Team:BCCS-Bristol

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Soil Indicator Project

Many crop types need to be harvested and replanted from scratch on an annual basis. To maintain nutrient levels in the soil, farmers often have to put down considerable quantities of fertiliser. This is costly, and a fair proportion of it ends up landing on soil that has enough nutrients anyway. Additionally, some of the nutrients in the fertiliser are often washed away, affecting local ecosystems. This process is called Eutrophication. This is a major environmental concern, as it can cause algal blooms that drain oxygen out of rivers and lakes, killing fish and other wildlife.

Our project aims to create a cheap, versatile soil fertility sensor to be used primarily by farmers. Our device will work by sensing whether nutrients in newly ploughed soil are above a given threshold. If this is the case, it will express a colour signal, identifying its area as high in nutrients. Our device will be based on an E-Coli chassis.

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Old Project Page (soon to be deleted)


Soil indicator


Mission Statement

Our project aims to create a cheap, versatile soil fertility sensor to be used primarily by farmers. Our device will work by sensing whether nutrients in newly ploughed soil are above a given threshold. If this is the case, it will express a colour signal, identifying its area as high in nutrients. Our device will be based on an E-Coli chassis, as this allows us the greatest flexibility in design. We intend to implement a simple version of this device in the lab, and then characterise it thoroughly as part of the modelling section of this project. The modelling section will also involve more complicated designs, and an investigation of how our bacteria can be grown, deployed, measured and killed in the field.

Motivation

Many crop types need to be harvested and replanted from scratch on an annual basis. To maintain nutrient levels in the soil, farmers often have to put down considerable quantities of fertiliser. This is costly, and a fair proportion of it ends up landing on soil that has enough nutrients anyway. Additionally, some of the nutrients in the fertiliser are often washed away, affecting local ecosystems. This process is called eutrophication. This is a major environmental concern, as it can cause algal blooms that drain oxygen out of rivers and lakes, killing fish and other wildlife. Our device is cheaper and more environmentally friendly than chemical nutrient detection systems, and can eventually be used directly on fields. This allows farmers to skip fertilising areas that are already nutrient-rich, saving them money on fertiliser. Less fertiliser on the fields means less nutrient runoff, and consequently less environmental damage. Finally, on a national level, countries can potentially produce more crops with the same quantity of resources. This could be very helpful to poorer nations with growing populations.

How does it work?

Our detector consists of a population of E-coli bacteria which have been modified to detect the presence a set of nutrients. When they sense that the quantity of a nutrient is above a certain threshold, they express a colour (GFP). Many crops, for instance maize or wheat, need to be planted in open soil, grow for an entire season and then be harvested completely out of the ground, leaving an open field for the next planting season. Our plan is to use the detection system immediately before planting a new crop. After a harvest, a farmer would generally plough the field. This is a process by which the topsoil of the field is replaced by the layer of soil immediately beneath it. This is done because topsoil is generally not very good for planting seeds in. This is because it is harder set and lower in nutrients. The newly ploughed soil is representative of the deeper soil in the area, so we intend to use it as the surface on which our detector works. Our bacteria can be grown in quantity and then sprayed across the newly ploughed soil. The colour that the bacteria express may be difficult to see with the naked eye, so we recommend a more mechanised method. An ultraviolet light source can be fitted underneath the tractor or vehicle used to apply fertiliser to the field. This UV light will cause the bacteria to luminesce, and this luminescence can be detected by a camera on the tractor. The fertiliser being deployed by the tractor can then be stopped whenever it detects it is travelling over ground that is already high in nutrients. By this method, the use of fertiliser is limited only to areas with low levels of nutrients.