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Calibration of Nitrogen and Phosphorus Soil Tests with Yield of Proso Millet
Author(s) -
Rodriguez J. B.,
Peterson G. A.,
Westfall D. G.
Publication year - 1989
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/sssaj1989.03615995005300060022x
Subject(s) - panicum miliaceum , sorghum , fertilizer , zea mays , soil test , agronomy , soil water , phosphorus , grain yield , nitrogen , field experiment , zoology , mathematics , poaceae , yield (engineering) , chemistry , environmental science , soil science , biology , organic chemistry , materials science , metallurgy
Current fertilizer recommendations for proso millet ( Panicum miliaceum L.) are based on soil test calibrations developed for related crops such as corn ( Zea mays L.) and sorghum [ Sorghum bicolor (L.) Moench]. Therefore, their accuracy may be questionable. A study was initiated to correlate and calibrate the AB‐DTPA, Olsen P, Bray P‐1, and Mehlich P‐1 soil tests for P and the soil profile NO 3 ‐N test with proso millet yields. Most of the soils studied were Argiustolls. Fourteen dryland field experiments were conducted from 1985 through 1987 in eastern Colorado. The experiments were N and P factorials with N levels of 0, 22, 45 and 67 kg ha −1 and P levels of 0, 8, and 17 kg ha −1 . Profile soil samples were taken and analyzed for P by each of the soil P tests and for extractable NO 3 ‐N. Grain yield was measured at maturity. Critical levels were established for each soil P and N test. Critical levels (point below which response to fertilizer is expected) were 6, 12, 20, and 35 mg kg −1 of P (0‐15‐cm sample depth) for the AB‐DTPA, Olsen P, Bray P‐1, and Mehlich P‐1 tests respectively. For N the critical level was 58 kg ha −1 in the 0‐ to 90‐cm soil profile. Soil test categories for each P test were established. The amount of P needed to correct deficiency and obtain maximum yield was 16, 12, 7 and 0 kg ha −1 for VL, L, M, and H categories, respectively. The amounts of N were 45, 25, 15 and 0 kg ha −1 for the respective categories.