Differences In Soybean Yield Research Articles

Effects of Replacing Chemical Nitrogen Fertilizer with Organic Fertilizer on Active Organic Carbon Fractions, Enzyme Activities, and Crop Yield in Yellow Soil

Taking the typical yellow soil in Guizhou as the research object, four treatments were set up： no fertilization （CK）, single application of chemical fertilizer （NP）, 50% organic fertilizer instead of chemical nitrogen fertilizer [1/2（NPM）], and 100% organic fertilizer instead of chemical nitrogen fertilizer （M）. The effects of organic fertilizer instead of chemical nitrogen fertilizer on organic carbon and its active components, soil carbon pool management index, soil enzyme activity, and maize and soybean yield in yellow soil were studied in order to provide theoretical basis for scientific fertilization and soil quality improvement in this area. The results showed that the replacement of chemical nitrogen fertilizer by organic fertilizer significantly increased soil pH, organic carbon （SOC）, total nitrogen （TN） content, and C/N ratio. Compared with those in the CK and NP treatments, the content and distribution ratio of soil active organic carbon components and soil carbon pool management index （CPMI） were improved by replacing chemical nitrogen fertilizer with organic fertilizer, and the effect of replacing chemical nitrogen fertilizer with 50% organic fertilizer was the best. Compared with those in the NP treatment, the 1/2 （NPM） treatment significantly increased the contents of soil readily oxidizable organic carbon （ROC333, ROC167）, dissolved organic carbon （DOC）, and microbial biomass carbon （MBC） by 22.90%, 8.10%, 29.32%, and 23.22%, respectively. Compared with those under the CK and NP treatments, organic fertilizer instead of chemical nitrogen fertilizer increased soil enzyme activities. The activities of catalase, urease, sucrase, and phosphatase in the 1/2 （NPM） treatment were significantly increased by 21.89%, 8.24%, 34.91%, and 18.78%, respectively, compared with those in the NP treatment. Compared with that of the NP treatment, the maize yield of the 1/2 （NPM） and M treatments was significantly increased by 44.15% and 17.39%, respectively. There was no significant difference in soybean yield among different fertilization treatments. Correlation analysis showed that soil SOC was significantly positively correlated with ROC333, ROC167, ROC33, DOC, MBC, and soil active organic carbon components, and CPMI was significantly positively correlated with soil organic carbon and its active components （P<0.01）. Corn yield was significantly positively correlated with soil enzyme activity, CPMI, total organic carbon, and its active components （P<0.05）. Therefore, from the perspective of yield increase and soil fertility, 50% organic fertilizer instead of chemical nitrogen fertilizer was conducive to improving soil quality and soil fertility, which is the key fertilization technology to achieve a high yield of crops in the yellow soil area of Anshun, Guizhou.

Could regulated and sustained deficit irrigation be applied in temperate climates? A case study of soybean production under field conditions

A field experiment was conducted to study the effects of full (F), regulated (RDI), and sustained deficit irrigation (SDI) on yield (Y), evapotranspiration (ET), and water use efficiency (WUE) of drip irrigated soybean. The yield response factor (Ky) was calculated to express the effect of water stress on soybean yield. The water balancing approach was used to schedule irrigation. Daily water used for plants' evapotranspiration was calculated by multiplying reference evapotranspiration with crop coefficients. Irrigation started when readily available water in the soil layer of 0.4 m was completely depleted by plants. There were statistical differences in yield between F (4.60 t ha−1) and SDI (3.71 t ha−1) treatments, but not between F and RDI (4.44 t ha−1). The evapotranspiration rate varied between 439 and 535 mm under irrigation and between 193 and 306 mm under rainfed conditions. The WUE values were consistent with the yield of the treatments. The statistical difference in soybean yield between F and SDI strategies suggests that the SDI cannot be used in the region's soybean farming. As no water savings were recorded for the same level of soybean yield between F and RDI, it indicates that RDI is not beneficial under the temperate climate of the Vojvodina region. The yield response factors of 0.69 and 0.71 in 2022 and 2023, respectively, show that soybean is tolerant to water stress and could be grown in rainfed conditions in Vojvodina's temperate climate. However, to achieve high and consistent yields, irrigation is advised.

