N efficiency and N residues of oilseed rape compared to sunflower

Transcription

1 N efficiency and N residues of oilseed rape compared to sunflower H.-P. Kaul, W. Wägner & W. Aufhammer WOSR Workshop Berlin, March 23/24, 29 I H.-P. Kaul 1

2 Objectives to compare WOSR to sunflower with view to productivity, N use and N residues to quantify residue mineralisation, potential leaching losses and N availability for a subsequent crop WOSR Workshop Berlin, March 23/24, 29 I H.-P. Kaul 2

3 Material & Methods Field experiment in south-west Germany (48 m a.s.l, 8.1 C, 69 mm a -1, 4 replicates) Factors and factor levels: Year 1994/95, 1995/96 Species WOSR, sunflower Cultivar WOSR: Lirajet, Bristol Sunflower: Albena, Irena low in crop residues N rate WOSR:, 12 kg N ha -1 Sunflower:, 5 kg N ha -1 WOSR Workshop Berlin, March 23/24, 29 I H.-P. Kaul 3

4 Objectives to compare WOSR to sunflower with view to productivity, N use and N residues to quantify residue mineralisation, potential leaching losses and N availability for a subsequent crop WOSR Workshop Berlin, March 23/24, 29 I H.-P. Kaul 4

5 General crop performance Characteristics WOSR Sunflower Grain yield (t ha -1 ) Crop residues (t ha -1 ) n.s. n.s. N in crop residues (kg ha -1 ) Residual SMN -9 cm (kg ha -1 ) Total N residues (kg ha -1 ) C:N in crop residues (-) n.s. N harvest index (-).67.6 N yield efficiency (kg grain kg -1 N) n.s. (Wägner, 1998) WOSR Workshop Berlin, March 23/24, 29 I H.-P. Kaul 5

6 Crop residue composition 1 Root Stem+Leaf Fruit parts Crop residues (t ha -1 ) n.s. Scattered plant litter missing! WOSR Sunflower n.s. WOSR Sunflower (Kaul, 24) WOSR Workshop Berlin, March 23/24, 29 I H.-P. Kaul 6

7 Effects of N rate and genotype on N residues N residue increase due to fertilizer due to genotype WOSR (kg N ha -1 ) WOSR Sunflower Sunflower N in crop residues Residual SMN -9 cm Total N residues = increase sign. (Kaul, 24) WOSR Workshop Berlin, March 23/24, 29 I H.-P. Kaul 7

8 Objectives to compare WOSR to sunflower with view to productivity, N use and N residues to quantify residue mineralisation, potential leaching losses and N availability for a subsequent crop WOSR Workshop Berlin, March 23/24, 29 I H.-P. Kaul 8

9 Residue mineralisation under optimum conditions mg NO 3 -N 1 g soil Days Sunflower (C:N 51) pure soil WOSR (C:N 79) (Kaul, 1998) WOSR Workshop Berlin, March 23/24, 29 I H.-P. Kaul 9

10 Simulation experiments Mineralisation model (Kersebaum & Richter 1994) Field experiment soil (ul, 1,37 % C org,,15 % N t ) Residues (mass, % C, % N, harvest date) from field experiments Temperature effect (longtime average) Assumptions: - no SMN export from the system (-3 cm) - sufficient soil water WOSR Workshop Berlin, March 23/24, 29 I H.-P. Kaul 1

11 Simulation results kg SMN (ha 3 cm) WOSR (C:N 64) Sunflower (C:N 48) SMN from soil from residues J A S O N D J A S O N D (Kaul, 1998) WOSR Workshop Berlin, March 23/24, 29 I H.-P. Kaul 11

12 Field simulation results 1994/ WOSR 3 25 Sunflower -3 cm 3-9 cm Soil mineral N (kg ha -1 ) A S O N D J F M A M Estimated leaching (kg N ha -1 ) A S O N D J F M A M A S O N D J F M A M A S O N D J F M A M (Kaul, 1998) WOSR Workshop Berlin, March 23/24, 29 I H.-P. Kaul 12

13 Subsequent wheat performance Winter wheat unfertilised Precrop Grain yield (t ha -1 ) N uptake (kg N ha -1 ) WOSR Sunflower LSD n.s. n.s. (Kaul, 24) WOSR Workshop Berlin, March 23/24, 29 I H.-P. Kaul 13

14 Conclusions WOSR and sunflower are similar in growth performance, but WOSR transports N more efficiently to grain. Residues of both crops initially immobilise SMN, but due to >2 months earlier harvest WOSR residue N is more prone to leaching and better available for subsequent crops. Consequently, winter wheat performed better after WOSR than after sunflower. WOSR Workshop Berlin, March 23/24, 29 I H.-P. Kaul 14

15 Thank you for your attention! Univ.Prof. Dr. Hans-Peter Kaul Gregor Mendel-Strasse 33, A-118 Vienna/Austria tel: , fax: hans-peter.kaul@boku.ac.at, WOSR Workshop Berlin, March 23/24, 29 I H.-P. Kaul 15