YIELD AND N2 FIXATION OF PEA AND LENTIL AS AFFECTED BY INTERCROPPING AND N APPLICATION

Abstract

Farmers in Saskatchewan have recently begun intercropping pea with nonlegumes in order to reduce lodging of the pea crop and thus improve harvesting operations. The response of pea and lentil to intercropping and N application was determined at five locations throughout Saskatchewan in 1987. At each site one of the following combinations was tested: lentil and flax, pea and rape, pea and yellow mustard or pea and oats. All treatments received 10, 30 or 50 kg N ha⁻¹ as urea. Nitrogen-15 microplots were included to measure N₂-fixation and percent fertilizer use efficiency (% FUE). Intercropping reduced lodging and improved harvesting conditions of pea and lentil. An increase in the land equivalent ratio (LER) due to intercropping was observed at two sites where growing conditions were poorer than at the other three sites. At the other sites intercropping systems had a similar or intermediate % FUE to that of the monocropped legume and non-legume. Percent N derived from N₂-fixation (% Ndfa) ranged from 4.6 to 87.6, depending on site, level of N application and cropping system. Intercropped legumes had a significantly higher % Ndfa than monocropped legumes at two sites. Nitrogen fertilization reduced the % Ndfa of monocropped legumes at two sites but never affected the % Ndfa of intercropped legumes. Total N₂ fixed was almost always less in intercropped than in monocropped systems, although only significantly at two sites. No significant lower values for atom % ¹⁵N of intercropped non-legumes as compared with monocropped non-legumes were observed, indicating that transfer of N from the legume to the non-legume was minimal. Key words: Intercropping, monocropping, flax, lentil, rape, pea, yellow mustard, oat