Effect of Rye cover crop on weed control, soybean (Glycine max L.) yield and profitability

Considerable variations in farm productivity were reported across soils and climates when winter cover crops (CC) were rotated with summer main cash crops. Hence, a three-year field study (2019-2021) was conducted on Dundee silt loam in a humid climate to assess soybean growth and yield, weed control, and profitability under no-till conditions in response to (i) no CC (NC), (ii) winter rye CC rolled when green, followed by soybean planting and desiccation by paraquat (GR) and iii) winter rye CC desiccated using paraquat and rolled followed by soybean planting (BR). No differences in phenological growth stages of soybean were observed among the treatments. Measured leaf area index was comparable among the treatments across the three seasons. The rate of rye CC biomass decay estimated eight weeks after planting (WAP) was much higher than at four WAP. In 2019, at eight WAP plant residue ranged from 29.3% under NC to 52.9% under GR, indicating the paraquat desiccated natural winter vegetation decays faster than the desiccated rye CC biomass. The weed biomass was 72% higher at eight WAP (0.29 Mg ha-1) than that of four WAP (0.17 Mg ha-1) and NC plots had higher weed biomass at both four WAP and eight WAP over CC plots. Field established soybean stand in the GR plots were consistently higher than the NC plots by 8%, 30%, and 22% in 2019, 2020, and 2021, respectively. Soybean yield in NC plot was 13% higher than GR and 15% higher than BR plots in 2019. However, in 2020 and 2021, soybean yield from BR and GR plots was significantly higher than NC plots (10% and 13%, respectively). In the three-year study, net returns from soybean with rye CC (regardless of GR or BR) in the first year was negative. In the second and third year, net returns in GR and BR were positive and comparable to NC. There were no differences in soybean yield and net returns between rye CC rolled green (GR) and rye CC desiccated (BR) prior to planting. These results show that a rye CC–based soybean conservation production system could be an economically a viable choice after the first year with an invaluable potential for carbon sequestration, weed suppression and positive impact on summer soybean productivity.

Long‐term reduced tillage and no‐till cropping systems affect crop yields and economics

AbstractThere has been increased implementation of conservation practices on highly erodible Missouri soils. The objectives were to evaluate the effects of long‐term no‐till and reduced tillage cropping systems on yields and economics of production systems. Research was initiated in 1994 near Novelty, MO. Treatments included a corn (Zea mays L.)–soybean [Glycine max (L.) Merr.]–wheat (Triticum aestivum L.) rotation with three tillage/cropping systems: (1) no‐till corn–soybean–wheat with double‐crop soybean (NT DCS), (2) no‐till corn–soybean–wheat with frost‐seeded red clover (Trifolium pratense L.) cover crop (NT FSC), and (3) reduced‐till corn–soybean–wheat (RT). Each crop and cropping system was represented each year in large plots (9.1 by 90 m). Significant differences in corn yields occurred in 1995–1996, 2000, 2009–2010, and 2015–2016 with the highest‐yielding treatments being five RT, one NT DCS, and one RT = NT DCS. Significant differences in soybean yield occurred in 3 yr with the highest‐yielding cropping system being NT DCS twice and RT once. Significant differences in wheat yield occurred in 4 yr with RT yielding the highest each time. Input costs were greatest in RT and NT DCS, while net income was greatest in NT DCS, which produces four cash crops in 3 yr. Highest net returns occurred in NT DCS, which was US$135 and 145 ha–1 greater than NT FSC and RT, respectively. The productivity and economics of systems need to be balanced with ecosystem benefits of NT. In this corn–soybean–wheat rotation, hybrid cropping systems including RT corn and wheat, followed by NT DCS, and NT soybean is recommended.

