Predicting crop yields and soil‐plant nitrogen dynamics in the US Corn Belt

We used the Agricultural Production Systems sIMulator (APSIM) to predict and explain maize and soybean yields, phenology, and soil water and nitrogen (N) dynamics during the growing season in Iowa, USA. Historical, current and forecasted weather data were used to drive simulations, which were released in public four weeks after planting. In this paper, we (1) describe the methodology used to perform forecasts; (2) evaluate model prediction accuracy against data collected from 10 locations over four years; and (3) identify inputs that are key in forecasting yields and soil N dynamics. We found that the predicted median yield at planting was a very good indicator of end‐of‐season yields (relative root mean square error [RRMSE] of ∼20%). For reference, the prediction at maturity, when all the weather was known, had a RRMSE of 14%. The good prediction at planting time was explained by the existence of shallow water tables, which decreased model sensitivity to unknown summer precipitation by 50–64%. Model initial conditions and management information accounted for one‐fourth of the variation in maize yield. End of season model evaluations indicated that the model simulated well crop phenology (R2 = 0.88), root depth (R2 = 0.83), biomass production (R2 = 0.93), grain yield (R2 = 0.90), plant N uptake (R2 = 0.87), soil moisture (R2 = 0.42), soil temperature (R2 = 0.93), soil nitrate (R2 = 0.77), and water table depth (R2 = 0.41). We concluded that model set‐up by the user (e.g. inclusion of water table), initial conditions, and early season measurements are very important for accurate predictions of soil water, N and crop yields in this environment

Genotype by Nitrogen Management Investigations Into Mitigating Stress and Soil Nitrogen Depletion in African Continuous Maize Production

Adoption of maize (Zea mays L.) hybrids with enhanced drought/heat/low N stress tolerance and increasing the application of N fertilizer have both been proposed as potential solutions for Sub-saharan Africa (SSA)’s food insecurity. Neither solution, however, has been able to increase grain yield in SSA at the same rate seen in other parts of the world as drought/heat/low N stress are often not the only yield-limiting factors in SSA. The primary objectives of this study were to determine what stresses are limiting grain yield response to N fertilizer, to evaluate differences among hybrids in terms of their relative stress tolerance and N use efficiency (NUE), and to quantify the impact of N fertilizer on improving grain yield and mitigating other stresses and soil N depletion. From 2010 to 2015, six maize hybrids, three with high anticipated stress tolerance (HAT) and three with low anticipated stress tolerance (LAT) were grown in a continuous maize cropping system at four N rates in Embu, Kenya (drought + nutrient stress), in Harare, Zimbabwe (nutrient stress), and in Kiboko, Kenya (heat + nutrient stress) for a total of 5 to 9 seasons. Nitrogen rates were 0, 30, 60, and 90 kg N ha-1 in Embu and 0, 40, 80, and 160 kg N ha-1 in Harare and Kiboko. Grain yield was measured every season and anthesis-silking interval (ASI) in most seasons. During at least one season in each site, grain and stover samples collected at harvest were analyzed for biomass response to N and essential macro/micro-nutrients. Post-harvest of the final season, soil was sampled to a depth of 90 cm in each plot at 5 depth increments (0-15, 15-30, 30-45, 45-60, 60-90 cm) and analyzed for general soil characteristics (pH, bulk density, OM, etc.), inorganic and total N, and plant essential macro/micro-nutrients. We found that grain yields of all hybrids increased when N fertilizer was applied and the agronomic optimal N rate either exceeded the N rates applied or fell between the highest 2 applied N rates. The NUE in Kiboko (\u3e40 kg grain kg-1N applied), however, was more than two-fold the NUE in Embu and Harare (~20 kg kg-1). There were negative correlations between grain yield and ASI (r=0.46 in Embu, r=0.64 in Kiboko), signifying that there was moderate drought stress in Embu and severe heat stress in Kiboko. The high soil N levels in Embu and application of N fertilizer in Kiboko appeared to have mitigated some drought/heat stress. In spite of there being anticipated differences in stress tolerance among hybrids, in this study, no hybrid consistently ranked higher or lower than other hybrids in terms of grain yield or NUE at any site. Soil K availability was limited by drought in Embu. In both Embu and Kiboko, the ratio of total plant N to total plant K did not decrease with N rate as it did in Harare, suggesting that the impact of higher N rates on K uptake is greater in drought/heat stressed sites than in non-drought/heat stressed sites. Two hybrids in Harare, TH127618 (a HAT hybrid) and S513 (a LAT hybrid) were apparently able to take up enough K to avoid deficiency, but the other Harare hybrids were found to be potentially K deficient at maturity. There was a high risk of Mn toxicity in Embu in all hybrids, but one hybrid (Duma43, a LAT hybrid) took up relatively low amounts of Mn and, thus, may have had some degree of Mn toxicity tolerance. Otherwise, there were no differences among hybrids within any site in terms of their apparent nutrient sufficiency status at maturity. Hybrids in both Embu and Kiboko, however, differed in their stover nutrient accumulation. DK8031, a HAT hybrid in Embu, and H513, a LAT hybrid in Kiboko, had the greatest capacity among hybrids in their respective sites to deplete soil nutrient pools via stover-enhanced nutrient mining. While a 15N sub-study found that only 13-25% of the N applied was recovered by the plants, all hybrids at most N rates took up more N than was applied, resulting in a negative N balance of as low as 103 kg N ha-1 in a season. The N balance calculation is likely to have underestimated actual N depletion as more N may have been lost from the rooting profile via runoff or leaching in all sites. Embu’s acidic, clay rich soils, however, sequestered more N than the other sites, reducing the loss of N via leaching. The N internal efficiencies (NIE) of the hybrids (grain yield produced per unit N taken up) were calculated at each N rate. Hybrids in all sites had low NIE (37 to 47 kg grain kg N-1 in Embu, 33 to 36 kg grain kg N-1 in Harare, and 34 to 52 kg grain kg N-1 in Kiboko) due to limited access to soil N and/or non-N stress induced reductions in N uptake and remobilization. Non-N soil nutrient interactions limited the uptake of P in Embu and of P, Cu, S, and Zn in Harare. While low soil pH and high soil amorphous Fe levels in Embu and Harare limited P availability and uptake, similar interactions between P and Zn in the Kiboko’s alkaline soil did not lead to corresponding deficiencies. The uptake of Cu appeared to suppress the uptake of Zn and vice versa. Similarly, the uptake of S and Cu were inversely linked. The availability of P and Cu were related to the degree to which each was stratified in the soil. Although the addition of N fertilizer did not eliminate nutrient deficiency, it did increase overall uptake of P and S in all sites and Cu and Zn in Harare and Kiboko on a total content basis. Grain P concentrations increased as the N rate increased in Embu and Kiboko, although not enough for hybrids to escape P deficiency in Embu. Grain Zn concentration also increased with higher N rates at Embu. This increased plant uptake of non-N nutrients at higher N rates did not result in measurable depletion of the corresponding soil nutrient pools with the exception of soil available P in Harare and Kiboko. This study found that an in-depth soil analysis can explain why stress tolerant hybrid performance and response to N is low in SSA. Drought stress in Embu and heat stress in Kiboko, coupled with non-N nutrient stress in Embu and Harare and below-replacement N fertilizer rates limited NIE in all sites and NUE in Embu and Harare. While the 15N sub-study found that only a small fraction of the fertilizer applied was recovered by the plant, the plants took up more total N than was applied in all sites at most N rates, resulting in soil N depletion. The idealized fertilizer N balance calculation likely underestimated actual N depletion; the extent to which soil N was depleted was dependent on soil texture and pH. The application of N fertilizer is a potential strategy for agronomic biofortification by increasing the uptake of P, S, Zn, and Cu (content) in maize. In summary, the co-existence of multiple stresses was found to limit the performance of single-stress tolerant hybrids, but the addition of N fertilizer was found to mitigate the impact of non-N stresses on hybrid performance

