Orchard floor management
The basis of organic orchard floor management is to grow grass to build mulch. Typically a range of preferred species are established that contribute various system functions including:
Generate biomass/organic matter (roots and tops) that feeds soil biological activity as the foundation for sustaining soil conditions, nutrient availability and organic matter cycling:
- build soil structure and improve resilience to soil compaction and erosion
- protect the soil from extremes of water stress, heat and cold
- attract and harbour beneficial predators and biodiversity to minimise pest pressure
- provide competition to suppress problem weeds
- facilitate rapid decomposition of diseased tissue
- improve trafficability
- attract bees and other pollinators.
Establishing floor cover species may include a mix of grass and legume pasture species. Other cover crops may also offer functional benefit or be more suited to local conditions. Careful management to ensure good establishment and persistence of sown cover plants is important, especially the legume component. However, excessive legume dominance can lead to an excess of nitrogen which can affect fruit quality and lead to storage problems.
The aim of building mulch can be achieved by simply bringing in straw. However, experienced growers caution that straw has often been responsible for bringing in too many problems – especially weed problems. An additional issue for mango production relates to avoiding excessive nitrogen release (resulting from decomposition of the organic material) especially during the fruit ripening period.
Costs associated with orchard floor cover management can relate to equipment and labour time for mowing, and additional irrigation costs to grow cover plants over more of the orchard floor.
Irrigation layout - micro-sprinklers
With the aim of growing grass to produce mulch, a number of growers use micro-sprinklers or fan jet sprinklers in place of drippers. This allows a greater area to be irrigated, so the benefits of the cover plants extend over a larger proportion of the orchard floor.