University of Hertfordshire

By the same authors

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Original languageEnglish
PublisherEnvironment Agency
Number of pages159
Publication statusPublished - 14 Nov 2006


The Environment Agency, Southern Region, commissioned this scoping study to assess the potential environmental risks and impacts of horticulture in the Region. Much of Southern Region is environmentally sensitive due to the diverse nature of its geology, habitats, ecology and landscape. Over half the region has vulnerable groundwater, which supplies 75% of public water supplies.40% of the Region is protected by some form of conservation designation, and 40% has nitrate vulnerable zone status.
There is about 25000ha of horticultural production within Southern Region representing about 3.3% of the farmed area. About 73% of this area is in Kent, where it makes up 60% of the farmed area, with a further 14% in Sussex, 9% in Hampshire and 3% on the Isle of Wight. Crop groups assessed included: Potatoes, Peas and beans, Other vegetables, Protected crops, Top fruit, Small fruit, Hardy nursery stock, and Bulbs and flowers. The largest area of horticultural cropping in the region is for top fruit, followed by vegetables, potatoes, small fruit and hardy nursery stock. There are also small areas of peas and beans, protected crops and bulbs and flowers. Significant proportions of these crops are grown near vulnerable groundwater and within or near NVZs. There are also areas of horticultural production near some of the Regions important environmental sites, such as the Stodmarsh nature reserve, Thanet, the Thames, Medway and Swale estuaries in Kent, and also the Chichester and Langstone Harbours.
For each main crop group an indicator crop was selected, based primarily on cropping area. A generic risk assessment was undertaken for each indicator crop, based upon their production scenarios, regional environmental sensitivities and knowledge of causal factors leading to environmental impact. The key findings are summarised below:
Crop Protection:
Top fruit receives the greatest amount of pesticide, mainly fungicides. Typically 14 spray rounds per crop are applied compared with the 5 or 6 normally applied to cereals. This is significant because at over 10,000 hectares it is also the largest horticultural crop group, most of which is in Kent and grown near to nationally environmentally important sites, such as Stodmarsh, Thanet and Sandwich Coast, and Thames, Medway and Swale estuaries. Over 6000 ha (66%) of top fruit is grown over vulnerable groundwater which could become contaminated with Diuron, myclobutanil, paclobutanol, fenoxycarb or pirimicarb, all of which are used on top fruit. Top fruit pesticides pose the greatest potential risk to aquatic life and it has been noted that pesticide practices influence the type and intensity of environmental impacts. Broadcast air-assisted sprayers are thought to have the greatest potential for spray drift and these are used on top fruit, thus increasing the risk of impact on aquatic life further. Other crop groups of concern include main crop potatoes and other vegetables. Both potatoes and field vegetables are high risk crop types in terms of susceptibility to soil run-off and erosion and this is significant considering 2977 ha (82%) of potatoes and 3646 ha (57%) of other vegetables are grown in areas vulnerable to soil loss. Both crop groups are mostly grown in Kent and West Sussex, with 2352 ha (65%) potatoes and 4919 ha (76%) other vegetables grown over vulnerable groundwater.
Nutrient Use:
It is estimated that almost 3000 tonnes of nitrogen (N) and 1000 tonnes of phosphorus (P) are applied to horticultural crops in the region per annum. On an average input per hectare basis, nitrogen inputs are lower and phosphate inputs are higher for horticulture in the region compared to the average for cereals grown in the UK. About 60% of the N and 75% of the P, could become available to be lost to the environment, depending on the crop. The risk of nitrogen and phosphorus loss to the environment for each indicator crop was classed as low, moderate or high with the highest risk attributed to other vegetables and potatoes. Top fruit is considered to have a low potential to loose nutrients, but due to the large area grown even small losses could accumulate and become significant. In the Stour catchment, potato and vegetable production, in combination with small areas of hardy nursery stock and peas and beans, could be significant contributors to high nutrient levels. High nutrient levels in the Stour, a chalk stream, could have a negative ecological impact on Stodmarsh national nature reserve. 19% of the farmed area around Stodmarsh is horticulture. It should be noted however that GQA assessment here indicates that the biological quality is good. Horticulture could also be contributing to nutrient levels found in the Arun and Medway catchments.
Energy Use and Global Warming Potential (GWP):
The main energy inputs for horticultural production in the region is almost 162000 GJ or an average of 15GJ ha-1. This is similar to oilseed rape (15.5 GJ ha-1) but lower than potatoes (31 GJ ha-1). However, energy use is highly variable with crop and production methods. Considering production area, the largest use of energy is for the production of potatoes, apples and strawberries. Much of the energy input and greenhouse gas (GHG) emissions for potato crop production are a result of nitrate fertiliser manufacture, in strawberries manufacture of polyethylene and soil fumigants and in dessert apples the manufacture and application of fungicides and herbicides. However, it should be noted that ideally comparisons should also be made on an ‘input per tonne’ basis. For example, tomatoes have a high input per hectare, but are also very high yielding. The Global Warming Potential (GWP) from the use of fossil fuels will follow a similar trend to energy use.
