Australia - Using roots to alleviate the effects of soil compaction in the Western Region

Description

Deep ripping is thought to be effective due to the reduction of physical resistance and the increase of aeration around the root growth area (BCG 2009). With less physical constraints, plant roots are able to explore a greater volume of soil for both soil water and nutrients (BCG 2009).
In studies looking at crop growth, it has been found that biopores within the soil allow roots to explore a greater volume of soil. Biopores are made naturally by activity within the soil such as earthworms or root growth (Kautz 2015). Using roots to create biopores is of particular interest, as it could be an effective method of dealing with soil compaction without the use of machinery.
Han et al. (2015) found that growing chicory, which has a tap root, had a positive effect on a subsequent wheat crop by increasing the frequency of biopores by 2.3% when compared to a tall fescue which grows with a fibrous root system. The wheat crop root length was measured, and it was found to be greater following the chicory crop both within the biopores and outside of the biopores.
Kautz (2015) also found that tap rooted crops grown in rotations created biopores and improved the root growth and yield of following crops. In this study it was found that forage radish had positive effects on the yield and root growth of both soybeans and maize, even when the maize was grown in a compacted soil.
Other studies have looked at different crops to find the penetration strength of their roots through strong (compacted) soils. Lofkvist et al. (2005) compared barley, chicory, lupin, red clover and lucerne roots and found lucerne to have the highest proportion of roots penetrating both a soft layer and a harder layer constructed of wax. Materechera et al. (1991) studied 22 plant species with both fibrous and tap roots and measured the root length and their diameter in an attempt to find the most suitable crop to grow in compacted soils. While root diameter was not seen to be a reliable measurement, root length had a good correlation. The top ten species growing the longest roots through compacted soil, in order, were: lupin, leucaena, medic, faba bean, soybean, pea, cotton, pigeonpea, sunflower and safflower. These were followed by vetch, lucerne and oil radish. All of the tap rooted species grew longer roots than the fibrous rooted grass species that were trialled.
The Esperance RCSN members are keen to look at growing different plant species as a non-mechanical method of reducing the impact of soil compaction; to establish if the same effective results seen from using machinery can be created, with much lower input costs, using deep rooted crops. Of particular interest are tillage radish, safflower, sugar beet, lucerne, lupins, and chicory as there has been some previous trials completed looking at these.
This proposed investment will evaluate the ability of multiple species of plants for ameliorating soil compaction for following crops. It is proposed that a detailed review of literature be undertaken to select plants that penetrate soils above 2500kpa which may also fit within the WA farming system. Suitable species that are found to have potential will be tested using replicated small plot trials.

Opportunity closing date

24 January 2020

Value of contract

to be confirmed