improving soil

i live on about six acres in central florida. the terrain and soil condition vary widely, but almost all the soil is very acidic and not exactly useful for intentionally growing much of anything. out in the open there's a lot of clay, but in the woods the soil is really pretty and dark and fluffy (tons of decaying trees and pine needles make for nice compost, still acidic and low in nutrients unfortunately). right now we get our resources like compost/manure/soil from local nurseries or farms, but the ultimate goal is to produce most of these things ourselves. what can one do to improve the fertility of the soil on a grand scale without importing and erupting a volcano??? we are sheet mulching in some areas, is this going to be the best method of improving our soil situation? make it suitable enough for other projects such as grow beds / germination / whatever? if possible it would be nice to be able to do it without having to outsource 100% of materials. wood ash is pretty accessible for starters

i'm thinking that distributing the materials ordinarily used in sheet mulching en masse with a manure spreader might be a decent idea but hrmrmrmrmmm

My first thought is that six acres is not all that large an area - but I am not the one trying to convert it

My second thought, partly related to six acres not being all that large an area, is that focusing effort on one portion, rather than diluting the effort over the entire area, might be the wiser plan. The sheer volume of material needed to impact six acres is daunting.

A lesser volume of material, on a smaller area, could have a greater impact. Say this year you put all your amendment efforts into your "best"acre. In a year or two of conecntrated effort you might get it to where it could provide a portion of your organic material for amending more of your land. From the edges of that improved acre you could then expand each year.

I know, sounds a little contradictory. It is not so big, so why do it in pieces? Because it is easier to achieve greater impact on the smaller increments. Plus, because six acres really is not that large, it will not take long to get results on all of it going a piece at a time.

Spread the effort over the entire area and you may not be able to do enough at once to make an impact. Focus on improving a smaller area, get results that you can leverage into more results, I think you get to the goal faster.

I totally agree with Peter on conquering a small portion and expanding as time and materials allow. Once that area is productive, work on the next bit.

Consider biochar. You can find some stuff about it on here, as well as on the web in general. There are lots of ways to make it from the primitive to the high-tech. Basically taking organic matter and making charcoal of it. This lasts much longer in the soil than if the organic matter were applied directly, whether composted or not. Especially in a warm humid climate, the average soil simply devours organic matter, breaks it right down and it largely disappears. You will have to continuously import it in quantity to see any real improvement in soil quality. The soil in the forest is better because nothing is removed and the mulch layer has a chance to build up, but even that isn't very deep, and if you clear it, it will soon be gone. But charcoal/biochar lasts and lasts, and acts as a sponge to bind nutrients. It really shines when inoculated with soluble fertilizers like urine. Like any organic matter, it will improve both clay and sand soils......

I will add to Alder's comments on biochar.

First off you mention you have acidic soil so let's address how biochar can help there.
Hardwood ash is alkaline (basic) so if you were to add hardwood ash or use a hardwood biochar you would reduce the acidity of the soil.
A blend of hardwood ash, hardwood biochar, and compost will be of great benefit to an acidic soil, it will sequester carbon, and many other noxious things that we don't want in our atmosphere, these items are best put to use as nutrients for plants and by consumption of those plants to animals.

Here are some of the most pertinent things about biochar.


Sustainable biochar is a powerfully simple tool that can 1) fight global warming; 2) produce a soil enhancer that holds carbon and makes soil more fertile; 3) reduce agricultural waste; and 4) produce clean, renewable energy. In some biochar systems all four objectives can be met, while in others a combination of two or more objectives will be obtained

Recent studies have indicated that incorporating biochar into soil reduces nitrous oxide (N2O) emissions and increases methane (CH4) uptake from soil. Methane is over 20 times more effective in trapping heat in the atmosphere than CO2, while nitrous oxide has a global warming potential that is 310 times greater than CO2. Although the mechanisms for these reductions are not fully understood, it is likely that a combination of biotic and abiotic factors are involved, and these factors will vary according to soil type, land use, climate and the characteristics of the biochar. An improved understanding of the role of biochar in reducing non-CO2 greenhouse gas (GHG) emissions will promote its incorporation into climate change mitigation strategies, and ultimately, its commercial availability and application.

