Early on in my farming career, I took a break from farming to go back to school at the University of Maine to study ag science. By the end of that stint, I was even more committed to farming as a career, deciding that traditional science took too much effort to answer fairly limited questions, and that I would prefer to work in food production and leave some mystery about why things happened one way or another on the farm. But my curiosity still gets the better of me, and there still end up being questions that I want to answer. This year, we have been comparing to two different schools of thought on how to analyze and fertilize our fields, with the help of a grant that I received from the Northeast SARE program.
In organic agriculture there is currently a little subgroup promoting soil fertility programs which they call “nutrient density.” The idea is that by providing full balanced nutrition to the plant, rather than just looking for the traditional nitrogen, potassium and phosphorus, you can grow more healthy plants that will resist insects and pests, give higher yields, and will also produce healthier produce. This full nutrition is achieved by testing the plants to see what nutrients are lacking, and providing those by spraying small doses of liquid fertilizer to the soil and/or to the plant leaves. We have played around over the past several years with some of these liquid fertilizers, and mostly liked the results, especially when we are able to put some of the fertilizers into the soil in our drip irrigation. We haven’t been quite as happy with our 2-row crops such as broccoli, cabbage and potatoes. It is clear that those crops need more of something, but we wanted to find out what they need more of. So this year, we divided one of our potato blocks into a number of randomized plots. In one treatment, we followed UMass soil test recommendations for fertilizer, and then tested the soil after the potatoes were planted to see if there was a need for more nitrogen. There was none, so we left them alone. In the other treatment, we applied microbial inoculants that are supposed to help fix nitrogen, and have kept up a spray regime of liquid fertilizers in a program that has been modified based on the results of plant tissue tests. We recently mowed our potato crop due to the late blight (the hope is that by killing off the plant and then waiting a little while before harvesting, we can limit the blight from infecting the tubers.) We didn’t really see much differences between the treatments in insect or disease pressure, but next week we will be digging subsections of that field to look at yields and quality of the potatoes in the ground. We are eagerly awaiting the results, and will let you know what we find out.
P.S. We have really been enjoying the “Purple Sun” potatoes–the ones with the purple skin and yellow flesh. That variety was released by Jeremy’s old advisor at the University of Maine, Greg Porter. The flavor and texture is wonderful in a potato salad!