An experiment was conducted at the Delta Research and Extension Center in Stoneville, MS during 2017 and 2018 to determine whether removal of the flood is an economical method of control for rice ...water weevil, Lissorhoptrus oryzophilus Kuschel. This experiment compared a continuous flood production system to draining a rice field completely and reestablishing a flood for the remainder of the growing season. In addition, two insecticide seed treatments, thiamethoxam and chlorantraniliprole, were compared with an untreated control within each system. Rice water weevil densities were measured prior to draining at 3 wk after flood and again after the flood was reestablished in drained plots. Rice water weevil densities were greater in 2017 than 2018. Chlorantraniliprole at the predrainage and postdrainage sample timing reduced larval numbers compared with the untreated control. The plots where water was removed until soil cracking then re-flooded had significantly lower weevil populations than plots that were continuously flooded during 2018 only. Draining of plots resulted in lower yields in 2018, but not in 2017. Additionally, both of the insecticide seed treatments resulted in greater yields and economic returns than the untreated control. Draining of flooded rice when rice water weevil larvae were present did not provide a consistent benefit, and may result in yield and economic penalties. Insecticide seed treatments consistently provided greater yield benefits in flooded rice. Based on these results, draining of flooded rice is not recommended to manage rice water weevil and insecticide seed treatments should be used to minimize economic losses.
Nutrient loading from conventional row‐crop production systems impairs surface waterbodies in the mid‐southern United States. This study was conducted to determine whether minimum tillage and winter ...cover crops can decrease nutrient loading in surface runoff from conventionally tilled row‐crop fields. The effects of winter cover crops and minimum tillage on N and P loading from a corn (Zea mays L.)–soybean Glycine max (L.) Merr. rotation system were investigated on production fields in northwestern Mississippi using a split‐field approach. As measured at the edge of the field, minimum tillage with cover crops had no effect on surface runoff from production fields regarding N or P loading (p > .10 for all nutrient loads), discharge (p > .10), or loss of suspended solids (p > .10). Minimum tillage and cover crops decreased sediment and nutrient concentrations in runoff for total N (p = .05) and total P (p = .09) but had no effect on other nutrients of interest. Although these practices decreased total N concentration by 36% in surface runoff to receiving waters, this reduction was only seen when aboveground cover crop biomass was present (p = .07). Regardless of the time of year, minimum tillage with cover crops decreased total P concentration in surface runoff by 27% (p = .09). These data indicate that it is unlikely that minimum tillage and cover crops will affect N and P loading while transitioning to a conservation production system in the mid‐southern United States.
Core Ideas
Cover crops and minimum tillage did not reduce nutrient loading or discharge in mid‐South corn–soybean rotations.
Cover crops and minimum tillage reduced total nitrogen concentrations when winter cover was present.
Cover crops and minimum tillage reduced total phosphorus concentration when cover was and was not present.
Liquid–liquid extraction or solid-phase extraction followed by gas chromatography (GC) or high-performance liquid chromatography are traditional herbicide residue determination methods for ...environmental samples. Solid-phase microextraction (SPME) is a solventless, fast, and sensitive alternative herbicide residue extraction method that can be applied to numerous environmental matrices. The objective of this paper was to review SPME literature regarding extraction theory, extraction modes, fiber types, and method optimization in conjunction with present and future SPME applications for herbicide determination in environmental samples.
Identifying management practices that conserve and protect water resources are very important to a wide variety of stakeholders within semiarid environments. The objective of this study was to ...develop water management strategies for transitioning tillage systems in cotton (Gossypium hirsutum L.) production within the Texas Rolling Plains when in a subsurface drip irrigation (SDI) system. Five irrigation regimes (0, 33, 66, 100, and 133% evapotranspiration ET replacement) and four tillage systems (conventional till, reduced till, no-till, and no-till with a terminated cover crop) were evaluated. The study was conducted for 3 yr and treatments were replicated three times in a randomized complete block design. Lint yields were not affected by the main effects of tillage or the interaction of tillage and ET replacement. In contrast ET replacement was a significant factor for lint yields, irrigation water use efficiency, and net returns. Greatest lint yields and net returns were achieved at 100% ET replacement. Fitted models indicated that optimum lint yields and net returns were achieved at 104.5% ET and 102% ET, respectively. Irrigation at 83% ET was within the 95% confidence interval for lint yield. Net returns were significantly higher for no-till systems compared with conventional till. Thus, adoption of conservation tillage systems should not negatively affect lint yield or net returns in deficit irrigated SDI cotton systems within the Texas Rolling Plains, particularly during the transition from intensively tilled systems to conservation tilled systems.
