Abstract
Little attention has been paid to root distribution in combined perennial legume and annual cereal crops. The main objectives of this study were to explore the regularity of root distribution and the influence on nitrogen (N) acquisition in different alfalfa (Medicago sativa L.) and corn (Zea mays L.) intercropping patterns. A three year (2007–2009) field experiment studied four intercropping patterns of alternating alfalfa and corn rows with alfalfa:corn rows sown at 2:2, 3:2, 4:2, and 5:2. Sole crops of corn and alfalfa were used as controls. Roots were sampled over 3 consecutive years by auger sampling method in the prime filling stage of corn from different soil depth, and the root length density (RLD) was used to describe the root spatial distribution of intercropped alfalfa and corn. The results showed that the alfalfa/corn intercropping system had the greater RLD values compared to the sole cropped alfalfa or corn. In addition, the root mass centre of intercropped alfalfa descended into deeper soil layers with advancing stand age, and likewise proliferated laterally towards associated corn rows. Whereas the corn root mass spread at relative shallow soil profile, and also more deployed laterally to neighboring alfalfa root zone. The gap between alfalfa and corn rows was the highest colonized area with greater intermingling and the highest RLD of both species root. The complementary and compatibility of the root spatial distribution of component crops in alfalfa/corn community were the essential cause for better biomass yield.
Highlights
The continued development and destruction of arable land is a serious threat to the world’s food supply for both humans and livestock
The results showed that the alfalfa/corn intercropping system had the greater root length density (RLD) values compared to the sole cropped alfalfa or corn
The objectives of the current study were to ascertain (1) whether the component crops in alfalfa/corn intercropping had greater root proliferation and increased RLD at different soil layers compared to respective their sole crops, (2) whether alfalfa and corn root mass alternatively distribute in different soil depths in vertical orientation and colonize greatly in horizontal direction, producing the compatible and complementary root spatial configuration, and (3) whether there is variation in root mass central distribution of component crops with the advancing of stand age
Summary
The continued development and destruction of arable land is a serious threat to the world’s food supply for both humans and livestock. Intercropping has shown great potential for increasing biomass yield in addition to reducing chemical fertilizer and pesticide input as well as increased biodiversity and land sustainability. Intercropping is considered to be a feasible strategy to relieve the food and feed crisis (Lenné & Thomas, 2006; Carrubba et al, 2008; Kn Rzer et al, 2009). Almost all previous studies involving alfalfa (Medicago sativa L.)/corn (Zea mays L.) (Smith & Carter, 1998), soybean Merr.)/wheat (Triticum aestivum L.) (Li et al, 2001), and alfalfa/wheat (Skelton & Barrett, 2005) intercropping have documented superior production and land sustainability compared to sole crops. Few experimental studies have explored in detail root distribution and interaction in intercropping systems, especially for the perennial/annual combination
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