Getting your pH right!

The first step to getting the pH ( figure expressing the acidity or alkalinity of a solution on a logarithmic scale on which 7 is neutral, lower values are more acid, and higher values more alkaline) of your soil right, is to measure the soil’s pH. This is as simple of making a50/50 mixture of soil and deionised water, waiting 5 minutes and then dipping a pH strip into the mixture. These inexpensive strips are available from Plant Health Solutions in a form that measures finer graduations than normal. You are seeking a pH of 6.4 for optimal plant health growth. It is always important to try to understand why your soil is acidic or alkaline.

The best option is a soil test so there is no guess work involved. If you have acreage, a soil test can be worth its weight in gold. It is common to waste huge amounts of precious time, driving blind in an acreage gardening project, when a soil test would immediately clarify options and strategies.

If you can’t justify a soil test then these guidelines may assist you to diagnose the source of your pH imbalance:

If you have a light, sandy soil that is acidic, then you probably need a mixture of calcium and magnesium (dolomite) to correct the imbalance.

If it is heavier soil with more clay component then you probably need limestone to alkalise the soil and you might choose to include some gypsum to help break up the clay. If the soil is heavy and alkaline, then there is probably too much magnesium and sodium, so gypsum is the correction of choice.

Colour me phosphorous (P)

Soil: Australian soils are often low in phosphorous (P). Native plants have adapted to this efficient take up of any available phosphorous, but exotic plants and food crops require supplementing with phosphorous. Phosphorous is most available to plants in a 6-7pH range.

Plants: This energy mineral is used in virtually every aspect of plant growth, including photosynthesis, and the formation of plant sugars and starches. Phosphorous promotes vigorous early root (excellent for root vegetables) as well as stem growth and flowering. The colour intensity of flowers, fruit and vegetables is determined by phosphorous.

People: Phosphorous is needed by every cell in the body and together with calcium, is essential for bone structure, pH balance and membrane structure in cells. This mineral  closely linked to reproductive health.

Animals: As with people, phosphorous is essential for bone structure and must be balanced with calcium and vitamin D for maximum benefit. It is essential in the production and mobilisation of energy and is required for reproductive efficiency.

Plant Deficiency Symptoms : Plants are usually stunted with a reduced capacity to produce fruit. Leaves can take on a dull green to purple hue, often affecting older leaves first. Purple lower leaves are a classic sign of phosphorous deficiency.

Old farm sites often have a good store of phosphorous locked away from years of super phosphate applications. Home gardeners can tap into this frozen reserve using inoculums of phosphate solubilising organisms.

Soil pH is a powerful guideline to nutrient uptake and it has been determined that a pH of 6.4 is ideal. At that level, the best balance of availabilities is found, so that your food plants will be providing the highest nutrient density for you and your family.

People often think pH as an indicator of calcium levels in soil, but magnesium is just as important, particularly in lighter soils. In these soils it is advised to use dolomite rather than limestone as you will require both calcium and magnesium.

An acid soil is equivalent to an empty pantry because it is dominated by the mineral, hydrogen, which is the acid element and it is not a plant food.