Soil doctors

Bean field

25 April 2014 by Sue Nelson

A collaboration between scientists and food suppliers is improving how we manage one of the most crucial ingredients for growing vegetables. Sue Nelson met Karl Ritz, Robert Simmons and Guy Thallon outside Cranfield University's National Soil Resources Institute, to find out about Soil for Life.

Sue Nelson: We take soil for granted; some of us may even have eaten it as a child. But what exactly is it?

Karl Ritz: Soil is one of the most remarkable materials on the planet. It's composed of a wide range of minerals, organic matter and, most importantly of all, space. Soil is porous and it's those pores that hold water, allow plant roots to penetrate and provide a habitat for the myriad of organisms that drive soil function.

Sue Nelson: What makes a good soil?

Karl Ritz: A good soil is one that is fit for purpose, so it depends what you want to do with it. You would need different properties if you want to grow things in it or if you want to make a cricket pitch on it.

Robert Simmons: A good soil for vegetables forms a good tilth - a crumby structure that allows enough contact between seed and soil for good germination but also means the soil is free draining. Soils have to retain and release nutrients and have good aeration, but after that requirements become specific for different crops, so you need different soils for onions and root crops, for example.

Sue Nelson: What actually happens when a soil has been overused, as can be the case when it's intensively farmed for vegetables for supermarkets?

Robert Simmons: A number of things happen; effectively the soil is getting tired - in Lincolnshire they say 'whacked'. The soil begins to degrade and starts to lose its ability to perform certain functions. So it can become compacted and that impacts on soil structure and its ability to receive, retain and release water. Soil structure can also decline through lack of organic matter; intensive production systems can affect the microbes in the soil which in turn affects nutrient recycling and soil structure. You also start having problems with capping of the surface, where the soil surface breaks down under rainfall and forms a cap which then stops water getting in.

You can also get a build-up of soil-borne diseases which are specific to particular crops - potato cyst nematodes for example - and that's why crop rotation is so important. You may need to look at some chemical solutions, like nematocides, or bio-fumigants.

Sue Nelson: Karl, several years ago you came up with an idea to help growers monitor their soil. But why - surely farmers keep an eye on this sort of thing themselves?

Karl Ritz: Individual growers and farmers of course monitor their soils regularly but agriculture is changing. Many farmers now grow crops for large supplier companies. Data about individual growers' own fields and produce, isolated from other growers, isn't very useful for understanding what's happening across a whole area being farmed for one supplier. The data needed to be integrated in a way that could provide important business-related information for the supplier which could also be passed back to the growers.

Sue Nelson: And this led to a link with Produce World, one of the largest vegetable suppliers in Europe. Guy, you worked with Produce World on the Soil for Life project for three years - what did you do?

Guy Thallon: The project was about bringing the individual farm-system data Karl was talking about together into one place where it could be analysed. Produce World is a large fresh produce company; they supply alliums - onions and leeks - brassicas - broccoli, cauliflower - green leafy veg, potatoes and root crops into supermarkets. About a third of that is grown on their own farms and the rest comes from partner farms and growers. I worked with in-house and partner farms, mapping the land being used and recording crop management and farm management data, information about their machinery and farm gear, and also on fertilizers and crop nutrition.

Sue Nelson: And yield as well I assume?

Guy Thallon: Absolutely. As suppliers Produce World has in-depth data on the yield and quality of produce coming through. Their goal is not necessarily about getting the most off the land though - it's about maximising the amount which is of saleable quality - marketable yield.

Thankfully I did have a laptop as I was moving around visiting farmers and growers and asking them to contribute data. Soil for Life itself is a database and information system which identifies fields and links data to those fields. We can then use that data to look at different case studies and understand the different soils growers are working with.

Karl Ritz: For the first time we'll have a large, coherent database which will grow every year as more information is added. As the data are connected we can start to explore it in new ways using what's called data mining - new statistical tools that can look at lots of data at once. One of the names for this is 'big data' - it's becoming common in genetics but here we're applying it to environmental information.

Sue Nelson: Guy, what area does the database cover?

Guy Thallon: Mainly the east of England at the moment - most of Produce World's farms and growers are in south Lincolnshire and East Anglia. We have data on about 800 fields covering about 10,000 hectares.

Sue Nelson: And what will the benefits be for farmers?

Robert Simmons: Some UK growers can lose 40 per cent of their product through defects. Soil for Life can identify which farming practices are most likely to produce marketable crops on a particular type of soil, to reduce wastage - for example fertilizer inputs, tillage practices and irrigation. The beauty of Soil for Life is you can use it to make economic assessments of your production system to identify where you can make savings, not just in terms of things like fertilizer but in terms of energy and carbon.

Sue Nelson: Is it useful for policy as well?

Guy Thallon: Definitely. Food production is really high on the government's agenda. This year's UK Agri-Tech Strategy introduced the idea of sustainable intensification, which basically means increasing food production whilst decreasing the environmental impacts - so minimising the damage you are doing to resources such as soil. The data we've got in Soil for Life and the understanding we can derive from it can have huge benefits for driving forward that sustainable intensification agenda.

This Q&A is adapted from the Planet Earth Podcast, 26 November 2013.