Field Crops Research 179 (2015) 113–119 Contents lists available at ScienceDirect Field Crops Research jou rn al hom epage: www.elsevier.com/locate/fcr Nitrogen uptake, use and utilization efficiency by oat–pea intercrops Reinhard W. Neugschwandtner ∗ , Hans-Peter Kaul Division of Agronomy, Department of Crop Sciences, University of Natural Resources and Life Sciences Vienna (BOKU), Konrad Lorenz-Straße 24, 3430 Tulln, Austria a r t i c l e i n f o Article history: Received 15 January 2015 Received in revised form 26 April 2015 Accepted 27 April 2015 Keywords: Intercropping Oat Pea N yield N use N utilization a b s t r a c t Cereal–legume intercropping in sustainable arable farming systems in temperate regions is of increasing interest for increasing productivity. This study assessed the influence of sowing ratio and N fertilization on nitrogen uptake, use and utilization efficiency of oat (Avena sativa L.) and pea (Pisum sativum L.) in intercrops. A two-year field study was carried out in eastern Austria with oat and pea sown in three substitutive sowing ratios and at different nitrogen levels. Oat was the dominant partner in the mixtures strongly outcompeting pea. Total grain yields were generally lower in intercrops than in pure stands. Consequently, nitrogen use and the partial factor nitrogen use efficiency for grain production were lower in intercrops. Nitrogen utilization efficiency was highest in pure oat stands and decreased with higher pea shares. Grain N concentration of oat and pea increased with N fertilization. In intercrops, grain N concentrations of oat increased with lower oat share whereas those of pea were not affected by cropping system. Due to higher grain N concentrations of oat in intercrops, intercrops could attain a higher grain N yield in unfertilized treatments. Thus, growing oat–pea intercrops can be reasonable for producing grain feed at low N input level. © 2015 Elsevier B.V. All rights reserved. 1. Introduction Intercropping is a traditional farming technique, which is impor- tant in farming systems of developing countries but far less widespread in mechanized systems (Lithourgidis et al., 2011). But there is an increased scientific interest in intercropping systems in temperate regions for developing sustainable farming systems for forage (Anil et al., 1998) or grain production (Neugschwandtner and Kaul, 2014; Zaj˛ ac et al., 2013, 2014). Yields of grain legumes are generally more variable than those of many other crop species (Jeuffroy and Ney, 1997). Thus, Jensen (1996) has shown that inter- cropping barley with pea resulted in a higher yield stability of intercrops than of pea pure stands. Yield and yield components (Neugschwandtner and Kaul, 2014) and yield per plant (Echarte et al., 2011) as well as concentrations and uptake of nutrients (Li et al., 2001) of individual crops may be affected in inter- crops compared to pure stands. Higher yields can be obtained by intercropping through an improved water and radiation cap- ture as shown for maize–soybean intercrops compared to soybean sole cropping (Coll et al., 2012). Thereby, intercropping can be an ∗ Corresponding author. Tel.: +43 1 47654 3311; fax: +43 1 47654 3342. E-mail address: reinhard.neugschwandtner@boku.ac.at (R.W. Neugschwandtner). alternative under rainfed conditions for reducing farm risk (Monzon et al., 2014). Further one, biological and chemical soil characteristics are positively influenced by intercropping (Oelbermann and Echarte, 2011); e.g. intercropping contributes to the long-term immobilization of N compared to sole cropping as shown for maize–soybean intercrops and, thus, could help to curb the currently growing reliance on N fertilizers (Regehr et al., 2015). Cereal–legume intercrops may allow for the optimal use of soil and atmospheric nitrogen sources to maintain high production and quality levels with low fertilizer N inputs to minimize potential environmental impacts, which may occur in intensive agricultural systems (Pelzer et al., 2012). Soil inorganic and atmospheric N sources can be complementarily used by the intercrop compo- nents. Cereals are more competitive than legumes for inorganic soil N (Jensen, 1996) due to a faster and deeper root growth of the cereal (Corre-Hellou and Crozat, 2005). In substitutive cereal–pea intercrops, the cereal has an even better access to soil N than in pure stands due to a lower plant density but at a similar amount of available N per unit area (Bedoussac and Justes, 2010). Legumes save the soil N pool due to their symbiotic N 2 fixation (Chalk et al., 1993; Hauggaard-Nielsen et al., 2001). The portion of N derived through fixation by pea is further increased in intercrops as the higher soil mineral N acquisition of the cereal fosters symbiotic N 2 fixation due to low NO 3 concentrations; symbiotic N 2 fixation is negatively affected by that chemical compound (Corre-Hellou et al., http://dx.doi.org/10.1016/j.fcr.2015.04.018 0378-4290/© 2015 Elsevier B.V. All rights reserved.