Agronomy Journal最新文献

Subsurface drainage is an important agricultural practice that has been widely utilized in the US Midwest to improve the productivity of poorly drained soils. Although widely adopted, long-term yield benefits of drainage, particularly with varying spacings, in an ever-changing climate are largely unknown. The goals of this study were to assess how various drainage spacings (5, 10, and 20 m) impacted crop yields compared to the undrained control in a long-term trial (started in 1984) in southeastern Indiana and how these effects were influenced by the amount of rainfall of specific periods of the growing season. Drainage treatments led to an increase in corn (Zea mays) yields (by 12%–17%) but did not significantly affect soybean (Glycine max) yields compared to the control. In the initial 10 years of the experiment, drainage benefits were subtle and corn yields did not vary significantly across spacing treatments, whereas in the most recent 10 corn years, the drainage treatment effects became more pronounced, likely due to the combined effects of long-term drainage system and conservation practices of no-till and cover crops. Over 37 years, corn yields remained stagnant in the undrained plots but progressively increased in the drained treatments. Both corn and soybean yields showed a negative correlation with rainfall 14 days post-planting, while drainage spacing treatments partially mitigated this negative effect. Our findings underscore the importance of effective drainage as a necessary prerequisite for realizing the potential benefits of conservation practices and improved crop genetics for increased crop productivity.

Integrated forage–row cropping systems provide important agronomic and economic benefits to producers. However, little attention has been given to incorporating forages into row crop systems unique to the southeastern United States. This study assessed the viability of intercropping cotton (Gossypium hirsutum L.) on perennial, cool-season legumes during the summer months in the Southeast Coastal Plain over two production years. Treatments included a weedy fallow, annual ryegrass (ARG; Lolium multiflorum Lam.) monoculture, a red clover (RC; Trifolium pratense L.) and white clover (WC; Trifolium repens L.) mixture, and a three-species mixture of ARG, RC, and WC. Plots were established in fall 2020 with forage grown until May 2021 and 2022, when plots were strip-tilled and planted with cotton. Cotton was managed with minimal herbicide use to preserve perennial clovers. Results indicated WC was more persistent than RC (>40 plants m⁻² vs. <40 plants m⁻²), and the presence of perennial clovers suppressed weeds at similar levels to the ARG monoculture (35 weeds m⁻²) during the second spring. Perennial clovers grew taller (4–5 cm) when mixed with ARG. The presence of clovers mixed with ARG during the second spring reduced acid detergent fiber (ADF) concentration and increased crude protein (CP) concentration (280 g ADF kg⁻¹; 167 g CP kg⁻¹) compared to the ARG monoculture (315 g ADF kg⁻¹; 126 g CP kg⁻¹). Benefits of intercropping perennial forages with cotton were maximized during the second year of growth, but future work is necessary to improve stand survival.

Intercropping is gaining interest from Western Canadian producers who are looking for information on how to incorporate intercrops into their production systems. This review summarizes agronomic research on intercropping from the last 40 years in Western Canada and discusses the potential challenges of integrating intercropping into existing crop rotations while identifying challenges and possible solutions. Reviewed literature indicates that several intercrop combinations have been tested in small plots involving up to four crops simultaneously grown, with over 60% comprising pulse–oilseed combinations followed by pulse–cereal combinations at ∼30%. The land equivalent ratio (LER) for pulse–oilseed and pulse–cereal averaged 1.11 and 1.13, respectively. Key agronomic factors that influenced LER in different intercrop combinations have been summarized, and the relationship of N and seeding rate with crop grain LER and partial land equivalent ratio has been assessed. While the relationship between N rate and LER was unclear in pulse–oilseed combinations such as pea (Pisum sativum L.)–canola (Brassica napus L.), LER decreased linearly with increasing N rate (p < 0.004) in pea–barley (Hordeum vulgare L.) intercrop. We highlighted that incorporating intercrops into current rotations will decrease crop rotation lengths with possible implications for disease management. There are many logistical challenges to intercropping but new technology may help producers to adapt.