Effects of long-term tillage systems on soil physical quality and crop yield in a Brazilian Ferralsol

Long-term soil tillage trials can provide important knowledge about sustainable changes in soil physical quality and crop yield. This study evaluated soil physical quality indicators under different long-term tillage systems and examined the relationships between quality indicators and crop yield. The study was carried out on a Rhodic Ferralsol with three tillage systems established in 1989: conventional tillage (CT), strategic tillage (ST), and no-tillage (NT). All treatments had long-term crop rotation. The soil parameters evaluated were total organic carbon (TOC), bulk density (ρs), macro and microporosity (Mac and Mic), relative gas diffusivity (D/D0), pore tortuosity (τ), relative field capacity (RFC), structural stability index (SSI), least-limiting water range (LLWR), and degree of compactness (DC, taking as reference the soil bulk density in which LLWR = 0). Soybean and maize yields in two consecutive summer seasons were measured. Conventional and strategic tillage provided higher ρs in the 0.15–0.30 m layer depth, leading to higher DC in CT. Using soil bulk density at LLWR = 0 as reference proved useful to assess soil DC and plant response. No-tillage provided lower DC in the 0–0.15 m (86 %) and 0.15–0.30 m (78 %) layers than CT (91 % and 94 %, respectively). The maize yield had a negative linear relationship to DC, with the lower values at DC > 87 %. All tillage systems affected D/D0, even at similar porosity values. The better soil physical quality under NT provided 1211 kg ha−1 higher maize yield compared with CT. The differences in soybean yield between treatments were not significant, but NT provided 381 kg ha−1 more than CT. These findings indicate that NT is the best system studied. Our results strongly suggest that ST does not improve physical properties of soils under NT with crop rotation, and that a diversified crop rotation in NT was efficient to avoid soil physical degradation.

Influence of Glyphosate/Dicamba Application Rate and Timing on the Control of Glyphosate-Resistant Horseweed in Glyphosate/Dicamba-Resistant Soybean

AbstractDicamba may be an efficacious option for the control of glyphosate-resistant (GR) horseweed in glyphosate/dicamba-resistant soybean; research is needed to optimize the application rate based on horseweed height at the time of application. The purpose of this study was to determine the effect of glyphosate/dicamba rate and application timing for the control of GR horseweed. Glyphosate/dicamba was applied at three rates (900, 1,350, and 1,800 g ae ha−1) at three horseweed application timings (5, 15, and 25 cm) in a factorial design. There was no interaction between glyphosate/dicamba rate and timing for GR horseweed control or soybean yield; however, there was an interaction for GR horseweed density and biomass. At 2 and 4 wk after application (WAA), there was a decrease in GR horseweed control as the height at the time application increased. At 4 WAA, the application of glyphosate/dicamba to GR horseweed that was 5-, 15-, and 25-cm tall provided 87%, 76%, and 62% control, respectively. There was no impact of glyphosate/dicamba application timing on soybean yield. At 2, 4, and 8 WAA, there was an increase in GR horseweed control as the rate of glyphosate/dicamba was increased. At 8 WAA, glyphosate/dicamba applied at 900, 1,350, and 1,800 g ae ha−1controlled GR horseweed 76%, 87%, and 92%, respectively. Earlier application timings and higher rates of glyphosate/dicamba caused the greatest reduction in GR horseweed density and biomass. Reduced GR horseweed competition resulted in a 100% to 144% increase in soybean yield, but there was no difference in soybean yield among glyphosate/dicamba rates tested.

Soybean Cyst Nematode Control with Pasteuria nishizawae Under Different Management Practices

