The aim of this article is to advise on a best line of action to take within a production budget to speed an increase in soil fertility for purposes of improved production system resilience in an attempt to partly insulate an agricultural operation against climate turmoil and weather variability.
Marius Willemse : https://bit.ly/2CShIiv
Agricultural and environmental systemsecology and biogeochemical cycling solutions
The weather is now regularly much different to long-term norm because the climate has changed and it will continue to change at an increasing rate for the foreseeable future. I repeat and elucidate for clarity and to stress the fact and its importance. Expect more frequent weather extremes as patterns are changing and shifting due to climate turmoil and this will/is happening sooner rather than later and significantly faster than currently widely expected or previously modelled.
The most prudent course of action in light of the changing weather and climate is to self-educate and to understand what is a stake and then to plan for the worst, followed up with actually doing what is absolutely necessary in your agricultural operation to ensure reasonably consistent and ongoing production. In the process critically review all management practices and the need/motivation for all and any production input and operational expense. In other words get to the essence, ask why, for what purpose and whether it is the most sensible way to improve ecosystem and operational resilience.
Improving the level of soil organic carbon and particularly the level of labile (active) organic carbon is one of the most important resilience necessities as it correlates very well with numerous other highly desirable soil and crop yield characteristics, and in particular with higher levels of soil fertility.
Methods for maintaining and or slowly increasing levels of soil organic carbon are well known and widely promoted. These include no-till or least soil disturbance, crop rotation, keeping living roots in soil, biomass return and organic soil cover, planting diverse cover crops, adding manure and or compost, amongst other. The common denominator in all these suggested practices is that they are targeted at increasing the potential for organic carbon soil input and its retention.
This article does impart faster methods for increasing soil organic carbon levels but that does not take away from the fact that every producer by default must strive towards methodically including as many of these practices as practically possible, financially prudent and environmentally sound, and do so as priority without delay in their management of the agriculture ecosystem. The more of these practices employed the greater the ecosystem resilience and yield realisation potential under difficult abiotic conditions.
Covering the soil with organic matter (crop residue mulch) and more preferably with living plants for the longest possible period in the year is most important as it greatly improves topsoil conditions for biology, reduces temperature fluctuations, evaporation and improves water infiltration. Living plants contribute much more significantly to labile organic carbon soil input in the form of root exudates. Plant root exudates are the main energy source for the soil microbial community, the fuel that keeps the ‘soil production machine’ going.
Planting for-purpose crop covers comprised of multi-species is the ideal. Seed and planting cost can however be high and prevent practice adoption. When faced with such a barrier distil the purpose to its essence. The purpose is to cover the soil and to increase plant root exudate, i.e. labile organic carbon, soil input. The purpose is not to capture soil nutrients or nitrogen specifically or to fix atmospheric nitrogen or to suppress weeds but may be additional benefits. Having even a single but preferably a mix of living, low seed cost plant species growing is therefore still significantly better than having none. It is also better than just having a mulch cover and incomparable to the disaster that is bare soil.
In conventional agriculture nitrogen is used to improve crop yield. This stand in stark contrast to labile organic carbon as most limited soil resource for the soil biology. The practice of nitrogen soil addition ignores the fact that plants exude carbon rich compounds that stimulate microbes to mobilize organically bound nitrogen, and that inorganic nitrogen fertilisation is actually counterproductive and ecosystem detrimental.
Without sufficient soil organic carbon soil fertility is compromised and most other climatic change adaptation (e.g. planting early maturing, heat, drought tolerant crop varieties) will have very limited, if any, effect on the resilience of the farm’s ecosystem and the economic sustainability of operation continues to be beholden to high input production.
Resilience, whether ecologically or economically, is tightly connected with self-reliance for production input. From a commercial perspective, the more capable the ecosystem is to produce without much or any outside production input the greater the operational resilience may become. Whether it is profitable and therefore sustainable will depend on the cost of own input production as compared to same input open market value. Self-reliance may reduce production risk but only to the extent that it is efficient and effective at realising a lower cost of production.
