Abstract:

Weeds have a direct impact on crop quality and yield in agricultural systems. In order to explore a production mode which can control and utilize weeds while maintaining a high weed diversity and a high crop yield, we experimentally compared weeds by raising geese in corn fields (hereinafter referred to as RGICF) and conventionally planting corn fields (CK) in 2013. Weed niche breadth, the structure of community and functional groups and diversity were compared between the periods of BG (before the RGICF treatment was grazed by geese) and AG (after the RGICF treatment was grazed by geese) to observe changes. RGICF is a compound production pattern based on the principle of “Agro-pastoral Integration”, a concept proposed in 2011, that uses resources like weeds and the bottom leaves of crops in a tillage system to raise poultry. However, questions remain about the system including its effects on biodiversity, weed community structure, and total biomass. Results indicated that Lolium multiflorum, Medicago sativa, and Chenopodium glaucum had the highest niche breadth during BG in RGICF, and the niche breadths of C. glaucum, Polygonum nepalense, Fragaria moupinensis and Geranium pratense increased to different extents while those of L. multiforum and M. sativa decreased during AG. Additionally, seven weed species were found only during AG. In the CK treatment, Bulbostylis densa had the highest niche breadth during BG, while Gnaphalium affine had the highest during AG. Here, two new weed species were found only during AG. The niche overlap of L. perenne and M. sativa was the highest during BG, and L. perenne overlapped most with F. moupinensis during AG. While in CK, the niche overlap of Bulbostylis densa and Digitaria sanguinalis was greatest during BG, and the niches of B. densa and Gnaphalium affine overlapped the most during AG. In the two treatments, the dicotyledonous annuals (DA) was the dominant functional group during both BG and AG, and the distribution proportion of perennials increased with a more balanced distribution during AG in RGICF. During BG, Shannon-Wiener diversity index and Margalef richness index were significantly higher in RGICF than in CK (P<0.05, n=3), and these measures increase during AG and remained higher in RGICF. Pielou evenness index did not differ between the treatments (P>0.05, n=3). Simpson diversity index of weeds in RGICF was higher than CK during BG but significantly lower than CK (P<0.05, n=3) during AG. The biomass of above ground weeds in RGICF was higher than that of CK (P>0.05, n=3), during both BG and AG. Compared with CK, the corn yield in RGICF was lower (P>0.05, n=3); yields decreased 4%. In summary, although the RGICF production mode reduced corn yields, the practice maintains high biodiversity in agro-ecosystems, and may compensate or even overcompensate yield loss through the production of geese.

Key words: weeds, agro-pastoral integration, niche, functional groups, biodiversity, yield