Feeding Soil: The Secret to High Quality Food

This series has addressed relationship-based nutrition practices, and fall garden tips. Feeding the soil is often an after thought. Soil is a living breathing organism, that must be fed and what we feed soil determines the quality of the food we eat. Feeding the soil is both art and science. Each time plants are grown nutrients are taken from the soil. In order to grow healthy plants the nutrients must be replenished.

Composting is a process that can take months. It can also be unsightly, but there are other ways to feed the soil. This post addresses three methods: trench composting, cover crops and adding free nutrient rich ingredients. Trench composing is the process of digging a trench or series of holes in a line and burying food waste, crushed egg shells, ground oyster shells, very small amounts of clean hardwood ash, coffee grounds and compostable paper then covering it. A cover crop may be a legume (such as beans or peas), red clover, buckwheat or rye grass. It is grown to add nitrogen and organic material to the soil and is often part of a rotation system. For instance if a company has four raised beds, three may be growing herbs, vegetables or small fruit and the fourth may be growing a cover crop to improve the soil. Each season a different bed is enriched. Lastly, nutrient rich organic matter may be added any time of year. Examples include unsprayed decomposing grass, fall leaves, shredded hedge or bush trimmings, washed seaweed, glue free sawdust, black and white newpaper, shredded cardboard, coffee grounds, and composted chicken or rabbit manure.

The science is that plants require a balance of nitrogen, phosporus and potassium in addition to small amounts of trace minerals. Good sources of free nitrogen include cover crops which are turned back into the soil while they are still green, composed animal manure, and coffee grounds. Organic food waste and grantite dust are good sources of free phosphorus. Composted food waste or fruit pulp is water soluable and a ready source of phosphorus whereas granite dust, because it is ground rock is released slowly into the soil. Hardwood ashes used sparingly can be worked into the soil and is a good source of potash. Composted leaves are one of natures best free sources of balanced trace minerals. This is because tree roots uptake nutrients reaching deep into the soil substructure and these trace minerals are present in the trees leaves. Not all leaves are created equally. Stay away from waxy  leaves or black walnut leaves. The former do not decompose well and will mat, while the latter exude a toxic substance that may interfere with plant growth. Maple leaves are probably the best, but leaves with a papery, crumbly texure will do. Leaves can be easily ground with a mulching lawn mower. They can dumped, then ground at a community garden site, or ground and bagged to add to raised beds.

Organic ingredients improve soil tilth. Tilth refers to the condition of the soil. Good soil tilth is essential to sustain healthy plant growth. Soil should be teeming with microorganisms, and earthworms. Earthworms digest organic matter leaving nutrient rich castings. Their burrowing activity also aerates the soil. For crops to grow soil must be within a preferred ph range, hold moisture adequately and drain well. Every living thing prefers a ph range including the human body. The ph scale ranges from 0 to 14, and 7 is neutral. Below 7 is acidic and above 7 is alkaline. Most plants prefer a mildly acidic level of 6.5. There is some slight variation between 5.5 which is considered very acidic for plants and 7.5 which is considered very alkaline. In broad terms berries and potatoes prefer a more acidic soil. Most vegetables prefer a ph level of 6 to 6.8. Ph affects a plants ability to uptake needed nutrients even if they are present in the soil. Just remember that free, natural ingredients are likely to produce a good result. If however, plants do not perform well testing ph and amending it if necessary can improve results. Ph is easily corrected.