Core Ideas We did not observe any significant differences in soybean yield, or soybean cyst nematode reproductive factor between the Clariva Complete treated soybean and the Cruiser Maxx Vibrance‐treated soybean. Row spacing and seeding rate alone, both significantly impacted soybean yield. Seeding rate significantly affected the soybean cyst nematode reproductive factor, but this was not consistent over the years of the study. The manipulation of row spacing and seeding rate resulted in greater differences in soybean yield and soybean cyst nematode reproduction than the biological control seed treatment. Soybean cyst nematodes (SCN, Heterodera glycines Ichinohe) are one of the most devastating pathogens of soybean [Glycine max (L.) Merr.], causing more than US$1.5 billion in yield losses annually. The current control measures of crop rotation and genetic resistance are not sufficient to manage SCN population densities. In this study, we evaluated the efficacy of a bacterial biological control agent of SCN, called Pasteuria nishizawae, found in the Clariva Complete seed treatment (Syngenta, Syngenta Headquarters, Wilmington, DE) and its interaction with row spacing and seeding rate against Cruiser Maxx Vibrance. We evaluated these seed treatments at three seeding rates (185,250, 370,500 and 555,750 seeds ha−1) and two row spacings (38 and 76 cm) to determine the effect of the biocontrol component on soybean yield and SCN reproduction and its interaction with management practices. We observed similar soybean yield and SCN reproductive factors for soybean treated with either the Clariva Complete or Cruiser Maxx Vibrance seed treatment (Syngenta, Syngenta Headquarters, Wilmington, DE). In 2014 and 2015, soybean yield increased with each increase in seeding rate and decrease in row spacing. The SCN reproductive factor response was variable among factors. Based on our findings the most economically advantageous combination of seed treatment, row spacing, and seeding rate was Cruiser Maxx Vibrance planted in 38 cm rows and 185,250 seeds ha−1. Overall, the manipulation of row spacing and seeding rate resulted in more significant differences in soybean yield and SCN reproduction than the biological control seed treatment and should be considered when planting into fields infested with SCN.

Effect of integrated nutrient and agronomic management on growth, productivity, nutrient uptake and soil residual fertility status of soybean

A field experiment on soybean was conducted at the regional research farm of the Punjab Agricultural University, Naraingarh (Distt. Fateh Garh Sahib) for three years under irrigated conditions for productivity enhancement through integrated nutrient and other agronomic interventions. There were twelve treatments comprising different levels of N, P, K, FYM and agronomic management practices. The results revealed that soybean significantly responded to the application of N, P, K and FYM. Maximum yield was recorded in the treatment where FYM was applied with NPK and resulted in an increase of 10.8 per cent over NPK alone. Application of additional 30 kg N ha-1 at pre-flowering or at pod initiation did not significantly enhance the yield over the basal dose of NP applied at sowing. Application of 4 tonnes wheat straw mulch + 30 kg N +60 kg P2O5 and 30 kg N + 60 kg P2O5 ha-1 showed similar effect on seed yield of soybean. No statistical difference in soybean yield was observed in the conventional flat and bed sowing treatments. Pre-emergence application of pendimethaline @ 1.5 l ha-1 along with one hand weeding at 40 days after sowing (DAS) and two hand weeding at 20 and 40 DAS were equally effective for weed control and in influencing the soybean yield. The application of N, P, K and FYM, in different treatments, treatment with Bradyrhizobium japonicum and sowing on beds all significantly improved the N, P and K uptake by soybean over control. Application of FYM to soybean resulted in maximum nutrient uptake by soybean. After three years a significant improvement in soil organic carbon, available N, P and K was observed in all treatments over control.

Evaluation of Herbicide Programs for Use in a 2,4-D–Resistant Soybean Technology for Control of Glyphosate-Resistant Palmer Amaranth (Amaranthus palmeri)

Two separate field experiments were conducted over a 2-yr period in Fayetteville, AR, during 2012 and 2013 to (1) evaluate POST herbicide programs utilizing a premixture of dimethylamine (DMA) salt of glyphosate + choline salt of 2,4-D in a soybean line resistant to 2,4-D, glyphosate, and glufosinate and (2) determine efficacy of herbicide programs that begin with PRE residual herbicides followed by POST applications of 2,4-D choline + glyphosate DMA on glyphosate-resistant Palmer amaranth. In the first experiment, POST applications alone that incorporated the use of residual herbicides with the glyphosate + 2,4-D premixture provided 93 to 99% control of Palmer amaranth at the end of the season. In the second experiment, the use of flumioxazin, flumioxazin + chlorimuron methyl, S-metolachlor + fomesafen, or sulfentrazone + chloransulam applied PRE provided 94 to 98% early-season Palmer amaranth control. Early-season control helped maintain a high level of Palmer amaranth control throughout the growing season, in turn resulting in fewer reproductive Palmer amaranth plants present at soybean harvest compared to most other treatments. Although no differences in soybean yield were observed among treated plots, it was evident that herbicide programs should begin with PRE residual herbicides followed by POST applications of glyphosate + 2,4-D mixed with residual herbicides to minimize late-season escapes and reduce the likelihood of contributions to the soil seedbank. Dependent upon management decisions, the best stewardship of this technology will likely rely on the use multiple effective mechanisms of action incorporated into a fully integrated weed management system.

