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What soil information do crop advisors use to develop nitrogen fertilizer recommendations for grain growers in New South Wales, Australia?
Author(s) -
Schwenke Graeme,
Beange Luke,
Cameron John,
Bell Mike,
Harden Steve
Publication year - 2019
Publication title -
soil use and management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.709
H-Index - 81
eISSN - 1475-2743
pISSN - 0266-0032
DOI - 10.1111/sum.12469
Subject(s) - crop rotation , environmental science , agriculture , soil fertility , fertilizer , agricultural engineering , dssat , agroforestry , business , agronomy , engineering , soil water , geography , soil science , biology , archaeology
The Australian grains industry relies on mineralized nitrogen (N) from soil organic matter and plant residues, but fertilizer N is increasingly needed to optimize yields. Most farmers are guided on N fertilizer 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 ( DSS s) 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 fertilizer 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 fertilizer 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 maximize long‐term profits. Advisors preferred “rules‐of‐thumb,” simple DSS s and knowledge of crop growth, to elaborate DSS s requiring detailed inputs and soil characterization. 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 mineralization 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 ongoing.