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Illinois Soil Nitrogen Test for Prediction of Fertilizer Nitrogen Needs of Corn in Virginia
Author(s) -
Spargo John T.,
Alley Marcus M.,
Thomason Wade E.,
Nagle Steven M.
Publication year - 2009
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2007.0437
Subject(s) - fertilizer , mineralization (soil science) , nitrogen , zoology , agronomy , yield (engineering) , biosolids , agroecosystem , soil test , environmental science , chemistry , soil water , agriculture , soil science , biology , ecology , environmental engineering , materials science , organic chemistry , metallurgy
Current N needs for corn ( Zea mays L.) in Virginia are estimated based on expected yield and are adjusted to account for the estimated amounts of N mineralized from organic sources such as manures, biosolids, and legumes. The dynamic nature of soil N creates significant uncertainty in estimates of N availability from these sources. Accurate quantification of organic N mineralization during the corn growing season should improve the precision of fertilizer N recommendations. The Illinois soil N test (ISNT) has shown promise as a tool for estimating mineralizable soil N and predicting corn fertilizer N needs. Other research has found the ISNT to be poorly related to labile soil N and unrelated to corn response to fertilizer N. The objective of this study was to determine if the ISNT predicts the fertilizer N response of corn grown in a diverse set of Virginia agroecosystems. We conducted 29 on‐farm fertilizer N response trials in major corn‐producing regions of Virginia. The ISNT was significantly related to estimated yield without fertilizer N ( R 2 = 0.57, P < 0.0001) and relative yield ( R 2 = 0.64, P < 0.0001). We also found that the ISNT extracted a consistent percentage of total soil N (16.3 ± 0.7%), suggesting that it is a poor indicator of labile N. In fact, total soil N did as well as the ISNT at predicting yield without fertilizer N ( R 2 = 0.53, P = 0.0002) and relative yield ( R 2 = 0.64, P < 0.0001). The ISNT offered no more information about corn yield response to fertilizer N than did total soil N content.