Exploring options for increasing maize yields and grain Zn concentrations in sub‑Saharan Africa

Background Increasing zinc (Zn) concentrations in maize grains could contribute to alleviating wide-spread human Zn deficiency in sub-Saharan Africa (SSA). However, trade-offs between grain Zn concentrations and maize yields have been observed.Scope Using data from researcher-managed, on-farm and on-station field trials in Kenya, Zambia and Zimbabwe, we aimed (i) to confirm whether this trade-off is found in current farming systems in SSA and (ii) to explore whether genotypic and management options, relevant for the African context, can increase both yields and grain Zn concentrations across several environments.Results An overall negative, but weak relation between maize yields and grain Zn concentrations was found. High yields and high grain Zn concentrations did not co-occur. The negative relation between grain Zn concentrations and yields cannot be bypassed by selecting one of the commercially available varieties used in this study. Nitrogen application increased yields, but had contrasting effects on grain Zn concentrations depending on variety and site. Grain Zn concentrations were positively related with soil organic carbon and P and K availability.Conclusions Attaining grain Zn concentrations above the HarvestPlus target of 38 mg kg−1 , considered adequate for reducing human Zn deficiency, with current commercially available maize varieties and presented management options, is not possible without compromising yield levels. Increasing soil organic matter content and balanced application of N, P and K fertilisers could increase grain Zn concentrations. These practices likely will also increase yields and could be a viable option to bypass the trade-off between maize yields and grain Zn concentrations