Biochar reduces soil acidity which decreases liming needs, but in most cases does not actually add nutrients in any appreciable amount. Biochar made from manure and bones is the exception; it retains a significant amount of nutrients from its source. Because biochar attracts and holds soil nutrients, it potentially reduces fertilizer requirements. As a result, fertilization costs are minimized and fertilizer (organic or chemical) is retained in the soil for longer. In most agricultural situations worldwide, soil pH (a measure of acidity) is low (a pH below 7 means more acidic soil) and needs to be increased. Biochar retains nutrients in soil directly through the negative charge that develops on its surfaces, and this negative charge can buffer acidity in the soil, as does organic matter in general.

CEC stands for Cation Exchange Capacity, and is one of many factors involved in soil fertility. “Cations” are positively charged ions, in this case we refer specifically to plant nutrients such as calcium (Ca2+), potassium (K+), magnesium (Mg2+) and others. These simple forms are those in which plants take the nutrients up through their roots. Organic matter and some clays in soil hold on to these positively charged nutrients because they have negatively charged sites on their surfaces, and opposite charges attract. The soil can then “exchange” these nutrients with plant roots. If a soil has a low cation exchange capacity, it is not able to retain such nutrients well, and the nutrients are often washed out with water.
The pores in biochar provide a suitable habitat for many microorganisms by protecting them from predation and drying while providing many of their diverse carbon (C), energy and mineral nutrient needs. With the interest in using biochar for promoting soil fertility, many scientific studies are being conducted to better understand how this affects the physical and chemical properties of soil and its suitability as a microbial habitat. Since soil organisms provide a myriad of ecosystem services, understanding how adding biochar to soil may affect soil ecology is critical for assuring that soil quality and the integrity of the soil subsystem are maintained.

The pores in biochar provide a suitable habitat for many microorganisms by protecting them from predation and drying while providing many of their diverse carbon (C), energy and mineral nutrient needs. With the interest in using biochar for promoting soil fertility, many scientific studies are being conducted to better understand how this affects the physical and chemical properties of soil and its suitability as a microbial habitat. Since soil organisms provide a myriad of ecosystem services, understanding how adding biochar to soil may affect soil ecology is critical for assuring that soil quality and the integrity of the soil subsystem are maintained.

There is a large body of peer-reviewed literature quantifying and describing the crop yield benefits of biochar-amended soil. Field trials using biochar have been conducted in the tropics over the past several years. Most show positive results on yields when biochar was applied to field soils and nutrients were managed appropriately.

There is also evidence from thousands of years of traditional use of charcoal in soils. The most well-know example is the fertile Terra Preta soils in Brazil, but Japan also has a long tradition of using charcoal in soil, a tradition that is being revived and has been exported over the past 20 years to countries such as Costa Rica. The Brazilian and Japanese traditions together provide long-term evidence of positive biochar impact on soils.

After centuries of agriculture, soils globally have become depleted of carbon, compared to pre-agricultural conditions. Agricultural development goals include restoring carbon to carbon-depleted soils. Unavoidably, adding carbon to soils darkens them, changing their albedo (a measure of sunlight reflectance). Fortunately, darker, carbon-rich soils are more fertile and will be more easily re-vegetated. Vegetation has a lighter albedo, so the albedo problem is very temporary in nature and is not a significant issue.

It is important to note that not all biochar is the same. Biochar is made by pyrolysing biomass—pyrolysis bakes the biomass in the absence of oxygen, driving off volatile gases and leaving behind charcoal. The key chemical and physical properties of biochar are greatly affected by the type of feedstock being heated and the conditions of the pyrolysis process. For example, biochar made from manure will have a higher nutrient content than biochar made from wood cuttings. However, the biochar from the wood cuttings may have a greater degree of persistence over time. The two different biochars will look similar but will behave quite differently.

Some biochar materials, for example those made from manures and bones, are mainly composed of ashes (so-called “high mineral ash biochars”), and thus can supply considerable amounts of nutrients to crops. Keep in mind that this fertilizer effect will likely be immediate and short-lived, just as is the case with synthetic fertilizers. Conversely, the carbon content of high mineral ash biochars is low (e.g. < 10%), and thus longer-term nutrient retention functions will be less for a given amount of material.

So, ideally a person could add other things to improve soil but the effect might not be as long lived as with the addition of biochar. Adding biochar to composting materials gives extra benefits to the compost's ability to provide nutrients to plants. It is fairly easy to make adjustments to soil acidity through the use of biochar, these adjustments tend to be longer lived than other methods of adjusting pH in soils.

As Peter Ellis stated, I would recommend attacking small portions of your land at a time. By selecting a smaller area, you can experiment with different methods of amendment and determine which is the best for your land.