Expectation of a premium for produce to offset a higher cost of production is therefore seriously flawed. Organic farming and certification as a method for unlocking a price premium from a niche market is a marketing ploy and not a model for self-reliant, resilient and quality, low cost of production produce capable of feeding and clothing a larger portion of the populace in a more environmentally friendly and ecosystem beneficial way.
Moving from a high chemical input model to a high organic matter input model (compost, manure and other) may make ecosystem sense but does not make much economic sense if the latter is to be purchased and distance transported to the farm, in which case it may also make no environmental sense.
Bulky organic matter, when used, should be from the farm or its immediate vicinity. And, even when the organic matter is available on farm its movement and processing for purposes of soil input should be carefully considered against potentially lower cost and more beneficial alternatives. Leaving organic matter in situ, without soil incorporating, is the cheapest and highly ecosystem beneficial. Utilising livestock to trample and reduce available organic matter in situ and spread manure is even more ecosystem-beneficial as well as economically.
Improved self-reliance and resilience flow from integrated ecosystem management. Its main product is a fertile soil that enables optimal biomass production. Its base is the soil biological system and its ability to create the environment and conditions suitable for expanding life through coherent organisation and interconnection of system parts.
Entropy rules in the physical and chemical soil sub-systems. Only components in the soil biological system can sufficiently and coherently organise the physical and chemical sub-systems to partly overcome entropy. Biology reduces the entropy of the system (after Diego Fernandez Sevilla, PhD).
Soil fertility refers to the ability of a soil to optimise biomass production for transfer to higher trophic levels. Biomass production is the result of soil fertility. Optimal biomass production is therefore an effect of soil fertility but microbial metabolic efficiency is its cause. System degradation is only prevented if the energy input and biomass contained nutrients of the primary producers (and others) are efficiently recycled within the system by the soil microbial community.
Microbial metabolic efficiency in turn is determined by kinetically advantageous nutrient concentrations within the collective microbial harvest volumes, the chemical potential energy of the substrate and the extent to which the nutrient ratios match heterotrophic bacterial stoichiometric needs.
The bacterial community (including archaeal) and not microbial, which include the fungi, are the initial focus in regenerating managed and disturbed environments based on their fast reaction to inputs and changes in nutrient concentration. Bacteria dominate in compromised systems as fungi populations are decimated on soil disturbance, whether chemical, including fungicide, or mechanical.
Soil amendment with organic inputs based on broad bacterial community stoichiometry and their energy need improve metabolic efficiency, and thereby increases nutrient assimilation and bacterial biomass and product production. A higher level of bacterial biomass strengthens system resilience and the resulting higher level of bacterial products (cell fragments and extracellular polymeric substances) lead to an increase in the level of system retained soil organic carbon and improved soil aggregation, structure, porosity, water movement and availability, and therefore soil fertility as result.
Soil application of a broad-spectrum amendment, an amalgam of parts containing matched chemical potential energy, improves the whole, i.e. increase total system fertility and resilience. The resulting sum of which is much greater than its parts as it simultaneously and coherently elevate, strengthen, organize and connect components in all three of the soil sub-systems; the physical, chemical and biological.
The litmus test for any soil amendment is therefore whether it is effective and efficient at supporting the soil biology to create the environment and conditions suitable for expanding life through integration of all three soil sub-systems concurrently, so as to cause an increase in total system fertility and resilience.
Amending the soil system with what is essentially only a component that strengthens one part of the system (chemical, e.g. nitrogen; physical, e.g. biochar; biology, e.g. inoculant) may or may not improve crop yield. Whilst the amendment may be efficient at lifting crop yield, it will contribute nothing to improved soil fertility or system resilience and may actually further weaken both unless the amended component was identified as a system’s limitation that prevents the biology from the coherent organisation and interconnection of system parts.
Differentiating between a limitation in presence and unavailability
Therefore, soil amendment with a single part or narrow range of parts (chemical, i.e. nutrient and or mineral) is only system effective when its presence in the system is limited and never when it is simply unavailable to the soil biology.
