally and climate-friendly their products are, have an additional competitive advantage, since retail consumers and wholesalers are paying increasing attention to responsibly produced goods and reward sustainable development.”

The calculating tool was trialled in close cooperation with two nurseries in Germany. mk jungpflanzen gmbH, a propagator of young vegetable plants and part of the Peter Stader group, and ornamental-plant grower Irßlinger GmbH & Co. KG provided operational data that were then processed using the calculating tool.

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