Neonicotinoid seed treatments of soybean provide negligible benefits to US farmers

Neonicotinoids are the most widely used insecticides worldwide and are typically deployed as seed treatments (hereafter NST) in many grain and oilseed crops, including soybeans. However, there is a surprising dearth of information regarding NST effectiveness in increasing soybean seed yield, and most published data suggest weak, or inconsistent yield benefit. The US is the key soybean-producing nation worldwide and this work includes soybean yield data from 194 randomized and replicated field studies conducted specifically to evaluate the effect of NSTs on soybean seed yield at sites within 14 states from 2006 through 2017. Here we show that across the principal soybean-growing region of the country, there are negligible and management-specific yield benefits attributed to NSTs. Across the entire region, the maximum observed yield benefits due to fungicide (FST = fungicide seed treatment) + neonicotinoid use (FST + NST) reached 0.13 Mg/ha. Across the entire region, combinations of management practices affected the effectiveness of FST + N ST to increase yield but benefits were minimal ranging between 0.01 to 0.22 Mg/ha. Despite widespread use, this practice appears to have little benefit for most of soybean producers; across the entire region, a partial economic analysis further showed inconsistent evidence of a break-even cost of FST or FST + N ST. These results demonstrate that the current widespread prophylactic use of NST in the key soybean-producing areas of the US should be re-evaluated by producers and regulators alike

Neonicotinoid seed treatments of soybean provide negligible benefits to US farmers

Neonicotinoids are the most widely used insecticides worldwide and are typically deployed as seed treatments (hereafter NST) in many grain and oilseed crops, including soybeans. However, there is a surprising dearth of information regarding NST effectiveness in increasing soybean seed yield, and most published data suggest weak, or inconsistent yield benefit. The US is the key soybean-producing nation worldwide and this work includes soybean yield data from 194 randomized and replicated field studies conducted specifically to evaluate the effect of NSTs on soybean seed yield at sites within 14 states from 2006 through 2017. Here we show that across the principal soybean-growing region of the country, there are negligible and management-specific yield benefits attributed to NSTs. Across the entire region, the maximum observed yield benefits due to fungicide (FST = fungicide seed treatment) + neonicotinoid use (FST + NST) reached 0.13 Mg/ha. Across the entire region, combinations of management practices affected the effectiveness of FST + N ST to increase yield but benefits were minimal ranging between 0.01 to 0.22 Mg/ha. Despite widespread use, this practice appears to have little benefit for most of soybean producers; across the entire region, a partial economic analysis further showed inconsistent evidence of a break-even cost of FST or FST + N ST. These results demonstrate that the current widespread prophylactic use of NST in the key soybean-producing areas of the US should be re-evaluated by producers and regulators alike

Intercropping winter cereals in Kura clover for spring forage production

Intercropping winter cereals into Kura clover (Trifolium ambiguum M. Bieb.) has the potential to improve forage nutritive value without reducing yields. The objective of this research was to compare forage yield and nutritive value of cereal–legume mixtures to cereals or Kura clover grown in monoculture and harvested at two different maturity stages in spring. Winter rye (Secale cereale L.), winter wheat (Triticum aestivum L.), and winter triticale (×Triticosecale Wittmack) were sown in autumn at two locations as monocultures and into herbicide suppressed and non-suppressed Kura clover and harvested for forage the following spring. Harvested at the cereal crop boot stage at Arlington, forage yields averaged 4.7, 4.8, 5.3, and 1.7 Mg ha−1 and 3.5, 3.7, 4.1, and 2.6 Mg ha−1 at Lancaster for mixtures with non-suppressed Kura clover, suppressed Kura clover, monoculture cereals, and monoculture clover, respectively. At the milk stage, yields across all mixture treatments increased by 46% to 115% compared to the boot stage at Arlington and by 88% to 101% at Lancaster. Kura clover in mixtures increased crude protein by 34% to 46% and in vitro true digestibility by 3% to 6%, neutral detergent fiber digestibility by 0% to 6%, and reduced neutral detergent fiber concentration by 8% to 18% relative to cereal monocultures. The nutritive value of mixtures and monoculture Kura clover was always greater than that of monoculture cereals. Winter cereals can be successfully managed with Kura clover for forage production by maximizing nutritive value with boot stage harvests or achieving higher yields by harvesting at the milk stage.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author