Speaker
Description
Introduction
Relay strip intercropping with maize has been well studied in China (Li et al., 2020). This system performs well in conventional high-input agriculture partially due to complementary light capture. However, environmental policies aiming at reducing N leaching require reduced N input. In Europe, intercropping has mostly been done by combining cereals and legumes in organic farming in alternate-row or mixed designs (Bedoussac and Justes, 2010), but the absolute yield gain is unstable and constrained due to limited N fertilizer (Li et al., 2020). We here explore the responses of N uptake of cereals and legumes in strip intercropping when applied with moderate species-specific N fertilization, and how these compare to intercrops of two cereals or two legumes.
Materials and Methods
Field experiments were done in 2018 and 2019 in Wageningen, the Netherlands. We compared above-ground N uptake (kg N ha-1) of maize (“LG30.223”), wheat (Triticum aestivum, “Fanfare”), faba bean (Vicia faba, “Nobless”), and pea (Pisum sativum, “Astronaute”) in six bi-specific intercrops and four sole crops. Intercrops involving maize were relay systems, with maize sown and harvested later than the companion species. Intercrops without maize were nearly simultaneous systems, wherein the component species had the same sowing dates and similar harvest dates. Sowing delay in relay intercrops in 2018 and 2019 were 45 and 37 days respectively, creating differences in temporal complementarity. Total N application was 170 kg N ha-1 in maize, 125 kg N ha-1 in wheat, and 20 kg N ha-1 in faba bean and pea.
Results
N uptake of maize relay-intercropped with wheat or pea was higher than that of sole maize, but only in 2018, the year with greater temporal complementarity between species (less overlap of growing periods). The early-sown species took up more N in the relay intercrops than in sole crops. Combining cereals and legumes in simultaneous intercrops did not improve N uptake of either species compared to sole crops. Thus, relay intercropping with sufficient temporal complementarity allowed an improved N uptake while simultaneous intercropping did not.
Discussion
Temporal complementarity improves resource capture in intercrops compared to sole crops (Yu et al., 2015). The early-sown species in relay intercrops benefits from improved access to light and soil resources due to the initial absence of a competitor species in the neighbouring strip. The late-sown maize required larger temporal complementarity to achieve higher N uptake than sole maize. Unlike high-input intercrops reported in China (Li et al., 2011), our cereals hardly had extra access to soil N remaining in legume strips, as the small amount starter fertilizer was fully taken up during legume establishment. In cereal/legume simultaneous intercrops conducted in organic farming, the mixed or alternate-row design allows a high degree of interaction between component species (Jensen et al., 2020). In our strip intercrops, interaction between conspecific species increased, which likely diminished the advantage of complementary N uptake. We conclude that in strip intercrops with moderate fertilization, complementary N uptake was strongly associated with temporal complementarity.
References
Bedoussac, L., Justes, E., 2010. The efficiency of a durum wheat-winter pea intercrop to improve yield and wheat grain protein concentration depends on N availability during early growth. Plant Soil 330, 19–35.
Jensen, E.S., Carlsson, G., Hauggaard-Nielsen, H., 2020. Intercropping of grain legumes and cereals improves the use of soil N resources and reduces the requirement for synthetic fertilizer N: A global-scale analysis. Agron Sustain Dev.
Li, C., Hoffland, E., Kuyper, T.W., Yu, Y., Zhang, C., Li, H., Zhang, F., van der Werf, W., 2020. Syndromes of production in intercropping impact yield gains. Nat Plants 6, 653–660.
Li, C., Li, Y., Yu, C., Sun, J., Christie, P., An, M., Zhang, F., Li, L., 2011. Crop nitrogen use and soil mineral nitrogen accumulation under different crop combinations and patterns of strip intercropping in northwest China. Plant Soil 342, 221–231.
Yu, Y., Stomph, T.J., Makowski, D., van der Werf, W., 2015. Temporal niche differentiation increases the land equivalent ratio of annual intercrops: A meta-analysis. Field Crops Res 184, 133–144.
| Keywords | Europe; Strip intercropping; Moderate fertilization; Nitrogen uptake; Temporal complementarity |
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