Soil Balance

In nature, everything tries to be in balance. Predators and parasites keep prey species in check. Pest insects have their natural enemies to control their population levels. Natural laws, process and cycles keep everything in balance. It is often called the “balance of nature.”

In soil, balance involves three areas: chemical, physical and biological. All are related to each other.

• Chemical = minerals and nutrient elements used by crops to grow.
• Biological = soil organisms – they decompose raw organic matter to make humus, which holds water and nutrients.
• Physical = the soil’s texture and structure, which relates to aeration and drainage. Tillage and soil life affect the soil’s physical properties.

All three are tied together are equally important for production of high quality crops.

Releasing soil nutrient reserves

We know that soil has far larger reserves of most nutrients than plants need, but most of the total is unavailable at one time. The amount of the nutrients that are available or exchangeable to plants each year is a fraction of the total nutrient content.

The nutrient reserves can be made available each year through several natural processes:

• Weathering of soil
• Decay of organic matter by microorganisms
• Breakdown of soil minerals and releasing of tightly held nutrients by acids and chelating agents from plant roots, microorganisms and humus.

Through these natural processes and wise farming methods, a balanced “living” soil can, with added food (organic matter) for organisms, supply all or nearly all of the yearly needs of most crops.

What matter is how much gets into the plant.

Since all of the essential nutrients are needed by plants (not just N,P and K) and they are needed in a certain proportion or balance (different species of plant may need different proportions), it follows that the productivity of the soil can never be greater than the nutrient in the least supply.

Nutrient interaction

• Excessive nitrogen makes poor quality feed (nitrates).
• Excessive nitrogen (ammonia) can “burn-up” humus.
• Excessive nitrogen can cause a potassium deficiency.
• Excessive magnesium can cause potassium, phosphate and nitrogen deficiency.
• Excessive potassium sodium and magnesium can cause a calcium deficiency.
• Excessive calcium can cause phosphorus and trace element deficiencies.
• Excessive manganese can cause effects similar to iron deficiency.
• Excessive boron can cause signs of potassium and magnesium deficiencies.
• Excessive sodium and/or chlorine can cause signs of potassium deficiency.

The other factor that influences nutrient availability and interactions is the soil’s pH.