Manure Efficacy Trial

Efficacy of Animal Manure Use in Broadacre Cropping Systems of Southern NSW

Project Partners: FarmLink
Project Code: MET20
Project Duration: 2020-2022
Project Location: FarmLink Region

Background

Animal manures are the by-products of animals grown to produce products for human use and consumption. They consist of mixtures of animal faeces, urine, bedding materials and other materials such as waste feed. Applying animal manures for plant nutrient supply is a well-established agricultural practice, representing the primary source of crop nutrient supply until the advent of synthetic fertilisers in the 1940’s. In large-scale contemporary broadacre cropping within southern New South Wales, the use of animal manures is predominantly limited to diversified enterprises containing an intensive livestock component or those with a low-cost (often geographically proximal) source. In these instances, the use of manures as part of an integrated fertiliser regime has a clear economic fit through the reduction of synthetic fertiliser requirements and hence input costs.

In recent times however, there has been increased interest from the broader agricultural community in the potential role of animal manures as a soil ameliorant, particularly on lighter textured soils and in continuous cropping situations. This has been driven by a number of studies demonstrating a range of soil health benefits associated with manure applications including:

  • Increased soil organic matter (e.g. Sauerbeck 1982, who observed a net increase in soil organic C in the order of green manure < straw < fresh manure < composted manure)

  • Increased soil microbial activity and diversity (e.g. McGill et al., 1986)

  • Increased soil aggregation and aggregate stability through the addition of humic substances (binding agents) and subsequent increases in total pore space, water holding capacity and infiltration capacity (Haynes & Naidu 1998)

It is important to note however that the majority of these studies have been undertaken outside of Australia using treatment rates that would be considered high to very-high by local standards (e.g. 60t/ha or multiple applications over a number of years). For growers without a readily available, low-cost manure source (i.e., the majority of broadacre croppers in southern NSW), there is a need to examine the extent of beneficial outcomes achievable at rates that would be considered ‘economically viable’.
This project seeks to address this question using a within paddock small-plot trial to contrast the effect of a number of locally available manure sources and rates. This project will:

  • Assess the impact of manure applications on crop yield, grain quality, soil physical, chemical and biological parameters

  • Quantify the timeframe required for any responses to be observed in addition to the longevity of any residual benefits

  • Assess the impact of incorporation versus surface spreading only of manures

  • Educate growers on locally available manure products, including their nutritional status (N, P, K, trace elements), moisture, salt content, heavy metals and the variability of these attributes

  • Explore the economics of manure applications both as a source of plant nutrition and as a source of Organic Carbon