Foliar application of such a part will thus produce good results in the crop irrespective of whether it is limited or unavailable. Foliar application of a bioavailable part enables direct crop uptake as it circumvents any potential negative impact relating to either the soil microbial community or resulting from a soil chemical reaction. Therefore, always foliar apply to prevent or reduce potential for a crop failure or underperformance but in addition use the opportunity to better understand the system.
When a limited part is soil applied the soil microbial community will quickly respond and as general rule a crop gain will be realised. However, when a part is soil applied under conditions of unavailability then soil chemical reaction will win the day and neither the soil microbes nor the crop will gain from the application. The latter reaction indicating system stress in a part or parts of the system other than that which is soil applied, resulting in biological system failure to coherently organise and establish interconnection.
To test and eliminate the inapplicable option, prevent the foliar application of the amendment to a small fraction of the standing crop but then soil apply the same part or parts to halve of that crop fraction, at twice the foliar application rate, whilst leaving the remaining crop fraction as control. Compare yield realised between blocks through measurement on harvest to decide future soil amendment action.
Lift the boat, not the cargo
A change in management focus is required, from fertilising for maximum crop yield, to building soil fertility and system resilience as means to achieving optimum crop yields. Both approaches use nutrients, and in both instances it may be of synthetic origin. The difference is in the focus, in perspective, in the producer’s brain and management practice. The difference is not in the yield or income but in self-reliance, resilience and operational sustainability. The difference is in understanding, in love for grandchildren and care for the future.
A focus on soil fertility and system resilience is not about giving anything up or doing less bad but on doing ‘good’. It is about increasing soil fertility and system resilience (i.e. lifting the boat) in the most cost effective and efficient way.
The boat is lifted when soil fertility is increased. Soil fertility is lifted when all system parts are coherently and simultaneously strengthened, when a soil limitation is removed, and when a condition of unavailability is ameliorated.
Lifting soil fertility is lifting microbial metabolic efficiency. Amending soil with a soil amendment comprised of a wide-range of chemicals (nutrients and minerals) and a carbohydrate resource based on broad soil bacterial community stoichiometry and their energy need improve metabolic efficiency and thereby increase soil fertility.
In practice this means a significant reduction in the amount of chemicals soil applied but the addition of a carbohydrate resource with sufficient labile organic carbon to meet the bacterial carbon building-block and reduced respiratory need. An improvement in carbon use efficiency results in improved carbon storage efficiency.
In terms of production input cost, if a similar to conventional fertiliser budget is spent for two to three growth seasons on the broad-range soil amendment then the agriculture ecosystem will be sufficiently regenerated to be significantly more fertile and resilient, and thereafter only require maintenance.
Restoring microbial diversity
The present soil microbial community species composition is a reflection of the ruling biotic and abiotic environment, and the latter includes the soil chemical component. Community composition is not static. It changes constantly, between seasons, with temperature, precipitation, pH and with a change in management practice.
Create an environment that is broadly the most favourable for the greatest diversity of organisms and the beneficial soil biology will exponentially increase and therewith soil fertility and system resilience. Don’t concern yourself too much about the soil microbes; if the environment is supportive then the correct populations of beneficial species within the broader soil microbial community will be dominant and at the same time suppressive of pathogens.
However, on adoption of a suite of regenerative soil management techniques (i.e. no-till, seizure of single or narrow range fertiliser soil application, and seizure of fungicide use, as a minimum) there is merit in attempting to speed restoration of the soil microbial community to reflect the location’s naturally occurring populations and to specifically boost the decimated fungal community.
Techniques for this include taking soil plugs from more natural locations on farm and the soil installation of these throughout the managed fields in addition to locally produced natural matter compost and compost tea application.
Without assistance the fungal community takes a number of years to regenerate whilst with assistance this period can be shortened to one or two growth seasons for an exponential increase in soil fertility and system resilience (See the work of Prof David C. Johnson, NMSU).