Productivity enhancement of soybean as influenced by integerated nutrient and other agronomic interventions in sub - humid Punjab, India

A field experiment was conducted for three years under irrigated conditions for productivity enhancement of soybean through integrated nutrient and other agronomic interventions. Application of N, P, K and FYM significantly enhanced the yield of soybean over control. Maximum yield was observed in the treatment where FYM was applied with NPK and resulted in an increase of 15.1 per cent over NPK alone. Application of additional 30 kg N ha-1 at pre-flowering or at pod initiation did not significantly enhance the yield over the basal dose of NP applied at sowing. Application of 4 tonnes wheat straw mulch + 30 kg N +60 kg P2O5 and 30 kg N + 60 kg P2O5 ha-1 showed similar effect on seed yield of soybean. No statistical difference in soybean yield was obtained in the conventional flat and bed sowing treatments. Pre-emergence application of pendimethaline @ 1.5 l ha -1 along with one hand weeding at 40 days after sowing (DAS) and two hand weeding at 20 and 40 DAS were equally effective for weed control and in influencing the soybean yield. The application of N, P, K, FYM, in different treatments, treatment with Bradyrhizobium japonicum and sowing on beds all significantly improved the N, P and K uptake by soybean over control. Application of FYM to soybean resulted in maximum enhancement of nutrient uptake by soybean. After three years a significant improvement in soil OC, available N, P and K was observed in all treatments over control.

Yield and dry matter productivity of Japanese and US soybean cultivars

The difference in yields of cultivars may be causing difference in soybean yield between Japan and the USA. The objective of this study was to identify the effect of the cultivar on dry matter production and to reveal the key factors causing the differences in yield by focusing utilization of solar radiation in recent Japanese and US soybean cultivars. Field experiments were conducted during two seasons in Takatsuki, Japan (34°50′), and in a single season in Fayetteville (36°04′), AR, USA. Five Japanese and 10 US cultivars were observed under near-optimal conditions in order to achieve yields as close to their physiological potential as possible. The seed yield and total aboveground dry matter (TDM) were measured at maturity as long as radiation was intercepted by the canopy. The seed yield ranged from 3.10t ha−1 to 5.91t ha−1. Throughout the three environments, the seed yield of US cultivars was significantly higher than that of Japanese cultivars. The seed yield correlated with the TDM rather than the HI with correlation coefficients from .519 to .928 for the TDM vs. .175 to .800 for the HI, for each of the three environments. The higher TDM of US cultivars was caused by a higher radiation use efficiency rather than higher total intercepted radiation throughout the three environments. The seasonal change in the TDM observed in four cultivars indicated that dry matter productivity was different between cultivars, specifically during the seed-filling period.

Residual herbicides in weed management for glyphosate-resistant soybean in Brazil

In agricultural production systems where the glyphosate-resistant soybean crop (Glycine max) is grown and the practice of crop rotation with alternative herbicides is not adopted, the exclusive and continuous use of glyphosate has led to the occurrence of resistant weed populations that may limit or compromise the benefits of this technology. Thus, the efficacy of weed management programs, including the use of residual herbicides (sulfentrazone, flumioxazin, imazethapyr, diclosulan, chlorimuron and s-metolachlor) applied in preemergence and followed by in-crop postemergence applications of glyphosate (PRE-POST) were compared to glyphosate postemergence only programs - POST. The study was conducted across nine locations during the 2009/2010 and 2010/2011 growing seasons. PRE-POST programs were efficient in the control of Amaranthus viridis, Brachiaria plantaginea, Bidens pilosa, Commelina benghalensis, Eleusine indica, Euphorbia heterophylla and Raphanus raphanistrum, with the level of control being similar when comparing the program with two applications of glyphosate POST. Some PRE-POST programs were not efficient in controlling Cenchrus echinatus, Ipomoea hederifolia and Ipomoea triloba. Sulfentrazone and diclosulam PRE-POST programs improved the control of Ipomoea triloba compared to sequential applications of glyphosate alone. No significant differences in soybean yield were observed between any of the herbicide treatments or study locations. The use of residual herbicides in preemergence followed by glyphosate in-crop postemergence provides consistent weed control and reducing early season weed competition. Furthermore, these programs utilize at least two herbicide modes of action for herbicide use diversity, which will be needed to stay ahead of resistance build-up, regardless of when weeds may appear.

