Publication Date:
2018
Description:
Abstract
The Australian grains industry relies on mineralised nitrogen (N) from soil organic matter and plant residues, but fertiliser N is increasingly needed to optimise yields. Most farmers are guided on N fertiliser requirements by commercial crop advisors. We surveyed (n = 132) and interviewed (n = 11) New South Wales grains advisors to gauge the usage of soil process understanding, soil data, and decision support systems (DSSs) when developing N recommendations.
Soil moisture at sowing, seasonal forecasts, crop rotation, soil mineral N, financial risk profiles and paddock history were all used to prepare N fertiliser advice, but stored soil moisture was most important. Farmer confidence in soil N testing was low due to high spatial variability. Most advisors calculated N fertiliser required for yields within 10–15% of crop potential, but clients’ attitude to financial risk guided final N recommendations. Conservative growers preferred a low input system, while more reliable rainfall or greater reliance on stored soil water led growers to apply higher N rates to maximise long‐term profits.
Advisors preferred ‘rules‐of‐thumb’, simple DSSs and knowledge of crop growth, to elaborate DSSs requiring detailed inputs and soil characterisation. Few used in‐crop N sensing. N decision methodologies need to be updated to account for changes in soil fertility, cropping systems and farming practices. New research is needed to answer practical questions regarding soil N mineralisation and N losses associated with alternative N application practices and extreme weather events. Training of new advisors in N processes and DSS use needs to be on‐going.
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Print ISSN:
0266-0032
Electronic ISSN:
1475-2743
Topics:
Geosciences
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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