Secondhand smoke and Smoke-Free Policy

Smoke-free Policy in Kentucky 2006 is designed for policymakers and community advocates who want to know more about the health effects of secondhand smoke and the effects of smoke-free laws on communities. Secondhand smoke is a toxic air contaminant. Secondhand smoke is the third leading cause of preventable death in the United States. Secondhand smoke affects nearly every organ of the body, causing heart disease, lung and other cancers, breathing disorders such as asthma, and sudden infant death syndrome. Most Kentuckians do not smoke, but at least 74% are regularly exposed to secondhand smoke in public places. Comprehensive smoke-free laws protect smokers and nonsmokers from secondhand smoke. Smoke-free laws significantly reduce air pollution. Workers who experience smoke-free laws have an almost immediate improvement in breathing symptoms. Lexington’s hospitality workers showed a dramatic 56% decline in hair nicotine levels in just three months after the smoke-free law took effect. The majority of workers and the public like smoke- free laws. There is no scientific evidence that smoke-free laws harm business. Currently, only 6.9% of Kentuckians are covered by comprehensive smoke- free laws. An additional 19.1% are covered by partial smoke-free laws. In these communities, some workers are protected from secondhand smoke, and the public is protected some of the time. Some schools and some workplaces have voluntarily adopted policies to reduce exposure to secondhand smoke. Less than half (46.6%) of Kentucky public and private middle and high schools prohibit smoking everywhere on their campuses. Similarly, 49% of Kentucky manufacturing facilities voluntarily prohibit indoor smoking. Healthy People 2010 is a nationwide health promotion initiative grounded in science and designed to promote health and prevent illness, disability, and premature death. Is Kentucky making progress toward the Healthy People 2010 Objectives for eliminating exposure to secondhand smoke? There is some progress toward increasing the percentage of smoke-free environments at schools and workplaces; and in reducing the proportion of nonsmokers exposed to secondhand smoke by implementing comprehensive smoke-free policies in public places

Predicting crop yields and soil‐plant nitrogen dynamics in the US Corn Belt

We used the Agricultural Production Systems sIMulator (APSIM) to predict and explain maize and soybean yields, phenology, and soil water and nitrogen (N) dynamics during the growing season in Iowa, USA. Historical, current and forecasted weather data were used to drive simulations, which were released in public four weeks after planting. In this paper, we (1) describe the methodology used to perform forecasts; (2) evaluate model prediction accuracy against data collected from 10 locations over four years; and (3) identify inputs that are key in forecasting yields and soil N dynamics. We found that the predicted median yield at planting was a very good indicator of end‐of‐season yields (relative root mean square error [RRMSE] of ∼20%). For reference, the prediction at maturity, when all the weather was known, had a RRMSE of 14%. The good prediction at planting time was explained by the existence of shallow water tables, which decreased model sensitivity to unknown summer precipitation by 50–64%. Model initial conditions and management information accounted for one‐fourth of the variation in maize yield. End of season model evaluations indicated that the model simulated well crop phenology (R2 = 0.88), root depth (R2 = 0.83), biomass production (R2 = 0.93), grain yield (R2 = 0.90), plant N uptake (R2 = 0.87), soil moisture (R2 = 0.42), soil temperature (R2 = 0.93), soil nitrate (R2 = 0.77), and water table depth (R2 = 0.41). We concluded that model set‐up by the user (e.g. inclusion of water table), initial conditions, and early season measurements are very important for accurate predictions of soil water, N and crop yields in this environment.This article is published as Archontoulis, Sotirios V., Michael J. Castellano, Mark A. Licht, Virginia Nichols, Mitch Baum, Isaiah Huber, Rafael Martinez‐Feria et al. "Predicting crop yields and soil‐plant nitrogen dynamics in the US Corn Belt." Crop Science (2020). doi: 10.1002/csc2.20039.</p

Functional near-infrared spectroscopy for neuroimaging in cochlear implant recipients

Functional neuroimaging can provide insight into the neurobiological factors that contribute to the variations in individual hearing outcomes following cochlear implantation. To date, measuring neural activity within the auditory cortex of cochlear implant (CI) recipients has been challenging, primarily because the use of traditional neuroimaging techniques is limited in people with CIs. Functional near-infrared spectroscopy (fNIRS) is an emerging technology that offers benefits in this population because it is non-invasive, compatible with CI devices, and not subject to electrical artifacts. However, there are important considerations to be made when using fNIRS to maximize the signal to noise ratio and to best identify meaningful cortical responses. This review considers these issues, the current data, and future directions for using fNIRS as a clinical application in individuals with CIs

Open Letter to The American Association for the Advancement of Science

This is an open letter concerning the recent launch of the new open access journal, Science Advances. In addition to the welcome diversification in journal choices for authors looking for open access venues, there are many positive aspects of Science Advances: its broad STEM scope, its interest in cross-disciplinary research, and the offering of fee waivers. While we welcome the commitment of the Association to open access, we are also deeply concerned with the specific approach. Herein, we outline a number of suggestions that are in line with both the current direction that scholarly publishing is taking and the needs expressed by the open access community, which this journal aims to serve