FutureSOILS
Future proofing the soils of southern and central NSW from acidification and soil organic carbon decline (FutureSOILS NLP)
Project Funder: National Landcare Program
Project Lead Organisation/Researcher: NSW DPI Wagga Wagga, Jason Condon
Project Duration: March 2020- March 2023
Project Locations: Condobolin Agricultural Research & Advisory Station (ARAS) & Trundle
Aim
The project aims to protect and improve the subsurface soil layers (5-20 cm) within southern and central NSW NRM regions grown under dryland cropping and modified pasture systems, of which >50% of soil is acidic. The successful completion of this project will have a direct positive impact on the crop (cereal/oilseed/pulse), sheep (meat/wool), beef industry and pasture productivity.
Description and background
Soil acidity and declining Soil Organic Carbon affects over half of agricultural soils in southern and central NSW and threatens the viability and resilience of farming systems. Current acid soil management practices are based on outdated models that are failing to prevent the widespread development of subsurface acidity in contemporary cropping and pasture systems. This urgently needed project brings together an expert team from three farming system groups (grower engagement/extension), the NSW DPI (agronomy/soil science) and ANU (computer modelling/visualisation) to develop a new, accurate acidification model using innovative machine learning methods. Model outputs will be used to develop a free online decision support system and API protocols for integration with existing digital platforms. These tools will provide updated liming recommendations and interactive scenario forecasting which will ultimately result in more sustainable soil management and productive farming enterprises. The tool will enable growers and advisers to input paddock locations, target pH, soil parameters, rotation and management actions to receive customised liming and management recommendations.
CWFS has two sites, one plot trial at the Condobolin Research Station and the other, a paddock scale trial, at Trundle. The small plot site at Condobolin has three treatments, a once off application of lime at 3 t/ha incorporated with offset discs, a yearly application of 80 kg/ha prilled lime down the tube at sowing and a control of nil lime. The paddock scale site at Trundle has six treatments, looking at two liming strategies; lime applied to lift the soil pH to 5 (CaCl) in the 0-10 cm soil depth, lime applied to lift the soil pH to 5.5 (CaCl) 0-10 cm soil depth, lime applied to lift the soil pH to 5.5 (CaCl) in the 0-5 cm soil depth, lime applied to lift the soil pH to 5.5 (CaCl) in the 0-10 cm soil depth incorporated with a speed tiller, control cultivated with a speed tiller and control no lime or cultivation.
Partnership
This project is a partnership between NSW DPI, the Australian National University’s Centre for Entrepreneurial Agri-Technology and School of Computing, Central West Farming Systems, Farmlink, Holbrook Landcare Network and Incitec Pivot Limited. Three farmers across the region have also been involved in this.
The project funded by the Australian Government through the National Landcare Program to improve on-farm management of acid soils and to increase soil organic carbon (SOC).
FutureSOILS Trundle farmer site 2020
Future proofing the soils of southern and central NSW from acidification and soil organic carbon decline
Author and organisation: Helen McMillan CWFS, Jason Condon and Helen Burns NSW DPI.
Introduction
Producer and advisor surveys indicate that current approaches to managing soil acidity are based on research and guidelines from the 1990s, and were therefore developed under very different and less productive farming systems. Most fertiliser, lime and crop selection decisions are guided by soil sample analyses collected at traditional depths of 0–10 cm. Depending on the crop or pasture sequence, the common trigger to apply lime is when soil pHCa is around 4.5–4.8. It is applied at minimal rates to remove toxic aluminium (target pHCa 5–5.2).
These traditionally reactive approaches and a failure to monitor the effectiveness of acid soil management programs are responsible for widespread, undetected subsurface acidification in marginally acidic soils, as well as those with a long history of soil testing and lime application (Burns and Norton 2018). Recent studies challenge the short-term focus of current acid soil management programs:
Li et al. (2019) recommended revising pH targets and re-liming intervals in order to address subsurface acidification, proposing soil maintenance pHCa above 5.5 in the 0–10 cm surface layer to gradually increase subsurface pH.
Condon et al. (2020) highlighted inadequacies of current acid soil management programs and reinforced the need for a shift from mitigating soil acidity to prevention, particularly in zero tillage farming systems.
Conyers et al. (2020) concluded that ongoing reaction of limestone and reacidification processes influenced soil pH and that ‘the slow but measurable improvement in subsurface acidity, and the sustained residual value to grain yield’ required a long-term approach to amelioration efforts to manage and prevent subsurface acidification.
This article reports preliminary results from the first year after liming treatments were implemented from the paddock scale site at Trundle in 2020. This site is one of five designed to monitor long-term changes in soil chemical properties as influenced by various liming rates and management to develop a predictive model to improve decision-making around optimum lime rates and incorporation strategies.
Site Details
Location: approx. 25 km north of Trundle NSW
Soil type: sandy loam; soil pHCa range of 4.3-5.6 down to 30 cm
Farming system: continuous cropping with pulses and canola included in the rotation
Treatments applied: March 2020
Growing season rainfall (April-October): 430 mm
