2015 looks to be an exciting and productive year in the garden with it being the International Year of Soils! This is definitely one of my favourite subjects and often one of the most overlooked when it comes to productive gardening.
A healthy soil is one that is alive! Im talking really alive, teaming with both plant and animal life, nutrient rich compost, sufficient water holding capacity and good porosity to enable it to breath. Yes, ALIVE! All of these things combined make it virtually impossible for plants not to grow health and productively.
To achieve a healthy soil environment like this certainly takes time. You are in essence trying to build a population of many million microorganisms, and then on top of that, waiting for the new populations to reach equilibrium and work productively to breakdown organic mater and transform it into soluble nutrients.
In previous years I have spoken of the raised bed, lasagna layering garden as my preferred productive gardening set-up. It is this combination of ingredients, Lucerne mulch, compost, lime/dolomite and blood and bone, that create a living soil.
Lucerne mulch provides organic mater that is quick to decompose, feeding microorganisms, and as this happens, a steady supply of available nitrogen is released. Plants grown in soils that are low in nitrogen will always grow slowly and appear to be a yellow/green instead of the usual healthy green. Humates, which are moisture retaining organic particles, are also a product of lucerne decomposition and aids in maintaining optimal soil moisture.
Compost provides the life - Bacteria, fungi, and actinomycetes that chemically decompose organic matter. There are literally millions of these little guys in just a teaspoon of healthy soil! The more you have, the quicker the decomposition process, and hence, the quicker plants are supplied with readily available nutrients. Plants can grow without compost and simply be supplied with synthetic fertilisers instead, however the beneficial microbial populations can prevent outbreaks of pathogens and increase the overall immunity of the plant.
Lime and/or dolomite aid in providing an ideal pH environment for soil organisms and facilitates the decomposition process. Furthermore it provides essential Calcium and Magnesium to the soil. An incorrect pH for a plant will prevent nutrients from becoming available to the plant regardless of whether they are in the soil matrix or not.
Blood and bone is a great quick way to maintain a food source for the soil organisms. It is also a good source of nitrogen that will assist with plant growth.
Finally, time is what is required to establish the physical decomposing macro-organisms such as worms, mites and millipedes. At this point, you will have the most productive soil teaming with life.