Growing food organically is a hot topic across the country. Most of the attention is on avoiding pesticides or using organic and environmentally friendly products to control insects and diseases. However, growing organically also means using organic fertilisers.

Building up the fertility of the soil is one of the most important aspects of gardening. For years many gardeners used only synthetic fertilisers on their gardens. Synthetic fertilisers are manufactured products, while organic fertilisers are derived from plants, animals, or naturally occurring minerals. While both can go through a manufacturing process, there are advantages to using an organic fertiliser that’s in a form close to its natural source.

Why Fertilise?

Just like our bodies need nutrients to function and grow, so do plants. The soil contains many of the vital nutrients needed, but as plants use them, the soil can become depleted. Soil also can get depleted from erosion by wind and rain. Fertilising is a way to replenish the fertility of the soil. The healthier the soil, the healthier the plants will be.

What do plants need? While there are at least 16 nutrient elements necessary for plant growth, the most important are nitrogen, phosphorous, and potassium (referred to by the elemental symbols, N, P, and K). Most soils contain large reserves of the other 13 nutrients — especially calcium, magnesium, sulfur, iron, zinc, and manganese — that might also hitchhike along when you fertilise with the “big three.”

To ensure that your soil has the right mix and balance of nutrients, you should do a soil test. Private laboratories and state cooperative extension services test garden soil for a nominal fee.