Land Equivalent Ratios, Light Interception, and Water Use in Annual Intercrops in the Presence or Absence of In‐Crop Herbicides

Abstract

IntercroppingA gronomy J our n al • Volu me 10 0 , I s sue 4 • 2 0 0 8 ABSTRACT Increased crop production (overyielding) oft en observed in intercrops compared to sole crops has been attributed to enhanced resource use. Th e objective of this study was to investigate intercropping complementarity of wheat (Triticum aestivum L.), canola (Brassica napus L.), and fi eld pea (Pisum arvense L.) for light and water use. Sole crop and intercrop combinations were evaluated for eff ects on land equivalent ratios (LERs), canopy light interception, soil moisture, water use (WU), and water use effi ciency (WUE), with or without in-crop herbicides at two fi eld sites in Manitoba, Canada. Th e mean LER was 1.1, but LERs varied greatly between site-years and herbicide treatments, and were signifi cantly greater than one in 22% of the site-year-treatment combinations. Th e wheat-canola-pea and canola-pea intercrops showed the greatest frequency of overyielding for dry matter (50%) and grain yield (38%), respectively. Peak light interception tended to occur earlier with canola than with fi eld pea, thus increasing the potential for light use complementarity between these crops. Th ere was a positive correlation between LER and light interception in half of the site-years with applied herbicides and a negative correlation between LER and weed biomass at most site-years without herbicides. Although crop treatments used water diff erently within the soil profi le, there were no diff erences in WU, but some diff erences in WUE, between crop treatments; however, WUE generally was not greater in intercrops compared to sole crops. In this study, overyielding in intercrops was inconsistent, and seemed to be related more to light interception than to water utilization.

As the level of crop productivity increases: Is there a role for intercropping in smallholder agriculture

“…In agreement with our results Tsubo et al (2003) reported no significant differences in water use efficiency between maize/bean intercrops and their sole crops in South Africa. Similar results were reported by Caviglia et al (2004) in a wheat/soybean intercropping in Argentina, and Szumigalski and Van Acker (2008) in Canada after intercropping wheat, canola and field peas. A caveat needs to be made in the interpretation of our results though, as we did not account for differences on deep drainage or evaporation losses in the soil water balance across the different levels of environmental productivity.…”

“…N and water) factors, photosynthetically active radiation (PAR, 0.4-0.7 m wavelength) is the most important resource for crop growth and development in intercropping systems with crops of different heights (Watiki et al, 1993). Several studies indicate improved radiation interception and utilization in intercrops compared to sole crops (Reddy and Willey, 1981;Natarajan and Willey, 1986;Pilbeam et al, 1994;Szumigalski and Van Acker, 2008;Gao et al, 2010). However, the opposite was also observed (Zhang et al, 2008).…”

Cover crop mixtures including legume produce ecosystem services of nitrate capture and green manuring: assessment combining experimentation and modelling

“…This was especially true for turnip rape (Brassicaceae) which had the highest partial LER, but which negatively affected the legumes associated indicating low complementarity between the two species. The literature reports similar results for mixtures composed of a Brassicaceae species and a legume species (Szumigalski and Van Acker 2008;Wortman et al 2012b). Overall, in our study, CC mixtures used abiotic resources more efficiently than SC to acquire N (i.e.…”

Biological nitrogen fixation and yield of pigeonpea and groundnut: Quantifying response on smallholder farms in northern Malawi

“…The relative proportion of each component species depends on the main crop of interest to the farmers, complimentarity in growth habits and use of resources. Productivity of intercrops can be maximized with careful selection of component crops and appropriate agronomic practices (Szumigalski and Van Acker, 2008).…”