Field experiments were conducted in 2009 and 2010 in Louisiana and Mississippi to evaluate ammonia volatilization loss and subsequent effects on apparent nitrogen recovery efficiency (ANRE) and grain ...yield for rice (Oryza sativa L.). A semi-open static chamber approach was used to measure ammonia volatilization loss from multiple N sources applied 10 days before flood (dbf) at the rate of 168 kg N ha-1. Cumulative ammonia volatilization losses for urea for Louisiana environments were 19 and 33% compared to 7% for both Mississippi environments. Urea + N-(n-butyl) thiophosphoric triamide (NBPT), urea + NBPT + dicyandiamide (DCD), and ammonium sulfate (AS) all minimized volatilization losses over all environments (range of 1.9-4.9%). Additionally, ammonia volatilization data fitted to the Gompertz model demonstrated that urea + NBPT and urea + NBPT + DCD had longer lag phases (7.2-7.7 d) relative to urea, AS, and urea + ammonium sulfate (UAS) blend (3.6 d). The same N sources and rate of N was applied 10, 7, 4, and 1 dbf to determine the effects on ANRE and yield. Apparent N recovery efficiency ranged from 43 to 71%. Grain yield was influenced by application time for two environments. Nitrogen application 10 dbf resulted in the least grain yield and yields tended to increase with fewer days between application and permanent flood. In Louisiana, urea + NBPT and urea + NBPT + DCD resulted in yields greater than urea alone. Where volatilization potential is substantial, NBPT should be included with the urea application to protect yield potential.
Abstract
The agricultural production in the Mississippi Delta is threatened by the water level declines in the Mississippi River Valley Alluvial Aquifer (MRVAA). This study assesses the growers’ ...perceptions of the value and availability of water for irrigation based on data collected in a survey in 2012 in the Delta region of Mississippi, USA. The total cooperation rate for this survey was 79.3%. The results showed that 97.39% (448 out of 460) of respondents believed that water is important for farming in the Delta region of the MRVAA. Fifty‐two percent of the survey respondents agreed that the major cause of groundwater depletion is agricultural irrigation water use. More than 50% of the survey respondents believed there is sufficient water in the Delta region, but it is not managed properly. The value of water for irrigation ranged from $463 to $690 per ha for corn (
Zea mays
L.), $399 to $615 per ha for soybean (
Glycine max
L.), and $223 to $336 per ha for cotton (
Gossypium hirsutum
L.). The majority of the respondents considered that there is a need for regulation of water use to protect the aquifer and ensure water availability in the future.
Abstract
Water withdrawals for irrigation at an unsustainable rate resulted in a decline in the groundwater levels in the Mississippi River Valley Alluvial Aquifer (MRVAA) in the central southern ...USA. This drawdown of groundwater threatens agricultural production in the Mississippi Delta, an important agricultural region in the state of Mississippi, USA. Effective and efficient use of available resources is important to sustain and enhance agricultural productivity in this area. This study assessed the opinions of farmers on water conservation management practices and technologies that improve irrigation management and save water in the Mississippi Delta region based on data collected in an irrigation survey conducted in 2012. Most landowners believed that water conservation practices were effective in reducing irrigation water use without reducing maximum crop yields and have a positive return on investment. Land forming, tailwater recovery system, on‐farm storage, instream weirs to pond surface water, computerized hole selection for furrow irrigation, short irrigation runs, and irrigation scheduling were considered efficient water conservation technologies by landowners. Perceptions about use of different practices also depend upon the crops produced by the respondents. About 20 to 24% and 14.9 to 86% of survey respondents thought that on‐farm storage and center pivot, respectively, were inefficient water conservation practices for irrigating crops in the Mississippi Delta. The adoption of these practices may be increased if the landowners know the economic returns of implementing them.
The tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), is a major pest of cotton in the midsouthern United States, including the states of Arkansas, Mississippi, Louisiana, western ...Tennessee, and southeastern Missouri. Insecticides provide the primary form of control for this pest, and numerous applications are required annually to control the tarnished plant bug. Little information exists regarding when to terminate insecticide applications targeting tarnished plant bugs in cotton. Numerous sprays are made late in the season to protect a small percentage of the overall yield. Experiments were conducted at the Mississippi State University Delta Research and Extension Center to determine the impact of tarnished plant bug infestation timings on cotton yield. Two separate planting dates were utilized to determine the weeks of flowering that tarnished plant bugs can cause significant yield losses. There was a significant planting date by treatment interaction. Overall, yields were greater in the first planting date than the second planting date. In both planting dates, the first 4 wk of flowering were the most critical for tarnished plant bug control, and this is when the greatest yield losses occurred. Also, when no insecticide applications were made after the fourth week of flowering, no significant yield loss was observed. These data demonstrate the importance of scouting and adhering to treatment thresholds during the early flowering period. These data also suggest that thresholds may be able to be modified or eliminated after the fourth week of flowering, but more research is needed to confirm this.
Polyacrylamides (PAMs), when applied as a soil amendment, purportedly improve soil infiltration, decrease erosion, and reduce offsite agrochemical transport. The effect of PAM on infiltration, ...erosion, agrochemical transport, and crop yield when applied in furrow to mid‐southern US production systems has not been evaluated. The objective of this study was to assess PAM effects on infiltration, erosion, corn (Zea mays L.) grain yield, and nitrogen (N) and phosphorus (P) transport when applied at 10 mg L−1 through lay‐flat polyethylene tubing. A 2‐yr field study was conducted at the Mississippi State Delta Research and Extension Center in Stoneville, MS, on a Dundee silt loam and a Forestdale silty clay loam. The experimental design was a randomized complete block with four replications of each treatment: irrigated plus no PAM (control) and irrigated plus PAM at 10 mg L−1. Each irrigation event delivered 102 mm of water at 18.9 L m−1 per furrow, and runoff was captured in a holding tank on the lower end of each plot. Pooled over year and soil texture, PAM increased infiltration and corn grain yield by 6% (P ≤ 0.0398). Polyacrylamide effects on the offsite transport of sediment and N and P were inconsistent, varying across year and soil texture. Results indicate that PAM improves infiltration and corn grain yield on silt loam and silty clay loam textured soils; however, further research is required before PAM can be recommended as a best management practice for mitigating erosion and offsite agrochemical transport in mid‐southern production systems.
Core Ideas
Polyacrylamide applied in furrow improves soil infiltration.
Polyacrylamide applied in furrow has minimal effect on erosion and nutrient transport.
Polyacrylamide applied in furrow improves corn yield.
Water conservation is an important factor for production of rice in the United States because of declining aquifer levels, but little research has been done to evaluate insect management in rice ...systems integrating water conservation practices. Rice water weevil, Lissorhoptrus oryzophilus Kuschel, is an important insect pest of rice in the U.S. Rice water weevil is a semiaquatic species that relies on flooded conditions to complete larval development, so water conservation practices are likely to impact their pest status. The study was conducted across the Mississippi River alluvial floodplain to compare rice water weevil population densities in different zones of a furrow irrigated rice field to a conventionally flooded rice field. All locations were sampled at 3, 4, and 5 wk after the initial irrigation. Larval densities were greatest in the lower end of furrow irrigated fields and in the adjacent flooded rice field compared with the upper and middle sections that did not hold standing water when averaged across three sample dates. Also, rice water weevil densities were greater during week five than week three. In terms of rice yields, the top third of furrow irrigated rice fields, the section that remained mostly dry, produced lower rough rice yields than all other sections and the flooded field. These results suggest that rice water weevil populations can be lower in a furrow irrigated rice system. As a result, more research is needed to determine whether a spatial management plan can be developed based on soil moisture zones in furrow irrigated rice.
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