Hard Red Spring Wheat Response Following the Intercropping of Legumes into Sunflower

Abstract

Intercropping legumes in sunflower (Helianthus annuus L.) may increase soil cover, reduce soil erosion, and increase soil C and N. Subsequent effects of this practice on hard red spring wheat (HRSW) [Triticum aestivum (L.) Emend. Thell.] yield and protein content were unknown. Our objective was to quantify effects of intercropping various legumes into sunflower on spring soil nitrate-nitrogen (NO 3 - -N) and grain yield and protein content of a subsequent HRSW crop. Field experiments were conducted near Carrington and Prosper, ND, from 1993 through 1995. Wheat was planted into non-legume plots and those previously intercropped with hairy vetch (Vicia villosa Roth), yellow-flowered sweetclover (Melilotus officinalis Lam.), alfalfa (Medicago sativa L.), snali medic [Medicago scutellata (L.) Mill.], or black lentil (Lens culinaris Medik.). Soil NO 3 - -N(0-30 cm) in plots previously intercropped with hairy vetch (41 kg ha -1 ) was greater than control plots (26 kg ha -1 ). Yield of HRSW was reduced at both Carrington and Prosper in 1993 when grown after a sweetclover intercrop. Yield of HRSW was reduced at Carrington in 1993 when grown after an alfalfa intercrop. Wheat grown after sweetclover intercropped in sunflower had higher protein content (142.0 g kg -1 ) than HRSW grown after sunflower (140.6 g kg -1 ) alone. Overall, intercropping hairy vetch at the V4 sunflower growth stage appears superior because it did not reduce sunflower yield, provided soil cover adding between 540 and 2400 kg ha -1 above ground dry matter to the system, and increased NO 3 - -N levels at the beginning of the HRSW season in two environments.