Enhancing nutrient use efficiency from biosolids for a resilient crop production system

There is an urgent need to increase the amount of food crops that must be produced in order to meet the demands of an increasing global population. There are many challenges to be overcome to increase the amount of food crops produced, especially as previously increasing yields of these crops have levelled off in recent years. Some of the causal challenges include changes in climatic conditions that affect rainfall and temperature patterns, decline in soil fertility, soil contaminants, spread of pests, weeds and disease and their control, and adoption of new plant varieties. It is not possible to overcome all these challenges simultaneously, but the issue can be tackled in stages. One promising approach is to use organic waste materials that are being generated to enrich soil quality and improve its fertility. As organic waste is readily available, this represents a good starting point in addressing the challenges noted. There are many choices of organic waste that could be utilised, including manure, compost, and biosolids. However this project will focus on biosolids, due to its high phosphorus levels. Phosphorus is one of the major elements needed by crops. Currently phosphorus is extracted in mines, which are located mostly in North Africa. In order not to rely solely on one such source, it is deemed more sustainable to use renewable source phosphorus such as biosolids have been turned into fertilisers.

Previous field scale applications were conducted for three years in three locations, in Bedfordshire, Shropshire and North Wales. That research showed there were no significant differences in biosolids-production yields of wheat, oilseed rape, barley, beans and forage maize, as compared with using chemical fertilisers. This is encouraging as the use of biosolids as fertiliser did not compromise yield and so over a number of years could potentially lead to reduced chemical fertilisers. However, these trials were undertaken at three specific sites. The focus of this current project is to build upon this to evaluate the factors that influence nutrient use efficiency (NUE) of crops applied with biosolids and, drawing on national collections of relevant environmental 'Big Data', to determine the widespread geographical opportunities to adopt biosolids across England and Wales. Nutrient use efficiency can be defined as ability in crops to utilise nutrients to produce yield (either as grain or fruit). The greater this is, the better will be the yield with lower use of nutrients. Challenges that influence crop production consequently influence NUE. However, as it will be challenging to consider all the factors that can influence NUE in a one year project, an alternative approach will be utilised in this work. Data on climate, crop variety, pest/disease and soil will be sourced from various organisations and harmonised to produce an analytical map. This map can then be utilised by end-users to better use biosolids in parts of the country where NUE will be high resulting in sustained or elevated crop yield. However before the map will be finalised two consultative sessions will be organised with stakeholders (such as farmers, Agricultural Trusts, National Farmers Union, water utilities, fertiliser and agro-chemical companies, policy makers, agronomists, Farm Assurance Schemes and food producing companies) that would benefit from using this map. The reason for consulting these groups is so the outcome can be produced by taking into account comments that can improve the quality to better suit demands of the end-users. There will also be produced a set of interpretative protocols that will accompany the maps which will help end-users interpret it in order to better use it to target areas where biosolids can be applied for increasing crop yield.

The digital map provided will be made available online, hosted from LandIS (www.landis.org.uk), as a resource to guide optimal land planning across England and Wales. This will be important as it can be utilised to determine the available landbank for biosolids application. The map will also be potentially modified when considering other organic amendments and also for future 'geo-temporal' predictions when using future climatic datasets. The map would be utilised to identify areas where, drawing on a combination of environmental factors that influence NUE, potential crop yield could be predicted in coming years. The map might also well be used as springboard and knowledge exchange to extend the outcome and methods of this work applied in other countries such as the Republic of Ireland, where there is an increasing trend of biosolids application to land. Such applications would be a logical progression following the completion, by example, of the new Irish Soil Information System (http://isis.teagasc.ie/) developed by Cranfield and Teagasc (Irish Agriculture and Food Development Authority). The map could, in future, be extended to include Scotland if all other relevant data were obtained.

The expected benefits to stakeholders include better use of biosolids as phosphorus based fertiliser which is targeted to increase crop yield and minimise any negative effects to soil. The map would be able to highlight areas where highest crop nutrient use efficiency associated with biosolids can be implemented by taking into account factors such as soil, climate, pest and crop variety that can influence it. The map can also be tweaked to suit other organic amendments such as farm yard manure and compost. The map will also be used as a predictive tool in the future by changing input data such as climate to forecast what potential effect this could have on other factors that influence nutrient use efficiency needed for resilient crop productivity. The use of biosolids is usually associated with build-up of heavy metals in soils and the map accounts for digital soil information on heavy metals. This would mean that the map can be used as a monitoring tool to assess changes against threshold values in soil heavy metals associated with application of biosolids.

The outcome to stakeholders will be role of the digital soil map as a focal point that brings together the main players that can mutually benefit from this project. As contributors to 'Big Data' have varied interest, the digital soil map can be a conduit to best use information that is underutilised for a common benefit which improves resilience in crop productivity.