Field notes

Notes about VRI

Steps for a VRI plan to run:

Decision to irrigate/how much to irrigate
Order water from irrigation district - this is often a text message, varies by irrigation district (or possibly even more granularly)
Maybe need to wait for delay between order and start of irrigation
If there are lots of pivots, may need to change pressure on pump to set it appropriately
Upload prescription to controller
Run plan

Farmers are used to only having a couple plans which they alternate between (or as few as one, which they just use as a static prescription for years at a time)

About $30k to add VRI to a centre pivot

Zimmatic pivots make up about 35-40% of the market, also Valley and Rinke pivots in the mix quite heavily.

Some pivots have extra "pivot arms" which allow them to cover much more of the square plot

these arms are the most common source of failures/issues on the pivots, so some farmers are opting to put shorter pivots out in the corners of their fields, which only do a quarter turn

There are large blocks at the boundaries of fields which have pivots doing half or quarter turns, and these both block the pivot and turn it off through a sort of sensor arrangement on the end of the pivot arm

Water pumps are a very important aspect of the whole set up, as sometimes people need to pump water out of the low areas of the fields that they are irrigating - the problem isn't just that there is too little water in some areas, there is also too much water in others

One of the challenges farmers have is how to make their zones. Many different techniques to follow when doing this, no clear best way.

One idea discussed is to only have 2-3 sensors in a field as a reasonable number, and then correlate multiple different polygons to the readings from a single sensor. For example, if there was one sensors in a wet area, one in a medium area, and one in a dry area, then the farmers would be interested in correlating the data from that one sensor to all of the wet areas that they know about in their field.

Another key factor in decision making around irrigation is that other tasks, such as spraying the crop, may not be able to happen on the same day as the irrigation. Farmers would like to see multiple different prescriptions, one for each day, with some basic stats (e.g. average depth applied) and then be able to choose which day they want to irrigate on.

Also, weather can greatly impact the plans generated, but weather is only a prediction. In cases where the model is impacted by something like a 40% chance of rain, farmers would probably like to see prescriptions for both cases, and choose what they prefer.

One thing which we noticed in the field is that while farmers may like the model, they also have other knowledge about the area and the crop, and they may want to increase or decrease the total amount applied to the field based off of the knowledge.

The model works to fill the field up to a certain percent of its capacity, and depending on the crop, farmers would like to be able to set this to what they have found works best.

In some regions during dry years, farmers can be limited in how much water they are allowed to apply for the season, so they will want to prioritize their higher-value crops for the water, and may under-irrigate other crops to compensate.

One thing to consider on the prescription/model side is the amount of time it takes for the pivot to go around. If the model is predicting one thing for today and another for tomorrow, but it takes the pivot 30 hours to do a full circle, then some polygons should be irrigated for the next days prescription, not the current one.

High winds (>90km/h) can cause lots of problems for pivots, so farmers would benefit from a heads up that they may want to anchor or orient their pivot such that it is not in danger

Farmers want to know if pie shaped irrigation (speed based, not VRI) will work with the models

Many farmers also saw value in having predictions of just how much to put down per field if they had no VRI installed

Often times, farmers will hire someone else to manage all the pivots, particularly on larger farms with multiple pivots

For sensors, there may be an annual task to install and remove the sensors from the soil