The efficiency of durum wheat and winter pea intercropping to increase wheat grain protein content depends on nitrogen availability and wheat cultivar

Grain protein concentration (GPC) of durum wheat is often a major concern particularly in low input systems where nitrogen acquisition is low due to limited resource of soil mineral N. By consequence, intercropping (IC) which can improve the use of light, nutrients and water resources (Willey, 1979) could be an alternative to the use of mineral fertilizer (Hauggaard-Nielsen, 2003 and Corre-Hellou, 2006). In this paper, we assessed the hypothesis that the performances of durum wheat and winter pea grown in intercrop (IC) to valorise natural resources are better than in sole crops (SC) in low-input systems. Besides, they would however depend on both nitrogen availability and wheat cultivar

Is durum wheat-winter pea intercropping efficient to improve the use of N in low input farming ?

Nitrogen acquisition and grain protein concentration (GPC) of durum wheat is often a major concern, particularly in low input systems where mineral N is a limited resource. In this present paper we assessed the hypothesis that the performance of durum wheat and winter pea, grown in intercrop (IC) is better than in sole crops (SC) for their ability to improve the use of N resources. Field experiment was carried out in SW France in 2005-2006 with three fertiliser-N supply: no fertilizer (N0), 100 kg N ha-1 (N100), and 180 kg N ha-1 (N180). For all treatments, N uptake of durum wheat was significantly greater in SC than in IC but was always lower than the whole IC cover. The nitrogen status (NNI) and the GPC of wheat were higher in IC than SC and obviously increased with N availability. The greatest NNI and GPC of wheat in IC was mainly due to a greater N uptake of soil mineral N per plant. Moreover, the complementary use of soil and symbiotic N2 fixation sources allowed a better N acquisition by the whole IC compared to wheat SC. This advantage was not observed for N180 because fertilizer-N increased wheat growth and induced a reduction of pea growth due to light competition

The efficiency of a durum wheat-winter pea intercrop to improve yield and wheat grain protein concentration depends on N availability during early growth

Grain protein concentration of durum wheat is often too low, particularly in low-N-input systems. The aim of our study was to test whether a durum wheat - winter pea intercrop can improve relative yield and durum wheat grain protein concentration in low-N-input systems. A 2-year field experiment was carried out in SW France with different fertilizer-N levels to compare wheat (Triticum turgidum L., cv. Nefer) and pea (winter pea, Pisum sativum L., cv. Lucy) grown as sole crops or intercrops in a row-substitutive design. Without N fertilization or when N was applied late (N available until pea flowering less than about 120 kg N ha-1), intercrops were up to 19% more efficient than sole crops for yield and up to 32% for accumulated N, but were less efficient with large fertilizer N applications. Wheat grain protein concentration was significantly higher in intercrops than in sole crops (14% on average) because more N was remobilized into wheat grain due to: i) fewer ears per square metre in intercrops and ii) a similar amount of available soil N as in sole crops due to the high pea N2 fixation rate in intercrops (88% compared to 58% in sole crops)

Dynamic analysis of competition and complementarity for light and N use to understand the yield and the protein content of a durum wheat-winter pea intercrop

In a previous paper (Bedoussac and Justes 2009, Plant and Soil DOI: 10.1007/s11104-009-0082-2), we showed that intercropping of durum wheat and winter pea increased the yield and protein concentration of durum wheat when early N availability was less than 120 kg N.ha-1. The aim of the present work was to understand these results by analysing intercrop species dynamics for growth, light and N acquisition. A 2-year field experiment was carried out in SW France with different fertilizer-N levels in order to compare wheat (Triticum turgidum L.) and pea (Pisum sativum L.) grown as sole crops and as an intercrop in a row substitutive design. The advantages of intercropping in low N conditions were mainly due to: i) better light use (up to 10%) thanks to species dynamic complementarity for leaf area index and height, ii) growth complementarity over time (higher growth rate of wheat until pea flowering and then of pea until wheat flowering), and iii) dynamic complementary N acquisition associated with better wheat N status throughout growth. Disadvantages, underlining poorer complementarity within the intercrop stand, were observed with ample available N in early growth. This induced higher cereal growth during winter which led to increase interspecies competition by reducing pea light absorption and consequently its biomass production

Durum wheat – winter pea intercropping is efficient to improve the use of environmental resources in low input farming in the French southern conditions

