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Individual study: Weed Seedbank Characterization in Long-Term Cotton–Tomato Rotations in California

Published source details

Shrestha A., Mitchell J.P. & Hembree K.J. (2015) Weed Seedbank Characterization in Long-Term Cotton–Tomato Rotations in California. Agronomy Journal, 107, 597-604


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Pest regulation: Use reduced tillage in arable fields Mediterranean Farmland

A replicated, randomized, controlled study in 1999–2011 in an irrigated tomato-cotton field in the San Joaquin Valley, California, USA, found that tillage had inconsistent effects on weed numbers, but different weed species were found in plots with reduced tillage, compared to conventional tillage. Pest numbers: Fewer weeds were found in plots with reduced tillage, compared to conventional tillage, in two of six comparisons (in June 2011: 61–126 vs 158–190 plants/m2), but more weeds were found in one of six comparisons (in tomatoes, in January 2003: 48 vs 45 plants/m2). Different communities of weeds were found in plots with reduced tillage, compared to conventional tillage, in one of two comparisons (in plots with winter cover crops; data reported as distance in ordination space). Methods: Reduced tillage or conventional tillage was used on 16 plots each, in 1999–2011. The plots (9 x 82 m) had six raised beds each. Winter cover crops (triticale, rye, and vetch) were planted on half of the plots, in October 1999–2010, and crop residues were chopped in March. Different numbers of tillage practices were used for conventional tillage (19–23 tractor passes, including disc and chisel ploughing) and reduced tillage (11–12 tractor passes, not including disc and chisel ploughing). All plots were fertilized (conventional tillage: 89.2 kg/ha dry fertilizer, 111.5 kg/ha urea; reduced tillage: 124.9 kg/ha urea). Weeds were counted in January 2003 (1 m2 quadrats, four quadrats/plot), as well as March 2006 and June 2011 (0.25 m2 quadrats, two quadrats/plot). Soil cores were collected in June 2011 (8.25 cm diameter, 0–10 cm depth). Seeds from these soil cores were germinated, and weed species were counted.

 

Pest regulation: Grow cover crops in arable fields Mediterranean Farmland

A replicated, randomized, controlled study in 1999–2011 in an irrigated tomato-cotton field in the San Joaquin Valley, USA, found more weeds and different weed species in plots with winter cover crops, compared to plots without winter cover crops. Pest numbers: More weeds were found in plots with cover crops, in six of 12 comparisons (28–121 vs 3–98 plants/m2). Different communities of weeds were found in plots with or without cover crops, in one of two comparisons (in plots with conventional tillage: data reported as distance in ordination space). Methods: Rainfed winter cover crops (triticale, rye, and vetch) were planted on 16 treatment plots, but not on 16 control plots, in October 1999–2010. Crop residues were chopped in March. Reduced tillage or conventional tillage was used on half of these plots, in 1999–2011. The plots (9 x 82 m) had six raised beds each. Different numbers of tillage practices were used for conventional tillage (19–23 tractor passes, including disk and chisel ploughing) and reduced tillage (11–12 tractor passes, not including disk and chisel ploughing). All plots were fertilized (conventional tillage: 89.2 kg/ha dry fertilizer, 111.5 kg/ha urea; reduced tillage: 124.9 kg/ha urea). Weeds were counted in January 2003 (1 m2 quadrats, four quadrats/plot), as well as March 2006 and June 2011 (0.25 m2 quadrats, two quadrats/plot). Soil cores were collected in June 2011 (8.25 cm diameter, 0–10 cm depth). Seeds from these soil cores were germinated, and weed species were counted.