Show simple item record Knox, Oliver 2021-04-06T01:30:48Z 2021-04-06T01:30:48Z 2019-06
dc.description.abstract UNE1601 came about from a merger of two proposals. One proposed to develop a more detailed understanding of C under cotton, whilst the other focused on the potential for rotations to modify the soil microbial biology. To address the combined goals of the project, work was undertaken at ACRI on the long term rotational trial managed by Dr Guna Nachimuthu and broken down into three areas of investigation. These were; (i) Mechanisms of whole-profile C and N cycling, (ii) Microbial processes in the soil profile, and (iii) Below ground agronomy and constraints to plant growth. Addressing the ‘Mechanisms of whole-profile C and N cycling’ became the focus for Dr Yui Osania. Her research in this area establishing that the maize rotation increased SOC stock in a Min Till/CW system. The mechanism for this was likely to be vertical movement of C in the form of DOC and that a strong correlation between SOC and soil N was evident, which indicated that C and N dynamics are interlinked. The conclusions from this were that agricultural management impacted SOC storage differently between the topsoil and the subsoil and that future research should explore the movement of C in the soil (i.e. leaching, root exudates), and the role of DOC in C stabilisation via microbial interactions or mineral interactions throughout the soil profile. ‘Microbial processes in the soil profile’ became the area of focus for Katherine Polain’s PhD candidature. Katherine’s work looked at both short and long term influence of the cotton rotaion under minimum tillage and found that microbial diversity was not influenced by rotational changes, which implied that there may be greater resistance and resilience in the system than previously presumed. Katherine’s work also highlighted that whilst the microbial biomass may be higher in the top 30 cm of the profile the activity can be as high in the 30-100 cm sub-soil of the cotton system profile as it is in the top. The implications from these observations are that we may need to look deeper in our systems if we want to truly understand the nutritional cycles that feed our plants nutrient demand and that might limit the losses of C from our soils. The final aspect of the project was the ‘Below ground agronomy and constraints to plant growth’, which initially had to become more aligned to other projects when the appointed candidate had to withdraw and could not be replaced. Oliver, Brendan, Katherine, Guna, Brian and Yui did their best to address this aspect of the project. The associated work showed that ~25% of cotton fields are affected by sub-soil constraint, whilst the work at ACRI clearly established that furrow traffic led to soil compaction and with this a loss in microbial activity. Field vehicular traffic remains a necessity of our production systems, but the work done here adds to the number of proponents pushing for farms not only to move to minimum tillage, but controlled traffic farming systems. en_US
dc.description.sponsorship Cotton Research & Development Corporation en_US
dc.publisher University of New England en_US
dc.relation.ispartofseries UNE1601;
dc.title Soil System Research – physical, chemical and biological processes for plant growth and nutrient cycling down the whole soil profile en_US
dc.type Technical Report en_US

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