Nitrogen acquisition and grain protein concentration (GPC) of durum wheat is often a major concern, particularly in low input systems where mineral N is a limited resource. In this present paper we assessed the hypothesis that the performance of durum wheat and winter pea, grown in intercrop (IC) is better than in sole crops (SC) for their ability to improve the use of N resources. Field experiment was carried out in SW France in 2005-2006 with three fertiliser-N supply: no fertilizer (N0), 100 kg N ha-1 (N100), and 180 kg N ha-1 (N180). For all treatments, N uptake of durum wheat was significantly greater in SC than in IC but was always lower than the whole IC cover. The nitrogen status (NNI) and the GPC of wheat were higher in IC than SC and obviously increased with N availability. The greatest NNI and GPC of wheat in IC was mainly due to a greater N uptake of soil mineral N per plant. Moreover, the complementary use of soil and symbiotic N2 fixation sources allowed a better N acquisition by the whole IC compared to wheat SC. This advantage was not observed for N180 because fertilizer-N increased wheat growth and induced a reduction of pea growth due to light competition

Predicting soil water and mineral nitrogen contents with the STICS model for estimating nitrate leaching under agricultural fields

The performance of the STICS soil-crop model for the dynamic prediction of soil water content (SWC) and soil mineral nitrogen (SMN) in the root zone (120 cm) of seven agricultural fields was evaluated using field measurements in a coarse-grained alluvial aquifer of the Garonne River floodplain (southwestern France) from 2005 to 2007. The STICS model was used to simulate drainage and nitrate concentration in drainage water in all the agricultural fields of the study area, in order to quantify and assess the temporal and spatial variability of nitrate leaching into groundwater. Simulations of SWC and SMN in the seven monitored fields were found to be satisfactory as indicated by root mean square error (RMSE) and model efficiency being 6.8 and 0.84% for SWC and 22.8 and 0.92% for SMN, respectively. On average, SWC was slightly overestimated by a mean difference of 10 mm (3%) and there was almost no bias in SMN estimations (<0.5%). These satisfactory results demonstrate the potential for using the STICS model to accurately simulate nitrate leaching. Across the study area, simulated drainage and nitrate concentration were extremely variable from one field to another. For some fields, simulated mean annual nitrate concentration in drainage water exceeded 300 mg NO3 − L−1 and predicted nitrate leaching was close to 100 kg N ha−1, while other fields had very low nitrate losses. About 15% of the farmers’ fields were responsible for 60–70% of nitrate leaching. The SMN in late autumn, before winter drainage, was found the main determining factor explaining this variability. This situation may be attributed to unsatisfactory cumulative nitrogen management over the medium term. Ineffective nitrogen management was found to be more detrimental than a single annual incident of overfertilization, particularly in situations of deep soils and in cases of low or highly variable drainage between years

Is durum wheat-winter pea intercropping efficient to reduce pests and diseases ?

Intercropping (IC) is known as an agricultural practice which can improve the use of environmental resources (light, nutrients and water) resulting in yield advantages compared to sole cropping (SC) (Willey, 1979) particularly in low input systems. But, diseases ands pests can strongly affect both yield and grain quality in such systems. Now, numerous studies have shown significant reductions in harmful insects and on diseases in IC compared to SC of the same species (Vandermeer, 1989; Kinane and Lyngkjaer, 2002) even if others studies did not confirmed these foundings. The aim of our study was to evaluate the assumption that IC can reduce pea pests (green aphids and weevils), pea ascochyta and main durum wheat diseases (mildew, brown rust, fusarium and septoria)

Est-il possible d’améliorer le rendement et la teneur en protéines du blé en Agriculture Biologique au moyen de cultures intermédiaires ou de cultures associées ?

L’objectif du travail est de trouver des systèmes de culture durables pour produire des rendements de blé réguliers et de bon niveau avec une teneur en protéines satisfaisante en AB. Notre démarche repose sur une valorisation optimale des ressources naturelles en azote provenant de la minéralisation du sol et de la fixation symbiotique. D’une part, des cultures intermédiaires ont été semées en été et enfouies avant le semis du blé afin de limiter les pertes hivernales d’azote nitrique. D’autre part, le blé a été cultivé en association avec une légumineuse à graines. Les cultures intermédiaires sont efficaces dans leur rôle de piège à nitrate et permettent d‘augmenter le rendement et la teneur en protéines du blé lors des années pluvieuses. En culture associée, le rendement du blé est réduit mais la teneur en protéines est significativement augmentée. Ainsi, en AB, les cultures associées sont plus efficaces pour utiliser les ressources naturelles en azote. Il reste cependant i) à optimiser les itinéraires techniques de ces deux systèmes de culture, et, ii) déterminer la place des associations au sein des rotations et analyser leur effet à moyen terme pour la gestion des bio-agresseurs