Farming Interest - Soil Test Results

One of the first principles of agriculture is that healthy plants grow in healthy soils. Many farmers have forgotten this and neglect the long term health of the soil for short term gain. In the United States we are in the middle of an agricultural crisis as we watch our topsoil erode and disappear in front of us. Farmers spray large amounts of chemical fertilizers onto transgenic crops on fields with little organic matter and the fertilizer run off pollutes our waterways and even larger bodies like the Gulf of Mexico. In the process we are able to produce such an abundance of grain that we don’t know what to do with it. We even burn it in our vehicles. In spite of this the price of grain is so low that few farmers can make a living by growing it.

In Tanzania, the crisis looks different and worse because the soils are less fertile and because they receive less rainfall. Few farmers have been trained in soil health and few think about what constitutes a healthy soil. I’m told that soil testing can be done in Tanzania but I have yet to come across a farmer who has done it. The soils that I have seen are marginal at best and are unable to produce healthy crops or large yields.

Before I left I purchased a LaMott Soil Testing Kit and I have it with me in Tanzania. The kit tests PH levels as well as Phosphorus and Potassium. There is also a nitrogen test but this test is not relevant for my purposes. This gives me one way to understand what is happening in the soil and what can be done to improve crops. I have taken 5 soil samples so far and have tested them using the testing kit. The soil samples were taken from different fields. Two fields were for future vegetable production, two were currently in vegetable production, and one had been a corn field. The test results were very similar. I found PH levels in the 6-7 range. The phosphorus levels were low at 20-70 pounds per acre. The potassium levels were high at 180-220 pound per acre.

Phosphorus is one of the macronutrients that is needed in large quantities in order to grow plants. It is necessary for the hardy growth of a plant. It encourages root development and increases total yield. It increases the palatability of plants and stimulates the formation of fats, convertible starches, and healthy seed. It also increases a plant’s resistance to disease. Seeds, bones, and milk are all high in phosphorus and therefore large amount of phosphorus are needed to create them. It is also possible for phosphorus to be in the soil but in a form inaccessible to plants. Soils with low phosphorus levels need large inputs of phosphorus in order to grow crops.

For comparison, the vegetable fields on my farm in Pennsylvania had phosphorus levels of 230 and 138 pounds per acre when I tested the soil in 2012. This was after the first year of growing in these fields and the fields were in the transition from conventional to organic production. By the time that I tested those same fields in 2015, the phosphorus levels had risen to 450 and 406 pounds per acre. In those three years, I had made several compost application totaling about 10 tons per acre. I had also grown several different green manure crops that I did not harvest but tilled directly back into the soil. Finally I had added some organic fertilizer blends and an application of soft rock phosphate. This has made a big difference in the productivity of my fields and of the health of my vegetable plants.