Peas Inoculant Science

Peas (such as snap peas, snow peas, or shelling peas) are co-dependent on a particular type of soil bacteria called rhizobia. This bacteria can only live within a plant's roots (the nodules). The rhizobia fixes nitrogen into the soil, and the host in turn grows better and produces more peas with the increased nitrogen. When the peas die off in the winter, they leave behind their decaying root structures, with dormant nodules. Next year's generation of peas will be even more productive than the last because of those nodules, as this paper shows.

What does this mean for a gardener who wants to start peas in a new plot? If no peas have been grown in the area, there will be no rhizobia to help feed the new peas nitrogen. Fortunately, you can mix in some soil from a previous spot where peas grew to add some native rhizobia. If you haven't ever grown peas, there are commercial rhizobial "inoculants" that you can apply to the soil to help the peas in their first year.

There are several different kinds of commercial inoculants: liquid, granular, and powdered peat inoculant. This paper discusses the results of applying those inoculants to soil with different pH levels. You might figure out what soil type you have and use that information to pick which type of inoculant you use.

Soil Type Test

Soil is just soil, right? Wrong. Soil is actually a mixture of different sized particles: clay, sand, and silt. If you've ever tried to dig a hole and bent your shovel, you've probably encountered soil with a high clay composition. This post has a good basic description of soil composition, and explains why some soil types are better than others.

The awesome thing is that a home gardener can do a simple test with a glass jar to determine what soil type they have. This page has a more precise description for the test. Use this handy chart to determine what type of soil you have:

Effects of Sunlight on Plants

Wikipedia has a good description of how plants are effected by daylight length, including an explanation of why they flower.