Biological soil health enhancement versus chemical farming:
Case study in broadacre grain production
Most of the food produce in a supermarket does not have anything close to the nutrient or mineral profile it is supposed to have according to nutritional textbooks. This is because minerals are not manufactured by plants, whereas vitamins and phytonutrients are produced by plants. Therefore, the addition of minerals to the soil may be a fruitless exercise unless the soil has a capacity through the diversity and abundance of microorganisms to transform these minerals into essential compounds that plants can take up and assimilate in a symbiotic manner. For example, it is better to apply an amino acid than nitrogen to a soil, as the amino acid is bio-available and ready to use by the plant to make protein.
Modern chemical farming involves the replacement of only a few mineral elements (eg. phosphorous, potassium, calcium, nitrogen, etc.) when a plant needs about 70 elements, and particularly trace minerals. These minerals or elements are lost in farming through the export of food from the paddock in grain, meat, fibre, etc. and in most cases never replaced. Also, the natural nutrient recycling, soil processes on a farm are diminished through the use of synthetic/chemical fertilisers, excessive tillage (causing compaction), used of herbicides and insecticides, and fire.
In the case of many farms they are running out of soil carbon, phosphorous and most of the essential trace and nano-minerals.
When plants create nutrients, they synthesise them through biological, chemical and energetic processes that can only be called miraculous. But as capable as they are, plants do not create minerals. Minerals have to be absorbed through the soil, and if they are not present in the soil, then the plant's roots cannot take them up, and therefore they will not be present in the plant.
The nutritional and mineral profile of the plant ultimately depends on the mineral content of the soil. Since soils today are so over-farmed and depleted of all but a few basic minerals, most of our produce lacks the minerals they should contain. For example, a lot of plants absorb selenium when selenium is present in the soil. But when selenium is not present in the soil, of course it's not available to the plant. The plant gets grown and taken to the store and sold and consumed anyway, even though it doesn't have the levels of selenium that it should contain according to traditional textbooks.
Soil enhancement processes
Soil enhancement processes have long been plagued by early-term yield losses as lower nutrient application and changes in land management practices are adopted. Prior studies have shown that low microbial abundance and low microbial diversity are the features of depleted soils and in particular of intensively farmed regions which have a strong reliance on applied nutrient. There is evidence to suggest that continued reliance on high rates of chemical fertiliser prevents regeneration of the microbial elements which are critical to the in-soil processing of these same nutrients. This fosters a cycle of increasing need for more nutrients in order to maintain yields. In an attempt to address this nexus, many landholders are seeking soil enhancement products which aim to help rebuild microbial diversity and biomass in soils. However, in most cases, farmers have been faced with accepting several seasons of lower yield or leaving land fallow altogether in order to promote microbial recovery in the soil.
This situation creates a commercial barrier for entry for most soil enhancement products, including those which involve the re-cycling or re-application of organic matter as a stimulant or a catalyst for in-soil biomass development.
Biological farming has advanced to the stage whereby highly adapted sets of organisms can be cultured. These formulations can then be specifically adapted to transform key nutrients from a targeted and source material (eg. rock dusts, lignite, herbs, etc.). It was found that the introduction of formulations containing these key sets of organisms, phyto-nutrients and trace minerals were able to supply a much faster development of soil biomass than had previously been possible. In addition these provides a strategy to allow farmers to manage reductions in the application of fertiliser over time rather than removing chemical inputs altogether in the early years of transition, if this is desired.
In a trial of a microbial formulation with a prominent farmer in the Riverina area of Australia there was a plan to make the transition to lower fertiliser input and improved soil. The objective was to maintain yield by managing the input of both organic (soil enhancement) products and conventional nutrients such that improvements in soil health were achieved without yield decrease.
Method
Comparisons are made between treated and untreated areas of the farm, being areas where biological or microbial formulations were applied (treated) versus those where chemical inputs only were applied (untreated). Buffer areas were left around the microbially treated areas to ensure separation of treated and untreated zones.