Comparison of Herbicide Tactics to Minimize Species Shifts and Selection Pressure in Glyphosate-Resistant Soybean

There are significant concerns over the long- and short-term implications of continuous glyphosate use and potential problems associated with weed species shifts and the development of glyphosate-resistant weed species. Field research was conducted to determine the effect of herbicide treatment and application timing on weed control in glyphosate-resistant soybean. Ten herbicide treatments were evaluated that represented a range of PPI, PRE, and POST-only application timings. All herbicide treatments included a reduced rate of glyphosate applied POST. PRE herbicides with residual properties followed by (fb) glyphosate POST provides more effective control of broadleaf weed species than POST-only treatments. There was no difference in soybean yield between PRE fb POST and POST-only treatments in 2008. Conversely, PRE fb POST herbicide treatments resulted in greater yield than POST-only treatments in 2009. Using PRE fb POST herbicide tactics improves weed control and reduces the risk for crop yield loss when dealing with both early- and late-emerging annual broadleaf weed species across variable cropping environments.

Introduction of cover crops in a maize–soybean rotation of the Humid Pampas: Effect on nitrogen and water dynamics

The agricultural system of the Humid Pampas consists of continuous cropping of soybean and maize under no tillage. This system may loose nitrogen (N) through leaching during the early and final stages of summer crops and during fallow. In this study (2005–2011) we evaluated the effect of fall–winter species (rescue grass, ryegrass, oats, barley, vetch, rape seed and forage radish) and a mixture of vetch and oats used as cover crops on water and N dynamics and main crop yield. Above-ground biomass production and N uptake by cover crops ranged from 1.1 to 11.9Mgha−1 and from 17 to 223kgNha−1, respectively, depending on sowing and killing dates and on the preceding crop. At killing, soil nitrate content in treatments with cover crops was 50–90% lower than in the control, reducing spring N leaching risk. When preceding maize, cover crops were killed in winter or early spring and their low C/N ratio (12–38) favored N release through residue decomposition. Vetch and rape seed as predecessors of fertilized maize increased residual N by ≈50kgNO3-N compared to the control, posing the risk of fall N leaching. When preceding soybean, cover crops were killed in spring and, although their C/N ratios were higher (13–85), crucifers and legumes increased soil nitrate content. Maize yield was related to soil N availability at sowing (control and legumes>crucifers>grasses) which was inversely related to the preceding cover crop C/N ratio at killing. In normal to high rainfall years there were no differences in soybean yield among treatments. Water use by cover crops did not affect the main crop production except during an exceptionally dry year. Best synchronicity between N release from cover crop residues and harvest crop demand was achieved with the oats–vetch mixture before maize and with grasses before soybean.

Rolled Rye Mulch for Weed Suppression in Organic No-Tillage Soybeans

Rising demand for organic soybeans and high price premiums for organic products have stimulated producer interest in organic soybean production. However, organic soybean producers and those making the transition to organic production cite weed management as their main limitation. Current weed management practices heavily rely on cultivation. Repeated cultivation is expensive and has negative consequences on soil health. Research is needed to improve organic reduced tillage production. Rye cover crop mulches were evaluated for weed suppression abilities and effects on soybean yield. Experiments were planted in 2008 and 2009 at three sites. Rye was planted in the fall of each year and killed at soybean planting with a roller/crimper or flail mower, creating a thick weed-suppressing mulch with potential allelopathic properties. The mulch was augmented with one of three additional weed control tactics: preemergence (PRE) corn gluten meal (CGM), postemergence (POST) clove oil, or postemergence high-residue cultivation. Roll-crimped and flail-mowed treatments had similar weed suppression abilities at most sites. There were no differences between CGM, clove oil, or cultivation at most sites. Sites with rye biomass above 9,000 kg ha−1of dry matter provided weed control that precluded soybean yield loss from competition. In Goldsboro 2008, where rye biomass was 10,854 kg ha−1of dry matter, the soybean yield in the rolled rye treatment was not significantly different from the weed-free treatment, yielding at 2,190 and 2,143 kg ha−1, respectively. Likewise, no difference in soybean yield was found in Plymouth 2008 with a rye biomass of 9,256 kg ha−1and yields of 2,694 kg ha−1and 2,809 kg ha−1in the rolled rye and weed-free treatments, respectively. At low rye biomass levels (4,450 to 6,606 kg ha−1), the rolled rye treatment soybean yield was 628 to 822 kg ha−1less than the weed-free treatment. High rye biomass levels are critical to the success of this production system. However, high rye biomass was, in some cases, also correlated with soybean lodging severe enough to cause concern with this system.

