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Effect of Timing and Nitrogen Fertilizer Application on Winter Oilseed Rape ( Brassica napus L.). II. Nitrogen Uptake Dynamics and Fertilizer Efficiency
Author(s) -
Barłóg P.,
Grzebisz W.
Publication year - 2004
Publication title -
journal of agronomy and crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.095
H-Index - 74
eISSN - 1439-037X
pISSN - 0931-2250
DOI - 10.1111/j.1439-037x.2004.00109.x
Subject(s) - fertilizer , ammonium nitrate , calcium nitrate , nitrogen , brassica , agronomy , ammonium , nitrate , chemistry , human fertilization , horticulture , calcium , zoology , biology , organic chemistry
Field experiments were carried out on grey‐brown podzolic soil in the four consecutive growing seasons (1998–2001) at Krzeslice Farm, central‐western Poland. The effect of seven N fertilization treatments (in kg N ha −1 ): 80 NF + 80 CAN ; 80 NF + 50 CAN + 30 CN ; 80 CAN + 80 CAN ; 80 CAN + 80 CAN + 30 CN ; 80 AN + 80 AN ; 80 AN + 50 AN + 30 CN , where, NF – nitrofos NPK, CAN – calcium‐ammonium nitrate, AN – ammonium nitrate, CN – calcium nitrate and control (without N) on N uptake dynamics and N efficiency was studied. Mineral fertilizers were applied at the start of spring regrowth, beginning of stem elongation and at the flower‐bud‐visibility stage. The study revealed two distinct strategies of oilseed rape plants’ adaptation to timing and N fertilizer application sequences. Both strategies based on nitrogen uptake rate (NUR), were analysed at different plant growth stages. Ammonium nitrate (AN) applied in the two‐split system gave the highest NUR (387 mg m −2 day −1 ) during stem elongation (for comparison, a value of 166 mg m −2 day −1 was obtained in the control). In the case of calcium‐ammonium nitrate (CAN), a moderate level of NUR was obtained (304 mg m −2 day −1 ) but N uptake lasted 12 days longer compared with the AN treatment. Hence, N accumulation in leaves at the end of flowering explained about 81 % of yield variability. The second adaptation strategy was attributed to the three‐split N treatment. Plants fertilized with AN and CAN fertilizers showed an inconsistent pattern of NUR with time. Nitrogen accumulation in stems at the beginning of maturity, explained 69 % of yield variability. Nitrogen‐use efficiency did not show any response to N treatments.