Cannabinoid hemp is a dioecious crop where pistillate plants are selectively grown to maximize cannabinoid yields. Errant pollination can reduce pistillate flower yields, cannabinoid concentrations, and lead to unmarketable flowers due to the presence of undesirable seeds. We compared pollen sensitivity and agronomic performance of diploid (2n = 2x = 20 chromosomes) and triploid (2n = 3x = 30 chromosomes) cannabinoid hemp in open-field conditions. The high-CBD variety Lifter and high-CBG variety White CBG were evaluated in both their diploid and triploid counterparts in fields with and without pollen. Trials were conducted during the 2021 and 2022 field seasons in Kentucky, New York, and North Carolina (n = 6 site years). Triploids produced taller and wider plants than diploids; however, this did not result in yield differences in the pollen-free environment. In the presence of pollen, triploid Lifter and White CBG produced 87% and 77% fewer seeds than their diploid counterparts, respectively. Increased seed production in diploids also resulted in a significant reduction of seed-free biomass and cannabinoid concentrations compared to triploids. In the absence of pollen, we did not find any appreciable differences in seed-free biomass or cannabinoid concentrations between triploids and diploids. Though not completely pollen-insensitive, triploidy is an effective means to reduce seed production and improve yields and quality in cannabinoid hemp in the presence of pollen.

The herbicidal activity of the fermentation broth, filtrate, and extracts of Bacillus altitudinis D30202 was evaluated against seed germination and seedling growth of wild oat (Avena fatua L.). The bacterial culture filtrate exhibited greater inhibition of the wild oat weed than the fermentation broth. The filtrate was also extracted with organic solvents. The herbicidal potency of the extracts on the growth of wild oat plants was as follows: chloroform (100% inhibition of germination) > n-butanol (93.8%) > ethyl acetate (66.7%) > petroleum ether (6.3%) > aqueous phase (2.1%); so the chloroform extract was evaluated further. It inhibited wild oat radicle growth by 100%, and plumule growth by 97.9%, while spraying young plants with a 5 mg/mL extract caused severe desiccation of the leaves, stalk wilting, and plant death. IC₅₀ values for inhibition of plumule and radicle growth and germination were 0.64–0.72 mg/mL. Scanning electron microscopy and transmission electron microscopy revealed changes in the microstructure of the leaves and root tips, and degradation of organelles following chloroform extract treatment. The 5 mg/mL extract had no adverse impact on the growth or health of highland barley (Hordeum vulgare L.), corn (Zea mays), and broad bean (Vicia faba L.), indicating that this novel bioherbicide is suitable for control of wild oat weeds in the production of these food crops (while having a minor impact on the health of pea plants and being phytotoxic to wheat plants).

Sugar beet (Beta vulgaris L.) accounts for 55% of the total sugar production in the United States. Optimizing fertilizer nitrogen (N) management is pivotal for its economical and sustainable production and is challenging. Three-year field experiments (2020–2022) were conducted in western Nebraska to evaluate the effects of fertilizer N rates on beet root yield, sugar concentration, sugar loss to molasses (SLM), estimated recoverable sugar (ERS), and nitrogen use efficiency (NUE). Treatments included 0%, 50%, 80%, 100%, and 125% of recommended N based on the current University of Nebraska-Lincoln recommendation. Fertilizer application increased the root yield, ERS, and SLM but decreased sugar concentration in most cases compared to the control treatment. Beet NUE decreased with increasing total available N. Linear-plateau regression models fitted to root yield and ERS response curves showed that the agronomic optimum N rates (AONRs) were 179 and 166 kg N ha⁻¹ for root yield of 68.86 Mg ha⁻¹ and ERS of 11.95 Mg ha⁻¹, respectively. The findings showed that the root yield-based model required 35% less N rate than the current UNL beet N algorithm, and the ERS-based model required 13 kg N ha⁻¹ less N rate than the root yield-based model. Because of the trade-off effect of total available N on root yield and quality, the ERS-based N recommendation can be a potential strategy to optimize N management for economic and environmentally sustainable sugar beet production.

Thirty soybean [Glycine max (L.) Merr.] genotypes, along with three checks, were evaluated over three seasons across five communes in Benin. The experiments were laid out in an alpha lattice design with three replicates. Additive multiplicative mean interaction (AMMI) and best linear unbiased predictor (BLUP) analysis were combined to assess differential agronomic performance and yield stability among genotypes. There was significant variation (p < 0.001) between genotypes for all traits, with highly significant environmental and genotype × environment interaction (GEI) effects on soybean grain yield (p < 0.001). The likelihood ratio test indicated that both genotype and interaction effects were highly significant (p < 0.001). The low R² (0.21) for GEI reflected the presence of high residual variation in the GEI component, in contrast to the AMMI analysis of variance, which explained a high proportion of the GEI through the first two interaction principal component axes (52%). The very high value of the predictive accuracy (0.89) confirmed the model's reliability in selecting superior genotypes. The low (0.33) genotypic correlation between environments indicated that it was difficult to select superior genotypes for each environment. Based on the superiority index (weighted average absolute scores from BLUP for yield) of BLUP, simultaneous selection led to the identification of Jenguma 2.67 ± 0.06 t ha⁻¹ as the most stable and productive genotype across environments, followed by Favour 2.34 ± 0.08 t ha⁻¹, and Afayak 2.46 ± 0.08 t ha⁻¹. The agronomic performance of soybean in this study suggested great potential for diversifying cotton-based cropping systems in Benin, thereby improving their sustainability. The effect of these soybean genotypes on the productivity of intercrop combinations and sequences of cash crops, such as cotton, is yet to be investigated.