Improved soil structure and significantly increased moisture retention were observed in treated areas as shown in the photographs following. Soil on this farm is predominately a sandy loam/clay which over time had become relatively unstructured and which held moisture poorly. The soil typically dries out to a fine light dust in dry periods and forms unstructured clay in wet periods. In the treated areas a rapid re-development of structure was observed over the three years with concurrent extended plant root development and higher levels of organic carbon measured.
The clear benefits in yield obtained by these trials (see table below) have been the catalyst for the property to adopt a lower nutrient regimen combined with selected soil enhancement products over the entire property for the 2008 growing season.
BRIX (sugar) readings in the
treated areas were
measured at or near 11.8%
compared to 5.8% in
untreated areas and this
testify to a higher nutrient
uptake and greater pest and
disease resilience in treated
areas.
Recent widespread soil tests have highlighted significant improvements in the soil's biology particularly in relation to total carbon and Phosphorus levels achieved. These results are highlighted in the tables on the following page.
The availability of phosphorous to plant roots is limited in acidic and alkaline soils, mainly due to the formation of sparingly soluble phosphate compounds with aluminium (Al) and iron (Fe) in acidic and calcium (Ca) in alkaline soils. Every year, farmers globally place large amounts of phosphorous fertiliser on soils for food, fibre and wood production and only 10-20% can be absorbed by plants. The remaining is rapidly transformed into unavailable phosphorous forms which are not readily absorbed by plant roots. However, the application of the microbial formulation products will stimulate the plant root system and the enzymatic activity associated with either acid or alkaline phosphates. This increases the availability of soil nutritional phosphates for plant function.
Note: these results are backed up by a 2005 NSW DPI report 'Microbes & Minerals' stating "Building soil organic matter helps to build the organic pool of Phosphorus". Phosphorus and other minerals are then made available to the plants via the microbes contained in the microbial formulation products. Soil samples taken in late winter showed strong increases in levels of available Phosphorous, despite low rainfall and cold weather. This higher nutrient availability is mirrored in significant increases in soil organic matter and in Total Carbon fractions.
Total Carbon increases in excess of 1.3% have been recorded in treated areas during the 2008 growing season. While areas of lower background carbon had proportionately higher rates of increase in both available Phosphorous and Total Carbon following microbial formulation treatment, it is important to note that the trend of increased biological activity is consistent across the property. The change in soil structure in a comparatively short period of time was a very encouraging outcome when the treated soil structure was compared with the untreated soil (See photographs below).
Examples of improved soil structure
and moisture retention in treated
versus untreated barley crops. The
higher organic carbon levels have
transformed the previously
unstructured loam/clay. Greater
levels of nutrient have been
delivered to the treated plants via
the significantly improved root
structure.
It is noticeable that the treated soil is
darker as it now holds more water,
nutrients and carbon in humus,
compared with the untreated plant
root bowl (lighter coloured soil).
Also, the size of the plant root bowl
is significantly larger for the treated
plant due to the increase in root
extension.
Outcomes
Overall production tonnages were consistently and significantly higher in the areas treated with bio-products over those left untreated. This result was encouraging given the adverse growing conditions experienced throughout the period and the much lower nutrient regime employed on treated areas. Input costs of the biological or microbial formulation products were less than half that of the chemical fertiliser inputs.
Similarly, a significant growth in soil organic matter and a commensurate improvement in soil organic carbon and moisture retention were noted in treated areas despite the farm experiencing severe drought. Dramatic improvements in available Phosphorous were observed in treated areas. This was particularly pertinent in the region in which the farm is located where landholders typically struggle to maintain levels of available Phosphorous despite high levels of applied P (as seen in untreated areas of this study). In this case, treated areas had applied P of approximately 1 kg per hectare. Untreated areas received applied P of approximately 20 kg per hectare. Despite the large disparity in applied nutrient, treated areas showed much higher available P levels throughout the growing season.
Improvements in soil structure and friability have also been noted. This mirrors an increasing pool of organic carbon measured in treated soil over the period. Further measurement of these factors is anticipated for following seasons with the soil enhancement program being applied to the entire property.