Paper Information

Journal:   IRANIAN JOURNAL OF FIELD CROPS RESEARCH   2004 , Volume 1 , Number 2; Page(s) 139 To 154.
 
Paper:  SPATIAL DYNAMICS OF WEED POPULATIONS IN A CORN FIELD USING GEOSTATISTICS
 
Author(s):  ASHRAFI A., BANAYAN M., RASHED MOHASEL M.H.
 
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Abstract: 

The importance of spatial distribution in sampling weed populations, modeling population dynamics, and long-term weed management has been particularly important for methods to describe and analyze the spatial and temporal distribution of weeds. In year 2002, in a field located at Mashhad, weeds were identified and counted at 171 points of a corn field (1 ha) based on a 7 (m) by 7 (m) grid in 0.15 m2 quadrates, 3 times within the season including prior to post emergence management, after post emergence management, and before harvest. Geostatistical techniques were used to analyze the spatial structure of weeds and dynamics of patches. Fifteen weed species were observed across the field. Semivariogram analysis indicated 3.5 to 236.5m as the range of influence (patch size) which depends on weed species and sampling time (stage of growth). The semivariogram analysis also indicated that 51 to 85 % of the variation of sample density was due to spatial dependence, which suggests that most of the species were patchy. Semivariogram parameters did not change significantly over time for field bindweed which indicated the relative stability patches of this weed. Barnyardgrass was not treated with herbicide, thus patches have rapidly spread. For other weed species, the range of influence decreased (patches were smaller), but spatial structure was more stable over time which results in consistent patch position. The maps also showed elongated patches (anisotropy) along the field which may be in response to direction of tillage, irrigation and all other management practices. The results of this study showed that spatial distribution monitoring allows prediction of weed behavior and thus can be a valuable tool for management decisions and increases our understanding of the dynamics of weed

 
Keyword(s): PATCH, SPATIAL DYNAMICS, GEOSTATISTICS, SITE-SPECIFIC WEED MANAGEMENT
 
References: 
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