Investment

This initiative provides growers with clear guidelines on management of acid soils that have low Al and have not anecdotally been responsive to lime applications in south west NSW.

Grower issue identification: Discussions in Grower Network forums in the GRDC sub-region of Southwest NSW and particularly in the Griffith, Hillston and Lake Cargelligo regions have highlighted the need to understand reports of poor lime responses on acid sandy soils that typically have low organic matter.
Some soils in low rainfall cropping regions of Western NSW are acid (pH <4.8 CaCl) but do not have elevated aluminium (Al) levels in the soil. These soils are typically low in organic carbon and commercial rates of lime anecdotally have not provide crop responses that are measurable in increased grain yield. Possible explications could include:
(i) secondary limitations exist that provide a handbrake on yield response which are unidentified,
(ii) manganese (Mn) toxicity which can be made plant available via chemical or biological means. Mn availability via biological processes is not as sensitive to pH conditions and hence more favourable soil pH conditions of 5.5 (CaCl) can still result in plant Mn stress,
(iii) the lime products being used are course, have a low reactivity and/or are not properly incorporated resulting in limited pH change,
(iv) despite liming a subsurface acid throttle exists that limits crop production.
There is a need to validate the issue of acid soils that are anecdotally unresponsive to lime in western NSW so that crop yield gaps can be reduced.
To ensure project success a range of soil and plant measures will be necessary to best target soil amendments. This should include a benchmark control of highly reactive lime incorporated to 15 cm. This project should link with the GRDC sandy soils investment (CSP1606-008RMX) and work being undertaken by Dr Jason Condon on acid soils (UCS2204-001RTX0) to ensure any learnings from past or existing research can be considered in this localised investment. Links to UCS2204-001RTX will provide connectivity with related activities being undertaken by FarmLink and Holbrook Landcare.
This initiative will provide growers with clear guidelines on management of acid soils that have low Al and have not anecdotally been responsive to lime applications.