Case studies by crop · Precision farming

Rice: variable-rate fertilization

DJI Agriculture case study, collected by FLYDROPS.

In Gifu, Japan, DJI and Yanmar tested variable-rate fertilization in rice: a multispectral drone mapped the field and an Agras T30 spread the dose by zone. The field that started in worse condition gave 8% more rice with about 80% of the fertilizer quantity.

The prescription map sets the quantity per zone.

At a glance

Location	Kaizu, Gifu Prefecture, Japan
Crop	Rice (Hoshijirushi variety)
Drone	DJI Phantom 4 Multispectral for mapping, DJI Agras T30 for spreading
Software	DJI Terra (prescription map)
Trial	Two fields: 3.11 ha variable rate and 3.43 ha fixed rate; July–November 2022
Partners	DJI Agriculture Japan, Yanmar, a local producer

The study uses the T30, an earlier generation. The current range is DJI Agras T100, T70P, T55 and T25P; find which one fits your acreage or compare the models.

The challenge

When fertilizer is spread evenly across a whole field there is a risk of over-fertilizing: nitrogen burn on seedlings, lodging later on, lower quality and waste. Prescription maps from satellite images depend on weather, revisit frequency and low resolution, while a tractor in a mature crop damages it and gets stuck in mud.

What was done

The trial ran on two fields. In the first step, the Phantom 4 Multispectral collected images and DJI Terra produced a prescription map. In the second, the Agras T30 spread the fertilizer at a height of 2 m:

Variable rate (3.11 ha): 75 kg/ha in good growth, 100 kg/ha average, 125 kg/ha in poor growth; average 100 kg/ha, speed 13.8 km/h.
Fixed rate (3.43 ha): 100.1 kg/ha, speed 25.2 km/h.

The map showed that the variable-rate field was in worse and more uneven condition than the other.

The results

Measure	Variable rate	Fixed rate
Yield	10,158 kg/ha	9,381 kg/ha
Fertilizer cost	22,296 JPY/ha	24,829 JPY/ha
Fertilizer quantity	About 80%	100%

The numbers come from the study and relate to that specific application.

The study sums up: a saving of 2,533 JPY/ha (about 18.5 USD) and 777 kg/ha extra yield. Two weeks later the RGB, NDVI and GNDVI images showed more even colour, as the multispectral drone had identified growth differences and the spreading followed them. This is a trial on two fields, not a statistical proof.

What it means for Greece

Greece grows rice, mainly around Thessaloniki and Serres, but the method applies more generally: first a growth map, then a dose per zone. The matching drone in our range is the Mavic 3 Multispectral, and we offer a VRA map and multispectral analysis service if you do not want to buy equipment. Fertilizer is spread by the models with a spreading system, for example T100, T70P and T55. The numbers come from two fields in Japan.

Rules and responsibilities

The study is about fertilizing and mapping, not plant protection products. Drone flights are always subject to the competent aviation authority’s rules; check the requirements before you plan work in your own field.