UAVs and organic farming: Lessons learned

Last week Agribotix had the pleasure of visiting our first organic farm to learn more about how drone-collected imagery could be used to increase efficiencies in a sector that traditionally doesn’t employ many precision agriculture techniques. While conventional farmers have the options of spatially controlling their fertilizer or chemical application based on UAV imagery, organic farmers have a much more limited toolbox to work with. Furthermore, this organic farm, sits atop a hole in the aquifer that provides many of their neighbors with water for irrigation.

The Agribotix team wanders a recently plowed field. Dryland organic farming requires a delicate balance of management decisions, which can be educated by UAV-collected images.

The Agribotix team wanders a recently plowed field. Dryland organic farming requires a delicate balance of management decisions, which can be educated by UAV-collected images.

Irrigated conventional farmers are confronted with dozens of management decisions on a continuous basis, but the dryland organic farming practiced by this farmer offers relatively few options for the grower. Critical decisions include how frequently to incorporate manure into the fields, when to leave fields fallow, what types of crop rotations to implement, and when to take a field out of organic rotation to spray for perennial weeds. Unlike conventional irrigated farmers who fertilize and spray several times per season, the dryland organic operational decisions are generally made once per season or once every several seasons, with some crop rotations taking seven years to complete.

While the informational frequency required to educate the dryland organic grower’s decision-making is fairly low, after the Agribotix visit we are convinced that images and vegetation maps collected from UAVs offer substantial value in this segment as well. Our top three applications for UAVs on dryland organic farms appear below:

First, dryland organic farmers struggle with perennial weeds. Annuals can be plowed under, but perennials, notably Poverty Weed, represent a nasty, reoccurring problem. They are so troublesome that once a certain fraction of a field becomes infested with poverty weed, the grower has no choice but to spray the field, leave it out of organic rotation for three years, and sacrifice significant revenue. This decision is a delicate balance between the revenues lost through Poverty Weed hurting yields by siphoning nitrogen and water from the desire crop, wheat in this case, and the revenues lost by leaving a field out of organic rotation post chemical application. Currently, this decision is made through heuristics and observations, but UAV imagery can accurately quantify the extent of Poverty Weed infestation. The fractional coverage of Poverty Weed can then be used to make educated decisions about exactly when to spray. In the field pictured below, 16% of the area was covered by poverty weed and, depending on the economics of that particular field, a chemical application may be on the horizon.

Poverty Weed coverage was quantified using Agribotix UAV collected color and infrared images and image processing software. The trapezoidal field above has 16% of its surface covered by poverty weed.

Poverty Weed coverage was quantified using Agribotix UAV collected color and infrared images and image processing software. The trapezoidal field above has 16% of its surface covered by poverty weed.

Second, dryland farmers are constantly allocating their precious water resources. The little rain that falls in Colorado will either be stored in the soil, evaporate from the soil, be perspired by the plants, or run off. Dryland farmers must decide whether the increased perspiration loss from ground cover outweighs the decreased evaporation from the soil when leaving a field fallow. Timely color and infrared images capable of quantifying the degree of plant growth allow the growers to back up their decisions with numbers. The image below shows a field that was let fallow, at right, next to a field in which wheat was grown the previous year, at left. There is dramatically more wheat growing in the field that was let fallow as seen in the Normalized Difference Vegetation Index (NDVI) image. The darker regions of the field let fallow represent areas where Poverty Weed inhibits wheat growth.

This NDVI image of two wheat field shows the benefits of letting a field go fallow in organic dryland farming. The water accumulated over the year that the field at right was not cultivated enabled robust crop growth, while the field at left is significantly behind.

This NDVI image of two wheat field shows the benefits of letting a field go fallow in organic dryland farming. The water accumulated over the year that the field at right was not cultivated enabled robust crop growth, while the field at left is significantly behind.

Finally, organic farmers generally fertilize with both manure and crop rotations that deposit nitrogen back into the soil. Soil compaction is a problem for every manure application and every clover rotation pulls water from the field. This delicate balancing act between saving water, preventing soil compaction, and ensuring adequate nitrogen for cash crops can be much better educated through high-resolution images to compare across years and fields.