Overwintering grass-clover as intercrop and moderately reduced nitrogen fertilization maintain yield and reduce the risk of nitrate leaching in an organic cauliflower (Brassica oleracea L. var. botrytis) agroecosystem

TY - JOUR

T1 - Overwintering grass-clover as intercrop and moderately reduced nitrogen fertilization maintain yield and reduce the risk of nitrate leaching in an organic cauliflower (Brassica oleracea L. var. botrytis) agroecosystem

AU - Xie, Yue

AU - Kristensen, Hanne Lakkenborg

PY - 2016/7/15

Y1 - 2016/7/15

N2 - Cauliflower (Brassica oleracea L. var. botrytis) has high nitrogen (N) demand during growing, but due to its low N use efficiency and N-rich residues, it may cause N losses by leaching after harvest. A field experiment was conducted to investigate the effect of overwintering grass-clover as an intercrop and moderately reduced N fertilization on organic cauliflower yield and risk of nitrate leaching. The experiment tested sole-cropped (S) and intercropped (I) systems using a substitution design and two N fertilizer rates (180 and 230 kg N ha -1). To investigate the competition between cauliflower and grass-clover, cauliflower grown alone with empty grass-clover rows (S emp) and grass-clover grown alone with empty cauliflower rows (GC emp) were included. The results showed that marketable yield was maintained in the I system compared to in the S system when calculated per meter crop row, and when N fertilization was moderately reduced. The Relative Competition Index (RCI) values in the I system were lower than 0, indicating that cauliflower growth was not interfered in the I system. The ability for aboveground N accumulation in the S and I systems was similar, but the N content of cauliflower residues in the S system was 33 and 23 kg ha -1 higher than in the I system in 2012 and 2013, respectively. The S system had 168 kg N inorg ha -1 in the soil layer of 0-1.5 m at the start of leaching in 2013, which was 40 kg N ha -1 higher than the I system. Reduced N fertilizer level led to 22 kg ha -1 lower soil N inorg at the end of leaching. However, the effect of system and N level on soil residual N inorg per unit marketable yield was not significantly different. Intercropping cauliflower with overwintering grass-clover and moderately reduced N fertilization was feasible in organic cauliflower production, with regard to maintaining marketable yield and reducing the risk of nitrate leaching in the agroecosystem.

AB - Cauliflower (Brassica oleracea L. var. botrytis) has high nitrogen (N) demand during growing, but due to its low N use efficiency and N-rich residues, it may cause N losses by leaching after harvest. A field experiment was conducted to investigate the effect of overwintering grass-clover as an intercrop and moderately reduced N fertilization on organic cauliflower yield and risk of nitrate leaching. The experiment tested sole-cropped (S) and intercropped (I) systems using a substitution design and two N fertilizer rates (180 and 230 kg N ha -1). To investigate the competition between cauliflower and grass-clover, cauliflower grown alone with empty grass-clover rows (S emp) and grass-clover grown alone with empty cauliflower rows (GC emp) were included. The results showed that marketable yield was maintained in the I system compared to in the S system when calculated per meter crop row, and when N fertilization was moderately reduced. The Relative Competition Index (RCI) values in the I system were lower than 0, indicating that cauliflower growth was not interfered in the I system. The ability for aboveground N accumulation in the S and I systems was similar, but the N content of cauliflower residues in the S system was 33 and 23 kg ha -1 higher than in the I system in 2012 and 2013, respectively. The S system had 168 kg N inorg ha -1 in the soil layer of 0-1.5 m at the start of leaching in 2013, which was 40 kg N ha -1 higher than the I system. Reduced N fertilizer level led to 22 kg ha -1 lower soil N inorg at the end of leaching. However, the effect of system and N level on soil residual N inorg per unit marketable yield was not significantly different. Intercropping cauliflower with overwintering grass-clover and moderately reduced N fertilization was feasible in organic cauliflower production, with regard to maintaining marketable yield and reducing the risk of nitrate leaching in the agroecosystem.

KW - Catch crop

KW - Cover crop

KW - N fertilizer level

KW - intercropping system

KW - organic cauliflower

KW - Fertilization

KW - Grass-clover

KW - NITROGEN

KW - intercrop

UR - https://www.scopus.com/pages/publications/84968754981

U2 - 10.1016/j.scienta.2016.04.034

DO - 10.1016/j.scienta.2016.04.034

M3 - Journal article

SN - 0304-4238

VL - 206

SP - 71

EP - 79

JO - Scientia Horticulturae

JF - Scientia Horticulturae

ER -