Nature keeps plants healthy through diversity
Diversity in soil microbial populations is pivotal for nutrient uptake and disease suppression. Soil microbes operate through multiple means, including developing symbiotic relationships with plant roots to protect the plant from disease; releasing nutrients from organic matter and stimulating plant growth; degrading pesticides and toxic substance; fixing atmospheric nitrogen and improving soil structure. The incidence and severity of root disease is an indirect assessment of soil health (Abawi 2000).
Why add microbes?
Soil microbial biomass and diversity has significantly declined with intensive agriculture which has negatively impacted on yield, disease & farm sustainability. The resultant decline in soil health is now a global issue. Intensive agriculture is at the cross road and needs to find ways to improve microbial biomass and diversity to reduce disease.
Many activities in modern agriculture deplete soil microbes resulting in increased disease and reduced nutrient uptake.
- Annual broad-acre crops – microbes soon die once crops are harvested and they are without the presence of living roots.
- Vegetable production – soils are cultivated & fumigated, destroying roots and beneficial microbes.
- Orchards and vineyards – spraying weeds with herbicides causes plant roots and beneficial microbes to die
There is considerable research outlining this eg under field conditions frequent use of fungicides, herbicides and insecticides caused a decrease in bacterial-feeding, fungal-feeding, predatory and omnivorous nematodes and an increase in plant-parasitic nematodes(Geense et al 2015; Bailey 2003; Imfeld2012) . In addition agrochemicals have been shown to have a strong negative impact on soil enzyme activity (Moeskops 2010; Ratnadass 2012).