She loves fries, Puck Mulders admits with a laugh. Above all, however, she thinks it’s very valuable her PhD research contributed to making farming a bit more futureproof, she continues in a more serious tone. “More and more food is needed for the growing world population. At the same time, agriculture has a negative impact on the environment, and we are increasingly faced with extreme weather due to climate change. This means it’s essential to change the way we farm. Data analyses can play an important part in this regard.” On Wednesday, March 6, Mulders will defend her dissertation at the Department of Mechanical Engineering.

With a grandpa who was the director of cooperative agricultural organization Cehave, another grandpa who traded in animal feed, and a father who chairs the Dutch Fruit Growers Organization (NFO), Mulders started learning about agriculture and horticulture at a young age. She knows how apples and potatoes grow, but also about the hardships of farming life. When she decided she wanted to learn more about statistics, she soon realized her PhD research was to have an agricultural connection. “Numbers and digging into the ground, that’s what makes me happy.”

Big data famer

Working with Wageningen University & Research (WUR), Mulders spent the past years analyzing data relating to innovative potato farmer Jacob van den Borne. He’s a frontrunner in the area of precision farming, collecting all kinds of data on his potatoes for years now, using a variety of sensors as well as drones that detect the growth of his crops and performs other measurements. In addition, he very regularly takes soil and plant samples, especially in the growth period. This gives him a host of data, which is intended to provide him with an insight into how to and economics can go hand in hand. How can precision farming contribute to less damage for the environment, less wastage, and a higher yield?

Mulders had a clear goal in mind. By creating models that can predict variability in potato yield, farmer Jacob would be ever better equipped to gauge what impact a certain choice would have, she explains. “We soon saw that choices made during the planting period, such as planting date and distance, have a major influence on the subsequent yield. Which makes sense, as farmer Jacob has a whopping 160 different fields, which are far apart to boot. Turns out this is typical of the south, where farming land was divided up among all of the sons. In other regions you see less fragmentation, because everything was passed on to the eldest son. But a farmer can’t plant all of those separate fields in one day. In fact, it takes farmer Jacob more than a month, which means the choices he makes are extra important. What you do one day, you cannot do the next.”

Weighing roots

As a result, Mulders spent a year regularly donning her boots and taking samples among the potato plants. Everything was measured and counted: from the number of stems and stem length to the weight of tubers, leaves, and roots. “This gave us a good picture of the season, and it yielded data to estimate a growth curve per field.” Mulders’ data analyses show that leave weight and stem length are the foremost predictive factors for yield, and that these parameters are influenced most by the choices made during the planting period. “Farmer Jacob initially planted his best propagating material on the fields that were the fastest to dry up, but now he’s switched to a different approach. Based on our data I can make a planting schedule for him, making sure the best propagating material ends up on the best fields. This already resulted in significant yield gains.”

Drowning potatoes

Mulders also used older data spanning six consecutive years to be able to say more about the impact of heavy rainfall or extreme drought on potato yield. “Extreme rain can be the death blow for a potato farmer. If you fail to get the water off the land, the potatoes will simply drown and you can kiss your yield goodbye. In case of dry weather, we see damage control is somewhat possible by providing extra water in the right way. The unpredictability of the weather makes everything very tricky. You can devise a perfect strategy beforehand, but the weather conditions may severely restrict your choices. In those circumstances in particular it’s good to have a model, because those choices are all the more important for the final yield.”