No-till, no-herbicide forage soybean (Glycine max (L.) Merrill) cropping system with an Italian ryegrass (Lolium multiflorum Lam.) living mulch

We conducted a field experiment to identify appropriate agronomic practices for a no-herbicide cropping system for the production of forage soybean (Glycine max (L.) Merrill) in northern Japan. We sowed a winter habit Italian ryegrass (Lolium multiflorum Lam. ‘Ace’) in the early spring and then soybeans using a no-till planter after harvesting the first crop of Italian ryegrass in June. Italian ryegrass then served as a living mulch for the soybean crop. Soybeans were harvested in October along with the Italian ryegrass dead aboveground biomass. We tested this cultivation method using different Italian ryegrass seeding rates, and replicated the experiment in two consecutive years and in two fields with different levels of weed pressure. Italian ryegrass yield tended to increase with increasing seeding rate. Few weeds remained in the plots in which Italian ryegrass was sown at a rate of 50 kg ha−1 and greater, and there was no significant difference in soybean yield between those plots and plots in which herbicide was used. Soybean yield in the plots where Italian ryegrass was sown at 20 kg ha−1 was no different from that at higher sowing rates in the field with medium weed pressure, but was significantly lower in the field with high weed pressure. We conclude that cropping with an Italian ryegrass living mulch is an effective system for producing forage soybean without herbicide, but to ensure sufficient weed suppression for adequate production of soybean forage, sowing rates of Italian ryegrass should be at least 50 kg ha−1.

Soybean yield and resource conservation field borders

The ecological and environmental shortcomings of landscapes dominated by monocultures of crops have led to increased pressure to farm in a more holistic, environmentally sound, socially acceptable manner. The USDA Continuous Conservation Reserve Program (CCRP) is one answer to this shift in philosophy. One program within CCRP, CP33, habitat buffers for upland birds, was designed to provide incentives for substituting herbaceous buffers for crop field margins to promote wildlife habitat. Farmers have been slow to sign up for CP33, possibly out of concern for the borders’ impact on insect pest abundance, crop yield and profitability. We examined the impact of three herbaceous border compositions on yield in soybean over 3 years. The border treatments were: (1) a cool-season grass/legume mixture, (2) a warm-season grass/legume mixture, and (3) tall fescue. In addition, the experimental control (soybean border) provided the opportunity to examine the effect of hedgerows on crop yield. We found only a few differences in soybean yield among border treatments and discerned no specific cause-and-effect relationship between buffers and soybean yield, or among distances into the soybean fields from the crop–border interface. We conclude that herbaceous conservation buffers would have little or no impact on soybean yield and should be promoted for their positive environmental benefits.

Effects of Tillage Practices on Dissemination and Spatial Patterns of Heterodera glycines and Soybean Yield.

