Precision Farming: Environmental Considerations

Here, we’ll look at the impact of precision farming approaches on the environment, both the benefits and the potential risks.

Benefits

The environmental benefits of precision farming are generally the result of reducing inputs. Monitoring the yield, biomass and soil condition can all lead to more precise application of agrochemicals (such as pesticides and fertilisers) and better use of other resources such as water.

Use and impact of pesticides, herbicides and fertilisers

More precise application can mean a decrease in the volumes of, for example, fertilisers applied, as they are only used when and where they are needed resulting in less leaching into the environment [1]. Some studies show a 30 – 50% decrease in residual nitrogen in soils with precision management of inputs [2]. Here are some examples of the technologies being adopted:

• John Deere automated sprayers use ‘Section Control’ to turn individual implementer sections on and off at predefined locations in the field. This also ensures no spraying outside of field boundaries.

Section control to reduce inputs. ©John Deere

• This photo shows a John Deere autonomous drone which scans the field to identify weeds before performing targeted spraying with herbicide. The environmental benefits include reduced compaction of the soil and reduced herbicide applications can slow the progression of herbicide resistance [3].

• Trials of a new automated weed-killing robot carried out at the University of Reading have reduced herbicide usage on crops by up to 95 per cent.

Increasing levels of precision are being achieved. For example, microdot sprayers only spray pesticides or fungicides directly on the crop leaves or herbicides directly onto weed leaves [4] and none is lost to the soil or the air in the form of spray drift. Targeted application of such agrochemicals reduces the negative impact of pesticides on non-target species in and near to the crops.

Precision farming, such as biomass monitoring, can also support more accurate or rapid diagnosis of crop diseases, enabling more rapid treatment before diseases have spread into the wider crop. For example, one study of cotton root rot used vegetation indices to identify the spread of the disease across several fields, enabling rapid, targeted treatment [5]. This can reduce both the quantity of fungicides needed and leaching into the environment.

Reduced emissions

Precision farming can lead to a reduction in greenhouse gas (GHG) emissions through:

i) enhancing the ability of soils to operate as carbon stock reserves, through reduced tillage and reduced nitrogen fertilisation;

ii) reducing fuel consumption through fewer in-field operations; and

iii) reducing inputs for agricultural field operations [6].

Variable rate application in particular, can reduce the application of nitrogen fertilisers leading to a reduction in nitrous oxide (N2O) emissions (a greenhouse gas produced by microbial activity in the soil) [7].

Reduced use of machinery and transportation

Lower input use could, in the long term, lead to lower production rates of agrochemicals and reduced transportation of inputs to the farm [6]. Precise applications also lead to reductions in on-farm fuel use [7] and reduce the impact of farm machinery and transport on the environment – both at a local and national level. And optimised in-field route planning can reduce both machinery use and soil compaction [8].

Impact on the soil

Precision farming supports various conservation systems such as minimum tillage and no tillage systems. Conventional tillage (turning and inverting the soil layers by ploughing) leads to loss of organic content, increases soil erosion and increases energy demands for machinery. Soil monitoring and machinery guidance can support a minimum or no tillage system, leading to better maintenance of the soil organic content, better capture of soil carbon and reducing emissions from agricultural vehicles [9, 6]. Using tractor guidance systems can also reduce soil compaction.

In this TED talk Asmeret Asefaw Berhe explains the benefits of carbon sequestration in the soil.

Water use and extraction

Globally, water is becoming more scarce and the quality is declining. With agriculture using 70% of all water withdrawn from aquifers, streams and lakes [10], variable rate irrigation (VRI) could enable more effective irrigation while using and extracting less water from the environment. Moisture levels of crops can be monitored remotely by satellite or drone, or soil moisture levels can be measured on the ground [11]. VRI also has the potential to reduce nutrient leeching from soils, with one study showing an 80-85% decrease in nitrogen in run-off water from grazing land when VRI was used rather than uniform irrigation [12].

Better decision making

Seeding and planting can also be modified to benefit the environment. For example, in high performance field zones a high demand and high yield hybrid can be planted whereas, in lower performance zones, a more resilient but lower yield hybrid can be planted, reducing the need for inputs such as fertilisers and pesticides [7].

Changing crops could also provide environmental benefits.

• Bioenergy: Several studies have looked at moving from growing arable crops to bioenergy crops on marginal land [13,14].
• Set aside: some areas cost more to manage than they make, so why not turn them over to increasing wildlife biodiversity [15]?

Biodiversity

Reduced and more targeted use of inputs on productive areas of land can also benefit wildlife – both plant and animal – that coexists in that space. And monitoring outputs and yields can highlight areas with lower productivity which could be better turned over to wildlife refuges [15].

Risks

The risks of precision farming are associated mostly with social and financial aspects. For example, the affordability of the technology and the impact on the agricultural workforce. However, some potential environmental risks have also been highlighted:

• Precision application of fungicides may lead to increasing resistance in fungal diseases as there’s the potential to miss infected crops, increasing the risk of resistant strains developing [16].
• Unsustainable intensification of agriculture in the future if the benefits are limited to industrialised countries and focused on the production of widely grown crops, such as wheat, maize, and rice [17,16].
• Loss of habitats if marginal land is turned over to profitable farming, leading to an impact on physical landscape [17].

It’s important too, to remember that although environmental benefits are seen in models and experimental data, the impact may be reduced, or take longer to emerge on working farms [18].

How might data-driven agriculture help you improve your impact on the environment?