Soil Health & Frog Decline

How do you know if you have bad soil?

This questionaire is not fool-proof. So many types of soil situations can exist such as whether you live on a flat plain or on a steep hillslope; whether you have clay soil or sandy soil; whether you live in a new estate or an old cattle property. This questionaire is a guide which can be used by most residents in this tropical region to determine the likelihood of your soil being healthy - or being a potential threat to your local frogs and yourself. But many of the factors influencing soil pH will exist anywhere so please go through the questionaire even if you live in Canada or Columbia, Turkey or Trinidad, New Zealand or New York!

Grab your pen and paper and write down the number of points which apply to your answers to each question in the two tables below. Add up your points at the end to find out whether you need to take any steps to restore your soil to good health. If a factor/situation listed does not apply to your property, then you get zero points for that item.

Cantella or Pennywort - another common occupant of poor soils, this is actually edible
For those living on sandy soil outside flood areas and fast draining soils such as rocky hillslopes, human diseases might not be such a problem but drought tolerant fungi can be affecting your frogs. See the special section for sandy soils in the recommendations page.

Soil health can be affected by many things but is largely a matter of two main processes:

if you are outside flood prone areas:- what is draining the good stuff out and what is happening to put the good stuff back in (the more that is removed, the more that must be put back); and
if you live in flood zones: what is being washed out of soils upstream and deposited into your soil when flood waters drop.
  sandy, fast draining soil that gets flooded during heavy wet seasons 1 point
  red volcanic clay soil 2 points
  yellow or grey coloured clay soils 4 points
  property is on a steep hillslope with exposed areas 2 points
  property is in a new housing estate that was forested before 1 point
  property is in a new housing estate which was recently cane field 1 point
  poor drainage during rainy season and some flooding 3 points
  vegetables don't grow well or die shortly after planting 4 points
  fruit trees don't produce any fruit or very few fruit 3 points
  lawn is made up largely of buffalo couch, nut grass, and/or sedge grass and weeds like sensitive weed (mimosa), singapore daisy 3 points
  if the ratio of lawn to garden beds is very high (say, 75%+ is lawn to less than 25% garden beds) 3 points
  recent soil disturbance has been done such as excavating a pool, ripping out large vegetation, total relandscaping 2 points
  herbicides are used once a month or in only a small spot 1 point
  herbicides are used more than once a month or over a wide area 2 points
  herbicides are used weekly and over a wide area 3 points
  parts of the property have exposed soil areas with no plant growth at all 1 point
  give yourself a point for each tree on your property and each tree on an adjoining property that is on your fenceline that has an aggressive root system - this includes Bleeding Heart (Omalanthus), figs (Ficus), citrus, Pink Euodia (Meliocope), Umbrella tree (Schefflera), Paperbark (Melaleuca) ___ points
  a dog or cat is kept on the property or aviaries/chickens are present - 1 point for each cat or dog; 1 point for each aviary ___ points
  a greywater or Biocycle system drains onto the property 1 point
  soil is like cement during dry weather and like a mud wrestling pit during rainy season 4 points
  mango trees are present - 2 points for each mango tree on the property ___ points
  you have not used any fertilizers on the yard itself in more than a year (this doesn't include pot plants) 3 points
  the fertilizer you normally use is dynamic lifter 1 point
  anyone in your household or a visiting tradesperson has actually gotten an infected cut while working or playing in the yard and especially while gardening 3 points
  if you have a thick, meticulous lawn which is fertilized with high nitrogen fertilizer at least four times per year 2 points
  if you use mulch which not properly decomposed (smells musty, awful) in the garden 3 points

Now for factors which are actually helpful to your soil -
If these items apply to your property, you can actually subtract the number of points
indicated from your total so far:

  subtract one point for each tree on your property in the legume family (this includes Cassias, poincianas, wattles (Acacia), saraca, brownea, raintrees and species with pea-flowers -___ points
  subtract half a point for each indvidual legume food plant you are growing in the garden (this includes beans, peas, lentils, chickpeas, peanuts) ___ points
  subtract one point if the only fertilizers you use are organic such as manures, seosol, Charlie Carp -1 point
  subtract one point for each time in the past year you have used organic fertilizers over a large part of the property -___ points
  subtract one point for each occasion in the last year you have treated more than half your property area with dolomite, gypsum or lime -___ points
  subtract one point if you are on a hillslope property that has been reinforced and leveled by terraces to stop soil loss -1 point
  subtract two points if your usual method of weed control is to hand pull by the roots -2 points
  subtract 2 points if you use tea tree or peanut shell mulches or well composted recycled mulches on your garden beds -2 points

Add up your total score and check below

If you have less than 13 points, your soil should be in good condtion. If your veggie and herb garden is doing well, your other garden plants look well and you don't have a lot of weeds, then no special attention is needed. Keep up nutrient levels with an organic fertilizer, especially at the end of the rainy season and about a month before the rainy season starts. Well done!

