Herbicide-Based Weed Management for Soybean Production in the Far Eastern Region of Russia

Abstract

This study was conducted to establish a weed management system based on the sequential application of pre-emergence (PRE) and post-emergence (POST) herbicides for soybean production in Primorsky krai. Field experiments were conducted for two years in a field located in Bogatyrka, Primorsky krai, Russia (N43°49′, E131°36′). No herbicide application resulted in significant soybean yield loss, 0.03–0.3 t ha−1, which is more than 91.6% yield loss compared with that of the weed-free plot. The PRE application of acetochlor showed good weed control efficacy (greater than 90% weed control) with acceptable soybean safety (less than 10% soybean damage), while the other PRE herbicides performed poorly in terms of weed control. The POST application of bentazon + acifluorfen, bentazon, and imazamox at 30 days after soybean sowing (DAS) showed good weed control efficacy with good soybean safety. Neither the PRE nor POST application alone showed a sufficient soybean yield protection, resulting in much lower soybean yield than the weed-free plot. The sequential application of acetochlor (PRE), followed by either bentazon + acifluorfen (POST) at 30 DAS in 2012 or bentazon + imazamox (POST) at 60 DAS in 2013 showed the best performance in soybean yields, 1.7 t and 1.9 t ha−1, respectively, provided with 724.5 US$ and 1155.6 US$ ha−1 of economic returns. For alternative PRE herbicides of acetochlor, which is now banned, our tests of the sequential application of S-metolachlor with other POST herbicides and the sole application of other PRE herbicides revealed that S-metolachlor and clomazone could also be considered. Our results thus demonstrate that the sequential applications of PRE and POST herbicides should be incorporated into the weed management system for soybean production in Primorsky krai, Russia.

Modeling the Effects of Nitrogen Fertilizer and Multiple Weed Interference on Soybean Yield

“…If target soybean yield is decided at a given N level, economic thresholds (ETs) of multiple-weed species can be predicted by comparing the cost of controlling weed species with the benefit gained by herbicide application (e.g., Song et al [8], Cousens [31], Zanin et al [32]). In this region, the sequential application of herbicides, S-metolachlor followed by bentazon + imazamox, is recommended for respective pre-and post-emergence weed control (e.g., Song et al [22]). Soybean price and herbicide cost are US $650 Mg −1 and US $87.2 ha −1 , respectively, and N costs are US $16.2, US $32.3, and US $48.5 ha −1 for 12, 24, and 36 kg N ha −1 , respectively (e.g., Song et al [22]).…”

“…In this region, the sequential application of herbicides, S-metolachlor followed by bentazon + imazamox, is recommended for respective pre-and post-emergence weed control (e.g., Song et al [22]). Soybean price and herbicide cost are US $650 Mg −1 and US $87.2 ha −1 , respectively, and N costs are US $16.2, US $32.3, and US $48.5 ha −1 for 12, 24, and 36 kg N ha −1 , respectively (e.g., Song et al [22]). Using these values, the proportion of yield loss caused by unit total density equivalent obtained in our study, and assuming a 90% herbicide efficacy, the calculated ETs are 1.46, 0.90, 0.57, and 0.38 plants m −2 at 0, 12, 24, and 36 kg N ha −1 , respectively (Table 5).…”

“…(C n is urea cost (US $ ha −1 ); C h is herbicide cost (US $ ha −1 ); C a is application cost (US $ ha −1 ); Y o is weed-free soybean yield (Mg ha −1 ); P is value per unit soybean (US $ Mg −1 ); L is a proportional loss per unit total density equivalent; H is herbicide efficacy (% weed control/100). Parameters C h , C a , and P were obtained from Song et al [22]. At a given nitrogen level, parameters Y o and L were calculated using the combined rectangular hyperbolic model and parameter estimates described in Table 4.…”

“…Field experiments were conducted in 2013 and 2014 to evaluate the effects of N fertilizer and multiple-weed interference on soybean yield in Bogatyrka, Primorsky krai, Russia (43.82 • N, 131.6 • E). The respective mean daily temperature and total rainfall during the growing season (May to October) were 16.7 • C and 557.1 mm in 2013 and 15.3 • C and 408.5 mm in 2014, respectively [8,22]. The soil in this region had a silty-loam texture with a cation exchange capacity of 22.6 cmol kg −1 , organic matter content of 29.6 g kg −1 , total N concentration of 1.58 g kg −1 , available phosphorus (P) concentration of 18.2 mg kg −1 , and a pH of 6.6 [8,22].…”

“…The respective mean daily temperature and total rainfall during the growing season (May to October) were 16.7 • C and 557.1 mm in 2013 and 15.3 • C and 408.5 mm in 2014, respectively [8,22]. The soil in this region had a silty-loam texture with a cation exchange capacity of 22.6 cmol kg −1 , organic matter content of 29.6 g kg −1 , total N concentration of 1.58 g kg −1 , available phosphorus (P) concentration of 18.2 mg kg −1 , and a pH of 6.6 [8,22]. N fertilizer was applied in the form of urea (CO(NH 2 ) 2 ) at 0, 12, 24, and 36 kg N ha −1 on 27 May 2013 and 22 May 2014.…”