The perennial rhizomatous weed Cirsium arvense (L.) Scop. is difficult to manage on semiarid organic farms. Our objective was to quantify the impact of eight 4-year crop sequences crossed with standard- and reduced-tillage on C. arvense occurrence (presence/absence), stem density, and aboveground biomass at two semiarid sites in Montana. The sequences represented a range of crop competition from high (multiple years of perennial forage [alfalfa, Medicago sativa L.]) to low (2 years of continuous fallow), with intermediate sequences consisting of different annual species. Final-year spring wheat (Triticum aestivum L. emend. Thell.) was planted in all sequences to determine impacts on subsequent cash crop production. Through time, alfalfa and double fallow sequences reduced C. arvense density and biomass where it was established, although its invasion into new areas increased in the double fallow. Final-year C. arvense occurrence and stem density were lower in the alfalfa sequence compared with six and four annual crop sequences, respectively (p < 0.05). Final year C. arvense biomass was higher at one site than the other, although not in the double fallow sequence. Wheat grain yields differed in response to crop sequences at the two sites: at one site, grain yield was lowest in the alfalfa sequence, especially when standard-tillage was used, while yields were highest in the alfalfa and double fallow sequences at the other site. Using perennial forages in semiarid organic systems can be effective for managing C. arvense, but subsequent cash crop yield may be depressed.

Irrigation termination timing is challenging for cotton producers in humid regions, especially for fields with varying soil types. A field experiment was conducted in Jackson, TN, to investigate the best cotton irrigation termination on different soil types. The water management treatments consisted of rainfed conditions (RF) and terminating irrigation 2 weeks before the first crack boll (ITBC1 and ITBC2), at the first crack boll (ITC1 and ITC2), and 2 weeks after the first cracked boll (ITAC1 and ITAC2). The irrigation rates consisted of normal irrigation (2) and increased irrigation (1) during the 2 weeks prior to irrigation termination. Irrigation treatments were implemented on three soils: a low, an intermediate, and a high available water-holding capacity (AWHC) soil. In sandy soil, seed yield increased by 127% in 2015 with the ITAC1 treatment and by 313% in 2016 with the ITC1 treatment, compared to the control (RF). These treatments were also found to be optimal for lint yield and irrigation water productivity in their respective years. The high AWHC soil did not require any irrigation in either growing season to optimize yield. In fact, irrigating at a high rate at every termination date caused yield loss in 2015. These results indicate that cotton can benefit from later termination and higher irrigation rates when soil water and rainfall are low at the end of the growing season or be harmed when the opposite is true.

Planting date and seeding rate affect the microclimate within a crop field. They can influence lepidopteran insect infestation and fungal infections and are an important part of crop management strategy. Altering planting date and seeding rate can also influence yield and quality of silage corn (Zea mays L.). Field research was conducted to identify optimum planting time and seeding rate to minimize insect feeding, ear rot infections, and mycotoxin accumulation in silage corn without compromising yield and quality. Replicated field trials were conducted across multiple site-years in Michigan with three planting dates (early: April 25–May 10; mid: May 11–25; and late: May 26–June 10) and/or four seeding rates (ranging from 69,160 to 113,620 seeds ha⁻¹, in increments of 14,800 seeds ha⁻¹). Mid-planting yielded 12%–15% less forage than early and late plantings, partly due to greater insect feeding injury and fungal infections observed in the former. Neutral detergent fiber digestibility, starch, and crude protein concentration were greatest for early planting. Greater predicted milk per hectare and milk per megagram for early planting also indicated superior silage quality. Increasing seeding rate increased insect feeding and ear rot injury only when severity was >5% and >15%, respectively. The impact of increasing seeding rate on dry forage yield was specific to each site-year. Overall, results showed that early planting of silage corn helps to escape insect and disease pressure and provides better yield and quality, while seeding rate response is variable and dependent on the field environment.