Not all water is the same. When we talk about water we usually refer to:
- Green water – this is rainwater that falls naturally on an area; the use of this water by a crop or livestock has minimal impact on the environment'
- Blue water – this is water that is extracted from streams, rivers, lakes or aquifers to provide supplementary water to crops or livestock in the form of irrigation or drinking water.
- Grey water – this is the amount of fresh water that is needed to dilute pollutants from crop or livestock production to meet specific water quality specifications.
Certain crops may have a high water requirement, but be grown in areas where there is abundant rainfall which meets that requirement. For example, grass production in the UK requires large volumes of water which it gets entirely from natural rainfall. However, in some locations there is insufficient rainfall to meet the needs of the crop and supplementary irrigation is required. This irrigation requires water to be extracted from other sources such as rivers or aquifers and this can have a negative impact on the environment.
The level of irrigation required is in part dictated by the location the crop is grown, and in part by the water demands of the crop. For example, most crops grown in arid regions of the world such as California will require irrigation, whilst in the UK, it is only crops that have a particularly high water demand (e.g. potatoes, vegetable crops and some soft fruit) that require irrigation.
All livestock require water to drink, but this is a small part of the water embedded in their production; the largest part is the water used to produce their feed. Therefore, if an animal is fed on ingredients that have a high reliance on irrigation, the embedded water in their production will have a greater negative impact on the environment than those fed on a diet that is mostly rain-fed.
Making the right food choices
If you want to eat foods that require less water, buy foods from countries that have low levels of water stress or are grown in season, when water stress is lower and are therefore less reliant on irrigation. Work by the World Resources Institute has mapped water stress by country, mapping total water withdrawals against total renewable water available (Figure 1). When buying cattle products, focus on those that are grass-fed or have low use of imported feed crops.
Crop production impact
Biodiversity and agriculture do not always go hand in hand.
When growing crops, one of the key aims is to minimise the pest, weed and disease pressure that is present within the crop area; however, the control of these inevitably results in the loss of biodiversity (both the bad, and some of the good too).
There are increasing efforts being made in certain production systems (such as protected cropping) to use natural predators and biological control agents to provide more targeted pest and disease management without harming beneficial insects. However, these approaches are much more challenging to implement at field scale where there is a far more complex series of interactions that occur between the crop, its pests, and other flora and fauna. Allowing weeds, pests and disease to go unchecked within a crop can lead to lower yields and higher land requirements for food production, so a balance must be struck.
Pesticides have a part to play in the management of crop, but they should be integrated into sustainable pest management plans that use a combination of cultural, non-chemical and chemical control options to maintain the health of the crop with minimal negative impacts on the environment.
Livestock have had a key role in shaping many of the traditional British landscapes, from the green hills in the lowlands to the purple moors in the uplands. Careful management of grazing can provide a range of habitats and promote a wide diversity of grassland species including plants and insects, as well as some larger animals. However poorly managed grassland where over grazing, poaching, or erosion is an issue can have greatly reduced biodiversity.
Improving biodiversity in agriculture
Options for improving biodiversity in agricultural systems include the introduction of agroforestry or silvopastoral systems, where crops or livestock are produced in combination with tree crops grown for fruit, nuts or timber. These systems require farmers to look at the management of their land, crops, and livestock in a completely different way, and develop new skills and understanding in order to be able to make them work. If done well, they have the potential to improve the biodiversity on farm, produce sustainable food supplies, and increase the amount of carbon that is captured and stored on farm.
In our next article, we’ll discuss low input and high welfare systems, and provide a summary of what to look for when making sustainable food choices.
About the Sustainable Food and Farming team
The ADAS Sustainable Food and Farming team help clients to address their sustainability challenges.
Our agricultural background means we’re equally at home meeting face-to-face with farmers as we are engaging with senior management in global food and drink businesses.
This gives us the unique ability to work across all stages of the supply chain. For more information on improving sustainability within your supply chain, please contact email@example.com.