If you have between 14 and 28 points, your soil could be better and you could enjoy your yard more if the plants were looking better, there were less weeds and you could get some nutritious veggies and fruit. Go to the recommendations page and consider some of these actions to make your yard better. A little help will go a long way!

If you have 29 points or more, your soil is screaming out for help and it would be very wise for your family, your backyard wildlife and your garden plants if you can follow as many of the recommendations as you can for correcting your soil's pH/condition. It's not that difficult and, in most situations, not expensive - and it can actually save you a lot of money in the long run!

You can also get some pH testing done on several spots on your property if you want to have some numerical feedback that your soil is too acid. There are testing services for this (in your yellow pages) or your garden nursery can sell you a simple kit to do this yourself at home. If you use the home kit, pick out several spots on the property to check as soil ph under a tree might not be the same as the middle of the lawn which might not be the same as the top or the bottom of a slope. Use a variety of places in the yard to test.

As you went through the list of bad factors and good factors, some situations would have jumped out at you as common causes of soil becoming acid/sour and disease-promoting. For example:

"garbage in - garbage out": If nearly all the time you spend tinkering in the garden is to spray herbicide on your weeds, you probably have a lackluster garden with struggling plants, sparse lawn and even your tomatoes will shrivel up and die unless grown in pots with purchased potting mix. Alternatively, hand pulling weeds by the roots, composting and using organic fertilizers leads to a more luxurious appearance to your garden beds and you might reap a steady supply of fresh herbs/veggies to enhance your cooking; what you may not have realised before is the more herbicide you use on the garden, the more you are actually promoting the growth of weeds!
long term rental properties: very few tenants will spend time looking after or expanding gardens in a rental property because the property belongs to "somebody else" so the gardens in long term rentals can be rather plain, weed infested and the soil can be depleted. You may not own it but while you live there, the property is there for you to enjoy on the inside and the outside. It costs very little to correct the soil ph and the results will make the property so much more enjoyable (and safe) for you and your family and the local wildlife that comes to visit your yard.
clay soils and flood prone areas: red clay is actually a very nutritious soil type and is desired for agriculture but yellow and grey clay is horrible stuff and is an excellent medium for growing soil diseases as well as suffocating plant roots. Poor drainage and/or regular flooding provides all the water diseases love.
new housing estates and ex-cane land: housing estates are often heavily bulldozed soils that are highly manipulated into being the foundations for a series of neatly aligned housing structures and driveways; filler top soil can be brought in from anywhere and who knows what kind of soil is it or where it came from or if it has any resemblance to the soil that is already there! Likewise, many sugar cane properties are being taken over by housing estates. Years of tillage, fertilizers, fungicides, pesticides and herbicides have been saturated into the soils and then covered with a thin layer of top soil, a house, a driveway and some minor landscaping.
severe drought: this causes great stress on soil condition due to the die-off of a whole group of microbials (the moisture dependent ones) and dominance of another, stronger group (the drought-tolerant ones); soils become looser during extended drought and even big trees died and fell down local Cairns hillslopes during 2000-03, causing scars in the sides of hills which will then be eroded further during rainy weather; droughts are likely to become worse under the climate change senario so widespread remedial treatment will be necessary after each drought. Another time which might promote drought conditions is during solar maximum (a period in an 11 year cycle when sunspot activity is high - the next solar max is due in late 2013).
heavy demands on nutrients: growing your own food is wonderful but just as food feeds you, you need to feed your food; a backyard sporting several fruit trees and especially citrus and mango needs to be fertilised more often or else the soil will be depleted quickly and become acid/sour; this also applies to some extent to a yard landscaped in a rainforest style with several large native trees with extensive root systems - when choosing any fertilizer, go for organics and avoid dynamic lifter or other highly processed products.

Please procede to our Recommendations page for suggestions how to improve your soil health, especially if you scored 29 points or more in the questionaire!

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