Two field experiments were conducted in central Iowa to assess the effects of tillage on Heterodera glycines dissemination and reproduction and soybean (Glycine max) yield. Plots in both experiments were artificially infested with equivalent numbers of H. glycines cysts. In one experiment, plots were left noninfested or received aggregated or uniform infestation, and a susceptible soybean cultivar was grown for 3 years. By the end of the first growing season and through the second, H. glycines population densities were consistently greater (P ≤ 0.05) in uniformly infested plots than in plots with aggregated infestations. No differences in soybean yield among the treatments were detected. In a second experiment, a 1-m2 area of each plot was infested with H. glycines cysts, susceptible soybeans were grown for four seasons, and crop residue was managed with either ridge-, conventional-, reduced-, or no-tillage. After 1 year, nematode population densities were significantly (P ≤ 0.05) greater in conventional- and reduced-tillage treatments than in no- and ridge-tillage treatments. After 2 years, H. glycines had been disseminated 6.9 m from the infestation site in conventional- and reduced-tillage treatments but only 0.5 and 1.4 m for no-tillage and ridge-tillage treatments, respectively. After 3 years, H. glycines population densities were 10 times greater in conventional- and reduced-tillage treatments than in the no-tillage treatment; conventional-tillage was the only treatment with yield significantly lower (P ≤ 0.05) than the noninfested control. Aggregation of H. glycines eggs was greater (P ≤ 0.05) in no- and ridge-tillage treatments than in conventional- and reduced-tillage treatments. Results indicate tillage can quickly disseminate H. glycines in newly infested fields, facilitating more rapid nematode reproduction and subsequent yield loss.

Banded herbicide, rotary hoeing and cultivation effects on weed populations in ridge-tilled soybean

Can banded herbicide be eliminated in ridge-tilled soybean (Glycine max)? The effects of banded herbicide, rotary hoeing and cultivation on weed populations and soybean yield in a ridge-tillage system were tested on three farms in Iowa, USA in 1989 and 1990. In 1989, plots either had no herbicide or had herbicide banded in the row at planting in mid-May; all plots received two rotary hoeings and two cultivations. In 1990, treatments were banded herbicide with no rotary hoeing, banded herbicide with one rotary hoeing, and no herbicide with one or two rotary hoeings; all plots received two or three cultivations. In both years, over all weed species [primarily giant foxtail (Setaria faberi), Pennsylvania smartweed (Polygonum pensylvanicum) and redroot pigweed (Amaranthus retroflexus)], seedling emergence was highest in late May and early June, with few seedlings emerging after mid-June. Weed populations were highest in May and June, after which rotary hoeing and cultivation reduced weed numbers in all plots. There were no consistent differences among treatments in weed numbers in early August for the 2 years. In both years, there was no significant difference in soybean yield among treatments. Within-farm mean yields ranged from 2.26 to 3.01 Mg ha−1among farms in 1989 and from 2.07 to 2.93 Mg ha−1among farms in 1990. Ridge-tillage without herbicide was generally equivalent to ridge-tillage with banded herbicide, with respect to total number of weeds and number of broad-leaved weeds remaining in August after tillage, and to soybean yield.

Is the application of a residual herbicide required prior to glyphosate application in no-till glyphosate-tolerant soybean ( Glycine max)?

In no-till glyphosate-tolerant soybean multiple applications of glyphosate may be required to maintain weed control throughout the season. Another approach that may improve weed control and aid in the stewardship of glyphosate use is to apply a pre-emergence residual herbicide such as flufenacet plus metribuzin prior to a single in-crop application of glyphosate. There is limited information on the optimal glyphosate application timing in glyphosate-tolerant soybeans ( Glycine max) following the application of a residual herbicide such as flufenacet plus metribuzin. Field trials using factorial designs were conducted at three Ontario locations, in 1999 and 2000 to evaluate the efficacy of flufenacet plus metribuzin applied pre-plant or pre-emergence followed by a post-emergence application of glyphosate in glyphosate-tolerant soybean. Crop tolerance was acceptable for all treatments (flufenacet plus metribuzin, glyphosate and flufenacet plus metribuzin followed by glyphosate). Control of Echinochloa crus-galli and Setaria viridis was excellent using glyphosate and thus soil-applied applications of flufenacet plus metribuzin did not improve control. Control of Chenopodium album, Ambrosia artemisiifolia and Abutilon theophrasti with flufenacet plus metribuzin was poor at all application timings whereas a post-emergence application of glyphosate provided excellent annual broadleaved weed control. There was no difference in soybean yield among the three glyphosate timings evaluated. Overall, there was no benefit from the application of the residual herbicide applied prior to glyphosate.