Effects of broad acre agricultural practices on mycorrhizal fungi:
- Cultivation:In most of the agricultural soils, the formation of mycorrhizal fungi is not affected due to any kind of cultivation practice. However, sometimes the growth of some agricultural plants might disrupt the network of hyphae formed by arbuscular mycorrhizal fungi. In such cases, the growth of such plants needs to be restricted.
- Phosphorus fertilizer:Phosphorus fertilizers are used extensively for cultivation of crops like wheat. It has been found from various surveys, that when the wheat crops were examined at the early stage of seedling and during spring for determining the presence of mycorrhizal fungi, it was found that 90% of the plants had low level of mycorrhizas. The only reason behind this deficiency was the high level of phosphorus present in the soil which was due to the extensive use of phosphorus fertilizer. The quantity of mycorrhizas was not up to the mark for benefitting the wheat plant with phosphate nutrition.
- Fungicides and herbicides:In general, when herbicides are applied to the recommended level it does not really affect the growth of mycorrhizal fungi. However, there may be other effects of the herbicides when the plant root type in the soil is changed like if weeds are being removed. Also, in case of residual herbicides, it can also restrict the normal development of roots and this, in turn, could also alter the formation of normal length mycorrhizal root. In the same way, fungicides also decrease the number of formed mycorrhizas in the soil.
- Crop rotation:The practice of crop rotation is very much common in Western Australia. When crop rotation is practiced in the presence of mycorrhizal fungi, its number gets increased during the phase of pasture. This is only because the phase of pasture involves a highly mycorrhizal variety of plants like clover, grasses and other types of legumes. This is also because at the phase of pasture the usage of phosphorus fertilizer is much less. However, when lupin and canola are used in crop rotation, it might result in reducing the number of mycorrhizal fungi. So, adding a phase of pasture in between crop rotations will always help in restoring and retaining the mycorrhizal functions, improving soil structure and also increasing the efficiency of fertilizers like phosphorus.
Can vineyard management affect the benefits which are gained from mycorrhizal fungi?
Vineyard management, when practiced properly, can really help in retaining the benefits gained from mycorrhizal fungi. However, it is very difficult to measure the benefits. Mycorrhizal fungi provide most of the benefits to its host plants only when the usage of phosphorus fertilizer is within limits. With high-level application of phosphorus, the beneficial effects of mycorrhizal fungi might get lost. This is because, with an increase in the level of phosphorus in the soil, it decreases the number of mycorrhizal fungi in the soil. In such case, slow-release phosphorus might help. However, inoculating grapevines at the stage of rootling with mycorrhizal fungi can provide much help to the vineyard.