The Fundamental Components of Soil Health
The regenerative agriculture movement has cast a spotlight on the way we farm, highlighting the need to get back to fundamental ecological principles. In cropping and pastoral farming it is possible to work up the ground and make changes to the soil environment, and the plant species being grown, with relative ease. Permanent row crops by definition however, present some different challenges to cropping or pastoral systems. Either way, the fundamentals of all soil ecosystems remain the same. Improving any ecosystem starts with the soil and involves looking at the three fundamental components of soil - physical, mineral and biological.
Physical Soil Attributes
The physical attributes of a soil are largely determined by geography and geology. Drainage and compaction are commonly addressed prior to the establishment of a permanent crop, however the constant movement of equipment along the same tracks of established row crops creates ongoing compaction issues. Mechanical ripping of the rows and periodic working and re-sowing are options in some cases, but not where the underlying structure is rocky or on sloping terrain. Changing the inter-row sward from shallow rooting grass to a mixed species cover with a variety of root structures offers an ongoing solution to mechanical compaction.
Mineral Balances & Soil Fertility
Having adequate availability of the minerals required for plant growth is fundamental to growing good crops. Soils can be analysed to determine the potential availability of minerals for plant growth, and there are many amendments available to address shortages. The relative simplicity of soil test data contradicts the complexity of the soil system and it is an art as much as a science to determine what should be applied to improve soil fertility.
The tools for measuring biological activity are far less cut and dry than those for measuring minerals in the soil. For this reason the complexity of biological systems is poorly understood. There are laboratories offering biological testing of soil life and while these have value for benchmarking from time to time, they are often too expensive for routine use.
Fortunately, there are many clues in nature itself that, when understood, create a very useful picture of how the ecosystem is functioning. Our predecessors relied on these observational clues in the absence of modern scientific analysis, and arguably were better farmers as a result. Sadly, many of their astute observations and practices have been forgotten.
The Fundamentals of Regenerative Agriculture
Regenerative agriculture is the latest practice being used to promote a soil focused approach to farming. It incorporates well proven practices that enhance soil health, with added understanding offered by modern science. Adapting regenerative practices to permanent monoculture settings requires a bit of lateral thinking.
Below I’ve taken, point by point, the fundamentals of regen ag - exploring current practices and offering suggestions as to how each point might be approached differently.
Minimising Soil Disturbance
This is easily achieved with herbicides, but then of course herbicides create bare soil. Careful use of herbicides to leave crop residue over the soil is one option. Understory planting with low growing, less competitive species is a viable option in many situations; however care is required with selection and management of these plantings and the impacts on crop nutrition and vigour.
Covering the Ground at All Times
This can be difficult if weed free strips are deemed necessary to exclude competition in young plantings, or for aesthetics. Growing inter-row crops that are layered under the crop can be a solution at some times of the year. Importing mulching materials is also effective, but expensive.
Understory plantings offer a long-term solution, but do not come without their management challenges.
Growing Active Roots
Growing active roots means there is a constant food source for soil microbes supplied from the plants above, maintaining biological activity. Bare strips by definition fail completely on this point. An improvement would be to reduce the width of the bare strip. Inter-rows can be utilised for growing valuable material for mulching and simultaneously feeding the soil below. Crimping green crops lowers them to the ground providing cover for the soil but not killing the plant, thereby maintaining food for the soil biology. Understory plantings clearly achieve this aim of growing active roots.
Returning Plant Wastes to the Soil
This is something that is done regularly nowadays, with mulching of pruning materials, mowing inter-rows and leaving fallen fruit to decompose. Composting is another valuable exercise, but expensive on any scale. Returning fruit waste or grape marc to vineyards is valuable if it is done thoughtfully.
This is most often achieved by winter grazing with sheep or other stock. This is valuable for the function of the soil ecosystem. It does have drawbacks that need to be understood and balanced against the benefits.
This is an area where large improvements are possible. The diversity of the plants grown in the inter-row and understory directly determines the diversity of the root systems in the soil. Plants send carbohydrates to the mycorrhizae in the soil in exchange for nutrients in readily usable forms.
A diverse plant community gives rise to a diverse soil community, resulting in what has been termed ‘disease suppressive soils’. Such soils support healthy plants that resist disease and produce nutrient dense food that supports healthy animals. A permanent cropping system has great potential to create and maintain disease suppressive soils.
Bringing it All Together
At Soil Matters we don’t just look at the soil test result and determine what fertiliser to put on. We look at how all the inter-related aspects of soils can be managed better to achieve improved crop performance. Many of the principles of regenerative agriculture are already being followed in orchards and vineyards to a greater or lesser extent, but excitingly there are improvements that can be made that don’t have large price tags.
Viticulture and Horticulture Soil Consultant