Water Use:
Abstraction for agricultural purposes accounts for only 3% of abstraction in the Region, but this demand tends to coincide with the times in which resources are already stretched (the summer months) and horticultural crops tend to be amongst the most demanding on water resources. On a per hectare basis protected crops are likely to use the most water, followed by small fruit, potatoes, other vegetables, hardy nursery stock, top fruit, peas and beans. However, this is variable depending on crop and location. Considering this, the largest potential user of irrigation water in the region is vegetable production followed by top fruit, potatoes, small fruit, protected crops, hardy nursery stock and peas and beans. Potatoes and vegetables both require large amounts of water and are grown in the driest areas of the region. This may impact on water demand and low flows in rivers, particularly in East Kent and South East Kent near Romney Marsh. Similarly vegetables and protected crops grown in South West Sussex near Chichester also have a high requirement for irrigation water. The large area of small fruit production in the Medway catchment has relatively high requirements for irrigation water, which could be an issue due to increasingly scarce water resources in the area. In addition to crop requirement, irrigation practices may also influence water demand for horticultural crops. Further research is required to quantify any impacts of irrigation methods.
Other Environmental Issues:
Soil management: About half of all the horticultural crops in the region are grown in areas where there is a potential risk of soil loss. The crops that present the highest risk of erosion are potatoes and vegetables. 82% of potatoes and 57% of vegetables are grown in areas vulnerable to soil loss. The potential impacts of soil loss include nutrient and pesticide pollution of water via particle bound transport. Sediments can also have an impact on the risk of flooding in a catchment and on some aquatic ecosystems particularly fisheries. There is a high risk of sediment loss from horticultural production on the Isle of Wight, in the Arun, Rother and Stour catchments as well as areas around Thanet, Romney Marsh and near Chichester on the South Coast. Soil properties that make these areas productive also make them vulnerable to soil loss, which combined with potato and vegetable crop production presents a high risk of soil loss. There is also the issue of losing soil as a resource and it has been identified that some Grade 1 and 2 agricultural land in the region is at a high risk of erosion.
Pollution incidents: In 2004, 10% and in 2005, 5% of all pollution incidents from agricultural sources were from horticultural premises in Southern Region. This compares with less than 3% attributable to horticulture nationally during 2004. Within Southern Region 133 pollution incidents from 2002-2005, were from horticultural/market gardening sources. Only 3 of these incidents had a significant environmental impact. The pollutants responsible for around half of these incidents were waste, fuel and smoke, and are probably the result of poor management practices. Preliminary data analysis therefore provides little evidence to indicate environmental impact from pollution incidents attributed to horticulture.
Waste management: Many waste types, such as scrap machinery, metal, oils, tyres and packaging are generic to agricultural and horticultural businesses. There are however other waste types, such as greenhouse or tunnel film, mulch and crop cover film, seed trays and pots and other horticultural plastics that are specific to horticulture. In 2003, 2215 tonnes of horticultural plastic waste was generated in the South East, which is approximately 0.05% of the total waste and by-product produced from agricultural activities and 18.5% of solid agricultural waste that now falls under regulatory control. Nevertheless horticultural plastic waste increased by 1869 tonnes (540%) between 1998 and 2003, despite a 19.6% reduction in overall agricultural waste production in the region. Horticultural plastic for example, requires large amounts of energy to produce, impacts upon landscape and biodiversity and requires safe methods of disposal or re-use. Potential waste arisings for each indicator crop have been identified, with packaging waste, plastic sheet/tubes and crop residues most common.
To conclude, this study identifies potential environmental impacts of horticulture in Southern Region. It focuses attention on some of the more important issues and locations. Horticultural crops are not the only crops in the areas highlighted in the study, and therefore, when drawing conclusions from the study, or planning further work, more detailed analysis is necessary to attribute findings to horticulture as distinct from agriculture in general. The areas of further research outlined would serve to develop a more thorough and better understanding of the identified potential impacts.

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