Summer cover crops after harvest of early potatoes control seed weeds

Abstract: To reduce pesticides and find greener alternatives for weed management in crop production has been a big issue worldwide. In Sweden, the Board of Agriculture has developed grants for farmers who use e.g. cover crops and new and greener strategies (e.g. using other crops to suppress weeds to reduce the use of chemical pesticides) to add to their weed management. Cover crops are usually fast-growing crops which can cover the ground quickly to prevent weed growth. Cover crops can also have different qualities and abilities which can benefit the other crops in the crop rotation, e.g. prevent nutrient leakage, increase soil structure and suppressing weeds. The aim of this study was to investigate the cover crop’s ability to suppress and minimize the number and biomass of annual weeds and see if there are any differences between the cover crops species ability to suppress weeds. Also, to investigate in literature the benefits cover crops can give the next main crop. A field experiment was set in the northwest of Scania, Sweden, with different cover crops. The cover crops used were buckwheat (Fagopyrum esculentum) in pure stock and mixed with crimson clover (Trifolium incarnatum), Persian clover (Trifolium resupinatum), Sudangrass (Sorghum x sudanense), Westerwoldisch ryegrass (Lolium multiflorum var. westerwoldicum), oat (Avena sativa) and black oat (Avena strigosa). Other cover crop mixes with lacy phacelia (Phacelia tanacetifolia) and Persian clover, hairy vetch (Vicia villosa ssp. Villosa) and winter rye (Secale cerale), and marigold (Tagetes patula) were tested. Due to a warm, dry and rainfree season this year, 2018 in Sweden, some cover crops didn’t establish well, and they were oat, black oat, lacy phacelia, hairy vetch, Persian clover, crimson clover and winter rye. The results showed a significant difference in weeds biomass between the control and the cover crops tested and this means that the cover crops tested suppress seed weeds. The cover crops had weeds biomass of 1-54 g/m2 the first sampling date and 4-47 g/m2 the second sampling date, compared to the control which had 150 g/m2 the first date and 192 g/m2 the second date. This means that the cover crops had 64-91% (first sampling) and 76-93% (second sampling) lesser weeds biomass than the control, which means that the cover crops suppressed the seed weeds well. Thou the results is good further studies need to be done in order to see if the effects and abilities are the same in different places.