Effect of Sowing Method and N Application on Seed Yield and N Use Efficiency of Winter Oilseed Rape

Abstract

Abstract:In northern Europe, replacing winter barley with winter wheat as the preceding crop for winter oilseed rape (Brassica napus L.; WOSR) often results in a delayed WOSR sowing and poor autumn growth. Based on data from a field experiment running in 2009/2010, 2010/2011, and 2012/2013, this study aims (i) to investigate how a delayed sowing method affects seed yield, N offtake with the seeds, and apparent N use efficiency (NUE) of WOSR; (ii) to test the ability of autumn and spring N fertilization to compensate for the negative effects of a delayed sowing method; and (iii) to estimate the minimum autumnal growth for optimal seed yield. In order to create sufficiently differentiated canopies, a combination of four sowing methods (first week of August until the third week of September) and four autumn N treatments (0, 30, 60, and 90 kg·N·ha −1 ) was established. Each of these 16 different canopies was fertilized with 5 N amounts (0/0, 40/40, 80/80, 120/120, 140/140 kg·N·ha −1 ) in spring in order to estimate separate N response curves. Above-ground N accumulation in autumn and seed yield and N offtake by the seeds were determined. Plant establishment after mid-September significantly decreased seed yield. Autumn N fertilization of at least 30 kg·N·ha −1 increased seed yield and N offtake by the seeds without any significant interaction with sowing method and spring N supply. However, the pathway(s) remain(s) unclear. Spring N fertilization up to 130 kg·N·ha −1 (estimated by a Linear-Plateau N response curve) increased seed yield. NUE decreased with increasing N supply, where WOSR used autumn N to a lesser extent than spring N. An above-ground N uptake of at least 10-15 kg·N·ha −1 at the end of autumn growth was required to achieve high seed yields. From an environmental point of view, optimal autumn growth should be attained by choosing an adequate sowing method, not by applying additional N in autumn.

Application of Artificial Neural Networks for Yield Modeling of Winter Rapeseed Based on Combined Quantitative and Qualitative Data

“…It took into account all neural networks produced. The independent variable "The kind of sowing date in the previous year" (KSD_PY) ( Table 5) obtained the highest rank 1 in each network, which is consistent with literature sources [31][32][33][34]. In the QQWR31_5 model, the error quotient was 1.2510.…”

Dissection of Year Related Climatic Variables and Their Effect on Winter Rapeseed (Brassica Napus L.) Development and Yield

“…The yield increased by increasing the N rates. The highest seed yield was achieved with the application of 150 kg ha −1 , while in the study of [53] the seed yield reached a plateau at 130 kg N ha −1 . Our findings were consistent with previous studies reporting a significant increase of the seed yield as the N application rate increased [54,55].…”

Dynamics of Growth and Nitrogen Capture in Winter Oilseed Rape Hybrid and Line Cultivars under Contrasting N Supply

“…Winter oilseed rape appeared to be more vigorous and took up more N than cereals before winter [53]. However, it used autumn N to a lesser extent than spring applied N [54,55]. In the present study, the high N supplied crops received 108 kg N ha −1 in autumn, but the average N uptake of the cultivars before winter was only 24.6 and 29.4 kg N ha −1 in the 2014-2015 and 2015-2016 seasons, much lower than that reported under European conditions [55].…”